The scope of this Protection Profile (PP) is to
describe the security functionality of operating systems in terms of [CC]
and to define functional and assurance requirements for such products.
An operating system is software that manages computer hardware and software
resources, and provides common services for application programs. The hardware
it manages may be physical or virtual.
1.2 Terms
The following sections list Common Criteria and technology terms used in this document.
1.2.1 Common Criteria Terms
Assurance
Grounds for confidence that a TOE meets the SFRs [CC].
Base Protection Profile (Base-PP)
Protection Profile used as a basis to build a PP-Configuration.
Collaborative Protection Profile (cPP)
A Protection Profile developed by
international technical communities and approved by multiple schemes.
Common Criteria (CC)
Common Criteria for Information Technology Security Evaluation (International Standard ISO/IEC 15408).
Common Criteria Testing Laboratory
Within the context of the Common Criteria Evaluation and Validation Scheme (CCEVS), an IT security evaluation facility
accredited by the National Voluntary Laboratory Accreditation Program (NVLAP) and approved by the NIAP Validation Body to conduct Common Criteria-based evaluations.
Common Evaluation Methodology (CEM)
Common Evaluation Methodology for Information Technology Security Evaluation.
Distributed TOE
A TOE composed of multiple components operating as a logical whole.
Extended Package (EP)
A deprecated document form for collecting SFRs that implement a particular protocol, technology,
or functionality. See Functional Packages.
Functional Package (FP)
A document that collects SFRs for a particular protocol, technology,
or functionality.
Operational Environment (OE)
Hardware and software that are outside the TOE boundary that support the TOE functionality and security policy.
Protection Profile (PP)
An implementation-independent set of security requirements for a category of products.
A comprehensive set of security requirements for a product type that consists of at least one Base-PP and at least one PP-Module.
Protection Profile Module (PP-Module)
An implementation-independent statement of security needs for a TOE type complementary to one or more Base-PPs.
Security Assurance Requirement (SAR)
A requirement to assure the security of the TOE.
Security Functional Requirement (SFR)
A requirement for security enforcement by the TOE.
Security Target (ST)
A set of implementation-dependent security requirements for a specific product.
Target of Evaluation (TOE)
The product under evaluation.
TOE Security Functionality (TSF)
The security functionality of the product under evaluation.
TOE Summary Specification (TSS)
A description of how a TOE satisfies the SFRs in an ST.
1.2.2 Technical Terms
Address Space Layout Randomization (ASLR)
An anti-exploitation feature which loads memory mappings into unpredictable
locations. ASLR makes it more difficult for an attacker to redirect control to code
that they have introduced into the address space of a process.
Administrator
An administrator is responsible for management activities, including setting policies that are
applied by the enterprise on the operating system.
This administrator could be acting remotely through a management server, from which the system
receives configuration policies.
An administrator can enforce settings on the system which cannot be overridden by non-administrator users.
Application (app)
Software that runs on a platform and performs tasks on behalf of the user
or owner of the platform, as well as its supporting documentation.
Application Programming Interface (API)
A specification of routines, data structures, object classes, and variables
that allows an application to make use of services provided by another software
component, such as a library. APIs are often provided for a set of libraries included
with the platform.
Credential
Data that establishes the identity of a user, e.g. a cryptographic key or
password.
Critical Security Parameters (CSP)
Information that is either user or system defined and
is used to operate a cryptographic module in processing encryption functions including
cryptographic keys and authentication data, such as passwords, the disclosure or modification
of which can compromise the security of a cryptographic module or the security of the
information protected by the module.
DAR Protection
Countermeasures that prevent attackers, even those with physical access,
from extracting data from non-volatile storage.
Common techniques include data encryption and wiping.
Data Execution Prevention (DEP)
An anti-exploitation feature of modern operating systems executing on
modern computer hardware, which enforces a non-execute permission on pages of memory.
DEP prevents pages of memory from containing both data and instructions, which makes
it more difficult for an attacker to introduce and execute code.
Developer
An entity that writes OS software. For the purposes of this document,
vendors and developers are the same.
General Purpose Operating System
A class of OSes designed to support a wide-variety of workloads consisting of many concurrent applications or services.
Typical characteristics for OSes in this class include support for third-party applications,
support for multiple users, and security separation between users and their respective resources.
General Purpose Operating Systems also lack the real-time constraint that defines Real Time Operating Systems
which are typically used in routers, switches, and embedded devices.
Host-based Firewall
A software-based firewall implementation running on the OS for filtering inbound and
outbound network traffic to and from processes running on the OS.
Hybrid Authentication
A hybrid authentication factor is one where a user has to
submit a combination of a cryptographic token and a PIN or password and both must pass.
If either factor fails, the entire attempt fails.
Operating System (OS)
Software that manages physical and logical resources and provides services
for applications. The terms TOE and OS are interchangeable in this
document.
Personal Identification Number (PIN)
An authentication factor that is comprised of a set of numeric or alphabetic characters
that may be used in addition to a cryptographic token to provide a hybrid authentication factor.
At this time it is not considered as a stand-alone authentication mechanism.
A PIN is distinct from a password in that the allowed character set and required length of a PIN
is typically smaller than that of a password as it is designed to be input quickly.
Personally Identifiable Information (PII)
Any information about an individual maintained by an agency, including, but
not limited to, education, financial transactions, medical history, and criminal or
employment history and information which can be used to distinguish or trace an
individual's identity, such as their name, social security number, date and place of
birth, mother's maiden name, biometric records, etc., including any other personal
information which is linked or linkable to an individual.[OMB]
Sensitive Data
Sensitive data may include all user or enterprise data or may be specific
application data such as PII, emails, messaging, documents, calendar items, and contacts.
Sensitive data must minimally include credentials and keys. Sensitive data shall
be identified in the OS's TSS by the ST author.
User
A user is subject to configuration policies applied
to the operating system by administrators. On some systems under certain
configurations, a normal user can temporarily elevate privileges to that of an administrator.
At that time, such a user should be considered an administrator.
1.3 Compliant Targets of Evaluation
1.3.1 TOE Boundary
The TOE boundary encompasses the OS kernel and its drivers, shared
software libraries, and some application software included with the OS. The applications considered within the TOE
are those that provide essential security services, many of which run with elevated
privileges. Applications which are covered by more-specific Protection Profiles cannot
claim evaluation as part of the OS evaluation, even when it is necessary to evaluate
some of their functionality as it relates to their role as part of the OS.
The TOE platform, which consists of the physical or virtual hardware on which the TOE executes,
is outside the scope of evaluation. At the same time, the security of the TOE relies upon it.
Other hardware components which independently run their own software and are
relevant to overall system security are also outside the scope of evaluation.
1.4 Use Cases
Requirements in this Protection Profile are designed to
address the security problems in at least the following use cases. These use cases are intentionally
very broad, as many specific use cases exist for an operating system. These use cases may also
overlap with one another. An operating system's functionality may even be effectively extended by
privileged applications installed onto it. However, these are out of scope of this PP.
[USE CASE 1] End User Devices
The OS provides a platform for end user devices such as desktops,
laptops, convertibles, and tablets.
These devices may optionally be bound to a directory server or management server.
As this Protection Profile does not address threats against data-at-rest,
enterprises deploying operating systems in mobile scenarios should ensure that these systems
include data-at-rest protection spelled out in other
Protection Profiles. Specifically, this includes the Protection Profiles for
Full Drive Encryption - Encryption Engine,
Full Drive Encryption - Authorization Acquisition,
and Software File Encryption. The Protection Profile for Mobile
Device Fundamentals includes requirements for data-at-rest protection and is appropriate
for many mobile devices.
[USE CASE 2] Server Systems
The OS provides a platform for server-side services, either on
physical or virtual hardware. Many specific examples exist in which the OS acts
as a platform for such services, including file servers, mail servers, and web servers.
[USE CASE 3] Cloud Systems
The OS provides a platform for providing cloud services running on
physical or virtual hardware. An OS is typically part of offerings
identified as Infrastructure as a Service (IaaS), Software as a Service (SaaS),
and Platform as a Service (PaaS).
This use case typically involves the use
of virtualization technology which should be evaluated against the
Protection Profile for Server Virtualization.
2 Conformance Claims
Conformance Statement
An ST must claim exact conformance to this PP,
as defined in the CC and CEM addenda for Exact Conformance, Selection-based SFRs, and
Optional SFRs (dated May 2017).
The following PP-Modules are allowed to be specified in a PP-Configuration with this PP.
The security problem is described in terms
of the threats that the OS is expected to address, assumptions about the
operational environment, and any organizational security policies that the OS
is expected to enforce.
3.1 Threats
T.NETWORK_ATTACK
An attacker is positioned on a communications channel or elsewhere on the
network infrastructure. Attackers may engage in communications with applications and
services running on or part of the OS with the intent of compromise. Engagement may
consist of altering existing legitimate communications.
T.NETWORK_EAVESDROP
An attacker is positioned on a communications channel or elsewhere on the
network infrastructure. Attackers may monitor and gain access to data exchanged between
applications and services that are running on or part of the OS.
T.LOCAL_ATTACK
An attacker may compromise applications running on the OS. The
compromised application may provide maliciously formatted input to the OS through a
variety of channels including unprivileged system calls and messaging via the
file system.
T.LIMITED_PHYSICAL_ACCESS
An attacker may attempt to access data on the OS while having a limited
amount of time with the physical device.
3.2 Assumptions
A.PLATFORM
The OS relies upon a trustworthy computing platform for
its execution. This underlying platform is out of scope of this PP.
A.PROPER_USER
The user of the OS is not willfully negligent or hostile, and uses the
software in compliance with the applied enterprise security policy. At the same time,
malicious software could act as the user, so requirements which
confine malicious subjects are still in scope.
A.PROPER_ADMIN
The administrator of the OS is not careless, willfully negligent or hostile,
and administers the OS within compliance of the applied enterprise security policy.
4 Security Objectives
4.1 Security Objectives for the TOE
O.ACCOUNTABILITY
Conformant OSes ensure that information exists that allows
administrators to discover unintentional issues with the configuration and operation of
the operating system and discover its cause. Gathering event information and immediately
transmitting it to another system can also enable incident response in the event
of system compromise.
O.INTEGRITY
Conformant OSes ensure the integrity of their update
packages. OSes are seldom if ever shipped without errors, and the
ability to deploy patches and updates with integrity is critical to enterprise network
security. Conformant OSes provide execution environment-based
mitigations that increase the cost to attackers by adding complexity to the task of
compromising systems.
O.MANAGEMENT
To facilitate management by users and the enterprise, conformant OSes
provide consistent and supported interfaces for their
security-relevant configuration and maintenance. This includes the deployment of
applications and application updates through the use of platform-supported deployment
mechanisms and formats, as well as providing mechanisms for configuration and
application execution control.
O.PROTECTED_STORAGE
To address the issue of loss of confidentiality of credentials in the event of
loss of physical control of the storage medium, conformant OSes
provide data-at-rest protection for credentials.
Conformant OSes also provide access controls which allow users to keep their files private from other
users of the same system.
O.PROTECTED_COMMS
To address both passive (eavesdropping) and active (packet modification)
network attack threats, conformant OSes provide mechanisms to create
trusted channels for CSP and sensitive data. Both CSP and sensitive data
should not be exposed outside of the platform.
4.2 Security Objectives for the Operational Environment
The following security objectives for the operational
environment assist the OS in correctly providing its security functionality.
These track with the assumptions about the environment.
OE.PLATFORM
The OS relies on being installed on trusted
hardware.
OE.PROPER_USER
The user of the OS is not willfully negligent or hostile,
and uses the software within compliance of the applied enterprise security policy.
Standard user accounts are provisioned in accordance with the least privilege model.
Users requiring higher levels of access should have a separate account dedicated for
that use.
OE.PROPER_ADMIN
The administrator of the OS is not careless, willfully
negligent or hostile, and administers the OS within compliance of the applied enterprise
security policy.
4.3 Security Objectives Rationale
This section describes how the assumptions, threats, and organizational
security policies map to the security objectives.
The threat T.NETWORK_ATTACK is countered by O.ACCOUNTABILITY as this
provides a mechanism for the OS to report behavior that may indicate a network
attack has occurred.
The threat T.NETWORK_EAVESDROP is countered by O.MANAGEMENT as this provides
for the ability to configure the OS to protect the confidentiality of its transmitted
data.
The objective O.ACCOUNTABILITY protects against local attacks by providing
a mechanism to report behavior that may indicate a local attack is occurring or
has occurred.
This chapter describes the security requirements which have to be fulfilled by the product under evaluation.
Those requirements comprise functional components from Part 2 and assurance components from Part 3 of
[CC].
The following conventions are used for the completion of operations:
Refinement operation (denoted by bold text or strikethrough
text): Is used to add details to a requirement (including replacing an assignment
with a more restrictive selection) or to remove part of the requirement that is made irrelevant
through the completion of another operation, and thus further restricts a requirement.
Selection (denoted by italicized text): Is used to select one or more options
provided by the [CC] in stating a requirement.
Assignment operation (denoted by italicized text): Is used to assign a
specific value to an unspecified parameter, such as the length of a password. Showing the
value in square brackets indicates assignment.
Iteration operation: Is indicated by appending the SFR name with a slash and unique identifier
suggesting the purpose of the operation, e.g. "/EXAMPLE1."
The OS shall generate asymmetric cryptographic keys in accordance with a
specified cryptographic key generation algorithm [selection:
RSA schemes using cryptographic key sizes of 3072-bit or greater that
meet the following: FIPS PUB 186-4, "Digital Signature Standard (DSS)", Appendix B.3
ECC schemes using "NIST curves" P-384 and
[selection: P-521, no other curves ] that meet the following: FIPS PUB 186-4, "Digital Signature Standard (DSS)",
Appendix B.4
FFC schemes using
[selection: cryptographic key sizes of 3072-bit
or greater that meet the following: FIPS PUB 186-4, "Digital Signature
Standard (DSS)", Appendix B.1, safe primes that meet the following:
NIST Special Publication 800-56A Revision 3, “Recommendation for Pair-Wise Key Establishment Schemes"
]
].
Application
Note:
The ST author will select all key generation schemes used for key establishment and entity authentication.
When key generation is used for key establishment, the schemes in
FCS_CKM.2 and selected cryptographic protocols must match the selection.
When key generation is used for entity authentication, the public key is
expected to be associated with an X.509v3 certificate.
If the OS acts only as a receiver in the RSA key establishment scheme,
the OS does not need to implement RSA key generation.
The evaluator will ensure that the TSS identifies the key
sizes supported by the OS. If the ST specifies
more than one scheme, the evaluator will examine the TSS to verify
that it identifies the usage for each scheme.
The evaluator will verify that
the AGD guidance instructs the administrator how to configure the OS
to use the selected key generation scheme(s) and key size(s) for all uses defined
in this PP.
Evaluation Activity Note: The following tests may require the
vendor to furnish a developer environment and developer
tools that are typically not available to end-users of the OS.
The evaluator will verify
the implementation of RSA Key Generation by the OS using the Key
Generation test. This test verifies the ability of the TSF to
correctly produce values for the key components including the public verification
exponent e, the private prime factors p and q, the public modulus n and the
calculation of the private signature exponent d. Key Pair generation specifies 5 ways
(or methods) to generate the primes p and q. These include:
Random Primes:
Provable primes
Probable primes
Primes with Conditions:
Primes p1, p2, q1,q2, p and q shall all be provable primes
Primes p1, p2, q1, and q2 shall be provable primes and p and q shall be
probable primes
Primes p1, p2, q1,q2, p and q shall all be probable primes
To test the key generation method for the Random Provable primes method and for
all the Primes with Conditions methods, the evaluator must seed the TSF
key generation routine with sufficient data to deterministically
generate the RSA key pair. This includes the random seed(s), the public exponent of
the RSA key, and the desired key length. For each key length supported, the evaluator
shall have the TSF generate 25 key pairs. The evaluator will verify
the correctness of the TSF's implementation by comparing values
generated by the TSF with those generated from a known good
implementation.
If possible, the Random Probable primes method should also be
verified against a known good implementation as described above. Otherwise, the
evaluator will have the TSF generate 10 keys pairs for each
supported key length nlen and verify:
n = p⋅q,
p and q are probably prime according to Miller-Rabin tests,
For each supported NIST curve, i.e., P-384 and P-521, the
evaluator will require the implementation under test (IUT) to generate 10
private/public key pairs. The private key shall be generated using an approved random
bit generator (RBG). To determine correctness, the evaluator will submit the
generated key pairs to the public key verification (PKV) function of a known good
implementation.
For each supported
NIST curve, i.e., P-384 and P-521, the evaluator will generate 10
private/public key pairs using the key generation function of a known good
implementation and modify five of the public key values so that they are incorrect,
leaving five values unchanged (i.e., correct). The evaluator will obtain in response
a set of 10 PASS/FAIL values.
Key Generation for Finite-Field Cryptography (FFC)
The evaluator will verify the implementation of the Parameters Generation
and the Key Generation for FFC by the TOE using the Parameter Generation
and Key Generation test.
This test verifies the ability of the TSF to correctly
produce values for the field prime p, the cryptographic prime q (dividing p-1),
the cryptographic group generator g, and the calculation of the private
key x and public key y.
The Parameter generation specifies 2 ways (or methods) to generate the
cryptographic prime q and the field prime p:
Cryptographic and Field Primes:
Primes q and p shall both be provable primes
Primes q and field prime p shall both be probable primes
and two ways to generate the cryptographic group generator g:
Cryptographic Group Generator:
Generator g constructed through a verifiable process
Generator g constructed through an unverifiable process
The Key generation specifies 2 ways to generate the private key x:
len(q) + 64 bit output of RBG, followed by a mod q-1 operation where 1 ≤ x ≤ q-1
The security strength of the RBG must be at least that of the security offered by the FFC parameter set.
To test the cryptographic and field prime generation method for the provable primes method and/or the
group generator g for a verifiable process, the evaluator must seed the TSF parameter
generation routine with sufficient data to deterministically generate the parameter set.
For each key length supported, the evaluator will have the TSF generate 25 parameter sets
and key pairs. The evaluator will verify the correctness of the TSF's implementation
by comparing values generated by the TSF with those generated from a known good
implementation. Verification must also confirm:
The OS shall implement functionality to perform cryptographic key establishment
in accordance with a specified cryptographic key establishment method:
[selection:
RSA-based key establishment schemes that meets the following:
RSAES-PKCS1-v1_5 as specified in Section 7.2 of RFC 8017, “Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.2"
Elliptic curve-based key establishment schemes that meets the following: NIST Special Publication 800-56A Revision 3, “Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography”
Finite field-based key establishment schemes
that meets NIST Special Publication 800-56A Revision 3, “Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography”
].
Application
Note:
The ST author will select all key establishment schemes used
for the selected cryptographic protocols.
The elliptic curves used for the key establishment scheme shall correlate with the curves specified in FCS_CKM.1.1.
The domain parameters used for the finite field-based key establishment scheme are specified by the key generation according to FCS_CKM.1.1.
The finite field-based key establishment schemes that conform to NIST SP 800-56A Revision 3 correspond to the "safe-prime" groups selection in FCS_CKM.1.1.
The evaluator will ensure that the supported key establishment schemes
correspond to the key generation schemes identified in FCS_CKM.1.1
If the ST specifies more than one scheme,
the evaluator will examine the TSS to verify that it identifies the usage for each scheme.
The evaluator will verify that the AGD
guidance instructs the administrator how to configure the OS to use the selected key
establishment scheme(s).
Evaluation Activity Note: The following tests require
the developer to provide access to a test platform that provides the evaluator with
tools that are typically not found on factory products.
Key Establishment Schemes
The evaluator will verify the implementation of
the key establishment schemes supported by the OS using the applicable tests below.
The evaluator will verify the OS's
implementation of SP800-56A key agreement schemes using the following Function and
Validity tests. These validation tests for each key agreement scheme verify that the OS
has implemented the components of the key agreement scheme according to the
specifications in the Recommendation. These components include the calculation of the
discrete logarithm cryptography (DLC) primitives (the shared secret value Z) and the
calculation of the derived keying material (DKM) via the Key Derivation Function
(KDF). If key confirmation is supported, the evaluator will also verify that the
components of key confirmation have been implemented correctly, using the test
procedures described below. This includes the parsing of the DKM, the generation of
MAC data and the calculation of MAC tag.
Function Test
The Function test verifies the ability of the OS to implement the key agreement schemes correctly.
To conduct this test the evaluator will generate or obtain test vectors from a known good implementation of the OS's supported schemes.
For each supported key agreement scheme-key agreement role combination, KDF type, and, if supported, key confirmation role- key confirmation type combination,
the tester will generate 10 sets of test vectors.
The data set consists of one set of domain parameter values (FCC) or the NIST approved curve (ECC) per 10 sets of public keys.
These keys are static, ephemeral or both depending on the scheme being tested.
The evaluator will obtain the DKM, the
corresponding OS's public keys (static and/or ephemeral), the MAC tag(s), and any
inputs used in the KDF, such as the Other Information field OI and OS id fields.
If the OS does not use a KDF defined in SP 800-56A, the evaluator will
obtain only the public keys and the hashed value of the shared secret.
The evaluator will verify the correctness of the TSF's implementation of a given scheme
by using a known good implementation to calculate the shared secret value, derive
the keying material DKM, and compare hashes or MAC tags generated from these values.
If key confirmation is supported, the OS will perform the above for each
implemented approved MAC algorithm.
Validity Test
The Validity test verifies the ability of the OS to
recognize another party's valid and invalid key agreement results with or without
key confirmation. To conduct this test, the evaluator will obtain a list of the
supporting cryptographic functions included in the SP800-56A Revision 3 key agreement
implementation to determine which errors the OS should be able to recognize.
The
evaluator generates a set of 24 FCC or 30 ECC test vectors consisting of data
sets including domain parameter values or NIST approved curves, the evaluator's
public keys, the OS's public/private key pairs, MAC tag, and any inputs used in the
KDF, such as the other info and OS id fields.
The evaluator will inject an
error in some of the test vectors to test that the OS recognizes invalid key
agreement results caused by the following fields being incorrect: the shared secret
value Z, the DKM, the other information field OI, the data to be MACed, or the
generated MAC tag. If the OS contains the full or partial (only ECC) public key
validation, the evaluator will also individually inject errors in both parties'
static public keys, both parties' ephemeral public keys and the OS's static private
key to assure the OS detects errors in the public key validation function and/or
the partial key validation function (in ECC only).
At least two of the test vectors will remain unmodified and therefore
should result in valid key agreement results
(they should pass).
The OS will use these modified test vectors to emulate
the key agreement scheme using the corresponding parameters. The evaluator will
compare the OS's results with the results using a known good implementation
verifying that the OS detects these errors.
The evaluator will verify the correctness of the TSF's implementation of RSAES-PKCS1-v1_5 by using a known good implementation for each protocol selected in FTP_ITC_EXT.1 that uses RSAES-PKCS1-v1_5.
FFC Schemes using "safe-prime" groups (identified in Appendix D of SP 800-56A Revision 3)
The evaluator will verify the correctness of the TSF's implementation of "safe-prime" groups by using a known good implementation for each protocol selected in FTP_ITC_EXT.1 that uses "safe-prime" groups. This test must be performed for each "safe-prime" group that each protocol uses.
The OS shall destroy cryptographic keys and key material in accordance with a specified cryptographic key destruction method
[selection:
For volatile memory, the destruction shall be executed by a
[selection:
single overwrite consisting of [selection: a pseudo-random pattern using the TSF's RBG, zeroes, ones, a new value of a key, [assignment:
any value that does not contain any CSP] ]
removal of power to the memory
destruction of reference to the key directly followed by a request for garbage collection
]
For non-volatile memory that consists of
[selection:
destruction
of all key encrypting keys (KEKs) protecting the target key
according to FCS_CKM_EXT.4.1, where none of the KEKs protecting the target key are derived
the invocation of an interface provided by the underlying platform that
[selection:
logically addresses the storage location of the key and performs a
[selection: single, [assignment:
ST author defined multi-pass] ]overwrite consisting of
[selection: zeroes, ones, pseudo-random pattern, a new value of a key of the same size, [assignment:
any value that does not contain any CSP] ]
instructs the underlying platform to destroy the abstraction that represents the key
]
]
]
.
Application
Note:
The interface referenced in the requirement could take different forms,
the most likely of which is an application programming interface to an OS kernel.
There may be various levels of abstraction visible.
For instance, in a given implementation that overwrites a key stored in non-volatile memory,
the application may have access to the file system details and
may be able to logically address specific memory locations.
In another implementation, that instructs the underlying platform to destroy the
representation of a key stored in non-volatile memory,
the application may simply have a handle to a resource and
can only ask the platform to delete the resource, as may be the case with a platforms secure key store.
The latter implementation should only be used for the most restricted access.
The level of detail to which the TOE has access will be reflected in the TSS section of the ST.
Several selections allow assignment of a 'value that does not contain any CSP.'
This means that the TOE uses some other specified data not drawn from a source that
may contain key material or reveal information about key material,
and not being any of the particular values listed as other selection options.
The point of the phrase 'does not contain any CSP' is to ensure that the overwritten
data is carefully selected, and not taken from a general 'pool' that might contain current or
residual data that itself requires confidentiality protection.
For the selection destruction
of all key encrypting keys (KEKs) protecting the target key
according to FCS_CKM_EXT.4.1,
a key can be considered destroyed by destroying the key that protects the key.
If a key is wrapped or encrypted it is not necessary to "overwrite" that key,
overwriting the key that is used to wrap or encrypt the key used to encrypt/decrypt data,
using the appropriate method for the memory type involved, will suffice.
For example, if a product uses a KEK to encrypt a Data Encryption Key
(DEK), destroying the KEK using one of the methods in FCS_CKM_EXT.4 is sufficient,
since the DEK would no longer be usable (of course, presumes the DEK is still encrypted
and the KEK cannot be recovered or re-derived.).
The OS shall destroy all keys and key material when no longer needed.
Application
Note:
For the purposes of this requirement, key material refers to authentication data, passwords, secret/private symmetric keys, private asymmetric keys, data used to derive keys, values derived from passwords, etc.
Key destruction procedures are performed in accordance with FCS_CKM_EXT.4.1.
The evaluator examines the TSS to ensure it describes how the keys are managed in volatile memory. This description includes details of how each identified key is introduced into volatile memory (e.g. by derivation from user input, or by unwrapping a wrapped key stored in non-volatile memory) and how they are overwritten.
The evaluator will check to ensure the TSS lists each type of key that is stored in in non-volatile memory, and identifies how the TOE interacts with the underlying platform to manage keys (e.g., store, retrieve, destroy). The description includes details on the method of how the TOE interacts with the platform, including an identification and description of the interfaces it uses to manage keys (e.g., file system APIs, platform key store APIs).
If the ST makes use of the open assignment and fills in the type of pattern that is used, the evaluator examines the TSS to ensure it describes how that pattern is obtained and used. The evaluator will verify that the pattern does not contain any CSPs.
The evaluator will check that the TSS identifies any configurations or circumstances that may not strictly conform to the key destruction requirement.
If the selection FCS_CKM_EXT.4.1 is included
the evaluator will examine the TOE’s keychain in the TSS and identify each instance when a
key is destroyed by this method.
In each instance the evaluator will verify all keys capable of decrypting the target key are
destroyed in accordance with a specified key destruction method in FCS_CKM_EXT.4.1.
The evaluator will verify that all of the keys capable of decrypting the target key are not
able to be derived to reestablish the keychain after their destruction.
Guidance
Operational Guidance
There are a variety of concerns that may prevent or delay key destruction in some cases. The evaluator will check that the guidance documentation identifies configurations or circumstances that may not strictly conform to the key destruction requirement, and that this description is consistent with the relevant parts of the TSS and any other relevant Required Supplementary Information. The evaluator will check that the guidance documentation provides guidance on situations where key destruction may be delayed at the physical layer and how such situations can be avoided or mitigated if possible.
Some examples of what is expected to be in the documentation are provided here.
When the TOE does not have full access to the physical memory, it is possible that the storage may be implementing wear-leveling and garbage collection. This may create additional copies of the key that are logically inaccessible but persist physically. In this case, to mitigate this the drive should support the TRIM command and implements garbage collection to destroy these persistent copies when not actively engaged in other tasks.
Drive vendors implement garbage collection in a variety of different ways, as such there is a variable amount of time until data is truly removed from these solutions. There is a risk that data may persist for a longer amount of time if it is contained in a block with other data not ready for erasure. To reduce this risk, the operating system and file system of the OE should support TRIM, instructing the non-volatile memory to erase copies via garbage collection upon their deletion. If a RAID array is being used, only set-ups that support TRIM are utilized. If the drive is connected via PCI-Express, the operating system supports TRIM over that channel.
The drive should be healthy and contains minimal corrupted data and should be end-of-lifed before a significant amount of damage to drive health occurs, this minimizes the risk that small amounts of potentially recoverable data may remain in damaged areas of the drive.
Tests
Test 1:
Applied to each key held as in volatile memory and subject to destruction by overwrite by the TOE (whether or not the value is subsequently encrypted for storage in volatile or non-volatile memory). In the case where the only selection made for the destruction method key was removal of power, then this test is unnecessary. The evaluator will:
Record the value of the key in the TOE subject to clearing.
Cause the TOE to perform a normal cryptographic processing with the key from Step #1.
Cause the TOE to dump the entire memory of the TOE into a binary file.
Search the content of the binary file created in Step #5 for instances of the known key value from Step #1.
Steps 1-6 ensure that the complete key does not exist anywhere in volatile memory. If a copy is found, then the test fails.
Test 2:
Applied to each key help in non-volatile memory and subject to destruction by the TOE. The evaluator will use special tools (as needed), provided by the TOE developer if necessary, to ensure the tests function as intended.
Identify the purpose of the key and what access should fail when it is deleted. (e.g. the data encryption key being deleted would cause data decryption to fail.)
Have the TOE attempt the functionality that the cleared key would be necessary for.
The test succeeds if step 3 fails.
Test 3:
Tests 3 and 4 do not apply for the selection
instructing the underlying platform to destroy the representation of the key
as the TOE has no visibility into the inner workings and completely relies on the underlying platform.
The following tests are used to determine if the TOE is able to request the platform to overwrite the key with a TOE supplied pattern.
Applied to each key held in non-volatile memory and subject to destruction by overwrite by the TOE. The evaluator will use a tool that provides a logical view of the media (e.g., MBR file system):
Record the value of the key in the TOE subject to clearing.
Cause the TOE to perform a normal cryptographic processing with the key from Step #1.
Search the logical view that the key was stored in for instances of the known key value from Step #1. If a copy is found, then the test fails.
Test 4:
Applied to each key held as non-volatile memory and subject to destruction by overwrite by the TOE. The evaluator will use a tool that provides a logical view of the media:
Record the logical storage location of the key in the TOE subject to clearing.
Cause the TOE to perform a normal cryptographic processing with the key from Step #1.
For the second selection, the ST author should choose the mode
or modes in which AES operates. For the third selection, the ST author should choose
the key sizes that are supported by this functionality.
The evaluator will verify that the AGD documents contains instructions required
to configure the OS to use the required modes and key sizes.
Tests
The evaluator will execute all instructions as specified to configure the OS
to the appropriate state.
The evaluator will perform all of the following tests for each
algorithm implemented by the OS and used to satisfy the requirements of this PP:
Three data unit (i.e., plaintext) lengths. One of the data unit lengths will be a nonzero
integer multiple of 256 bits, if supported. One of the data unit lengths will be an
integer multiple of 256 bits, if supported. The third data unit length will be either the
longest supported data unit length or 216 bits, whichever is smaller.
using a set of 100 (key, plaintext and 256-bit random tweak value) 3-tuples and obtain the
ciphertext that results from XTS-AES encrypt.
The evaluator may supply a data unit sequence number instead of the tweak value if the
implementation supports it. The data unit sequence number is a base-10 number ranging
between 0 and 255 that implementations convert to a tweak value internally.
The evaluator will test the decrypt functionality of XTS-AES using the same test as for
encrypt, replacing plaintext values with ciphertext values and XTS-AES encrypt with XTSAES
decrypt.
There are four Known Answer Tests (KATs), described below. In all KATs, the
plaintext, ciphertext, and IV values will be 256-bit blocks. The results from each
test may either be obtained by the evaluator directly or by supplying the inputs to
the implementer and receiving the results in response. To determine correctness, the
evaluator will compare the resulting values to those obtained by submitting the same
inputs to a known good implementation.
Test 5:
To test the encrypt functionality of AES-CBC, the evaluator will supply
a set of 5 plaintext values and obtain the ciphertext value that results from
AES-CBC encryption of the given plaintext using a key value of all zeros and an IV
of all zeros.
The plaintext values will encrypted with a 256-bit all-zeros key. To test
the decrypt functionality of AES-CBC, the evaluator will perform the same test as
for encrypt, using 5 ciphertext values as input and AES-CBC decryption.
Test 6:
To test the encrypt functionality of AES-CBC, the evaluator will supply
a set of five 256-keys and obtain the ciphertext value that results from AES-CBC
encryption of an all-zeros plaintext using the given key value and an IV of all
zeros.
To test the decrypt functionality of AES-CBC, the evaluator will perform
the same test as for encrypt, using an all-zero ciphertext value as input and
AES-CBC decryption.
Test 7:
To test the encrypt functionality of AES-CBC, the evaluator will supply
the a sets of key values described below and obtain the ciphertext value that
results from AES encryption of an all-zeros plaintext using the given key value
and an IV of all zeros.
Key i will have the leftmost i bits be ones and the rightmost N-i bits be zeros, for i in [1,N].
To test the decrypt functionality of AES-CBC, the evaluator will supply the set of key
and ciphertext value pairs described below and obtain the plaintext value that
results from AES-CBC decryption of the given ciphertext using the given key and an
IV of all zeros.
The set of key/ciphertext pairs will have 256 256-bit key/ciphertext pairs.
Key i in each set will have the leftmost i bits be
ones and the rightmost N-i bits be zeros, for i in [1,N]. The ciphertext value in
each pair will be the value that results in an all-zeros plaintext when decrypted
with its corresponding key.
Test 8:
To test the encrypt functionality of AES-CBC, the evaluator will supply
the set of 256 plaintext values described below and obtain the ciphertext
values that result from AES-CBC encryption of the given plaintext using a 256-bit key value of
all zeros with an IV of all zeros.
Plaintext value i in each set will have the leftmost i bits be ones and
the rightmost 256-i bits be zeros, for i in [1,256].
To test the decrypt functionality of AES-CBC, the evaluator will perform the
same test as for encrypt, using ciphertext values of the same form as the plaintext in
the encrypt test as input and AES-CBC decryption.
The evaluator will test the encrypt functionality by encrypting an i-block
message where 1 < i ≤ 10. The evaluator will choose a key, an IV and plaintext
message of length i blocks and encrypt the message, using the mode to be tested, with
the chosen key and IV. The ciphertext will be compared to the result of encrypting
the same plaintext message with the same key and IV using a known good implementation.
The evaluator will also test the decrypt functionality for each mode by decrypting an
i-block message where 1 < i ≤10. The evaluator will choose a key, an IV and a
ciphertext message of length i blocks and decrypt the message, using the mode to be
tested, with the chosen key and IV. The plaintext will be compared to the result of
decrypting the same ciphertext message with the same key and IV using a known good
implementation.
The evaluator will test the encrypt
functionality using a set of 100 plaintext, IV, and key 3-tuples.
The keys, plaintext, and IV values are each 256-bits.
For each 3-tuple, 1000 iterations will be run as follows:
# Input: PT, IV, Key
for i = 1 to 1000:
if i == 1:
CT[1] = AES-CBC-Encrypt(Key, IV, PT)
PT = IV
else:
CT[i] = AES-CBC-Encrypt(Key, PT)
PT = CT[i-1]
The
ciphertext computed in the 1000th iteration (i.e., CT[1000]) is the result for that
trial. This result will be compared to the result of running 1000 iterations with the
same values using a known good implementation.
The evaluator will test the
decrypt functionality using the same test as for encrypt, exchanging CT and PT and
replacing AES-CBC-Encrypt with AES-CBC-Decrypt.
There are four Known Answer Tests (KATs) described below.
For all KATs, the plaintext, initialization vector (IV), and ciphertext values shall be 256-bit blocks.
The results from each test may either be obtained by the validator directly or by supplying the inputs to the implementer and receiving the results in response.
To determine correctness, the evaluator will compare the resulting values to those obtained by submitting the same inputs to a known good implementation.
Test 9:
To test the encrypt functionality, the evaluator will supply 5 plaintext values and obtain the ciphertext value that results from encryption of the given plaintext using a 256-bit key value of all zeros and an IV of all zeros.
To test the decrypt functionality, the evaluator will perform the same test as for encrypt, using the 5 ciphertext values as input.
Test 10:
To test the encrypt functionality, the evaluator will supply 5 256-bit key values and obtain the ciphertext value that results from encryption of an all zeros plaintext using the given key value and an IV of all zeros.
To test the decrypt functionality, the evaluator will perform the same test as for encrypt, using an all zero ciphertext value as input.
Test 11:
To test the encrypt functionality, the evaluator will supply a set of key values described below and obtain the ciphertext values that result from AES encryption of an all zeros plaintext using the given key values and an IV of all zeros.
The set of keys shall have shall have 256 256-bit keys.
Keyi shall have the leftmost i bits be ones and the rightmost 256-i bits be zeros, for i in [1, N].
To test the decrypt functionality, the evaluator will supply the set of key and ciphertext value pairs described below and obtain the plaintext value that results from decryption of the given ciphertext using the given key values and an IV of all zeros.
The set of key/ciphertext pairs shall have 256 256-bit pairs.
Keyi shall have the leftmost i bits be ones and the rightmost 256-i bits be zeros for i in [1, N].
The ciphertext value in each pair shall be the value that results in an all zeros plaintext when decrypted with its corresponding key.
Test 12:
To test the encrypt functionality, the evaluator will supply the set of 256 plaintext values described below and obtain the two ciphertext values that result from encryption of the given plaintext using a 256 bit key value of all zeros, respectively, and an IV of all zeros.
Plaintext value i in each set shall have the leftmost bits be ones and the rightmost 256-i bits be zeros, for i in [1, 256].
To test the decrypt functionality, the evaluator will perform the same test as for encrypt, using ciphertext values of the same form as the plaintext in the encrypt test as input.
Multi-Block Message Test
The evaluator will test the encrypt functionality by encrypting an i-block message where 1 less-than i less-than-or-equal to 10.
For each i the evaluator will choose a key, IV, and plaintext message of length i blocks and encrypt the message, using the mode to be tested, with the chosen key.
The ciphertext shall be compared to the result of encrypting the same plaintext message with the same key and IV using a known good implementation.
The evaluator will also test the decrypt functionality by decrypting an i-block message where 1 less-than i less-than-or-equal to 10.
For each i the evaluator will choose a key and a ciphertext message of length i blocks and decrypt the message, using the mode to be tested, with the chosen key.
The plaintext shall be compared to the result of decrypting the same ciphertext message with the same key using a known good implementation.
Monte-Carlo Test
For AES-CTR mode perform the Monte Carlo Test for ECB Mode on the encryption engine of the counter mode implementation. There is no need to test the decryption engine.
The evaluator will test the encrypt functionality using 100 plaintext/key pairs.
Each key shall be 256-bit.
The plaintext values shall be 256-bit blocks.
For each pair, 1000 iterations shall be run as follows:
# Input: PT, Key
for i = 1 to 1000:
CT[i] = AES-ECB-Encrypt(Key, PT)
PT = CT[i]
The ciphertext computed in the 1000th iteration is the result for that trial.
This result shall be compared to the result of running 1000 iterations with the same values using a known good implementation.
AES Key Wrap (AES-KW) and Key Wrap with Padding (AES-KWP) Test
The evaluator will test the authenticated encryption functionality of AES-KW for EACH
combination of the following input parameter lengths:
256 bit key encryption keys (KEKs)
Three plaintext lengths.
One of the plaintext lengths will be two semi-blocks (256 bits).
One of the plaintext lengths will be three semi-blocks (192 bits).
The third data unit length will be the longest supported plaintext
length less than or equal to 64 semi-blocks (4096 bits).
using a set of 100 key and plaintext pairs and obtain the ciphertext that results from AES-KW
authenticated encryption. To determine correctness, the evaluator will use the AES-KW
authenticated-encryption function of a known good implementation.
The evaluator will test the authenticated-decryption functionality of AES-KW using the
same test as for authenticated-encryption, replacing plaintext values with ciphertext values
and AES-KW authenticated-encryption with AES-KW authenticated-decryption.
The evaluator will test the authenticated-encryption functionality of AES-KWP using the
same test as for AES-KW authenticated-encryption with the following change in the three
plaintext lengths:
One plaintext length will be one octet. One plaintext length will be 20 octets (160
bits).
One plaintext length will be the longest supported plaintext length less than or equal
to 512 octets (4096 bits).
The evaluator will test the authenticated-decryption functionality of AES-KWP using the
same test as for AES-KWP authenticated-encryption, replacing plaintext values with
ciphertext values and AES-KWP authenticated-encryption with AES-KWP authenticated-decryption.
The evaluator will test the generation-encryption and decryption-verification
functionality of AES-CCM for the following input parameter and tag lengths:
256 bit key
Two payload lengths. One payload length will be the shortest supported payload
length, greater than or equal to zero bytes. The other payload length will be the
longest supported payload length, less than or equal to 32 bytes (256 bits).
Two or three associated data lengths. One associated data length will be 0, if
supported. One associated data length will be the shortest supported payload length,
greater than or equal to zero bytes. One associated data length will be the longest
supported payload length, less than or equal to 32 bytes (256 bits). If the
implementation supports an associated data length of 2
16 bytes, an associated data length of 216 bytes will be tested.
Nonce lengths.
The evaluator will test all nonce lengths between 7 and 13 bytes, inclusive, that are supported by the OS.
Tag lengths.
The evaluator will test all of the following tag length values that are supported by the OS: 4, 6, 8, 10, 12, 14 and 16 bytes.
To test the generation-encryption functionality of AES-CCM, the evaluator will perform the
following four tests:
Test 13:
For EACH supported key and associated data length and ANY supported
payload, nonce and tag length, the evaluator will supply one key value, one nonce
value and 10 pairs of associated data and payload values and obtain the resulting
ciphertext.
Test 14:
For EACH supported key and payload length and ANY supported associated
data, nonce and tag length, the evaluator will supply one key value, one nonce value
and 10 pairs of associated data and payload values and obtain the resulting ciphertext.
Test 15:
For EACH supported key and nonce length and ANY supported associated
data, payload and tag length, the evaluator will supply one key value and 10
associated data, payload and nonce value 3-tuples and obtain the resulting ciphertext.
Test 16:
For EACH supported key and tag length and ANY supported associated data,
payload and nonce length, the evaluator will supply one key value, one nonce value
and 10 pairs of associated data and payload values and obtain the resulting ciphertext.
To determine correctness in each of the above tests, the evaluator will compare the
ciphertext with the result of generation-encryption of the same inputs with a known good
implementation.
To test the decryption-verification functionality of AES-CCM, for EACH combination of
supported associated data length, payload length, nonce length and tag length, the evaluator
will supply a key value and 15 nonce, associated data and ciphertext 3-tuples and obtain
either a FAIL result or a PASS result with the decrypted payload. The evaluator will supply
10 tuples that should FAIL and 5 that should PASS per set of 15.
Additionally, the evaluator will use tests from the IEEE 802.11-02/362r6 document
"Proposed Test vectors for IEEE 802.11 TGi", dated September 10, 2002, Section 2.1 AESCCMP
Encapsulation Example and Section 2.2 Additional AES CCMP Test Vectors to
further verify the IEEE 802.11-2007 implementation of AES-CCMP.
The evaluator will test the authenticated encrypt functionality of AES-GCM for each
combination of the following input parameter lengths:
256 bit keys
Two plaintext lengths. One of the plaintext lengths will be a non-zero integer
multiple of 256 bits, if supported. The other plaintext length will not be an integer
multiple of 256 bits, if supported.
Three AAD lengths. One AAD length will be 0, if supported. One AAD length will
be a non-zero integer multiple of 256 bits, if supported. One AAD length will not be
an integer multiple of 256 bits, if supported.
Two IV lengths. If 96 bit IV is supported, 96 bits will be one of the two IV lengths
tested.
The evaluator will test the encrypt functionality using a set of 10 key, plaintext, AAD, and
IV tuples for each combination of parameter lengths above and obtain the ciphertext value
and tag that results from AES-GCM authenticated encrypt. Each supported tag length will be
tested at least once per set of 10. The IV value may be supplied by the evaluator or the
implementation being tested, as long as it is known.
The evaluator will test the decrypt functionality using a set of 10 key, ciphertext, tag, AAD,
and IV 5-tuples for each combination of parameter lengths above and obtain a Pass/Fail result
on authentication and the decrypted plaintext if Pass. The set will include five tuples that
Pass and five that Fail.
The results from each test may either be obtained by the evaluator directly or by supplying
the inputs to the implementer and receiving the results in response. To determine correctness,
the evaluator will compare the resulting values to those obtained by submitting the same
inputs to a known good implementation.
The evaluator will test the authenticated encrypt functionality of AES-GCM for
each combination of the following input parameter lengths:
256 bit keys
Two plaintext lengths. One of the plaintext lengths will be a non-zero integer
multiple of 256 bits, if supported. The other plaintext length will not be an
integer multiple of 256 bits, if supported.
Three AAD lengths. One AAD length will be 0, if supported. One AAD length will
be a non-zero integer multiple of 256 bits, if supported. One AAD length will not
be an integer multiple of 256 bits, if supported.
Two IV lengths. If 96 bit IV is supported, 96 bits will be one of the two IV
lengths tested.
The evaluator will test the encrypt functionality using a set of 10 key,
plaintext, AAD, and IV tuples for each combination of parameter lengths above and
obtain the ciphertext value and tag that results from AES-GCM authenticated encrypt.
Each supported tag length will be tested at least once per set of 10. The IV value
may be supplied by the evaluator or the implementation being tested, as long as it is
known.
The evaluator will test the decrypt functionality using a set of 10 key,
ciphertext, tag, AAD, and IV 5-tuples for each combination of parameter lengths above
and obtain a Pass/Fail result on authentication and the decrypted plaintext if Pass.
The set will include five tuples that Pass and five that Fail.
The results from
each test may either be obtained by the evaluator directly or by supplying the inputs
to the implementer and receiving the results in response. To determine correctness,
the evaluator will compare the resulting values to those obtained by submitting the
same inputs to a known good implementation.
The intent of this requirement is to specify the hashing function.
The hash selection must support the message digest
size selection.
The hash selection should be consistent with the overall strength of
the algorithm used.
The evaluator will check that the association of the hash function with
other application cryptographic functions (for example, the digital signature
verification function) is documented in the TSS.
The TSF
hashing functions can be implemented in one of two modes. The first mode is the
byte-oriented mode. In this mode the TSF only hashes messages that
are an integral number of bytes in length; i.e., the length (in bits) of the message
to be hashed is divisible by 8. The second mode is the bit-oriented mode. In this mode
the TSF hashes messages of arbitrary length. As there are different
tests for each mode, an indication is given in the following sections for the
bit-oriented vs. the byte-oriented test MACs. The evaluator will perform all of the
following tests for each hash algorithm implemented by the TSF and
used to satisfy the requirements of this PP.
The following tests require the
developer to provide access to a test application that provides the evaluator with
tools that are typically not found in the production application.
Test 17:
Short Messages Test (Bit oriented Mode) - The evaluator will generate an input set
consisting of m+1 messages, where m is the block length of the hash algorithm. The
length of the messages range sequentially from 0 to m bits. The message text will
be pseudorandomly generated. The evaluator will compute the message digest for each of
the messages and ensure that the correct result is produced when the messages are
provided to the TSF.
Test 18:
Short Messages Test (Byte oriented Mode) - The evaluator will generate an input set
consisting of m/8+1 messages, where m is the block length of the hash algorithm.
The length of the messages range sequentially from 0 to m/8 bytes, with each
message being an integral number of bytes. The message text will be
pseudorandomly generated. The evaluator will compute the message digest for each of
the messages and ensure that the correct result is produced when the messages are
provided to the TSF.
Test 19:
Selected Long Messages Test (Bit oriented Mode) - The evaluator will generate an input
set consisting of m messages, where m is the block length of the hash algorithm.
The length of the ith message is 512 + 99⋅i, where 1 ≤ i ≤ m. The message
text will be pseudorandomly generated. The evaluator will compute the message digest
for each of the messages and ensure that the correct result is produced when the
messages are provided to the TSF.
Test 20:
Selected Long Messages Test (Byte oriented Mode) - The evaluator will generate an
input set consisting of m/8 messages, where m is the block length of the hash
algorithm. The length of the ith message is 512 + 8⋅99⋅i,
where 1 ≤ i ≤ m/8. The message text will be pseudorandomly generated.
The evaluator will compute
the message digest for each of the messages and ensure that the correct result is
produced when the messages are provided to the TSF.
Test 21:
Pseudorandomly Generated Messages Test - This test is for byte-oriented
implementations only. The evaluator will randomly generate a seed that is n bits long,
where n is the length of the message digest produced by the hash function to be
tested. The evaluator will then formulate a set of 100 messages and associated digests
by following the algorithm provided in Figure 1 of [SHAVS]. The evaluator will then
ensure that the correct result is produced when the messages are provided to the
TSF.
The OS shall perform [cryptographic signature services (generation and
verification)] in accordance with a specified cryptographic algorithm [selection:
RSA schemes using cryptographic key sizes of 2048-bit or greater
that meet the following: FIPS PUB 186-4, "Digital Signature Standard (DSS)", Section 4
ECDSA schemes using "NIST curves" P-384 and [selection: P-521, no other curves ]
that meet the following: FIPS PUB 186-4, "Digital Signature Standard (DSS)", Section 5
]and cryptographic key sizes [assignment: cryptographic algorithm]
that meet the following: [assignment: list of standards].
Application
Note:
The ST Author should choose the algorithm implemented to
perform digital signatures; if more than one algorithm is available, this requirement
should be iterated to specify the functionality. For the algorithm chosen, the ST
author should make the appropriate assignments/selections to specify the parameters
that are implemented for that algorithm.
The following tests require the developer to
provide access to a test application that provides the evaluator with tools that are
typically not found in the production application.
Test 22:
ECDSAFIPS 186-4 Signature Generation Test. For each supported NIST curve
(i.e., P-384 and P-521) and SHA function pair, the evaluator will generate
10 1024-bit long messages and obtain for each message a public key and the
resulting signature values R and S. To determine correctness, the evaluator will
use the signature verification function of a known good implementation.
Test 23:
ECDSAFIPS 186-4 Signature Verification Test. For each supported NIST curve
(i.e., P-384 and P-521) and SHA function pair, the evaluator will generate
a set of 10 1024-bit message, public key and signature tuples and modify one of
the values (message, public key or signature) in five of the 10 tuples.
The evaluator will verify that 5 responses indicate success and
5 responses indicate failure.
Test 24:
Signature Generation Test. The evaluator will verify the implementation of
RSA Signature Generation by the OS using the Signature
Generation Test. To conduct this test the evaluator must generate or obtain 10
messages from a trusted reference implementation for each modulus size/SHA
combination supported by the TSF.
The evaluator will have the
OS use its private key and modulus value to sign these
messages. The evaluator will verify the correctness of the TSF'
signature using a known good implementation and the associated public keys to
verify the signatures.
Test 25:
Signature Verification Test. The evaluator will perform the Signature
Verification test to verify the ability of the OS to recognize
another party's valid and invalid signatures. The evaluator will inject errors
into the test vectors produced during the Signature Verification Test by
introducing errors in some of the public keys, e, messages, IR format, and/or
signatures.
The evaluator will verify that the OS returns failure when
validating each signature.
The OS shall perform [keyed-hash message authentication services]
in accordance with a specified cryptographic algorithm
[selection: SHA-256, SHA-384, SHA-512 ]
with key sizes [assignment:
key size (in bits) used in HMAC]
and message digest sizes
[selection: 160 bits, 256 bits, 384 bits, 512 bits ] that meet the following: [FIPS Pub 198-1 The Keyed-Hash Message
Authentication Code and FIPS Pub 180-4 Secure Hash Standard].
Application
Note:
The intent of this requirement is to specify the keyed-hash
message authentication function used for key establishment purposes for the various
cryptographic protocols used by the OS (e.g., trusted channel).
The hash selection must support the message digest size selection.
The hash selection should be consistent with the overall strength of the
algorithm used for FCS_COP.1/HASH.
The evaluator will perform the following activities based on the selections
in the ST.
For each of the supported parameter sets, the
evaluator will compose 15 sets of test data.
Each set consists of a key and message data.
The evaluator will have the OS generate HMAC tags for these sets of test data.
The resulting MAC tags will be compared against the result of generating HMAC
tags with the same key using a known-good implementation.
Application
Note:
NIST SP 800-90A contains three different methods of generating random numbers;
each of these, in turn, depends on underlying cryptographic primitives (hash functions/ciphers).
The ST author will select the function used and include the specific underlying cryptographic primitives used in the requirement or in the TSS.
While any of the identified hash functions (SHA-224, SHA-256, SHA-384, SHA-512) are allowed for Hash_DRBG or HMAC_DRBG,
only AES-based implementations for CTR_DRBG are allowed.
The deterministic RBG used by the OS shall be seeded by an entropy source that
accumulates entropy from a
[selection:
software-based noise source
platform-based noise source
]
with a minimum of 256 bits
of entropy at least equal to the greatest security strength (according to NIST SP 800-57)
of the keys and hashes that it will generate.
Application
Note:
For the first
selection in this requirement, the ST author selects 'software-based noise source' if
any additional noise sources are used as input to the DRBG.
In the second selection in this requirement, the ST author selects the
appropriate number of bits of entropy that corresponds to the greatest security
strength of the algorithms included in the ST.
Security strength is defined in Tables
2 and 3 of NIST SP 800-57A.
For example, if the implementation includes 3072-bit RSA
(security strength of 128 bits), AES 256 (security strength 256 bits), and
HMAC-SHA-256 (security strength 256 bits), then the ST author would select 256 bits.
The evaluator will perform 15 trials for the RNG implementation. If the RNG
is configurable, the evaluator will perform 15 trials for each configuration. The
evaluator will also confirm that the operational guidance contains appropriate
instructions for configuring the RNG functionality.
If the RNG has prediction resistance enabled, each trial consists of (1) instantiate DRBG, (2)
generate the first block of random bits (3) generate a second block of random bits
(4) uninstantiate. The evaluator verifies that the second block of random bits is
the expected value. The evaluator will generate eight input values for each
trial. The first is a count (0 – 14). The next three are entropy input, nonce, and
personalization string for the instantiate operation. The next two are additional
input and entropy input for the first call to generate. The final two are
additional input and entropy input for the second call to generate. These values
are randomly generated. "generate one block of random bits" means to generate
random bits with number of returned bits equal to the Output Block Length (as
defined in NIST SP 800-90A).
If the RNG does not have prediction resistance,
each trial consists of (1) instantiate DRBG, (2) generate the first block of
random bits (3) reseed, (4) generate a second block of random bits (5)
uninstantiate. The evaluator verifies that the second block of random bits is the
expected value. The evaluator will generate eight input values for each trial.
The first is a count (0 – 14). The next three are entropy input, nonce, and
personalization string for the instantiate operation. The fifth value is
additional input to the first call to generate. The sixth and seventh are
additional input and entropy input to the call to reseed. The final value is
additional input to the second generate call.
The following list contains more information on some of the input values to be generated/selected by the evaluator.
Entropy input: The length of the entropy input value must equal the seed
length.
Nonce: If a nonce is supported (CTR_DRBG with no Derivation Function does
not use a nonce), the nonce bit length is one-half the seed length.
Personalization string: The length of the personalization string must be
less than or equal to seed length. If the implementation only supports one
personalization string length, then the same length can be used for both values.
If more than one string length is support, the evaluator will use personalization
strings of two different lengths. If the implementation does not use a
personalization string, no value needs to be supplied.
Additional input: The additional input bit lengths have the same defaults
and restrictions as the personalization string lengths.
The OS shall implement functionality to encrypt sensitive data
stored in non-volatile storage and provide interfaces to applications to invoke this functionality.
Application
Note:
Sensitive data will be identified in the TSS by the ST
author, and minimally includes credentials and keys. The interface for invoking the
functionality could take a variety of forms: it could consist of an API,
or simply well-documented conventions for accessing credentials stored as files.
The evaluator will check the TSS to ensure that it lists all persistent
sensitive data for which the OS provides a storage capability. For each of these
items, the evaluator will confirm that the TSS lists for what purpose it can be used,
and how it is stored.
The evaluator will confirm that cryptographic operations used to protect the data occur as specified in FCS_COP.1/ENCRYPT.
Guidance
The evaluator will consult the developer documentation to verify that instructions
exists on applications should securely store credentials.
5.1.2 User Data Protection (FDP)
FDP_ACF_EXT.1 Access Controls for Protecting User Data
The OS shall implement access controls which can prohibit unprivileged users from
accessing files and directories owned by other users.
Application
Note:
Effective protection by access controls may also depend
upon system configuration. This requirement is designed to ensure
that, for example, files and directories owned by one user in a multi user system
can be protected from access by another user in that system.
The evaluator will confirm that the TSS comprehensively describes the access control policy enforced by the OS.
The description must include the rules by which accesses to particular files and directories
are determined for particular users.
The evaluator will inspect the TSS to ensure that it describes the access control rules
in such detail that given any possible scenario between a user and a file governed by
the OS the access control decision is unambiguous.
Tests
The evaluator will create two new standard user accounts on the system and conduct the following tests:
Test 26:
The evaluator will authenticate to the system as the first user and create a file within that user's home directory.
The evaluator will then log off the system and log in as the second user.
The evaluator will then attempt to read the file created in the first user's home directory.
The evaluator will ensure that the read attempt is denied.
Test 27:
The evaluator will authenticate to the system as the first user and create a file within that user's home directory.
The evaluator will then log off the system and log in as the second user.
The evaluator will then attempt to modify the file created in the first user's home directory.
The evaluator will ensure that the modification is denied.
Test 28:
The evaluator will authenticate to the system as the first user and create a file within that user's user directory.
The evaluator will then log off the system and log in as the second user.
The evaluator will then attempt to delete the file created in the first user's home directory.
The evaluator will ensure that the deletion is denied.
Test 29:
The evaluator will authenticate to the system as the first user.
The evaluator will attempt to create a file in the second user's home directory.
The evaluator will ensure that the creation of the file is denied.
Test 30:
The evaluator will authenticate to the system as the first user and attempt to modify the file created in the first user's home directory.
The evaluator will ensure that the modification of the file is accepted.
Test 31:
The evaluator will authenticate to the system as the first user and attempt to delete the file created in the first user's directory.
The evaluator will ensure that the deletion of the file is accepted.
5.1.3 Security Management (FMT)
FMT_MOF_EXT.1 Management of security functions behavior
The OS shall restrict the ability to perform the function indicated in the "Administrator" column in
FMT_SMF_EXT.1.1 to the administrator.
Application
Note:
The functions with an "X" in the "Administrator" column must be restricted
to (or overridden by) the administrator in the TOE.
The functions with an "O" in the "Administrator" column may be restricted
to (or overridden by) the administrator when implemented in the TOE at
the discretion of the ST author. For such functions, the ST author indicates this
by replacing an "O" with an "X" in the ST.
The evaluator will verify that the TSS describes those management functions
that are restricted to Administrators, including how the user is prevented
from performing those functions, or not able to use any interfaces that
allow access to that function.
Tests
The evaluator will also perform the following test.
Test 32:
For each function that is indicated as restricted to the administrator,
the evaluation will perform the function as an administrator, as specified in the
Operational Guidance, and determine that it has the expected effect as outlined by
the Operational Guidance and the SFR. The evaluator will then perform the function
(or otherwise attempt to access the function) as a non-administrator and observe
that they are unable to invoke that functionality.
FMT_SMF_EXT.1 Specification of Management Functions
Configure minimum number of special characters in password
OOptional
OOptional
7
Configure minimum number of numeric characters in password
OOptional
OOptional
8
Configure minimum number of uppercase characters in password
OOptional
OOptional
9
Configure minimum number of lowercase characters in password
OOptional
OOptional
10
Configure lockout policy for unsuccessful authentication attempts through
[selection: timeouts between attempts, limiting number of attempts during a time period ]
OOptional
OOptional
11
Configure host-based firewall
OOptional
OOptional
12
Configure name/address of directory server with which to bind
OOptional
OOptional
13
Configure name/address of remote management server from which to receive management settings
OOptional
OOptional
14
Configure name/address of audit/logging server to which to send audit/logging records
OOptional
OOptional
15
Configure audit rules
OOptional
OOptional
16
Configure name/address of network time server
OOptional
OOptional
17
Enable/disable automatic software update
OOptional
OOptional
18
Configure Wi-Fi interface
OOptional
OOptional
19
Enable/disable Bluetooth interface
OOptional
OOptional
20
Enable/disable [assignment:
list of other external interfaces]
OOptional
OOptional
21
[assignment:
list of other management functions to be provided by the TSF]
OOptional
OOptional
.
Application
Note:
The ST should indicate which of the optional management functions are implemented in the TOE.
This can be done by copying the above table into the ST and adjusting the "Administrator"
and "User" columns to "X" according to which capabilities are present or not present,
and for which privilege level. The Application Note for FMT_MOF_EXT.1 explains
how to indicate Administrator or User capability.
The terms "Administrator" and "User" are defined in the glossary.
The intent of this requirement is to ensure that the ST is populated with the
relevant management functions that are provided by the OS.
Sophisticated account management policies, such as intricate password complexity requirements and handling of temporary accounts, are a function of directory servers.
The OS can enroll in such account management and enable the overall information system to achieve such policies by binding to a directory server.
The evaluator will verify that every management function captured in the ST is described in the operational guidance and that the description contains the information required to perform the management duties associated with the management function.
Tests
The evaluator will test the OS's ability to provide the management functions by configuring the operating system and testing each option selected from above.
The evaluator is expected to test these functions in all the ways in which the ST and guidance documentation state the configuration can be managed.
The evaluator will confirm that the TSS specifies the locations of kernel drivers/modules, security
audit logs, shared libraries, system executables, and system configuration files. Every
file does not need to be individually identified, but the system's conventions for storing and protecting
such files must be specified.
Tests
The evaluator will create an unprivileged user account.
Using this account, the evaluator will ensure that the following tests result in a negative
outcome (i.e., the action results in the OS denying the evaluator permission to
complete the action):
Test 33:
The evaluator will attempt to modify all kernel drivers and modules.
Test 34:
The evaluator will attempt to modify all security audit logs generated by the logging subsystem.
Test 35:
The evaluator will attempt to modify all shared libraries that are used throughout the system.
Test 36:
The evaluator will attempt to modify all system executables.
Test 37:
The evaluator will attempt to modify all system configuration files.
Test 38:
The evaluator will attempt to modify any additional components selected.
The evaluator will create an unprivileged user account.
Using this account, the evaluator will ensure that the following tests result in a negative
outcome (i.e., the action results in the OS denying the evaluator permission to
complete the action):
Test 39:
The evaluator will attempt to read security audit logs generated by the auditing subsystem
Test 40:
The evaluator will attempt to read system-wide credential repositories
Test 41:
The evaluator will attempt to read any other object specified in the assignment
The OS shall always randomize process address space memory locations with
[selection: 8, [assignment:
number greater than 8] ]
bits of entropy except for
[assignment:
list of explicit exceptions].
The evaluator will select 3 executables included with the TSF.
If the TSF includes a web browser it must be selected.
If the TSF includes a mail client it must be selected.
For each of these apps, the evaluator will launch the same executables on two separate instances of the
OS on identical hardware and compare all memory mapping locations.
The evaluator will ensure that no memory mappings are placed in the same location.
If the rare chance occurs that two mappings are the same for a single executable and
not the same for the other two, the evaluator will repeat the test with that executable to verify
that in the second test the mappings are different.
This test can also be completed on the same hardware and rebooting between application launches.
The OS shall [selection: employ stack-based buffer overflow protections, not store parameters/variables in the same data structures as control flow values ].
Application
Note:
Many OSes store control flow values (i.e. return addresses) in stack data structures that also contain parameters and variables.
For these OSes, it is expected that most of the OS, to include the kernel, libraries, and application software from the OS vendor be compiled with stack-based buffer overflow protection enabled.
OSes that store parameters and variables separately from control flow values do not need additional stack protections.
For stack-based OSes, the evaluator will determine that the TSS contains a description of stack-based buffer overflow protections used by the OS.
These are referred to by a variety of terms, such as stack cookie, stack guard, and stack canaries.
The TSS must include a rationale for any binaries that are not protected in this manner.
The evaluator will also preform the following test:
Test 42:
The evaluator will inventory the kernel, libraries, and application binaries
to determine those that do not implement stack-based buffer overflow protections. This list should
match up with the list provided in the TSS.
For OSes that store parameters/variables separately from control flow values, the evaluator will verify that the TSS describes what data structures control values, parameters, and variables are stored.
The evaluator will also ensure that the TSS includes a description of the safeguards that ensure parameters and variables do not intermix with control flow values.
The OS shall verify the integrity of the bootchain up through the OS kernel and
[selection:
all executable code stored in mutable media
[assignment:
list of other executable code]
no other executable code
]
prior to its execution through the use of
[selection:
a digital signature using a hardware-protected asymmetric key
a digital signature using an X509 certificate with hardware-based protection
a hardware-protected hash
]
.
Application
Note:
The bootchain of the OS is the sequence of software, to include the OS loader, the kernel, system
drivers or modules, and system files, which ultimately result in loading the OS.
The first part of the OS, usually referred to as the first-stage bootloader,
must be loaded by the platform.
Assessing its integrity, while critical, is the platform's responsibility; and therefore outside
the scope of this PP.
All software loaded after this stage is potentially within the control of the OS and is in scope.
The verification may be transitive in nature:
a hardware-protected public key, X509 certificate or hash may be used to verify the mutable bootloader code
which contains a key, certificate, or hash used by the bootloader to verify the mutable OS kernel code,
which contains a key, certificate, or hash to verify the next layer of executable code, and so on.
However, the way in which the hardware stores and protects these keys is out of scope.
If all executable code (including bootloader(s), kernel, device drivers, pre-loaded applications, user-loaded
applications, and libraries) is verified, all executable code stored in mutable media should
be selected.
If certificates are used, they can be hardware-protected trust store elements or leaf certificates in a certificate chain that terminates in a root CA which is an element of a hardware protected trust store.
If the certificates themselves are not trust store elements, revocation information is expected to be available for each CA certificate in the chain that is not a trust element, in accordance to FIA_X509_EXT.1.
The evaluator will verify that the TSS section of the ST includes a comprehensive description of the boot
procedures, including a description of the entire bootchain, for the TSF.
The evaluator will ensure that the OS cryptographically verifies each
piece of software it loads in the bootchain to include bootloaders and the kernel.
Software loaded for execution directly by the platform (e.g. first-stage bootloaders) is out of scope.
For each additional category of executable code verified before
execution, the evaluator will verify that the description in the TSS describes how that
software is cryptographically verified.
The evaluator will verify that the TSS contains a description of the
protection afforded to the mechanism performing the cryptographic verification.
Tests
The evaluator will also perform the following tests:
Test 43:
The evaluator will perform actions to cause TSF software to load and observe that the
integrity mechanism does not flag any executables as containing integrity errors and that the
OS properly boots.
Test 44:
The evaluator will modify a TSF executable that is part of the bootchain verified by the TSF (i.e. Not the first-stage bootloader)
and attempt to boot.
The evaluator will ensure that an integrity violation is triggered and the OS does not boot
(Care must be taken so that the integrity
violation is determined to be the cause of the failure to load the module, and not the fact that
in such a way to invalidate the structure of the module.).
]:
If the ST author indicates that the integrity verification is performed
using public key in an X509 certificate, the evaluator will verify that the boot integrity mechanism includes a certificate
validation according to FIA_X509_EXT.1 for all certificates in the chain from the certificate used for
boot integrity to a certificate in the trust store that are not themselves in the trust store.
This means that, for each X509 certificate in this chain that is not a trust store element, the evaluator must ensure that revocation information is available to the TOE during the bootstrap mechanism (before the TOE becomes fully operational).
The OS shall provide the ability to check for updates to the OS
software itself and shall use a digital signature scheme specified in FCS_COP.1/SIGN to validate the authenticity of the response.
Application
Note:
This requirement is about the ability to check for the availability of
authentic updates, while the installation of authentic updates is covered by
FPT_TUD_EXT.1.2.
Use of the digital signature scheme ensures that an attacker cannot influence the response,
regarding of whether updates are available.
The OS shall
[selection: cryptographically verify, invoke platform-provided functionality to cryptographically verify ]
updates to itself using a digital
signature prior to installation using schemes specified in FCS_COP.1/SIGN.
Application
Note:
The intent of the requirement is to ensure that only digitally signed and verified TOE updates are applied to the TOE.
The evaluator will check for an update using procedures described in the
documentation and verify that the OS provides a list of available updates.
Testing this capability may require
installing and temporarily placing the system into a
configuration in conflict with secure configuration guidance
which specifies automatic update.
The evaluator is also to ensure that the response to this query is authentic by using a digital signature scheme specified in FCS_COP.1/SIGN.
The digital signature verification may be performed as part of a network protocol occurs over a trusted channel as described in FTP_ITC_EXT.1.)
If the signature verification is not performed as part of a trusted channel, the evaluator will send a query response with a bad signature and verify that the signature verification fails.
The evaluator will then send a query response with a good signature and verify that the signature verification is successful.
For the following tests, the evaluator will initiate the download of an update and
capture the update prior to installation.
The download could originate from the vendor's website, an enterprise-hosted
update repository, or another system (e.g. network peer).
All supported origins
for the update must be indicated in the TSS and evaluated.
Test 46:
The evaluator will ensure that the update has a digital
signature belonging to the vendor prior to its installation.
The evaluator will modify the downloaded update in such a way
that the digital signature is no longer valid. The evaluator
will then attempt to install the modified update. The
evaluator will ensure that the OS does not install the
modified update.
Test 47:
The evaluator will ensure that the update has a digital
signature belonging to the vendor. The evaluator will then
attempt to install the update (or permit installation to continue).
The evaluator will ensure that
the OS successfully installs the update.
FPT_TUD_EXT.2 Trusted Update for Application Software
The OS shall provide the ability to check for updates to
application software and shall use a digital signature scheme specified in
FCS_COP.1/SIGN to validate the authenticity of the response.
Application
Note:
This requirement is about the ability to check for authentic updates,
while the actual installation of such updates is covered by FPT_TUD_EXT.2.2.
Use of the digital signature scheme ensures that an attacker cannot influence the response,
regarding of whether updates are available.
The OS shall cryptographically verify the integrity of updates
to applications using a digital signature specified by
FCS_COP.1/SIGN prior to installation.
The evaluator will check for updates to application software
using procedures described in the
documentation and verify that the OS provides a list of available
updates. Testing this capability may require
temporarily placing the system into a configuration in conflict
with secure configuration guidance which specifies automatic
update.
The evaluator is also to ensure that the response to this query is authentic by using a digital signature scheme specified in FCS_COP.1/SIGN.
The digital signature verification may be performed as part of a network protocol
as described in FTP_ITC_EXT.1.
If the signature verification is not performed as part of a trusted channel, the evaluator will send a query response with a bad signature and verify that the signature verification fails.
The evaluator will then send a query response with a good signature and verify that the signature verification is successful.
The evaluator will initiate an update to an application. This may vary depending on the application,
but it could be through the application vendor's website, a commercial app store, or another system.
All origins supported by the OS must be indicated in the TSS and evaluated. However, this only includes
those mechanisms for which the OS is providing a trusted installation and update functionality.
It does not include user or administrator-driven download and installation of arbitrary files.
Test 48:
The evaluator will ensure that the update has a digital
signature which chains to the OS vendor or another trusted
root managed through the OS. The evaluator will modify the
downloaded update in such a way that the
digital signature is no longer valid. The evaluator will then attempt to install the
modified update. The evaluator will ensure that the OS does not install the modified
update.
Test 49:
The evaluator will ensure that the update has a digital
signature belonging to the OS vendor or another trusted root
managed through the OS. The evaluator will then attempt to
install the update. The evaluator will ensure that the OS
successfully installs the update.
The OS shall prevent allocation of any memory region with both write and
execute permissions except for [assignment:
list of exceptions].
Application
Note:
Requesting a memory mapping with both write and execute
permissions subverts the platform protection provided by DEP.
If the OS provides no exceptions (such as for just-in-time compilation),
then "no exceptions" should be indicated in the assignment.
Full realization of this requirement requires hardware support, but this is commonly available.
The evaluator will inspect the vendor-provided developer documentation and
verify that no memory-mapping can be made with
write and execute permissions except for the cases listed in the assignment.
Tests
The evaluator will also perform the following tests.
Test 50:
The evaluator will acquire or construct a test program which attempts
to allocate memory that is both writable and executable.
The evaluator will run the program and confirm that it fails to
allocate memory that is both writable and executable.
Test 51:
The evaluator will acquire or construct a test program which
allocates memory that is executable and then
subsequently requests additional write/modify permissions on that memory.
The evaluator will run the program and confirm that at no time
during the lifetime of the process is the memory both writable and executable.
Test 52:
The evaluator will acquire or construct a test program which
allocates memory that is writable and then
subsequently requests additional execute permissions on that memory.
The evaluator will run the program and confirm that at no time
during the lifetime of the process is the memory both writable and executable.
The OS shall record within each audit record at least the following information:
Date and time of the event, type of event, subject identity (if applicable),
and outcome (success or failure) of the event; and
For each audit event type, based on the auditable event
definitions of the functional components included in the PP/ST,
[assignment:
other audit relevant information]
.
Application
Note:
The term subject here is understood to be the user that the process
is acting on behalf of. If no auditable event definitions of
functional components are provided, then no additional audit-relevant information
is required.
The evaluator will check the administrative guide and ensure
that it lists all of the auditable events. The evaluator will
check to make sure that every audit event type selected in the ST
is included.
The evaluator will check the administrative guide and ensure
that it provides a format
for audit records. Each audit record format type must be covered,
along with a brief description of each field. The evaluator will
ensure that the fields contains the information required.
Tests
The evaluator will test the OS's ability to correctly generate
audit records by having the TOE generate audit records for the
events listed in the ST. This should include all instance types
of an event specified.
When verifying the test results, the evaluator will ensure the
audit records generated during testing match the format specified
in the administrative guide, and that the fields in each audit
record have the proper entries.
The evaluator will test the OS's ability to correctly generate
audit records by having the TOE generate audit records for the
events listed in the ST.
The evaluator will
ensure the audit records generated during testing match the
format specified in the administrative guide, and that the fields
in each audit record provide the required information.
When the defined number of unsuccessful authentication attempts for an
account has been met, the OS shall:
[selection: Account Lockout, Account Disablement, Mandatory Credential Reset, [assignment:
list of actions] ]
.
Application
Note:
The action to be taken will be populated in the assignment of the ST and defined
in the administrator guidance.
The evaluator will set an administrator-configurable threshold for
failed attempts, or note the ST-specified assignment. The evaluator
will then (per selection) repeatedly attempt to authenticate with an
incorrect password, PIN, or certificate until the number of attempts
reaches the threshold. Note that the authentication attempts and
lockouts must also be logged as specified in
FAU_GEN.1.
Test 53:
The evaluator will attempt to authenticate repeatedly to the system with a
known bad password. Once the defined number of failed authentication attempts has been
reached the evaluator will ensure that the account that was being used for testing
has had the actions detailed in the assignment list above applied to it. The evaluator will ensure that
an event has been logged to the security event log detailing that the account has had these actions applied.
Test 54:
The evaluator will attempt to authenticate repeatedly to the system with a
known bad certificate. Once the defined number of failed authentication attempts has been
reached the evaluator will ensure that the account that was being used for testing
has had the actions detailed in the assignment list above applied to it. The evaluator will ensure that
an event has been logged to the security event log detailing that the account has had these actions applied.
Test 55:
The evaluator will attempt to authenticate repeatedly to the system using both a bad password and a bad certificate.
Once the defined number of failed authentication attempts has been
reached the evaluator will ensure that the account that was being used for testing
has had the actions detailed in the assignment list above applied to it. The evaluator will ensure that
an event has been logged to the security event log detailing that the account has had these actions applied.
The OS shall authenticate any user's claimed identity according to the
[assignment:
rules describing how the multiple authentication
mechanisms provide authentication
].
The evaluator will ensure that the TSS describes
the rules as to how each authentication mechanism specified in
FIA_UAU.5.1 is implemented and used.
Example rules are how the authentication mechanism authenticates the user
(i.e. how does the TSF verify that the correct password or authentication
factor is used),
the result of a successful authentication
(i.e. is the user input used to derive or unlock a key) and which
authentication mechanism can be used at which authentication factor
interfaces (i.e. if there are times, for example, after a reboot,
that only specific authentication mechanisms can be used).
Rules regarding how the authentication factors interact in terms of
unsuccessful authentication are covered in FIA_AFL.1.
Guidance
The evaluator will verify that
configuration guidance for each authentication mechanism is
addressed in the AGD guidance.
Test 56:
The evaluator will attempt to authenticate to the OS using
the known user name and password. The evaluator will ensure
that the authentication attempt is successful.
Test 57:
The evaluator will attempt to authenticate to the OS using
the known user name but an incorrect password. The evaluator
will ensure that the authentication attempt is unsuccessful.
The evaluator will examine the TSS for guidance on supported
protected storage and will then configure the TOE or OE to establish a PIN
which enables release of the asymmetric key from the protected storage (such as a TPM, a hardware token, or
isolated execution environment) with which the
OS can interface. The evaluator will then conduct the following tests:
Test 58:
The evaluator will attempt to authenticate to the OS using the known user name and PIN.
The evaluator will ensure that the authentication attempt is successful.
Test 59:
The evaluator will attempt to authenticate to the OS using the known user name but an incorrect
PIN. The evaluator will ensure that the authentication attempt is
unsuccessful.
The evaluator will configure the OS to authentication to authenticate to the OS using
a username, password, and one-time password mechanism.
The evaluator will then perform the following tests.
Test 60:
The evaluator will attempt to authenticate using a valid username, valid password, and valid one-time password.
The evaluator will ensure that the authentication attempt is successful.
Test 61:
The evaluator will attempt to authenticate using a valid username, invalid password, and valid one-time password.
The evaluator will ensure that the authentication attempt fails.
Test 62:
The evaluator will attempt to authenticate using a valid username, valid password, and invalid one-time password.
The evaluator will ensure that the authentication attempt fails.
Test 63:
The evaluator will attempt to authenticate using a valid username, invalid password, and invalid one-time password.
The evaluator will ensure that the authentication attempt fails.
The OS shall implement functionality to validate certificates in accordance with the following rules:
RFC 5280 certificate validation and certificate path validation
The certificate path must terminate with a trusted CA certificate
The OS shall validate a certificate path by ensuring the presence of the
basicConstraints extension, that the CA flag is set to TRUE for all CA certificates,
and that any path constraints are met.
The TSF shall validate that any CA certificate includes "Certificate Signing" as a purpose the key usage field
The OS shall validate the revocation status of the certificate using
[selection: OCSP as specified in RFC 6960, CRL as specified in RFC 8603, an OCSPTLS Status Request Extension (OCSP stapling) as specified
in RFC 6066, OCSPTLS Multi-Certificate Status Request Extension
(i.e., OCSP Multi-Stapling) as specified in RFC 6961 ]
with
[selection: no exceptions, [assignment:
exceptional use cases and alternative status check] ]
The OS shall validate the extendedKeyUsage field according to the following rules:
Certificates used for trusted updates and executable code integrity verification shall have the Code Signing Purpose (id-kp 3 with OID 1.3.6.1.5.5.7.3.3) in the extendedKeyUsage field.
Server certificates presented for TLS shall have the Server Authentication purpose (id-kp 1 with OID 1.3.6.1.5.5.7.3.1) in the extendedKeyUsage field.
Client certificates presented for TLS shall have the Client Authentication purpose (id-kp 2 with OID 1.3.6.1.5.5.7.3.2) in the EKU field.
S/MIME certificates presented for email encryption and signature shall have the Email Protection purpose (id-kp 4 with OID 1.3.6.1.5.5.7.3.4) in the EKU field.
OCSP certificates presented for OCSP responses shall have the OCSP Signing Purpose (id-kp 9 with OID 1.3.6.1.5.5.7.3.9) in the EKU field.
Server certificates presented for EST shall have the CMC Registration Authority (RA) purpose (id-kp-cmcRA with OID 1.3.6.1.5.5.7.3.28) in the EKU field. (conditional)
.
Application
Note:
FIA_X509_EXT.1.1 lists the rules for validating certificates.
The ST author will select whether revocation status is verified using OCSP or CRLs.
FIA_X509_EXT.2 requires that certificates are used for HTTPS, TLS, and DTLS;
this use requires that the extendedKeyUsage rules are verified.
OCSP stapling and OCSP multi-stapling only support TLS server certificate validation. If other certificate types are validated, either OCSP or CRL should be claimed.
If OCSP is not supported the EKU provision for checking the OCSP Signing purpose is met by default.
If the OS receives server certificates presented for EST, then the ST author should make the selection for EST in the SFR.
If the OS cannot perform revocation in accordance with one of the specified revocation methods,
then the specific use cases where revocation checking is not possible must be described, along with any alternative to certificate status checking for each use case.
For example, for the use case "update functions when network connections are not available, notice of a compromised certificate disables automatic updates."
The OS shall only treat a certificate as a CA certificate if the
basicConstraints extension is present and the CA flag is set to TRUE.
Application
Note:
This requirement applies to certificates that are used and
processed by the TSF and restricts the certificates that may be
added as trusted CA certificates.
The evaluator will ensure the TSS describes where the
check of validity of the certificates takes place.
The evaluator ensures the TSS also provides a description of the certificate path validation algorithm.
If the OS cannot perform revocation in accordance with one of the revocation methods, the evaluator will ensure the TSS describes each revocation checking exception use case, and for each exception, the alternate functionality the TOE implements to determine the status of the certificate and disable functionality dependent on the validity of the certificate.
Tests
The tests described must be performed in conjunction with the other certificate services evaluation activities, including the functions in FIA_X509_EXT.2.1.
The evaluator will create a chain of at least four certificates: the node certificate to be tested, two Intermediate CAs, and the self-signed Root CA.
Test 64:
The evaluator will demonstrate that validating a certificate without a valid certification path results in the function failing, for each of the following reasons, in turn:
by establishing a certificate path in which one of the issuing certificates is not a CA certificate,
by omitting the basicConstraints field in one of the issuing certificates,
by setting the basicConstraints field in an issuing certificate to have CA=False,
by omitting the CA signing bit of the key usage field in an issuing certificate, and
by setting the path length field of a valid CA field to a value strictly less than the certificate path.
The evaluator will then establish a valid certificate path consisting of valid CA certificates, and demonstrate that the function succeeds.
The evaluator will then remove trust in one of the CA certificates, and show that the function fails.
Test 65:
The evaluator will demonstrate that validating an expired certificate results in the function failing.
Test 66:
The evaluator will test that the OS can properly handle revoked certificates - conditional on whether CRL, OCSP, OCSP stapling, or OCSP multi-stapling is selected; if multiple methods are selected, then a test will be performed for each method.
The evaluator will test revocation of the node certificate and revocation of the intermediate CA certificate (i.e. the intermediate CA certificate should be revoked by the root CA).
If OCSP stapling per RFC 6066 is the only supported revocation method, testing revocation of the intermediate CA certificate is omitted.
The evaluator will ensure that a valid certificate is used, and that the validation function succeeds.
The evaluator then attempts the test with a certificate that has been revoked (for each method chosen in the selection) to ensure when the certificate is no longer valid that the validation function fails.
Test 67:
If any OCSP option is selected, the evaluator will configure the OCSP server or use a man-in-the-middle tool to present a certificate that does not have the OCSP signing purpose and verify that validation of the OCSP response fails.
If CRL is selected, the evaluator will configure the CA to sign a CRL with a certificate that does not have the cRLsign key usage bit set and verify that validation of the CRL fails.
Test 68:
The evaluator will modify any byte in the first eight bytes of the certificate and demonstrate that the certificate fails to validate.
(The certificate will fail to parse correctly.)
Test 69:
The evaluator will modify any byte in the last byte of the certificate and demonstrate that the certificate fails to validate.
(The signature on the certificate will not validate.)
Test 70:
The evaluator will modify any byte in the public key of the certificate and demonstrate that the certificate fails to validate.
(The signature of the certificate will not validate.)
Test 71.1:
The evaluator will establish a valid, trusted certificate chain consisting of an EC leaf certificate, an EC Intermediate CA certificate not designated as a trust anchor, and an EC certificate designated as a trusted anchor, where the elliptic curve parameters are specified as a named curve.
The evaluator will confirm that the TOE validates the certificate chain.
Test 71.2:
The evaluator will replace the intermediate certificate in the certificate chain for Test 71.1 with a modified certificate, where the modified intermediate CA has a public key information field where the EC parameters uses an explicit format version of the Elliptic Curve parameters in the public key information field of the intermediate CA certificate from Test 71.1, and the modified Intermediate CA certificate is signed by the trusted EC root CA, but having no other changes.
The evaluator will confirm the TOE treats the certificate as invalid.
]:
For each exceptional use case for revocation checking described in the ST, the evaluator shall attempt to establish the conditions of the use case, designate the certificate as invalid and perform the function relying on the certificate. The evaluator shall observe that the alternate revocation checking mechanism successfully prevents performance of the function.
The evaluator will generate an X.509v3 certificate for a user with the Client Authentication Extended Key Usage field set.
The evaluator will provision the OS for authentication with the X.509v3 certificate.
The evaluator will ensure that the certificates are validated by the OS as per
FIA_X509_EXT.1.1 and then conduct the following tests:
Test 73:
The evaluator will attempt to authenticate to the OS using the X.509v3 certificate.
The evaluator will ensure that the authentication attempt is successful.
Test 74:
The evaluator will generate a second certificate identical to
the first except for the public key and any values derived
from the public key.
The evaluator will attempt to authenticate to the OS with this certificate.
The evaluator will ensure that the authentication attempt is unsuccessful.
The tests described must be performed in conjunction with the other
certificate services evaluation activities, including the functions in
FIA_X509_EXT.2.1.
The evaluator will create a chain of at least four certificates:
the node certificate to be tested, two Intermediate CAs, and the
self-signed Root CA.
Test 75:
The evaluator will construct a certificate path, such that the certificate
of the CA issuing the OS's certificate does not contain the
basicConstraints extension. The validation of the certificate path fails.
Test 76:
The evaluator will construct a certificate path, such that the certificate
of the CA issuing the OS's certificate has the CA flag in the
basicConstraints extension not set. The validation of the certificate path fails.
Test 77:
The evaluator will construct a certificate path, such that the certificate
of the CA issuing the OS's certificate has the CA flag in the
basicConstraints extension set to TRUE. The validation of the certificate path
succeeds.
The OS shall use X.509v3 certificates as defined by RFC 5280 to support
authentication for TLS and
[selection: DTLS, HTTPS, [assignment:
other protocols], no other protocols ]
connections.
The evaluator will acquire or develop an application that uses the OSTLS mechanism with an X.509v3 certificate. The evaluator will then run the
application and ensure that the provided certificate is used to authenticate the
connection.
The evaluator will repeat the activity for any other selections listed.
]
to provide a trusted communication channel between itself and
authorized IT entities supporting the following capabilities:
[selection: audit server, authentication server, management server, [assignment:
other capabilities] ]
that is logically distinct from other communication
channels and provides assured identification of its end points and protection of the channel
data from disclosure and detection of modification of the channel data.
Application
Note:
The ST author must include the security functional requirements for the trusted
channel protocol selected in FTP_ITC_EXT.1.1 in the main body of the ST.
The evaluator will configure the OS to communicate with another
trusted IT product as identified in the second selection.
The evaluator will monitor network traffic while the OS performs communication with each of the
servers identified in the second selection.
The evaluator will ensure that for each session a trusted channel was established
in conformance with the protocols identified in the first selection.
The OS shall provide a communication path between itself and
[selection: remote, local ]
users that is logically distinct from other communication paths and provides assured
identification of its endpoints and protection of the communicated data from
[modification, disclosure].
Application
Note:
This requirement ensures that all remote administrative actions are protected.
Authorized remote administrators must initiate all communication with the OS via
a trusted path and all communication with the OS by remote administrators must
be performed over this path. The data passed in this trusted communication
channel is encrypted as defined in FTP_ITC_EXT.1.1.
If local users access is selected and no unprotected traffic is sent to remote
users, then this requirement is met.
If remote users access is selected, the
ST author must include the security functional requirements for the trusted
channel protocol selected in
FTP_ITC_EXT.1.1 in the main body of the ST.
The OS shall require use of the trusted path for
[[all remote administrative actions]].
Application
Note:
This requirement ensures that authorized remote administrators initiate all communication
with the OS via a trusted path, and that all communication with the OS by remote administrators
is performed over this path. The data passed in this trusted communication channel is encrypted as
defined in FTP_ITC_EXT.1.
The evaluator will examine the TSS to determine that the methods of remote OS administration
are indicated, along with how those communications are protected. The evaluator will also
confirm that all protocols listed in the TSS in support of OS administration are consistent with those
specified in the requirement, and are included in the requirements in the ST.
Guidance
The evaluator will
confirm that the operational guidance contains instructions for establishing the remote
administrative sessions for each supported method.
Tests
The evaluator will also perform the following
tests:
Test 78:
The evaluator will ensure that communications using each remote administration method is
tested during the course of the evaluation, setting up the connections as described in the
operational guidance and ensuring that communication is successful.
Test 79:
For each method of remote administration supported, the evaluator will
follow the operational guidance to ensure that there is no available interface that can be
used by a remote user to establish a remote administrative sessions without invoking the
trusted path.
Test 80:
The evaluator will ensure, for each method of remote administration, the
channel data is not sent in plaintext.
Test 81:
The evaluator will ensure, for each method of remote administration,
modification of the channel data is detected by the OS.
5.1.8 TOE Security Functional Requirements Rationale
The following rationale provides justification for each security objective for the TOE,
showing that the SFRs are suitable to meet and achieve the security objectives:
FPT_BLT_EXT.1 supports the objective by requiring the TSF to disable certain Bluetooth profiles when they are inactive such that explicit user authorization is required to re-enable them.
Supports the objective by requiring the OS to provide a trusted channel for critical communication.
5.2 Security Assurance Requirements
The Security Objectives in Section 4 Security Objectives were constructed to
address threats identified in Section 3.1 Threats.
The Security Functional Requirements (SFRs) in Section 5.1 Security Functional Requirements
are a formal instantiation of the Security Objectives.
The PP identifies the Security Assurance Requirements (SARs) to frame
the extent to which the evaluator assesses the documentation applicable for the
evaluation and performs independent testing.
This section lists the set of SARs from CC part 3
that are required in evaluations against this PP.
Individual evaluation activities to be performed are specified both in
Section 5 Security Requirements as well as in this section.
The general model for evaluation of TOEs against STs written to conform to this PP is as follows:
After the ST has been approved for evaluation, the ITSEF
will obtain the OS, supporting environmental IT, and the administrative/user guides for
the OS. The ITSEF is expected to perform actions mandated by the Common Evaluation
Methodology (CEM) for the ASE and ALC SARs.
The ITSEF also performs the evaluation activities contained within
Section 5 Security Requirements, which are intended to be an interpretation of the
other CEM assurance requirements as they apply to the specific technology instantiated in the
OS.
The evaluation activities that are captured in
Section 5 Security Requirements also provide
clarification as to what the developer needs to provide to demonstrate the OS is compliant
with the PP.
5.2.1 Class ASE: Security Target
The following ASE components as defined in [CEM] are required:
The information about the OS is contained in the guidance documentation available to the end user as
well as the TSS portion of the ST. The OS developer must concur with the description of the product that is
contained in the TSS as it relates to the functional requirements. The evaluation activities
contained in Section 5.1 Security Functional Requirements should provide the ST authors with
sufficient information to determine the appropriate content for the TSS section.
The
functional specification describes the TSFIs. It is not
necessary to have a formal or complete specification of these interfaces. Additionally,
because OSes conforming to this PP will necessarily have interfaces to
the operational environment that are not directly invokable by OS
users, there is little point specifying that such interfaces be described in and of
themselves since only indirect testing of such interfaces may be possible. For this PP,
the activities for this family should focus on understanding the interfaces presented in
the TSS in response to the functional requirements and the interfaces
presented in the AGD documentation. No additional "functional specification" documentation
is necessary to satisfy the evaluation activities specified. The interfaces that need to be
evaluated are characterized through the information needed to perform the assurance
activities listed, rather than as an independent, abstract list.
The developer shall provide a tracing from the functional specification to the
SFRs.
Application
Note:
As indicated in the introduction to this section, the
functional specification is comprised of the information contained in the AGD_OPE and
AGD_PRE documentation. The developer may reference a website accessible to application
developers and the evaluator. The evaluation activities in the functional requirements
point to evidence that should exist in the documentation and TSS
section; since these are directly associated with the SFRs, the tracing in element
ADV_FSP.1.2D is implicitly already done and no additional documentation is
necessary.
There are no specific evaluation activities associated with these SARs, except
ensuring the information is provided. The functional specification documentation is
provided to support the evaluation activities described in Section 5.1 Security Functional Requirements, and
other activities described for AGD, ATE, and AVA SARs. The requirements on the content
of the functional specification information is implicitly assessed by virtue of the
other evaluation activities being performed; if the evaluator is unable to perform an
activity because there is insufficient interface information, then an adequate
functional specification has not been provided.
5.2.3 Class AGD: Guidance Documentation
The guidance documents will be
provided with the ST. Guidance must include a description of how the IT
personnel verifies that the operational environment can fulfill its role for the security
functionality. The documentation should be in an informal style and readable by the IT
personnel. Guidance must be provided for every operational environment that the product
supports as claimed in the ST. This guidance includes instructions to
successfully install the TSF in that environment; and Instructions to
manage the security of the TSF as a product and as a component of the
larger operational environment. Guidance pertaining to particular security functionality is
also provided; requirements on such guidance are contained in the Evaluation Activities
specified with each requirement.
The developer shall provide operational user guidance.
Application
Note:
The operational user guidance does not have to be contained in a
single document. Guidance to users, administrators and application developers can be
spread among documents or web pages.
Rather than repeat information here, the developer should
review the evaluation activities for this component to ascertain the specifics of the
guidance that the evaluator will be checking for. This will provide the necessary
information for the preparation of acceptable guidance.
The operational user guidance shall describe, for each user role, the
user-accessible functions and privileges that should be controlled in a secure
processing environment, including appropriate warnings.
Application
Note:
User and administrator are to be considered in the definition
of user role.
The operational user guidance shall describe, for each user role, the available
functions and interfaces, in particular all security parameters under the control of
the user, indicating secure values as appropriate.
Application
Note:
This portion of the operational user guidance should be presented
in the form of a checklist that can be quickly executed by IT personnel (or end-users,
when necessary) and suitable for use in compliance activities.
When possible, this guidance is to be expressed in the eXtensible Configuration
Checklist Description Format (XCCDF) to
support security automation.
Minimally, it should be presented in a structured
format which includes a title for each configuration item,
instructions for achieving the secure configuration, and any relevant rationale.
The operational user guidance shall, for each user role, clearly present each
type of security-relevant event relative to the user-accessible functions that need to
be performed, including changing the security characteristics of entities under the
control of the TSF.
The operational user guidance shall identify all possible modes of operation of
the OS (including operation following failure or operational
error), their consequences, and implications for maintaining secure operation.
The operational user guidance shall, for each user role, describe the security
measures to be followed in order to fulfill the security objectives for the
operational environment as described in the ST.
Some of the contents of the operational guidance are verified by the
evaluation activities in Section 5.1 Security Functional Requirements and evaluation of the OS according to the [CEM].
The following additional information is also required.
If cryptographic functions are provided by the OS, the operational guidance ill contain instructions for configuring
the cryptographic engine associated with the evaluated configuration of the OS.
It will provide a warning to the administrator that use of other
cryptographic engines was not evaluated nor tested during the CC evaluation of the
OS.
The documentation must describe the process for verifying
updates to the OS by verifying a digital signature – this may be
done by the OS or the underlying platform.
The evaluator will
verify that this process includes the following steps: Instructions for obtaining the
update itself.
This should include instructions for making the update accessible to
the OS (e.g., placement in a specific directory).
Instructions for initiating the update process, as well as discerning whether the process was
successful or unsuccessful.
This includes generation of the hash/digital signature.
The OS will likely contain security functionality that does not
fall in the scope of evaluation under this PP.
The operational guidance will make it
clear to an administrator which security functionality is covered by the evaluation
activities.
The developer shall provide the OS, including its preparative
procedures.
Application
Note:
As with the operational guidance, the developer should look to
the evaluation activities to determine the required content with respect to preparative
procedures.
The preparative procedures shall describe all the steps necessary for secure
acceptance of the delivered OS in accordance with the developer's
delivery procedures.
The preparative procedures shall describe all the steps necessary for secure
installation of the OS and for the secure preparation of the
operational environment in accordance with the security objectives for the operational
environment as described in the ST.
As indicated in the introduction above, there are significant expectations
with respect to the documentation—especially when configuring the operational
environment to support OS functional requirements. The evaluator
will check to ensure that the guidance provided for the OS
adequately addresses all platforms claimed for the OS in the ST.
5.2.4 Class ALC: Life-cycle Support
At the assurance level provided
for OSes conformant to this PP, life-cycle support is limited to end-user-visible aspects of
the life-cycle, rather than an examination of the OS vendor's development and configuration
management process. This is not meant to diminish the critical role that a developer's
practices play in contributing to the overall trustworthiness of a product; rather, it is a
reflection on the information to be made available for evaluation at this assurance level.
ALC_CMC.1 Labeling of the TOE (ALC_CMC.1)
This component is
targeted at identifying the OS such that it can be distinguished from
other products or versions from the same vendor and can be easily specified when being
procured by an end user.
The evaluator will check the ST to ensure that it contains
an identifier (such as a product name/version number) that specifically identifies the
version that meets the requirements of the ST. Further, the
evaluator will check the AGD guidance and OS samples received for
testing to ensure that the version number is consistent with that in the ST. If the vendor maintains a web site advertising the OS, the evaluator will examine the information on the web site to
ensure that the information in the ST is sufficient to distinguish
the product.
ALC_CMS.1 TOE CM Coverage (ALC_CMS.1)
Given the scope of the OS and its associated evaluation
evidence requirements, this component's evaluation activities are covered
by the evaluation activities listed for ALC_CMC.1.
The "evaluation evidence required by the SARs" in this PP is limited to the
information in the ST coupled with the guidance provided to
administrators and users under the AGD requirements. By ensuring that the OS is specifically identified and that this identification is
consistent in the ST and in the AGD guidance (as done in the
evaluation activity for ALC_CMC.1), the evaluator implicitly confirms the information
required by this component. Life-cycle support is targeted aspects of the developer's
life-cycle and instructions to providers of applications for the developer's devices,
rather than an in-depth examination of the TSF manufacturer's
development and configuration management process. This is not meant to diminish the
critical role that a developer's practices play in contributing to the overall
trustworthiness of a product; rather, it's a reflection on the information to be made
available for evaluation.
The evaluator will ensure that the developer has
identified (in guidance documentation for application developers concerning the
targeted platform) one or more development environments appropriate for use in
developing applications for the developer's platform. For each of these development
environments, the developer will provide information on how to configure the
environment to ensure that buffer overflow protection mechanisms in the environment(s)
are invoked (e.g., compiler and linker flags). The evaluator will ensure that this documentation
also includes an indication of whether such protections are on by default, or have to
be specifically enabled. The evaluator will ensure that the TSF is
uniquely identified (with respect to other products from the TSF
vendor), and that documentation provided by the developer in association with the
requirements in the ST is associated with the TSF
using this unique identification.
ALC_TSU_EXT.1 Timely Security Updates
This component requires the
OS developer, in conjunction with any other necessary parties, to provide information as
to how the end-user devices are updated to address security issues in a timely manner. The
documentation describes the process of providing updates to the public from the time a
security flaw is reported/discovered, to the time an update is released. This description
includes the parties involved (e.g., the developer, carriers(s)) and the steps that are
performed (e.g., developer testing, carrier testing), including worst case time periods,
before an update is made available to the public.
The developer shall provide a description in the TSS of how users are notified
when updates change security properties or the configuration of the product.
The description shall include the mechanisms publicly available for reporting
security issues pertaining to the OS.
Note:
The reporting mechanism could include web sites, email addresses, as well as a
means to protect the sensitive nature of the report (e.g., public keys that could be
used to encrypt the details of a proof-of-concept exploit).
The evaluator will verify that the TSS contains a description of the timely
security update process used by the developer to create and deploy security updates.
The evaluator will verify that this description addresses the entire application. The
evaluator will also verify that, in addition to the OS developer's process, any
third-party processes are also addressed in the description. The evaluator will also
verify that each mechanism for deployment of security updates is described.
The
evaluator will verify that, for each deployment mechanism described for the update
process, the TSS lists a time between public disclosure of a vulnerability and public
availability of the security update to the OS patching this vulnerability, to include
any third-party or carrier delays in deployment. The evaluator will verify that this
time is expressed in a number or range of days.
The evaluator will verify that
this description includes the publicly available mechanisms (including either an email
address or website) for reporting security issues related to the OS. The evaluator
will verify that the description of this mechanism includes a method for protecting
the report either using a public key for encrypting email or a trusted channel for a
website.
5.2.5 Class ATE: Tests
Testing is specified for functional aspects of
the system as well as aspects that take advantage of design or implementation weaknesses.
The former is done through the ATE_IND family, while the latter is through the AVA_VAN
family. At the assurance level specified in this PP, testing is based on advertised
functionality and interfaces with dependency on the availability of design information. One
of the primary outputs of the evaluation process is the test report as specified in the
following requirements.
Testing is performed to confirm the
functionality described in the TSS as well as the administrative
(including configuration and operational) documentation provided. The focus of the testing
is to confirm that the requirements specified in Section 5.1 Security Functional Requirements being met,
although some additional testing is specified for SARs in
Section 5.2 Security Assurance Requirements.
The
evaluation activities identify the additional testing activities associated with these
components. The evaluator produces a test report documenting the plan for and results of
testing, as well as coverage arguments focused on the platform/OS
combinations that are claiming conformance to this PP.
Given the scope of the OS and its associated evaluation evidence requirements, this component's
evaluation activities are covered by the evaluation activities listed for ALC_CMC.1.
The evaluator will prepare a test plan and report documenting the testing
aspects of the system, including any application crashes during testing. The evaluator
will determine the root cause of any application crashes and include that information
in the report.
The test plan covers all of the testing actions contained in the [CEM]
and the body of this PP's evaluation activities.
While it is
not necessary to have one test case per test listed in an evaluation activity, the
evaluator must document in the test plan that each applicable testing requirement in
the ST is covered. The test plan identifies the platforms to be
tested, and for those platforms not included in the test plan but included in the
ST, the test plan provides a justification for not testing the
platforms. This justification must address the differences between the tested
platforms and the untested platforms, and make an argument that the differences do not
affect the testing to be performed. It is not sufficient to merely assert that the
differences have no affect; rationale must be provided. If all platforms claimed in
the ST are tested, then no rationale is necessary. The test plan
describes the composition of each platform to be tested, and any setup that is
necessary beyond what is contained in the AGD documentation. It should be noted that
the evaluator is expected to follow the AGD documentation for installation and setup
of each platform either as part of a test or as a standard pre-test condition. This
may include special test drivers or tools. For each driver or tool, an argument (not
just an assertion) should be provided that the driver or tool will not adversely
affect the performance of the functionality by the OS and its
platform.
This also includes the configuration of the cryptographic engine to be
used. The cryptographic algorithms implemented by this engine are those specified by
this PP and used by the cryptographic protocols being evaluated (IPsec, TLS). The test
plan identifies high-level test objectives as well as the test procedures to be
followed to achieve those objectives. These procedures include expected results.
The test report (which could just be an annotated version of the test plan) details
the activities that took place when the test procedures were executed, and includes
the actual results of the tests. This will be a cumulative account, so if there was a
test run that resulted in a failure; a fix installed; and then a successful re-run of
the test, the report would show a "fail" and "pass" result (and the supporting
details), and not just the "pass" result.
5.2.6 Class AVA: Vulnerability Assessment
For the first generation of
this protection profile, the evaluation lab is expected to survey open sources to discover
what vulnerabilities have been discovered in these types of products. In most cases, these
vulnerabilities will require sophistication beyond that of a basic attacker. Until
penetration tools are created and uniformly distributed to the evaluation labs, the
evaluator will not be expected to test for these vulnerabilities in the OS.
The labs will be expected to comment on the likelihood of these vulnerabilities given
the documentation provided by the vendor. This information will be used in the development
of penetration testing tools and for the development of future protection profiles.
The evaluator will perform a search of public domain sources to identify
potential vulnerabilities in the OS.
Application
Note:
Public domain sources include the Common Vulnerabilities
and Exposures (CVE) dictionary for publicly-known vulnerabilities. Public domain
sources also include sites which provide free checking of files for viruses.
The evaluator will conduct penetration testing, based on the identified
potential vulnerabilities, to determine that the OS is resistant to
attacks performed by an attacker possessing Basic attack potential.
The evaluator will generate a report to document their
findings with respect to this requirement. This report could physically be part of the
overall test report mentioned in ATE_IND, or a separate document. The evaluator
performs a search of public information to find vulnerabilities that have been found
in similar applications with a particular focus on network protocols the application
uses and document formats it parses.
The evaluator documents the sources consulted and
the vulnerabilities found in the report.
For each vulnerability found, the evaluator
either provides a rationale with respect to its non-applicability, or the evaluator
formulates a test (using the guidelines provided in ATE_IND) to confirm the
vulnerability, if suitable. Suitability is determined by assessing the attack vector
needed to take advantage of the vulnerability. If exploiting the vulnerability
requires expert skills and an electron microscope, for instance, then a test would not
be suitable and an appropriate justification would be formulated.
Appendix A - Optional Requirements
As indicated in the introduction to this PP, the baseline requirements (those that must be
performed by the TOE) are contained in the body of this PP.
This appendix contains three other types of optional requirements that may be included in the ST, but are not required in order
to conform to this PP.
However, applied modules, packages and/or use cases may refine specific requirements as mandatory.
The first type (A.1 Strictly Optional Requirements) are strictly optional requirements that are independent of the
TOE implementing any function.
If the TOE fulfills any of these requirements or supports a certain functionality, the vendor is encouraged to include the SFRs
in the ST, but are not required in order to conform to this PP.
The second type (A.2 Objective Requirements) are objective requirements that describe security functionality not yet
widely available in commercial technology.
The requirements are not currently mandated in the body of this PP, but will be included in
the baseline requirements in future versions of this PP. Adoption by vendors is
encouraged and expected as soon as possible.
The third type (A.3 Implementation-based Requirements)
are dependent on the TOE implementing a particular function.
If the TOE fulfills any of these requirements, the vendor must either add the related SFR or disable the functionality for the
evaluated configuration.
The evaluator will configure the OS, per instructions in the OS manual,
to display the advisory warning message "TEST TEST Warning Message TEST TEST".
The evaluator will then log out and confirm that the advisory message is
displayed before logging in can occur.
A.2 Objective Requirements
A.2.1 Protection of the TSF (FPT)
FPT_BLT_EXT.1 Limitation of Bluetooth Profile Support
The TSF shall disable support for
[assignment:
list of Bluetooth profiles]
Bluetooth profiles when they are not currently being used by
an application on the TOE and shall require explicit user action to enable
them.
Application
Note:
Some Bluetooth services incur more serious consequences if
unauthorized remote devices gain access to them.
Such services should be protected by measures like disabling support for
the associated Bluetooth profile unless it is actively being used by an application on the OS
(in order to prevent discovery by a Service Discovery Protocol search), and then requiring explicit user
action to enable those profiles in order to use the services.
It may be further appropriate to require additional user action before granting a remote device access
to that service.
For example, it may be appropriate to disable the
OBEX Push Profile until a user pushes a button in an application
indicating readiness to transfer an object.
After completion of the object transfer,
support for the OBEX profile should be suspended until the next time the user requests
its use.
The evaluator will ensure that the TSS lists all Bluetooth profiles that are
disabled while not in use by an application and which need explicit user action in
order to become enabled.
Guidance
There are no guidance evaluation activities for this component.
Tests
The evaluator will perform the following tests:
Test 82:
The evaluator will perform this test with a test device that does not have a trust relationship with the TOE.
While the service is not in active use by an application on the TOE, the
evaluator will attempt to discover a service associated with a "protected"
Bluetooth profile (as specified by the requirement) on the TOE via a Service
Discovery Protocol search.
The evaluator will verify that the service does not
appear in the Service Discovery Protocol search results.
Next, the evaluator shall attempt to gain remote access to the service from a device that does not
currently have a trusted device relationship with the TOE.
The evaluator will verify that this attempt fails due to the unavailability of the service and
profile.
Test 83:
The evaluator will repeat Test 1 with a device that currently has a trusted
device relationship with the TOE and verify that the same behavior is exhibited.
The OS shall restrict execution to only programs which match an administrator-specified
[selection:
file path
file digital signature
version
hash
[assignment:
other characteristics]
]
.
Application
Note:
The assignment permits implementations which provide a low
level of granularity such as a volume.
The restriction is only against direct execution of
executable programs.
It does not forbid interpreters which may take data as an input, even if
this data can subsequently result in arbitrary computation.
The evaluator will ensure that the description of the supported characteristics in the TSS is consistent with the SFR.
The evaluator will also ensure that any characteristics specified by the ST-author are described in sufficient detail to understand how to test those characteristics.
Guidance
The evaluator will ensure that that the characteristics are described in sufficient detail for administrators to configure policies using them, and that the list of characteristics in the guidance is consistent with the information in the TSS.
]:
The evaluator will configure the OS to only allow code execution from the core
OS directories. The evaluator will then attempt to execute code from a directory
that is in the allowed list. The evaluator will ensure that the code they
attempted to execute has been executed.
]:
The evaluator will configure the OS to only allow code execution from the core
OS directories. The evaluator will then attempt to execute code from a directory
that is not in the allowed list. The evaluator will ensure that the code they
attempted to execute has not been executed.
]:
The evaluator will configure the OS to only allow code that has been signed by
the OS vendor to execute. The evaluator will then attempt to execute code signed
by the OS vendor. The evaluator will ensure that the code they
attempted to execute has been executed.
]:
The evaluator will configure the OS to only allow code that has been signed by
the OS vendor to execute. The evaluator will then attempt to execute code signed
by another digital authority. The evaluator will ensure that the code they
attempted to execute has not been executed.
]:
The evaluator will configure the OS to allow execution of a specific
application based on version. The evaluator will then attempt to execute the same
version of the application. The evaluator will ensure that the code they attempted
to execute has been executed.
]:
The evaluator will configure the OS to allow execution of a specific
application based on version. The evaluator will then attempt to execute an older
version of the application. The evaluator will ensure that the code they attempted
to execute has not been executed.
]:
The evaluator will configure the OS to allow execution based on the hash of the application
executable. The evaluator will then attempt to execute
the application with the matching hash. The evaluator will
ensure that the code they attempted to execute has been executed.
]:
The evaluator will configure the OS to allow execution based on the hash of the application
executable. The evaluator will modify the
application in such a way that the application hash is changed. The evaluator
will then attempt to execute the application with the matching hash. The evaluator will
ensure that the code they attempted to execute has not been executed.
]:
The evaluator will then attempt to run an application that should not be allowed the defined software restriction policy and ensure that it does not run.
A.3 Implementation-based Requirements
This PP does not define any
Implementation-based requirements.
Appendix B - Selection-based Requirements
As indicated in the introduction to this PP,
the baseline requirements
(those that must be performed by the TOE or its underlying platform)
are contained in the body of this PP.
There are additional requirements based on selections in the body of
the PP:
if certain selections are made, then additional requirements below must be included.
B.1 User Data Protection (FDP)
FDP_IFC_EXT.1 Information flow control
The inclusion of this selection-based component depends upon selection in
FTP_ITC_EXT.1.1.
This component may also be included in the ST as if optional.
provide an interface which allows a VPN client to protect all IP traffic using IPsec
provide a VPN client that can protect all IP traffic using IPsec
]
with the exception of IP traffic required to establish the VPN connection
and
[selection: signed updates directly from the OS vendor, no other traffic ]
.
Application
Note:
Typically, the traffic required to establish the VPN connection is referred to as "Control Plane" traffic,
whereas the IP traffic protected by the IPsec VPN is referred to as "Data Plane" traffic.
All Data Plane traffic must flow through the VPN connection and the VPN must not split-tunnel.
If no native IPsec client is validated or third-party VPN clients may
also implement the required Information Flow Control, the first
option must be selected. In these cases, the TOE provides an API to
third-party VPN clients that allows them to configure the TOE's
network stack to perform the required Information Flow Control.
In the future, this requirement may also make a distinction between the
current requirement (which requires that when the IPsec trusted
channel is enabled, all traffic from the TSF is routed through that
channel) and having an option to force the establishment of an IPsec
trusted channel to allow any communication by the TSF.
The evaluator will verify that the TSS section of the ST describes the
routing of IP traffic when a VPN client is enabled.
The evaluator will ensure that the description indicates which traffic does not go
through the VPN and which traffic does, and that a configuration exists for each
in which only the traffic identified by the ST author as necessary
for establishing the VPN connection (IKE traffic and perhaps HTTPS or DNS traffic) is
not encapsulated by the VPN protocol (IPsec).
Tests
The evaluator will perform the following test:
Test 94:
Step 1: The evaluator will enable a network connection.
The evaluator will sniff packets while performing running applications that use the network such as web browsers and email clients.
The evaluator will verify that the sniffer captures the traffic generated by these actions, turn off the sniffing tool, and save the session data.
Step 2:
The evaluator will configure an IPsec VPN client that supports the routing specified in this requirement.
The evaluator will turn on the sniffing tool, establish the VPN connection, and perform the same actions with the device as performed in the first step.
The evaluator will verify that the sniffing tool captures traffic generated by these actions, turn off the sniffing tool, and save the session data.
Step 3:
The evaluator will examine the traffic from both step one and step two to verify that all non-excepted Data Plane traffic in Step 2 is encapsulated by IPsec.
The evaluator will examine the Security Parameter Index (SPI) value present in the encapsulated packets captured in Step 2 from the TOE to the Gateway and will verify this value is the same for all actions used to generate traffic through the VPN.
Note that it is expected that the SPI value for packets from the Gateway to the TOE is different than the SPI value for packets from the TOE to the Gateway.
Step 4:
The evaluator will perform a ping on the TOE host on the local network and verify that no packets sent are captured with the sniffer.
The evaluator will attempt to send packets to the TOE outside the VPN tunnel (i.e. not through the VPN gateway), including from the local network, and verify that the TOE discards them.
Appendix C - Extended Component Definitions
This appendix contains the definitions for all extended requirements specified in the PP.
C.1 Extended Components Table
All extended components specified in the PP are listed in this table:
Table 3: Extended Component Definitions
Functional Class
Functional Components
Cryptographic Support (FCS)
FCS_CKM_EXT Cryptographic Key Handling FCS_RBG_EXT Random Bit Generation Services FCS_STO_EXT Storage of Special Data
FPT_ACF_EXT Access controls FPT_ASLR_EXT Address Space Layout Randomization FPT_BLT_EXT Limitation of Bluetooth Profile Support FPT_SBOP_EXT Stack Buffer Overflow Protection FPT_SRP_EXT Software Restriction Policies FPT_TST_EXT Integrity Tests FPT_TUD_EXT Trusted Update FPT_W^X_EXT Write XOR Execute
Security Management (FMT)
FMT_MOF_EXT Management of security functions behavior FMT_SMF_EXT Specification of Management Functions
Trusted Path/Channels (FTP)
FTP_ITC_EXT Trusted channel communication
User Data Protection (FDP)
FDP_ACF_EXT Access Controls for User Data FDP_IFC_EXT Information flow control
C.2 Extended Component Definitions
C.2.1 Cryptographic Support (FCS)
This PP defines the following extended components as part of the
FCS class originally defined by CC Part 2:
C.2.1.1 FCS_CKM_EXT Cryptographic Key Handling
Family Behavior
This family defines requirements for handling cryptographic keys.
Component Leveling
C.2.1.2 FCS_RBG_EXT Random Bit Generation Services
Family Behavior
This family defines requirements for generating random bits
Component Leveling
C.2.1.3 FCS_STO_EXT Storage of Special Data
Family Behavior
This family defines requirements concerning the storage of certain types of data.
Component Leveling
C.2.2 Identification and Authentication (FIA)
This PP defines the following extended components as part of the
FIA class originally defined by CC Part 2:
C.2.2.1 FIA_X509_EXT X.509 Certificate Validation
Family Behavior
This family of requirements defines how the X.509 performs validation and what they should be used for.
Component Leveling
C.2.3 Protection of the TSF (FPT)
This PP defines the following extended components as part of the
FPT class originally defined by CC Part 2:
C.2.3.1 FPT_ACF_EXT Access controls
Family Behavior
This family of requirements defines the access controls to system resources.
Component Leveling
C.2.3.2 FPT_ASLR_EXT Address Space Layout Randomization
Family Behavior
This family of requirements defines the behavior of ASLR.
Component Leveling
C.2.3.3 FPT_BLT_EXT Limitation of Bluetooth Profile Support
Family Behavior
This family defines requirements for limiting Bluetooth capabilities without user action.
Component Leveling
FPT_BLT_EXT.1,
Limitation of Bluetooth Profile Support,
requires the TSF to maintain a disabled by default posture for Bluetooth profiles.
Management: FPT_BLT_EXT.1
There are no management activities foreseen.
Audit: FPT_BLT_EXT.1
There are no auditable events foreseen.
FPT_BLT_EXT.1 Limitation of Bluetooth Profile Support
Hierarchical to: No other components.
Dependencies to: No dependencies.
FPT_BLT_EXT.1.1
The TSF shall disable support for
[assignment:
list of Bluetooth profiles]
Bluetooth profiles when they are not currently being used by
an application on the TOE and shall require explicit user action to enable
them.
This family of requirements defines the protections for the stack.
Component Leveling
C.2.3.5 FPT_SRP_EXT Software Restriction Policies
Family Behavior
This family of requirements defines how access to executes is restricted.
Component Leveling
C.2.3.6 FPT_TST_EXT Integrity Tests
Family Behavior
This family of requirements defines how the TOE validates the integrity of critical components.
Component Leveling
C.2.3.7 FPT_TUD_EXT Trusted Update
Family Behavior
This family of requirements defines how the TOE validates software updates.
Component Leveling
C.2.3.8 FPT_W^X_EXT Write XOR Execute
Family Behavior
This family of requirements defines how the TOE ensures that it executes only those items that are non-writable with specified exceptions.
Component Leveling
C.2.4 Security Management (FMT)
This PP defines the following extended components as part of the
FMT class originally defined by CC Part 2:
C.2.4.1 FMT_MOF_EXT Management of security functions behavior
Family Behavior
This family of requirements define the behavior of security function management.
Component Leveling
C.2.4.2 FMT_SMF_EXT Specification of Management Functions
Family Behavior
This family of requirements defines the management of security functions.
Component Leveling
C.2.5 Trusted Path/Channels (FTP)
This PP defines the following extended components as part of the
FTP class originally defined by CC Part 2:
C.2.5.1 FTP_ITC_EXT Trusted channel communication
Family Behavior
This family of requirements defines communication for trusted channels.
Component Leveling
C.2.6 User Data Protection (FDP)
This PP defines the following extended components as part of the
FDP class originally defined by CC Part 2:
C.2.6.1 FDP_ACF_EXT Access Controls for User Data
Family Behavior
This family defines requirements for controlling access to user data.
Component Leveling
C.2.6.2 FDP_IFC_EXT Information flow control
Family Behavior
This family of requirements defines how flows of information are controlled.
Component Leveling
Appendix D - Implicitly Satisfied Requirements
This appendix lists requirements that should be considered satisfied by products
successfully evaluated against this PP. These requirements are not featured
explicitly as SFRs and should not be included in the ST. They are not included as
standalone SFRs because it would increase the time, cost, and complexity of evaluation.
This approach is permitted by [CC] Part 1, 8.2 Dependencies between components.
This information benefits systems engineering activities which call for inclusion of particular
security controls. Evaluation against the PP provides evidence that these controls are present
and have been evaluated.
Requirement
Rationale for Satisfaction
FIA_UAU.1 - Timing of authentication
FIA_AFL.1 implicitly requires that the OS perform all necessary actions,
including those on behalf of the user who has not been authenticated,
in order to authenticate;
therefore it is duplicative to include these actions as a
separate assignment and test.
FIA_UID.1 - Timing of identification
FIA_AFL.1 implicitly requires that the OS perform all necessary actions,
including those on behalf of the user who has not been identified,
in order to authenticate;
therefore it is duplicative to include these actions as a
separate assignment and test.
FMT_SMR.1 - Security roles
FMT_MOF_EXT.1 specifies role-based management functions that implicitly defines
user and privileged accounts;
therefore, it is duplicative to include separate role requirements.
FPT_STM.1 - Reliable time stamps
FAU_GEN.1.2 explicitly requires that the OS associate timestamps with audit records;
therefore it is duplicative to include a separate timestamp requirement.
FMT_MOF_EXT.1 defines requirements for managing session locking;
therefore, it is duplicative to include a separate session locking requirement.
FTA_SSL.2 - User-initiated locking
FMT_MOF_EXT.1 defines requirements for user-initiated session locking;
therefore, it is duplicative to include a separate session locking requirement.
FAU_STG.1 - Protected audit trail storage
FPT_ACF_EXT.1 defines a requirement to protect audit logs;
therefore, it is duplicative to include a separate protection of audit trail requirements.
FAU_GEN.2 - User identity association
FAU_GEN.1.2 explicitly requires that the OS record
any user account associated with each event; therefore, it is duplicative
to include a separate requirement to associate a user account with each
event.
FAU_SAR.1 - Audit review
FPT_ACF_EXT.1.2 requires that audit logs (and other objects)
are protected from reading by unprivileged users; therefore, it is duplicative
to include a separate requirement to protect only the audit information.
Appendix E - Entropy Documentation and Assessment
This appendix describes the required supplementary information for the entropy source used by the OS.
The documentation of the entropy source should be detailed enough that, after reading, the
evaluator will thoroughly understand the entropy source and why it can be relied upon to provide
sufficient entropy. This documentation should include multiple detailed sections: design
description, entropy justification, operating conditions, and health testing. This documentation
is not required to be part of the TSS.
E.1 Design Description
Documentation will include the design of the entropy source as a whole, including the
interaction of all entropy source components. Any information that can be shared regarding the
design should also be included for any third-party entropy sources that are included in the
product.
The documentation will describe the operation of the entropy source to include,
how entropy is produced, and how unprocessed (raw) data can be obtained from within the
entropy source for testing purposes. The documentation should walk through the entropy source
design indicating where the entropy comes from, where the entropy output is passed next, any
post-processing of the raw outputs (hash, XOR, etc.), if/where it is stored, and finally, how
it is output from the entropy source. Any conditions placed on the process (e.g., blocking)
should also be described in the entropy source design. Diagrams and examples are encouraged.
This design must also include a description of the content of the security boundary of
the entropy source and a description of how the security boundary ensures that an adversary
outside the boundary cannot affect the entropy rate.
If implemented, the design
description will include a description of how third-party applications can add entropy to the
RBG. A description of any RBG state saving between power-off and power-on will be included.
E.2 Entropy Justification
There should be a technical
argument for where the unpredictability in the source comes from and why there is confidence
in the entropy source delivering sufficient entropy for the uses made of the RBG output (by
this particular OS). This argument will include a description of the expected min-entropy
rate (i.e. the minimum entropy (in bits) per bit or byte of source data) and explain that
sufficient entropy is going into the OS randomizer seeding process. This discussion will be
part of a justification for why the entropy source can be relied upon to produce bits with
entropy.
The amount of information necessary to justify the expected min-entropy rate
depends on the type of entropy source included in the product.
For developer provided
entropy sources, in order to justify the min-entropy rate, it is expected that a large number
of raw source bits will be collected, statistical tests will be performed, and the min-entropy
rate determined from the statistical tests. While no particular statistical tests are required
at this time, it is expected that some testing is necessary in order to determine the amount
of min-entropy in each output.
For third-party provided entropy sources, in which the
OS vendor has limited access to the design and raw entropy data of the source, the
documentation will indicate an estimate of the amount of min-entropy obtained from this
third-party source. It is acceptable for the vendor to "assume" an amount of min-entropy,
however, this assumption must be clearly stated in the documentation provided. In particular,
the min-entropy estimate must be specified and the assumption included in the ST.
Regardless of type of entropy source, the justification will also include how the DRBG is
initialized with the entropy stated in the ST, for example by verifying that the min-entropy
rate is multiplied by the amount of source data used to seed the DRBG or that the rate of
entropy expected based on the amount of source data is explicitly stated and compared to the
statistical rate. If the amount of source data used to seed the DRBG is not clear or the
calculated rate is not explicitly related to the seed, the documentation will not be
considered complete.
The entropy justification will not include any data added from any
third-party application or from any state saving between restarts.
E.3 Operating Conditions
The entropy rate may be
affected by conditions outside the control of the entropy source itself. For example, voltage,
frequency, temperature, and elapsed time after power-on are just a few of the factors that may
affect the operation of the entropy source. As such, documentation will also include the range
of operating conditions under which the entropy source is expected to generate random data. It
will clearly describe the measures that have been taken in the system design to ensure the
entropy source continues to operate under those conditions. Similarly, documentation will
describe the conditions under which the entropy source is known to malfunction or become
inconsistent. Methods used to detect failure or degradation of the source will be included.
E.4 Health Testing
More specifically, all entropy source
health tests and their rationale will be documented. This includes a description of the health
tests, the rate and conditions under which each health test is performed (e.g., at start,
continuously, or on-demand), the expected results for each health test, and rationale
indicating why each test is believed to be appropriate for detecting one or more failures in
the entropy source.
Appendix F - Validation Guidelines
This appendix contains "rules" specified by the PP Authors that indicate whether certain selections
require the making of other selections in order for a Security Target to be valid. For example, selecting
"HMAC-SHA-3-384" as a supported keyed-hash algorithm would require that "SHA-3-384" be selected
as a hash algorithm.
This appendix contains only such "rules" as have been defined by the PP Authors, and does not necessarily
represent all such dependencies in the document.
