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TD0695:  Choice of 128 or 256 bit size in AES-CTR in SSH Functional Package.

Publication Date

Protection Profiles

Other References
Section 1.3, FCS_COP.1

Issue Description

Section 1.3 of the SSH Functional Package incorrectly states that key sizes of both 128 and 256 are required for AES-CTR, when either one could be included depending on the algorithms selected.


The explanation for component FCS_COP.1 in Section 1.3 of SSH Functional Package v1.0 is modified as follows, with yellow highlight indicating additions and strike through red highlights indicating deletions:



To support the cryptography needed for SSH communications, the incorporating document must include FCS_COP.1 (iterating as needed) to specify AES with corresponding key sizes and modes, digital signature generation and verification function (at least one of RSA or ECDSA), a cryptographic hash function, and a keyed-hash message authentication function. In particular, the incorporating document must support AES-CTR as defined in NIST SP 800-38A with key sizes of both 128 orand 256 bits, depending on the algorithms selected.


Some PPs (such as OS PP v4.3) do not use 128 bit size.

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