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mlswg / mls-implementations

Coordination of implementation and interop specific details
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passive-client-welcome: invalid key size for MLS_256_DHKEMP521_AES256GCM_SHA512_P521 #183

Closed emersion closed 5 months ago

emersion commented 5 months ago

Test vectors indices 32, and 34 to 39 inclusive have an encryption private key size of 65 and a cipher suite set to MLS_256_DHKEMP521_AES256GCM_SHA512_P521. This doesn't match the requirement of a private key length of 66 in RFC 9180 section 7.1 for DHKEM(P-521, HKDF-SHA512).

emersion commented 5 months ago

Interestingly, test vector index 33 is the only other vector using MLS_256_DHKEMP521_AES256GCM_SHA512_P521, and has a correct encryption private key size of 66.

OtaK commented 5 months ago

I'd recommend looking at this issue https://github.com/mlswg/mls-implementations/issues/176#issuecomment-1817043142

You need to prepad keys with 0x00 to reach 66 bytes.

emersion commented 5 months ago

Ah, yes, indeed. Closing as a duplicate.