Re: [Cfrg] hpke which HKDF to use for eae_prk?

[Stephen Farrell <[e-mail]>]

Hiya,

On 20/08/2020 19:53, Stephen Farrell wrote:
> 
> 
> On 20/08/2020 19:42, Richard Barnes wrote:
>> I think the spec is right here.  The DHKEM instances are defined with a
>> curve and a KEM, so assuming your descriptor "x25519,hkdf-sha512,aesgcm128"
>> is meant to be "KEM,KDF,AEAD", it's either incomplete or it represents a
>> DHKEM instance that isn't defined in the document.  In the schemes in the
>> document, the KDF in DHKEM is matched to the size of the curve, so x25519
>> goes with SHA-256.
> 
> Could be. Lemme delve a bit more into the openssl APIs
> to see if that's easily extracted or needs some new
> config before I give up :-) That'll be tomorrow. That
> said it still seems unnatural to have an IANA registry
> for KDFs as part of the ciphersuite and yet use something
> else at this point in the process.

Just to close the loop: I fixed this on my end and
agree the spec was correct.

Cheers,
S.

PS: With that and the x-coord thing, I'm now able
to verify all the base mode test vectors that were
updated yesterday. Will move on to auth/psk/pskauth
in a bit.