[Babel-users] Blake2S, blake2B or neither? [was: rather than ripemd160...]

[Juliusz Chroboczek]

>> (1) leave the document as it is;
>> (2) add a mention that implementation of Blake2S is RECOMMENDED (SHOULD);
>> (3) add a mention that implementation of Blake2B is RECOMMENDED;
>> (4) add a mention that implementation of both 2B and 2S is RECOMMENDED.

> I'm in favour of (2).

Where is Blake2S-based HMAC defined?  RFC 7693 merely says:

   BLAKE2 does not require
   a special "HMAC" (Hashed Message Authentication Code) construction
   for keyed message authentication as it has a built-in keying
   mechanism.

but it does not appear to clearly define the HMAC construction.