The COSE HPKE draft has this security consideration:

   The COSE_Encrypt structure MUST be authenticated using COSE
   constructs like COSE_Sign, COSE_Sign1, COSE_MAC, or COSE_MAC0.

It is really good this text is there, but I’d like to tweak it a bit:

Change MUST to SHOULD because there are (theoretically) cases where 
authenticity is not needed.  Perhaps some comment that most use cases will need 
authenticity to defend against forgery attacks — the attacker is likely to have 
access to the recipients public key. (Also prefer to avoid 2119 terms belong in 
security considerations).
Say that the AEAD in HPKE base_mode is not a substitute for the authenticity 
provided by COSE_Sign and such.

LL

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