Subject: [Cfrg] GMAC algorithm

From: "Erik Andersen" <[email-masked]>
Date: Wed, 8 Apr 2020 16:59:48 +0200

I am trying to find the exact definition of the GMAC algorithm, inclusive
the OID. I have checked ISO/IEC 9797-3, which refer to ISO/IEC 18033-3. They
seems to use an OID structure very different from NIST and IETF. For
example, for AES they use the key length as a parameter, while NIST and IETF
defines a separate algorithm for each key length. Also, the OIDs are quite
different.

What is the IETF view on the GMAC algorithm?

Best regards,

Erik

---

From: Michael StJohns <[email-masked]>
Date: Wed, 8 Apr 2020 13:12:16 -0400

On 4/8/2020 10:59 AM, Erik Andersen wrote:
>
> I am trying to find the exact definition of the GMAC algorithm, 
> inclusive the OID. I have checked ISO/IEC 9797-3, which refer to 
> ISO/IEC 18033-3. They seems to use an OID structure very different 
> from NIST and IETF. For example, for AES they use the key length as a 
> parameter, while NIST and IETF defines a separate algorithm for each 
> key length. Also, the OIDs are quite different.
>
> _______________________________________________
> Cfrg mailing list
> [email-masked]
> https://www.irtf.org/mailman/listinfo/cfrg

Hi Erik -

GMAC isn't generally used as a standalone, but when it is, it's 
basically GCM with nothing encrypted (e.g. no plaintext, only AAD), so 
use the various NIST AES OIDS for those.

aes OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)
           organization(1) gov(101) csor(3) nistAlgorithm(4) 1 }

       id-aes128-GCM OBJECT IDENTIFIER ::= { aes 6 }

       id-aes192-GCM OBJECT IDENTIFIER ::= { aes 26 }

       id-aes256-GCM OBJECT IDENTIFIER ::= { aes 46 }

RFC 5084

Mike