Re: [Cfrg] GMAC algorithm

[Michael StJohns <[e-mail]>]

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.
>
> What is the IETF view on the GMAC algorithm?
>
> Best regards,
>
> Erik
>
>
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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