Re: [lamps] Two comments on draft-ietf-lamps-key-attestation-ext

[Russ Housley <[e-mail]>]

Thomas:

I think you are asking for a CMS Content Type OID for Conceptual Message Wrapper.  I'm wondering if two OIDs would be better, one for JSON encoding and one for CBOR encoding.

If this mades sense, then an appendix with the ASN.1 Module is super simple:

   CMWContentTypes
     { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
       smime(16) modules(0) id-mod-contentTypes(TBD1) }

   DEFINITIONS IMPLICIT TAGS ::=
   BEGIN
  
   IMPORTS
     CONTENT-TYPE
     FROM CryptographicMessageSyntax-2009
       { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
         smime(16) modules(0) id-mod-cms-2004-02(41) } ;

   -- Conceptual Message Wrapper (CMW) with JSON encoding

   ct-CMW-JSON CONTENT-TYPE ::=
      { TYPE CMW-JSON IDENTIFIED BY id-ct-CMW-JSON }

   id-ct-CMW-JSON OBJECT IDENTIFIER ::=
      { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
        smime(16) id-ct(1) TBD2 }

   CMW-JSON ::= IA5String

   -- Conceptual Message Wrapper (CMW) with CBOR encoding

   ct-CMW-CBOR CONTENT-TYPE ::=
      { TYPE CMW-CBOR IDENTIFIED BY id-ct-CMW-CBOR }

   id-ct-CMW-CBOR OBJECT IDENTIFIER ::=
      { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
        smime(16) id-ct(1) TBD3 }

   CMW-CBOR ::= OCTET STRING

   END

Of course, you also need an IANA considerations to assign the OID values.

Russ



> On Dec 21, 2022, at 1:56 PM, Thomas Fossati <[e-mail]> wrote:
> 
> Thanks authors for a clear and useful document.
>  
> Would it be possible to get an OID for CMWs [1] alongside WebAuthn?
> That would help the case for passing attestation results when the RA/CA
> cooperates with a separate verifier.
>  
> Another question I have is related to defining a symmetric cert
> extension for carrying attestation evidence & results.
> There is an extension that would do the job defined by the TCG.  Maybe
> this document could reference it?
>  
> cheers, thank you
>  
> [1] https://datatracker.ietf.org/doc/draft-ftbs-rats-msg-wrap/ <https://datatracker.ietf.org/doc/draft-ftbs-rats-msg-wrap/>
>