Re: [lamps] Call for adoption of draft-housley-lamps-cms-aes-mac-alg

On Fri, Nov 13, 2020 at 2:06 PM Russ Housley <housley@vigilsec.com> wrote:
>
> I was unaware of the ISO/IEC 9797-3 OID, which seems to allow any block cipher, and thus is not able to constrain the tag length based on the specifics of that block cipher.

That is true that 9797-3 does not constrain the tag length based on
the block cipher.  In the normative text for GMAC, it states "GMAC can
be used with any block cipher from ISO/IEC 18033-3 that has a block
length of 128 bits. The resulting MAC is t bits long, where t is a
multiple of 8 and satisfies 64 ≤ t ≤ 128."

Jonathan

> > On Nov 13, 2020, at 1:42 PM, Jonathan Hammell <jfhamme.cccs@gmail.com> wrote:
> >
> > I support adoption of this draft.
> >
> > For reference, the ASN.1 module including GMAC in ISO/IEC 9797-3 specifies:
> > is9797-3 OID ::= {iso standard message-authentication-codes(9797) part3(3)}
> > id-gmac OID ::= {is9797-3 gmac(4)}
> > GmacParameters ::= SEQUENCE {
> >    bcAlgo BlockAlgorithms,
> >    taglength INTEGER,
> >    noncelength INTEGER
> > }
> >
> > where bcAlgo would specify AES-128, AES-192 or AES-256.  Matching
> > other algorithms in 9797-3, the nonce is assumed to be transmitted
> > separately.
> >
> > However, I think the definition of GMACParameters in your I-D makes more sense.
> >
> > Best regards,
> > Jonathan
> >
> > On Fri, Nov 13, 2020 at 9:12 AM Russ Housley <housley@vigilsec.com> wrote:
> >>
> >>
> >>
> >>> On Nov 12, 2020, at 5:10 PM, Michael Richardson <mcr+ietf@sandelman.ca> wrote:
> >>>
> >>> Signed PGP part
> >>>
> >>> Tim Hollebeek <tim.hollebeek=40digicert.com@dmarc.ietf.org> wrote:
> >>>> https://www.ietf.org/archive/id/draft-housley-lamps-cms-aes-mac-alg-00.txt
> >>>
> >>>
> >>>
> >>>> Please indicate by November 25th whether you support adoption of
> >>>> draft-housley-lamps-cms-aes-mac-alg by the LAMPS WG.
> >>>
> >>> Seems short and to the point.
> >>>
> >>> An example message in an appendix would be nice.
> >>
> >> Sure.  That is something I can do in the next version.
> >>
> >> Russ
> >>
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>