Re: [lamps] draft-housley-lamps-crmf-update-algs - proposal on adding text regarding iterationCount and pwd quality

[Jonathan Hammell <[e-mail]>]

Russ:
> > However, I'm concerned about the ASN.1 for PBMParameter Section 4.4 of
> > RFC 4211 for the following reasons.  If one wanted to use scrypt (RFC
> > 7914) for the owf, there is duplication of the salt parameter and the
> > iterationCount in PBMParameter would no longer be relevant.  One might
> > even want to use Argon2 (draft-irtf-cfrg-argon2), but unfortunately
> > there is no ASN.1 module in that I-D to specify parameterization.  I
> > realize that backwards compatibility needs to be maintained for
> > PBMParameter so those parameters cannot be made OPTIONAL, but perhaps
> > some guidance like the following should be added?
> >
> >  "If a salt value is specified in the AlgorithmIdentifier parameters
> > for owf (such as in [RFC7914]), the salt value in PBMParameter MUST
> > NOT be used and it SHOULD be the zero-length octet string.  Similarly,
> > if the mechanism specified in owf has its own cost parameter for
> > deriving a key (such as in [RFC7914]), then the iterationCount value
> > in PBMParameter MUST NOT be used and it SHOULD be set to 0."
>
> I do not think I agree.  If you want to use one of these other constructions, wouldn't completely replace id-PasswordBasedMAC?

You would not be able to just replace id-PasswordBasedMAC with
id-scrypt since you need the specification for the MAC construction to
perform the proof of possession.  However, you are right, it might be
best to use a new OID and define a new parameters structure to use a
MAC with one of these alternative PBKDF mechanisms.

Best regards,
Jonathan