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

[Russ Housley <[e-mail]>]

Jonathan:

>>> 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.

It seems like a two page document + boilerplate.

Russ