ietf-smime
[Top] [All Lists]

Re: CMS attributes question

2009-03-19 16:23:45

Some specification that make use of CMS mandate support for additional attributes. These attributes are vital in the application environment. I know that S/MIME requires support for some, and recommends support for a few others. I think that time stamps are in a similar situation.

Russ

At 04:31 AM 3/19/2009, Julien Stern wrote:
Russ,

thank you for your answer.

Isn't it dangerous to ignore a _signed_ attribute ?
In the case of an attribute such as ESSCertID or ESSCertIDV2 (RFC 2634 ou RFC 5035), an implementation ignoring the attribute can give inconsistent results versus a implementation not ignoring the result (e.g. the signature is valid vs the signature has been forged).

Also, when you are writing the these attributes are ignored, do you mean that they MUST be ignored or that they MAY be ignored? E.g. if my implementation fails upon receiving a signature with an unknown signed attribute, would you consider this non-standard? Or is this behavior up to the implementor?

Regards,

--
Julien


Russ Housley a écrit :

Unrecognized attributes are ignored. RFC 3852 requires support for the content type and message digest attributes, but all others can be ignored if they are not recognized.

Russ

At 01:40 PM 3/18/2009, Julien Stern wrote:

Hi list,

We have a question related to CMS that was raised during an ETSI session around the CAdES standard:

we were wondering whether the behavior of an implementation encountering an unknown attribute was defined. One line of thinking is that an _unsigned_ attribute can be ignored by an implementation, but that the signature validation should fail if an unknown _signed_ attribute is encountered.

Is this behavior somehow defined in CMS (I did not see it, but I might have missed it)? Otherwise, what do you think? What does your implementation do when it encounters an unknown signed attribute?

Regards,

--
Julien

<Prev in Thread] Current Thread [Next in Thread>