[Cscwg-public] Invalidity Date

[Corey Bonnell]

Hi Bruce,

I agree that using the invalidityDate CRL entry extension to express when
the key corresponding to a revoked code signing certificate can no longer be
trusted as opposed to the revocation date is conceptually cleaner and more
in line with 5280 (which states that the revocation date SHOULD NOT be
backdated such that it is before the issue date of the latest CRL). 

 

However, in all the documentation I've seen regarding Authenticode, it
appears that the revocation date is the value that is checked by Windows and
invalidityDate is seemingly not used.

 

Could Ian or Mike confirm Windows's behavior in this regard?

 

Thanks,

Corey

 

 

From: Cscwg-public <cscwg-public-bounces at cabforum.org> On Behalf Of Bruce
Morton via Cscwg-public
Sent: Wednesday, August 25, 2021 1:59 PM
To: cscwg-public at cabforum.org
Subject: [Cscwg-public] Invalidity Date

 

CSBR 13.2.1 states: A Certificate MAY have a one-to-one relationship or
one-to-many relationship with the signed Code. Regardless, revocation of a
Certificate may invalidate the Code Signatures on all signed Code, some of
which could be perfectly sound. Because of this, the CA MAY specify a
revocation date in a CRL or OCSP response to time-bind the set of software
affected by the revocation, and software should continue to treat objects
containing a timestamp dated before the revocation date as valid.

 

The CSBRs are referring to "revocation date', which I believe should be
referring to "invalidity date" as specified in RFC 5280,
https://datatracker.ietf.org/doc/html/rfc5280#section-5.3.2.

 

Note that we need to think of the following dates:

*	Valid from
*	Invalidity date
*	Revocation date
*	Valid to

 

The purpose of the Invalidity date is to provide a date in the past, when
the key was compromised. The revocation date would be on the date that the
certificate was revoked and cannot be a past date.

 

Would there be any objections in changing "revocation date" to "invalidity
date" in a future ballot? 

 

 

Thanks, Bruce

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