RE: [dss] Validation semantics of time-stamping

["John Ross" <Ross@Secstan.com>]

Nick,

To be precise TS 101 733 does not itself make any statement about the
validity of the signature at the time of the timestamp, nor is there any
conformance requirements to do so. It just provides timestamped of the
signature and relevant available data like the certificates, CRL or OCSP
data. So it can be used to verify that a signature was not invalid at a
certain time, if all that information is available. It does not require all
the information to be available before creating the timestamp and without
all the information you cannot be sure that the signature is valid. So the
same applies to XAdES.

JR 

-----Original Message-----
From: Nick Pope [mailto:pope@secstan.com] 
Sent: 26 July 2004 19:08
To: OASIS DSS TC
Subject: [dss] Validation semantics of time-stamping

Following on from the issue that I raised at the DSS conference call ....

I understand that some implementations of the XAdES / TS 101 733
time-stamping attributes / properties are applying the time-stamp after
validation and using this to imply that the signature was valid at the time
given in the time-stamp.

However, I do not believe that there is any standard way to know whether
whether a certain time-stamp is applied only if the signature is known to be
valid at that time.

So I have a question:
 - Is there something that can be added to the XAdES profile or some part of
DSS to enable a party relying on an old signature to be know if the
time-stamp was applied immediately subsequent to successful validation?

Nick




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