Subject: Interpretation of the Timestamp Accuracy

From: "Gary Visser" <[email-masked]>
Date: Mon, 2 Apr 2001 15:40:12 -0700

Up until now I have interpreted the accuracy field of a Timestamp Token to
give an indication as to how accurate the genTime field is in relation to
the actual time of day GMT. In other words its a statement of how accurate
the clock is.

But there is another interpretation, the accuracy is an indication of how
timely the timestamp was created. In other words the accuracy states that
the Timestamp Token was generated within the time span allowed by the
accuracy and not necessarily at the exact time state in the genTime field.
For example: if GMT is 13:00:00, the clock of the TSA is 13:01:00, the
genTime of a timestamp token from this TSA is 13:01:00 and the accuracy is 1
second, then the token may have been created between 12:59:59 GMT and
13:00:01 GMT. There are some other subtlety different interpretations: the
difference in time between when the Timestamp Request was received and when
the Token was issued, the difference in time between when the Request was
validated and when the Token was created, or the difference in time between
the genTime and when the actual timestamp Signature was generated, and so
on.

So I have either overlooked something or there may be an ambiguity in the
draft.

Sincerely,
Gary Visser
Timestamp.com

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From: Denis Pinkas <[email-masked]>
Date: Tue, 03 Apr 2001 13:13:33 +0200

Gary,

> the actual time of day GMT. In other words its a statement of how accurate

It is not a statement of how accurate the clock is.

The text says:

By adding the accuracy value to the GeneralizedTime, an upper limit 
of the time at which the timestamp has been created by the TSA can 
be obtained. In the same way, by subtracting the accuracy to the 
GeneralizedTime, a lower limit of the time at which the timestamp 
has been created by the TSA can be obtained.

> accuracy and not necessarily at the exact time state in the genTime field.

This is along the lines of the right interpretation.

Regards,

Denis

> 13:00:01 GMT. 
> There are some other subtlety different interpretations: the