Re: secure sign & encrypt

["vedaal" <[e-mail]>]

----- Original Message -----
From: "Terje Braaten" <[e-mail]>
To: "OpenPGP (E-mail)" <[e-mail]>
Sent: Wednesday, May 22, 2002 6:51 AM
Subject: RE: secure sign & encrypt

[...]
> > If there could be a packet added linking the time of
> > encryption to the time
> > of signing,
> > {including elapsed time in seconds [or 0.00x seconds], and
> > therefore not
> > attackable by trying to re-set the re-encrypting
> > computer to the time recorded in the original signed message.}
>
> I do not understand how you intend this packet to be added.
> If it is a signature packet, would not the changes to be done
> be about the same as if we added an 'encrypted to' packet?

Yes,     it could be done your way too, with about the same amount of
change.

I thought that a packet that simply records the elapsed time in fractions of
a second, between signing and encrypting,
could be added without affecting the signature or encryption packets, and
might be easier to implement without affecting
backward compatiblity.

[...]

> If it is not a signature packet, I do not understand what would
> keep the attacker from making a fake timestamp when re-encrypting the
> message.

It would be an 'record of actual elapsed time' packet,  measured from the
time the program calls for the time of signing,
to the time it calls for encrypting.  It would not be 'calculated' by
measuring the recorded (old) timestamp of the signature,
and then re-setting the attacker's computer to the same time and measuring
the fractions of seconds till the encryption.

{ i do not yet know how to read and write code :(  , so it is only my
opinion of what seems plausibly 'do-able' ,
it may be that it has flaws that experienced programmers can instantly see,
if so, i apologize in advance}

--vedaal