[43100] in Cypherpunks
Re: expiration dates on cryptography
daemon@ATHENA.MIT.EDU (David E. Smith)
Wed Nov 8 11:14:07 1995
Date: Wed, 08 Nov 1995 09:39:29 -0600
To: John Curtis <jbell@capecod.net>
From: "David E. Smith" <dsmith@midwest.net>
Cc: cypherpunks@toad.com
At 07:21 AM 11/8/95 -0500, John Curtis wrote:
>Given that trust is often of an ephemeral nature, it would be
>quite useful to set time limits on secrets. Would it be possible
>to cryptographically protect a secret such that it could not be
>decrypted after a certain time?
It's a nice idea, really. The problem is - how do you verify the
absolute time? For instance, by resetting a PC's internal clock
you can instantly circumvent that measure. Possibly by forcing
the application to consult a "reliable" clock like one of the
cesium clocks, but that could be hacked.
Unless you can absolutely, reliably, and without fear/danger of
being hacked around, verify the correct time, self-destruct crypto
probably won't happen.
----- David E. Smith, dsmith@midwest.net, PGP ID 0x92732139
http://www.midwest.net/scribers/dsmith
