[4211] in cryptography@c2.net mail archive
Later validation of Electronic Signatures
daemon@ATHENA.MIT.EDU (Robert Hettinga)
Mon Feb 15 14:01:48 1999
Date: Mon, 15 Feb 1999 11:21:27 -0500
To: cryptography@c2.net
From: Robert Hettinga <rah@shipwright.com>
--- begin forwarded text
Date: Mon, 15 Feb 1999 15:21:57 +0100
Reply-To: Digital Signature discussion <DIGSIG@LISTSERV.TEMPLE.EDU>
Sender: Digital Signature discussion <DIGSIG@LISTSERV.TEMPLE.EDU>
From: Hans Nilsson <hans.nilsson@ID2TECH.COM>
Subject: Later validation of Electronic Signatures
To: DIGSIG@LISTSERV.TEMPLE.EDU
The validation of Electronic Signatures poses several difficult and
interesting problems, in particular when it is necessary to validate an
Electronic signature for example 20 years later, when the signer key has
been compromised and revoked, the CA keys have been compromised, the crypto
algorithm or key length used at the signature time is no longer secure, and
the hash function used
at at the signature time now exhibits message collisions.
The validation problem changes over the different time frames:
- near term, when all involved certificates are still valid and generally
available,
- long term, when one or more of the involved certificates have expired,
- archival, when the initial cryptography used is no longer secure.
Another interesting point to consider is how it is possible to know and
trust the signing time as indicated by the signer.
Denis Pinkas from Bull and I have written a "white paper" which deals with
these kinds of situations and demonstrates the use of time-stamping.
Hopefully this paper can serve as a tutorial to this difficult subject, but
also as input for the discussion of a common validation model for electronic
signatures.The paper can be found at the following addresses:
http://www.id2tech.com/news/pdf/ES_validation.pdf
http://www.openmaster.com/whitepapers/es_validation.pdf
Hope you enjoy it!
Hans Nilsson
iD2 Technologies
Stockholm SWEDEN
http://www.id2tech.com
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-----------------
Robert A. Hettinga <mailto: rah@philodox.com>
Philodox Financial Technology Evangelism <http://www.philodox.com/>
44 Farquhar Street, Boston, MA 02131 USA
"... however it may deserve respect for its usefulness and antiquity,
[predicting the end of the world] has not been found agreeable to
experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'
