[31215] in cryptography@c2.net mail archive
Re: Interesting bit of a quote
daemon@ATHENA.MIT.EDU (Jason Holt)
Sun Jul 16 11:14:32 2006
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Sat, 15 Jul 2006 04:28:31 +0000 (UTC)
From: Jason Holt <jason@lunkwill.org>
To: "Travis H." <solinym@gmail.com>
Cc: David Mercer <radix42@gmail.com>, cryptography@metzdowd.com
In-Reply-To: <d4f1333a0607142022p733f3d1at187f06f8323969db@mail.gmail.com>
On Fri, 14 Jul 2006, Travis H. wrote:
> Absent other protections, one could simply write a new WORM media with
> falsified information.
>
> I can see two ways of dealing with this:
>
> 1) Some kind of physical authenticity, such as signing one's name on
> the media as they are produced (this assumes the signer is not
> corruptible), or applying a frangible difficult-to-duplicate seal of
> some kind (this assumes access controls on the seals).
> 2) Some kind of hash chain covering the contents, combined with
> publication of the hashes somewhere where they cannot be altered (e.g.
> publish hash periodically in a classified ad in a newspaper).
My MS Thesis was on this topic:
http://lunkwill.org/cv/logcrypt_update.pdf
If you store a value with a TTP (say, an auditor), and follow the protocol
honestly, it's impossible to go back later and falsify records. The symmetric
version uses hash chains, and was invented several times before I came along.
-J
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