[TriLUG] OT: crytographic timestamps

[Steve Holton]

The typical protocol is:

1. make a cryptographic hash of the file you need to timestamp.
2. publish the hash in a well-known location (like the "personals" section
of the New York Times, or whatever equivalent.)
3. retain a physical copy of the published hash, as well as a copy of the
file you hashed as your proof.

To substantiate your claim, you produce the original file, hash the contents
again to produce your hash, and compare it to the public library's copy of
the hash in the paper.

To make this work, the publicly-kept hash has to be secure against
tampering. It's cost prohibitive to try to change every copy of the New York
Times, but that might not be the case if the publicly-held copy exists only
on the Internet.

IIRC there are timestamping services which offer models similar to this for
a fee, but i have never researched them.


On Fri, Apr 18, 2008 at 12:44 PM, Joseph Mack NA3T <jmack at wm7d.net> wrote:

> I'm writing some proprietary code at home in stages and will
> be submitting it remotely. It would be helpful if I could
> conveniently show the date that I submitted each stage. One
> way I can think to do this is to cryptographically timestamp
> it. This in turn needs a trusted timestamp authority (TSA).
> The only FOSS TSA project I could find with google appears
> to have died (at least from timestamps on the postings).
> There are plenty of people selling proprietary TSA hardware.
> If it comes to that, I'll just do without.
>
> Alternately I could swipe some time sensitive material from
> an on-line news source and cryptographically encapsulate
> that in the code. This would give me a "no older than" date,
> which is not terribly useful.
>
> I would like this to be as paperless as possible, as I may
> need to keep records for a long time (10yrs). eg I don't
> really want to go to the Post Office and collect pieces of
> paper, saying when I mailed the code.
>
>
> Any ideas?
>
> Thanks Joe
>
> --
> Joseph Mack NA3T EME(B,D), FM05lw North Carolina
> jmack (at) wm7d (dot) net - azimuthal equidistant map
> generator at http://www.wm7d.net/azproj.shtml
> Homepage http://www.austintek.com/ It's GNU/Linux!
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-- 
Steve Holton
sph0lt0n at gmail.com