

Hash escrow - Boxer
http://pdf23ds.net/2010/09/28/hash-escrow/

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spinron
What's actually needed is a secure time stamping service. You can read about
those at:

<http://en.wikipedia.org/wiki/Trusted_timestamping>

A personal favorite which I highly recommend is the following:

<http://www.itconsult.co.uk/stamper.htm>

Under normal circumstances, one would need an expert witness to authenticate
the signature, but in several jurisdictions which enacted digital signature
laws statues, that may not be necessary depending on the evidentiary status of
e-signatures.

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JulianTosh
ah ya beat me to it. double vote for bamf right here.

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kijinbear
These guys did exactly what's being proposed in the article.

<http://www.win.tue.nl/hashclash/Nostradamus/>

In November 2007, they posted the MD5 hash of a PDF file containing the name
of the winner of the 2008 election. That of course doesn't prove that they
knew who would win the election, because they prepared 12 different PDFs with
12 different names in it, all of which were crafted to generate the same MD5
hash. I don't think the hypothetical jury is going to like it.

Okay, let's try again with SHA256...

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drv
The article mentions hashing the same data with multiple hashing algorithms; I
would think this would be effective at preventing collisions (presumably
different hashing algorithms are not vulnerable to the same collision
attacks).

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zxer
Isn't this whole timestamping thing overcomplicated? Just set up a twitter
account and post the hash codes. The code in itself is useless, so it does not
have to be kept secret, and you will have a way to proof that you had the
document generating it at that time.

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bcl
This would work if you could search all of your tweets. I don't think that is
currently possible, is it?

It also assumes that twitter is going to be around when you finally need the
timestamped hashes, and that you can prove that twitter (or any other service
for that matter) can't have back-dated hashes inserted.

Posting to a usenet group, like alt.test, where independent systems store and
timestamp the message would be a better idea.

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mthoms
Why not just use multiple webmail services?

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pmjordan
Email timestamps are laughably easy to fake.

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mthoms
Surely Google et al, record the _actual_ arrival time of the email in the
headers do they not?

If not, then I'm sure they do in their logs.

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pmjordan
What stops you copying in a crafted email via IMAP, though?

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ErrantX
_In criminal cases I can see it often being necessary to within a day or two_

Oh, if only. Digital evidence is seeing a lot more acceptance in recent years
- but just recently there has been a sudden resistance to it, partly, I think,
because of all the noise being made in the media about the ease of faking such
things and the prevalence of viruses.

Oftentimes an audio recording tagged to within a couple of days will be fine.

But don't rely on that - it could easily be rejected out of hand by a judge
who is not convinced.

Any sort of ambiguity in digital evidence and timestamps is being frowned on
at the moment - at least here in the UK.

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thereticent
Is there anything wrong with the idea in the first blog comment? I would think
sending the hashes to one or more webmail accounts in your own name would
accomplish the feat of proof, and it would not require you to rely on other
people to safeguard the data or give testimony.

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JoachimSchipper
How do you prove the e-mail wasn't changed? At least gmail allows you to
upload pretty much anything (which is useful when migrating mail), and may not
be able/willing to turn over (old) logs.

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DennisP
If they were simply unwilling, a subpoena would fix that.

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nodata
<http://www.registeredcommons.org/>

