PlayStation 3 predicts next US president

William Allen Simpson william.allen.simpson at
Mon Dec 3 08:47:09 EST 2007

Dirk-Willem van Gulik wrote:
> Keep in mind that the notary is still 'careful' -- effectively they sign 
> the hash -- rather than the document; and state either such (e.g. in the 
> case of some software/code where you do not hand over the actual code) 
> or state that _a_ document was presented with said hash.
And that makes all the difference.  The digital notary is not certifying the
original document.  You described the notary generating its own tuples
(credentials as presented, the hash, a timestamp, and a notarized declaration
that such was presented).  There is no problem, and the described attack does
not apply.

Note that the notary bears no responsibility for presentation of false
credentials.  Here, in a case with which I'm personally familiar, somebody
with the SAME NAME as his father got a new driver's license, signed it in
the same fashion as his father, then went to banks and presented the
driver's license and signature, causing all his father's deposits to be
transferred to his wife's name, and adding his son to the house deed (and
then mortgaging the house).  It was certainly not the several notaries'
fault that identical names were used.  The "certificate" (same name driver's
license and signature) appeared valid.

All the cryptography in the world will not prevent false certification,
where the underlying information is already compromised.

To reiterate the topic at hand: trust is not transitive!

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