PlayStation 3 predicts next US president

[William Allen Simpson]

James A. Donald wrote:
>  Not true.  Because they are notarizing a signature, not
> a document, they  check my supporting identification,
> but never read the document being signed.
> 
This will be my last posting.  You have refused several requests to stick
to the original topic at hand.

Apparently, you have no actual experience with the legal system, or
are from such a different legal jurisdiction that your scenario is
somehow related to MD5 hashes of software and code distribution.

Because human beings often try to skirt the rules, there's a long
history of detailed notarization requirements.  How it works here:

(1) You prepare the document(s).  They are in the form prescribed by law
-- for example, Michigan Court Rule (MCR 2.114) "SIGNATURES OF ATTORNEYS
AND PARTIES; VERIFICATION; EFFECT; SANCTIONS"

(2) The clerk checks for the prescribed form and content.

(3) You sign and date the document(s) before the notary (using a pen
supplied by the notary, no disappearing ink allowed).

(4) The notary signs and dates their record of your signature, optionally
impressing the document(s) with an embossing stamp (making it physically
difficult to erase).

You have now attested to the content of the documents, and the notary has
attested to your signature (not the veracity of the documents).  Note
that we get both integrity and non-repudiation....

The only acceptable computer parallel would require you to bring the
documents to the notary, using a digital format supplied by the notary,
generate the digital signature on the notary's equipment, and then the
notary indempotently certify your signature (on the same equipment).

In the real world, the emphasis is on binding a document to a person, and
vice versa.  Any digital system that does not tie the physical person to
the virtual document is not equivalent.

This is simply not equivalent to a site producing its own software and
generating a hash of its own content.  There should be no third party
involved as a certifier.


> If they were to generate an MD5 hash of documents
> prepared by someone else, then the attack described
> (eight different human readable documents with the same
> MD5 hash) works.
> 
If a notary were to do that, they'd be looking at a fairly severe penalty.
By definition, such a notary was compromised.

But nothing like the prison sentence that you'd be facing for presenting
the false documents to the court.  And I'd be pushing the prosecutor for
consecutive sentences for all 8 fraudulent documents, with enhancements.

Nobody has given any examples of "human readable documents" that will
produce the same hash when re-typed into the system.  All those proposed
require an invisible component.  They are "machine readable" only.

That's why we, as security analysts, don't design or approve such systems.
We're not (supposed to be) fooled by parlor tricks.

---------------------------------------------------------------------
The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo at metzdowd.com