[Cryptography] Two distinct DSA keys sign a file with the same signature. Is this repudiation issue?

Georgi Guninski guninski at guninski.com
Tue Sep 27 14:03:43 EDT 2016


On Tue, Sep 27, 2016 at 12:20:29PM +0300, Georgi Guninski wrote:
> Two distinct DSA keys sign a file with the same signature. Is this repudiation issue?
>

Offlist and on the cypherpunks list, some people suggested that I don't
check correctly the signatures or am using the _same_ key.

This is not the case, since with the ``paired keys'' I checked:

-- toy implementation in Sage
-- python's Crypto.*.DSA
-- in openssl random similar key fails to verify the signature with
exactly the same openssl command
-- the parameters of the paired keys are different, counting
congruences, since they were generated by a proggie.

 


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