Digital signatures 165
25. Suppose you intercept the following message and RSA signature, with
the parameters from the previous question:
150 dollars
56840167481593713576269217621738921774093
Show how to use the factor command to break this system, and send
on the amended message
250 dollars
with a digitally forged signature.
26. Now try with the public key
n = (6
67
− 1)/5, e = 17
to verify the RSA signature:
Please feed my dog!
626856799200851747349472197394071658906087003772992
27. For a Rabin signature scheme, I provide the public key N = (7
47
−1)/6,
which I know can be factorized into two large primes .
Check the following message and signature:
Arrive Thursday.
77982630048255907681798126464740755348
28. For an El Gamal signature scheme, I choose the next ...