Binary: http://goo.gl/OeuWCD

We was given 70 lines of text, each line had format (*h*, *r*, *s*), with *h* is SHA1 hash of a message *m*, and pair (*r*, *s*) is digital signature of message *m* using ElGamal signature scheme. And our task is to “sign” a message, “*Mat3CtfDummyPKI*“. At a glance we can easily recognize that *r* is repeated, it means that the signer use same random value *k* to sign every messages. This mistake can lead us to recover the random value *k*, and after that, the secret key *x,* so we can sign with our own message.* * After a few minutes searching, I had found something great. A guy answers this question on crypto.stackexchange.com and explains the method to solve this task very easy to understand.

Now it is easier, write a small script to solve it.