Patent ID: 7822987

Claim:
A non-transitory computer readable medium comprising computer executable instructions for verifying authenticity of messages exchanged between a pair of correspondents in an electronic transaction conducted over a data transmission system, said correspondents each including respective signing and verifying portions of a first signature scheme and a second signature scheme different to said first scheme and utilizing an elliptic curve cryptosystem, said computer executable instructions comprising instructions for a first of said correspondents: obtaining a first signed message from a second of said correspondents, said first signed message having been generated by one of said first and second correspondents signing a message according to a signing portion of one of said signature schemes associated with said one of said first and second correspondents; utilizing said verifying portion of said one signature scheme to verify said first signed message; signing a message by utilizing said signing portion of the other of said signature schemes to provide a second signed message; sending said second signed message to said second of said correspondents to enable said second of said correspondents to verify said second signed message by utilizing said verifying portion of said other of said signature schemes; and rejecting said transaction if either verification fails; wherein signing one of said signed messages and verification of one of said signed messages are performed according to said second signature scheme utilizing the elliptic curve cryptosystem.