Existential Forgery Attack The attacker tries to find a pair of a message and its signature from the public key (m, s): pair of pu olic ublic key Existential message Forgery Attacker and signature (d: secret key The message of the pair may have no meanings 1717 Existential Forgery Attack Existential Forgery Attacker public key (m,s): pair of message and signature. The attacker tries to find a pair of a message and its signature from the public key. The message of the pair may have no meanings. (d: secret key )