Cryptanalysis of Short Signature Scheme Without Random Oracles Assumption

This paper presents an attack on a new short signature scheme from bilinear pairing proposed by Dan Boneh et al. at J. Crypt. We show that an attacker can alter the public key of the signer and then can forge the signer´ s signature for any message m. Furthermore, we argue that the well-accepted notion of security for signature schemes, namely existential unforgeability against adaptive chosen-message attacks, is not adequate for the multi-user setting. We firstly define a new notion of security named non-repudiation for the short signature schemes. We believe that the signature scheme, which satisfies non-repudiation, is more secure.