Security analyses of an ID-based aggregate signature scheme presented by Song, Kim, Lee and Yoon were given in this paper. It is found that the scheme is universally forgeable. We presented a new identity-based aggregate signature scheme from bilinear pairings. Its security proof was given in the random oracle model and it could be tightly reduced to computational Diffie-Hellman problem. Compared with the existing ID-based aggregate signature schemes, our scheme greatly improves the efficiency of signature communication and verification since the verification algorithm only requires 3 pairing evaluations and the size of the signature generated by our scheme is only about 320 bits.
