A provably secure ID-based ring signature scheme

Identity-based (ID) cryptosystems avoid the necessity of cer-tiicates to authenticate public keys in a digital communications system. This is desirable, specially for these applications which involve a large number of public keys in each execution. For example, any computation and veriication of a ring signature, where a user anonymously signs a message on behalf of a set of users including himself, requires to authenticate the public keys of all the members of the set. We use bilinear pairings to design a new ID-based ring signature scheme. We extend to the ID-based scenario some known results about the security of generic ring signature schemes. This allows us to formally prove the security of our scheme, under the assumption that the Computational Diie-Hellman problem is hard to solve.