A fault-tolerant conference key distribution scheme based on mechanism of identity-based cryptography and (t,n) threshold secret sharing is proposed in this paper This scheme is much different to traditional ones, its secret shadows are not brought from the sponsor of conference, but from each server's private key signature. By getting together these n secret shadows, the sponsor can construct polynomial. Any of conferees invited by the sponsor can request these secret shadows from t of these n servers, and then restitute conference key by them. In all courses of conference key distribution and reconstruction, every member's identity can be easily validated, so it can be prevented from all kinds of cheat

We propose an identity-based proxy ring signature scheme from bilinear pairings which combines the advantages of proxy signature and of ring signature. Furthermore, our scheme can prevent the original signer form generating the proxy ring signature, thus the profits of the proxy signer are guaranteed. We introduce bilinear pairings to minimize the computation overhead and to improve the related performance of our scheme. As compared with Zhang's scheme, our scheme is a computational efficiency improvement for signature verification because the computational cost of bilinear pairings required is reduced form O(n) to O(1). In addition, the proxy ring signature presented in This work is signer ambiguous, nonforgeable, verifiable, nonrepudiable and identifiable.

We propose an identity-based proxy blind signature scheme from bilinear pairings which combines the advantages of proxy signature and of blind signature. Furthermore, our scheme can prevent the original signer from generating the proxy blind signature, thus the profits of the proxy signer are guaranteed. We introduce bilinear pairings to minimize computational overhead and to improve the related performance of our scheme. In addition, the proxy blind signature presented in This work is nonrepudiable and it fulfills perfectly the security requirements of a proxy blind signature.

We propose a new micropayment scheme in which possible overspending is radically reduced by the adoption of probabilistic polling in a transaction. On the other hand, the losses caused by a dishonest overspending consumer must be shared by banks and merchants, furthermore, an iterative interactive payment protocol is performed which protects the profits of both consumers and merchants. Compared with PayWord, the fairness of our scheme is much higher and restricted anonymity of a customer is provided.