An Improved ID based Proxy Signature Scheme based on Elliptic Curve Cryptography

摘要

Proxy signature schemes allow the original signer of a message to delegate his signing capability to a proxy signer to generate a valid proxy signature on behalf of the original signer. One such scheme is proposed by Zhang and Kim which is based on Elliptic Curve Cryptography and Identity based Signature. However, Zhang's scheme requires secure channel for transmission of private key, has no provision of private key revocation and signature verification by any user. In this paper, we propose an improved ID based proxy signature scheme based on bilinear pairing. The scheme employs Knapsack algorithm for key distribution which eliminates the need for secure channel for sending the private keys from Private key generator (PKG) to respective users. The scheme also supports private key revocation by concatenating time parameter with public key of proxy signers. The signature can be verified only by a designated verifier. It is shown that the proposed proxy signature scheme satisfies all security requirements. Finally, the proposed proxy signature scheme is compared with that of Zhang and Kim's scheme and is shown to have merits over the latter one. Therefore, the proposed scheme can be a potential candidate for implementation of future proxy signature schemes.