Short computational Diffie-Hellman-based proxy signature scheme in the standard model

Proxy signature is an important delegation technique. It allows that the original signer delegates his or her signing capability to a proxy signer that can generate valid signatures on behalf of the original signer. Until now, most of proxy signature schemes only were proven secure in the random oracle model. And the length of a proxy signature is usually a sum of the lengths of two signatures in most of the proxy signature schemes. Therefore, the factors make the proxy signature unsuitable for many applications with the constrained space or bandwidth. In this paper, we propose a novel short proxy signature scheme in the standard model. And the scheme is probably secure in the standard model. Compared with all existing proxy signature schemes without random oracles, the scheme achieves the following advantages: stronger security, shorter system parameters, shorter signature length and higher efficiency. To the best of our knowledge, this is the first shortest proxy signature scheme in the standard model, whose length is only 320 b for practical 80-bit security level and the same as that of Digital Signature Algorithm. Copyright (C) 2012 John Wiley & Sons, Ltd.