An Efficient Proxy Signature Scheme with Full-delegation

Proxy signature is a new signature type and allows an original signer to delegate his signing rights to a proxy signer. At present, most of proxy signature schemes are based on the warrant. Thus the signature produced by the proxy signer is different with the signature produced by the original signer. While, in some cases, we only need the own signature of the original signer. The traditional way to achieve is to send the private key of the original signer to the proxy signer, while the original signer cannot do so. In this work, we propose a novel proxy signature scheme with full-delegation to solve the problem above. Our proposed proxy signature scheme with full-delegation is the genuine simulation of written-hand proxy signature. It allows an entity to produce a signature on behalf of the original signer. But, any one cannot distinguish that the signature is produced by the original signer or by the proxy signer. And we show that the security of the scheme is related to the difficulty of solving the discrete logarithm problem in random oracle model.