A New Forward-Secure Proxy Signature Scheme

Based on the shortcomings of WCF scheme, this paper proposed an improved forward-secure proxy signature scheme. The new scheme does not evolve the authorized keys, but the proxy signer´s private key, making it have the forward security. Even if the proxy signer´s signature key at a certain time segment is given away, the attacker could not get the proxy signer´s signature key in the previous time segment. Under these assumptions of strong RSA problem, computational Diffie-Hellman problem being hard, and discrete logarithm problem being hard in a finite field, the scheme has favorable security.