Research On Proxy Signature Scheme

Digital signatures, one of the most important components of cryptography, can protect the integrity, authenticity and undeniability of information. Base on different applications, all kinds of special digital signatures are used widely and deeply in practice.The main content of this paper is the research of proxy signature scheme. As a kind of new digital signature schemes, proxy signature is first proposed by Mambo et al. in 1996. In a proxy signature scheme, an original signer is allowed to delegate his signing power to a designed person or group, who is called the proxy signer and can sign messages on behalf of the original signer. Proxy signature plays an important role in some applications such as mobile communication, mobile agents, electronic commerce, electronic voting, electronic auction etc.My contributions are:1. A proxy signature scheme from bilinear pairings is proposed in this paper. We prove it is secure and a little more efficient than Zhang et al.'s scheme.2. The proxy signature scheme of warrant recovery can reduce the communications and increase the efficiency. This paper points out that the proxy signature scheme of warrant recovery proposed by Awasthi and Lal is not secure which doesn't ensure the property of undeniability and gives two improved schemes. And then, the security of the two improved schemes is proved.3. Proposes a forward-secure proxy signature scheme in order to deal with the key exposure problem and prove our scheme is forward secure by updating secret key frequently. When the proxy signature secret key is stolen, the attacker cannot forge the former proxy signature. And then we can reduce the loss, which caused by the key exposure to a great extent.