Research On Proxy Signture Schemes

Along with the development of computer and network communication technology, digital signature arises at the historic moment. The proxy signature is one kind of special signature, it was proposed for the first time by Mambo,Usudu and Okamoto 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 message on behalf of the original signer. Proxy signature schemes find applications in a variety of computing environments such as mobile communication, mobile agents, electronic commerce, electronic voting, electronic auction etc.Combined with some other digital signature schemes, in this paper, some proxy signature schemes are studied. The main contributions are as follows.(1) Through the cryptanalysis of Dai et al.'s designated-receiver proxy signature scheme and Xue et al.'s threshold proxy signature scheme using self-certified public keys, it was found that these schemes were both insecure against the forgery attack. To eliminate the weakness of two schemes, improved schemes which satisfy the required secure properties of the proxy signature are proposed, respectively.(2) A first class of blind proxy multi-signature scheme and a second class of blind proxy multi-signature scheme on the combination of proxy multi-signature and blind signature were proposed by Kang et al. However, it is found that the first class of blind proxy multi-signature scheme suffers with message owner's forgery attack, original signer's forgery attack and proxy signer's inside forgery attack. Based on the analysis of forgery attacks, an improvement to mend the security leaks was proposed, which overcame the disadvantages and retained the merits of the original blind proxy multi-signature scheme.(3) Based on the elliptic curve, a new multi-proxy multi-signature scheme is proposed. Furthermore, we also analyzed the new scheme's security problem. In this scheme, an original group of signers can authorize a group of proxy signers under the agreement of all singers, and only all singers in proxy group can generate multi-proxy multi-signatures instead of the original group of signers. (4) Based on the two-party Schnorr signature, a new designated-verifier proxy blind signature scheme is proposed. In this scheme, only the recipient can recover the message and verify the signature. Through performing a zero-knowledge protocol, the recipient can prove validity of signature to a third party.(5) In this paper, we give a formal definition of proxy multi-signcryption scheme and propose the ID-based proxy multi-signcryption scheme. Finally, we prove new signacryption scheme having high security.