Nonrepudiable Proxy Multi-Signature Scheme

The concept of proxy signature introduced by Mambo,Usuda, and Okamoto allows a designated person, called a proxy signer,to sign on behalf of an original signer. However, most existingproxy signature schemes do not support nonrepudiation. In this paper,two secure nonrepudiable proxy multi-signature schemes are proposed thatovercome disadvantages of the existing schemes. The proposed schemes canwithstand public key substitution attack. In addition, the new schemeshave some other advantages such as proxy signature key generation andupdating using insecure channels. This approach can also be applied toother ElGamal-like proxy signature schemes.