New Nominative Proxy Signature Scheme for Mobile Communication

Recently, Park and Lee [6] proposed the nominative proxy signature scheme for mobile communication. In [6], they argued that their scheme satisfies the following security requirements: user anonymity, authentication and non-repudiation. However, in this paper, we show that their scheme does not satisfy the non-repudiation among their security requirements. And then we propose a new nominative proxy signature scheme that solves the weakness of their scheme. Unlike their scheme, our scheme provides a non-repudiation property and moreover, it does not need a secure channel between the original signer and the proxy signer.