The Design Of The Two Digital Signature Schemes

The emergence of computer network indicates that people have entered an era of information technology and the popularity of the Internet, more network applications permeate people's daily life and is also an important tool to promote social development.As a valuable resource, information has become a hot issue for people to pay attention to keep it safe and not to be transferred and stored. As the core and foundation of information security, cryptography plays an important role in the area of information security. In cryptography, there is an important branch of digital signature, which has been widely studied by scholars because of its unique function and application value.Proxy signature and undeniable signature are two kinds of special digital signatures. The special feature of proxy signature is that the original signer can delegate the signature power to the proxy signer and the proxy signer represents the signature. The uniqueness of the undeniable signature is that the verifier would not be able to verify the validity of the signature, without the cooperation of the signer. Such characteristics make it be widely used in Electronic Commerce and Electronic Government, so it is the focus of scholars and become a hot research topic.This paper mainly bases on Mambo's proxy signature scheme, Chaum and van Ant-werpen's undeniable signature scheme. Under the assumption that it is hard to solve the Computational Diffie-Hellman problem, the Computational Bilinear Diffie-Hellman problem and the Decisional Bilinear Diffie-Hellman problem. On the identity of the proxy signature and undeniable signature were studied in the random oracle model. The main results are as follows:1. We proposed a new identity-based strong designated verifier proxy signature and proved unforgeability and untransferability under the random oracle model. Besides,compared to other similar scheme, our scheme is much more efficient.2. We proposed a new provably secure undeniable signature scheme based on identity,we also proved its unforgeability and invisibility in the random oracle model. Besides,compared to other similar scheme, our scheme is much more efficient.