Forward-Secure Digital Signatures

Digital signatures, one of the most important components of cryptography, are the base of theory for protecting the integrity and authenticity of information. Base on different applications, all kinds of special digital signatures are used widely and deeply in practice. The theory and security of forward-secure digital signature, key-insulated digital signature and proxy signature are mainly analyzed and studied in this paper. The main results are the following:1. The overview of forward-secure digital signature is presented and generic constructions and security models of forward-secure digital signature are analyzed. Generic constructions and security models of key-insulated digital signature are also studied. Strong (t, N) key-insulated blind signature scheme is proposed, which is stronger security than forward-secure blind signature scheme, and the signing procedure is more efficient and computational cost of verification is smaller. In the random oracle model, the new scheme has been proved against adaptive chosen messageattack.2. Proxy signature is summarized and analyzed. To avoid using the secure channel and immune the transferring attack of the LKK scheme, a revised LKK scheme has been proposed by Lee. However, Guilin Wang et al. pointed out that the revised LKK scheme is still insecure and vulnerable to the forgery attack by the original signer and the original signer changing attack. In this paper, a modification scheme of the revised LKK scheme is introduced, and our scheme is stronger security than the revised LKK scheme.