Research On ID-Based Signature And Signcryption

In the traditional public key cryptosystem, CA certificate is used to provide an assurance of the relationship between the identitity and public key, which is corresponding to its private key. This means that the traditional public key cryptosystem must spend a lot of time and space to calculate and preserve these certificates.In 1984 Shamir first proposed the concept of ID-Based cryptographic system. Public key can be directly obtained from the user's identity information, for example, user's names or email addresses. So that there is no need for certificate in the authentication of public key any more. The proposal advances the traditional certificate PKI a lot.In recent years, various identity-based signature and encryption schemes have been proposed. The safety and efficiency have been continuously improved. However, there is a common problem in these schemes, which is the model must be based on the unconditional trust to the PKG Because PKG has the private key of any user in its domain, it may forge user's signature and decrypt information. To this issue, the major work of this paper is as follows:1,Adoping the formation of the private key generation of CXF scheme, we proposed a new ID-based signature scheme without rusted PKG (Zheng 1). The scheme verifies the system's master key and the user's secret information at the same time. Compared with CXF scheme, the algorithm efficiency has been greatly improved, what's more, we prove that the scheme can be against the existential forgery on adaptively chosen message attack under random oracle model.2,We first proposed an ID-based signcryption without tusted PKG (Zheng2).It gets rid of the disadvantages that users must unconditionally trust the PKG in traditional signcryption. We proved that the scheme's security is equivalent to the GDH group calculation of the Diffie-Hellman problem under the random oracle model. 3,To the issues that there may be many PKGs in the real network environment, we improved our scheme(zheng2) and proposed an ID-based signcryption(Zheng3) which can cross the PKGs. It maintained the hard of CDHP in the GDH group, and it can realize safe communication in the real networks which have many PKGs.