The Analysis And Design On Signcryption

With the rapid development of information technique and the large-scale application of network technique, information security has been becoming more and more important. Usually, we make use of encryption which can ensure the confidentiality of messages transmitted on the international computer or network application field and the security of messages stored on the memorizer; moreover, we use digital signature to provide messages integrity,authenticity,and non-reputability. The traditional technique to send messages in a confidential and authenticate way is"signature-then-encryption". At the same time, it costs no matter computational costs and communication overheads are huge.Signcryption is a new cryptographic primitive which can simultaneously fulfills both digital signture and encryption in a logically single step. Because of its lower computational costs and communication overheads than the traditional approach, the signcryption is an ideal method which can provide a good choice to transmit messages when both confidentiality and authenticity are needed. Signcryption is the improved method compared with the traditional technique. At present, signcryption is the key point of the cryptographic research, further more, it has been an important topic of the network technique security.In this paper, we mainly study the theanalys ,design and applications of signcryption schemes. Exactly, it consists of the following three aspects.1. This dissertation proposes an identity based signcryption scheme with both public verifiability and forward security using bilinear pairings. Our scheme can separate the signature verification from message recovery . It can be applied in mobile E—business scenario,such as filtration of bad instant messages of mobile equipment.The proposed scheme is proved to be secure assuming the bilinear Diffle-Hellman problem is hard. This scheme is also very efficient regarding the computation costs and the communication overheads after analyzing and being compared with other schemes.2. This paper analyzes the identity-based threshold proxy signcryption scheme proposed by Li, and pointes out that there are obvious errors in his scheme, which cause his scheme won't do. Then this paper gives a new identity-based threshold proxy signcryption scheme using bilinear pairings.This scheme not only can fulfill both public verifiability and forward security, but also has great advantages in efficiency.3. Based on the idea of identity based cryptography ,this dissertation proposes an identity based multi-proxy multi-signcryption scheme using bilinear pairings defined on elliptic curves .The new scheme successfully fulfills the transformation from single-user to multi-user. Analysis shows that the scheme has many good secure properties and the efficiency is high. At last, this paper also gives two new identity based multi-proxy multi-signcryption schemes which can resist proxy warrant attack. The new schemes successfully avoid proxy signer revising the proxy warrant.The two schemes have many good secure properties and the efficiency is high.