Signcryption Schemes With Forward Secrecy Based on Elliptic Curve Cryptography

Abstract

In this thesis two efficient signcryption schemes based on elliptic curve cryptosystem are proposed which can effectively combine the functionalities of digital signature and encryption and also take a comparable amount of computational cost and communication overhead. They provide confidentiality, authentication, integrity, unforgeability and nonrepudiation, along with forward secrecy of message confidentiality and public verification. By forward secrecy of message confidentiality function we mean, although the private key of the sender is divulged inattentively, it does not affect the confidentiality of the previously stored messages. By the public verification function we mean, any third party can verify directly the signature of the sender of the original message without the sender's private key when dispute occurs. It enhances the justice of judge. In addition, proposed schemes save great amount of computational cost. The proposed scheme II gives a better result as compare to the proposed scheme I, but it requires a zero-knowledge interactive protocol to exchange recipient's private key to a third party or judge for verification. The proposed schemes can be applied to the lower computational power devices, like mobile devices, smart card based applications, e-voting and many more, due to their lower computational cost.