Hybrid Signcryption Scheme Design And Implementation

Signcryption is a security scheme that simultanenously provides confidentialityand unforgeability. It is more efficient than signature-then-encryption scheme. With thedevelopment of modern information technology, the amount of electroniccommunication increase rapidly. The demand of cryptographic algorithm on efficiencysecurity and practicality increase simultaneously. Under high amount of communication,we need an efficient cryptographic algorithm to guarantee confidentiality andauthentication. Traditional signcryption algorithm can guarantee confidentiality andauthentication simultaneously. But it has a length limit for message. When a messagebecomes too long, signcryption can’t handle it. Moreover, when there are multipleparties that take part in the communication, the efficiency will become underground.Traditional signcryption algorithm can’t satisfy the demand under high amount ofcommunication.In order to solve the above-mentioned problems, this thesis combines signcryptionscheme and encryption for multiple parties technology, propose a new hybridsigncryption scheme for multiple parties with public verifiability. This scheme is anefficient way that combine confidentiality and authenticity when communication inmultiple parties. This paper researched this paper deeply. The main content of this thesisis illustrated as follow:1. A general hybrid signcryption scheme is presented. Then we prove the securityof the general scheme. The scheme describes the basic components and construction ofhybrid signcryption scheme for multiple parties. Based on the general scheme, thedesigner can design different hybrid signcryption scheme for multiple parties accordingto different security environment.2. We present a specific hybrid signcryption scheme for multiple parties based onthe general scheme. This scheme has public verifiability and it is an efficient way thatcombine confidentiality and authenticity when communication in multiple parties. Weuse discrete logarithm problem and decision Diffie-Hellman problem to prove thesecurity of hybrid signcryption scheme for multiple parties under random oracle model. The scheme is indistinguishable under chosen ciphertext attack and existentialunforgeable against adaptive chosen message attacks.This thesis comparescomputational complexity of our scheme with that of other scheme. Then we use Miracllibrary to implement the scheme and compare the efficiency of our scheme with that ofother schemes intuitively.3. We present a threshold hybrid signcryption scheme for multiple parties. Thisscheme is based on threshold secret sharing theory and substantially increases theefficiency of the scheme. We use the provable security theory to prove theconfidentiality and unforgeability of our scheme.4. We give an application in group comunication using threshold hybridsigncryption scheme for multiple parties. This application improves efficiency of groupcomunication.