Signcryption Scheme And Its Application In Key Escrow

Signcryption is a new paradigm in public key cryptography. It simultaneously fulfills both the functions of digital signature and public key encryption in a single logical step, with the cost significantly lower than that required by the traditional "signature followed by encryption" approach. It has many applications, such as in electronical funds transfer systems, electronical auction and electronical voting, etc. The research of this dissertation focuses on signcryption scheme and threshold key escrow scheme based on signcryption scheme.The following are the results of the thesis:1. Based on the survey of secret sharing especially of some verifiable secret sharing protocols, we constructs a secure secret sharing scheme on general access structures,.2. We construct a new signcryption schemes. With respect to a publicly verifiable signcryption scheme, a threshold verifiable signcryption scheme is presented.3. Applying the threshold key escrow scheme, a new threshold key escrow scheme based on GOST signcryption scheme is proposed. The scheme solves the problems of "once monitor, monitor forever".