Research On Key Problem Of Proxy Cryptography

With the rapid development of computer network and communication technology, especially the rise of the electronic commerce, digital signature technology is widely used. Digital signature is an important guarantee to prevent the information fraud. But how to effectively solve the problem of authorization transfer in digital signature and cipher decryption has become more and more concerned. Proxy cryptography is just one of the most effective methods to solve such problems. It mainly consists of two parts:proxy signature and proxy cryptosystem. The former generally studies the Problem of authorization in digital signature while the latter concerns more on authorization in cipher decryption. Along with the deepen research on proxy cryptosystem, many extended proxy cryptography with special properties have been proposed by the experts. How ever, as far as we know, the research on proxy cryptography’s formal security is not ideal enough. Thereby our point in this thesis is to study and design a series of proxy signature and proxy signcryption. It include formalize a notion of security for proxy cryptography. And present the provable security scheme in the random oracle model or in the standard model.