Theory And Application Of Proxy Signature

The concept of 'digital signature' was firstly proposed in W.Diffie and M.Hellman's seminal paper, "New directions in Cryptography". With the development of networks and the wide application of information systems, there are increasing demands on processing various digital documents in systems of E-Government and E-Commerce. Being a legal replacement for handwritten signatures, Digital signature is sure to be more extensively used in the coming years. This dissertation mainly studies theory and application of signature schemes with proxy properties------proxy signature.In real life, people always entrust some rights to a trusted proxy, it is the trusted proxy who exerts these rights. In these entrusted rights, signing right is included. The concept of proxy signature was first appeared in 1991. Since the idea of proxy signature was introduced by Mambo, Usuda and Okamoto in 1996, the salient features of proxy signature make them come to front. The proxy signature is a signature scheme that an original signer delegates his/her signing capability to a proxy signer, and then the proxy signer creates a valid signature on behalf of the original signer, the receiver of the signature verifies the signature itself and the original signer's delegation together. So far, many proxy signature schemes and cryptography protocols based on them have been proposed.The thesis summarizes proxy signature scheme and its application's research results and developing status, From analyzing typical proxy signature, we can see the proxy key pair is generated from the original signer's signature on delegation information, then the validation of original signer's agreement and the proxy signature are simultaneous, that is to say, the verifier can assure that the document signed by proxy signer is on original signer's agreement. Consequently, when the original signer disables exercise authority for signing, he authorizes the proxy signer to generate proxy signature on behalf of himself by use of proxy signature system, which is a good idea. The threshold proxy signature scheme is a variant of the proxy signature...