Research On Multi-Grade Proxy Signature Scheme

Being the legal substitutes of the handwritten signatures in daily life,the digital signatures have been one of the important means to provide integrality, authentication and incontestableness. With the rapid development of the digital signature in systems of E-government and E-commerce, the increasing requirement of network information technique can not be satisfied by general digital signatures. Under the various application conditions,many special digital signatures emerge as the times require,and several new research directions come into being.In real life,people always delegate some rights to a designed person who is called the trusted proxy,and the proxy signer can exert these rights on behalf of the original signer. In these entrusted rights, the power of signing is included..Since the idea of proxy signature was introduced to solve the problem of delegation of the digital signing power,which is ineluctable in digital information society,the nicer salient features of proxy signatures make them come to front. So far, a great deal of schemes on proxy signature and cryptography protocols based on them have been proposed.This dissertation mainly discusses proxy signature schemes,including identity based proxy signature,proxy signcryption, multi-grade proxy signature and multi-grade proxy signcryption. The main result that the author obtained are as follows:1. A new ID-Based proxy signature scheme with proxy revocation is proposed,in which scheme, once finding that the proxy signer is malicious,the original signer can revoke the malicious proxy signer's signing power efficiently in time through the trusted authority. By this way,the expense paied by the original signer can be decreased greatly.2. There are some identities between Key-insulated scheme and multiple grade proxy signature scheme. Using the idea of Key-insulated scheme a new multiple grade proxy signature scheme is presented,which based on the assumption of Interger Factoration Problem. The new scheme based on the new Key-insulated scheme is more security,and achieves the requirements of the multiple grade proxy signature scheme.3. Compared with the traditional mode—encrypting after siging ,the schemes on digital signcryption pay a less price. Applying the idea of digital signcryption to multi-grade proxy signature, the concept of multi-grade proxy signcryption is proposed,and solves the problem of the secrecy involved in signing.Furthermore,the new proxy signcryption scheme needs less memory ,and have no use for functions to encrypt and decrypt. So the complexity of the scheme is reduced.