Research On Quantum Proxy Signature Scheme

With the development of computer and network technologies, the information security has be-come more and more crucial. Digital signature can provide message integrity,authenticity and non-reputability, so it has been widely used in military, communication, e-commerce and e-government, etc. Quantum cryptography have two basic characteries:unconditional security and eavesdropping detectability. Compared with the classical encryption methods based on complex mathematic com-pution, quantum cryptography is "absolutely secure" in theory. And with the rapid exchange of information, quantum cryptography has a broad prosect of application and significance in science. Focusing on the frontier research subjects of quantum cryptography, this dissertation mainly research into quantum proxy signature scheme. Main achievements in this dissertation are summarized as follows:1. Research on the single-user quantum proxy signature scheme(1) At present, the making technologies of photonic state are being perfected. In this dissertation, a quantum proxy signature scheme based on EPR pairs is presented. The protocol can sign and verify the q-bit string by the two-photon entanglement properties; (2) The signature of the unknown quantum state is equivalent to the blind signature in the classic system, so it have high research value. A proxy signature scheme for unknown quantum state is proposed. First prepare corresponding quantum state by proxy certificates, then generate a valid proxy signature; (3) Secret sharing is a hot spot study in the cryptography because its great applied worth. This dissertation give a quantum proxy signature scheme based on secret sharing. The method is split signature message by secret sharing ideas, one part of it is used to generate proxy signature, another part is used to the signature verification.2. Research on the threshold proxy signature schemeA threshold proxy signature scheme based on Shamir threshold sharing ideas is presented. Ac-cording to this scheme, only the number of proxy user meet or exceed a threshold value, can they generate a valid proxy signature. The security of this scheme is provided by quantum fingerprinting function.3. Research on the quantum proxy multi-signature schemesAll of these days, proxy multi-signature has been emphasized because it's wide applications. In quantum cryptography, the key can only be generated in the form of sharing, so the effectiveness of various types signatures can only be verified by a designated person. In this dissertation, a quantum proxy multi-signature scheme which can public verify is presented. This scheme has solves the problem of the quantum signature's verify by using the property of unitary transformation.4. Research on the quantum multi-proxy multi-signature schemesUnder the multi-user circumstance, this dissertation gives a further research on quantum proxy schemes, and a new quantum multi-proxy multi-signature scheme is brought out. This scheme's secu-rity be ensured by the probability of two mixed quantum state's measurement results. This scheme support no-limited amounts of signatories and can be applied in the situations where a file should be signed by all proxy users in a group.Besides, all schemes presented in this dissertation have been required at every stages to verify the results of the previous phase, so they disengage from dependence on the arbitration and require no trusted center.