Research About Quantum Multi-proxy Signature Protocol

With the development of information technology,the security of information becomes more important.Digital signature technology can plays an important role in the field of information security due to its application in the field of identity authentication,data integrity,reliability,anonymity and so on.However,the security of the digital signature technology is based on the computational complexity of mathematics,such as large prime factorization and discrete logarithm.With the level of computing continues to improve,especially the quantum computer gradually becomes a reality,the safety of traditional digital signature technology faces some challenges.In order to cope with the possible crisis,the theory of quantum cryyptography has been put forward.Quantum cryptography is focused on researchers because of its unconditional security.At the same time,this feature makes the quantum cryptography has a good advantage in the protection of information and information security.Quantum signature technology,as a branch of quantum cryptography,which uses the basic principle of quantum mechanics and the knowledge of cryptography,designs a series of quantum signature protocols which have been proved to be unconditionally secure in theory.As a new cross subject,quantum signature has higher research value.In this thesis,we follow the forefront of quantum cryptography,using the knowledge of quantum mechanics and different methods,design several quantum multi-proxy signature schemes.The main contents are as follows:1)A quantum blind multi-proxy signature protocol has been proposed.This protocol uses the correlation between Bell state and Bell measurement,in order to constitute the relations between the original signers' key and the proxy signer's key.So,it completes the signing operation that more than one person on behalf of a person.At the same time,the number of signers can be changed according to actual needs,which increasingly improve the flexibility of the protocol.Moreover,the original message can be blinded,which guarantees the security of the message to be signed.Because the key used in the protocol,distributed by BB84 protocol or B92 protocol,it ensures the unconditional security of the protocol.2)Although the first protocol solves the signing operation that more than one person on behalf of a person,there are still some questions,such as too much number of quantum and quantum utilization rate is low.Therefore we put forward a second protocol about quantum multi-proxy signature.This protocol uses a set of Bell state and appropriate unitary operation,constitutes relations between the original signer's key and the proxy signer's key.So,it solves signature operation of more than one person on behalf of a person.The implementation for the protocol is simple and efficient,in the current technology,it is completely feasible.3)Most of the current signature protocol,the rights of the verifier is too concentrated because of only having one verifier.Therefore a quantum blind multi-proxy signature protocol with multiplayer verification is proposed.The protocol only uses a set of single quantum bits and the corresponding unitary transformation to complete the operation that more than one person on behalf of a person.There are some advantages in this protocol,such as the low number of quantum,and it can be verified by more than one person,proxy signature,verification operation can be disorderly and so on.The existence of these characteristics greatly improves the flexibility,and applicability of this agreement.Finally,we analyze and summarize the existing problems which is proposed in this thesis,as well as the existing problems in the quantum signature protocol.Also,we indicate the direction for further research in the future.