Research And Application Of Lattice-based Ring Signature

In recent years,quantum computer has developed rapidly.from the latest "Nine chapters" in China,it is a realizable technology to build quantum computer for specific problems.Quantum computers can solve the difficult problems based on large integer decomposition and bilinear pairs in polynomial time,which makes the most widely used RSA algorithm based on large integer decomposition lose its security.Therefore,it is the most urgent need to study a new anti-quantum attack algorithm based on the existing security requirements,and scholars call it post-quantum cryptography.Lattice-based cryptosystem is an important candidate scheme in post-quantum cryptosystem.Latticebased theory has the NP completeness problem as the basis of cryptographic theory and has complete from the general case reduce to the worst case.Therefore,the complete theoretical system of lattice cryptosystem has a rich application prospect.In this thesis,the ring signature is realized by the lattice cipher algorithm,and the lattice base ring signature scheme and its application are studied.The main research work is as follows:(1)A traceable ring signature scheme is designed by making use of the structural advantage of ideal lattice.In view of the low efficiency of the lattice cryptosystem,the Trapdoor Generation Function and the Pre-image Sampling Algorithm on the ideal lattice are used to generate the user's public and private keys,which can effectively reduce the key length and time cost.The scheme also achieves traceability by adding additional information,which can meet the security needs of special application scenarios when necessary.The analysis results of the scheme show that the new scheme satisfies strong unforgeability,traceability and anonymity,and the signature size is smaller.(2)In some decentralized application scenarios(such as block chain,electronic money,etc.),the unconditional anonymity of ring signatures and the unforgettability of anti-internal corruption attacks are important properties to ensure data privacy and information security.According to the requirements of these application scenarios and the current needs of anti-quantum attack ciphers,an identity-based ring signature scheme on an ideal lattice is proposed.The scheme reduces the overall cost of the scheme through the special algebraic structure of ideal lattice and reduces the complexity of the signature algorithm by rejecting sampling theorem.And it can provide unconditional anonymity and unforgettability against internal corruption attacks.(3)A privacy protection model of vehicle network is proposed through the application of ring signature.In VANET,there is a problem of privacy disclosure of vehicle broadcast information.In order to solve this problem,the data can be anonymized by ring signature,which can effectively protect the privacy of users.Ring signature has the characteristics of unsupervised and unconditional anonymity,which can protect the privacy of users to the maximum extent.The model communication adopts a traceable ring signature scheme based on ideal lattice,which can not only protect the privacy of users,but also track the signer when necessary,so as to achieve the balance between security and privacy.The simulation results show that the average delay of this scheme is better than that of similar schemes.