Research On Several Key Techiques Of Public Key Cryptography For Data Information Security

With the rapid development of Internet and communication technology,the society has become increasingly informationized and intelligent.However,when more and more enterprises and individuals enjoy the convenient services provided,they also face more and more security attacks.There are many reasons for these security incidents,such as information leakage by internal employee,malicious attacks by hackers,lack of awareness,negligence and so on.The goal of data information security is to ensure its confidentiality,integrity,availability and non-repudiation.The attribute based cryptosystem realizes one-to-many communication encryption and decryption,and provides fine-grained access control to data,which has obvious performance advantages in distributed application scenarios.Lattice based cryptography,with the characteristics of anti-quantum attack,has become one of the main representatives of the post-quantum cryptography era.Based on attribute based cryptography and lattice based cryptography,scholars have proposed many research schemes with different functions for different scenarios.These research schemes ensure the security of data information well,but there are still some problems to be solved in the face of new practical application scenarios.This dissertation analyzes the mathematical basis of attribute based cryptography and lattice based cryptography and combines the security problems in specific application scenarios,and then construct the schemes of attribute based encryption,attribute based signcryption,attribute based keyword search and signature based on number theory research unit,which ensure the security of information in the collection,storage and transmission of data.The main achievements are as follows:(1)Research on key abuse accountability in key policy and ciphertext policy attribute based encryptionIn order to solve the problem of key abuse in attribute based encryption mechanism with a higher efficiency,key abuse accountable key policy attribute based encryption scheme and key abuse accountable ciphertext policy attribute based encryption scheme are proposed.A unique identity representing the user's identity is introduced in the generation of the user's private key to make the user's private key different,but does not affect the system to take the advantage of attribute based encryption.When key exposure or key abuse happens,attribute authority can pinpoint the traitor's identity and revote his privileges.(2)Research on ciphertext policy attribute based signcryptionIn view of the traditional method of signing first and then encrypting,which not only takes up a lot of computing resources,but also brings a high computing cost to the communication system in the process of data verification and key updating,a ciphertext policy attribute based signcryption scheme is proposed by combining ciphertext policy attribute based encryption with attribute based signature.In this scheme,the private key of the user corresponds to a set of attributes,while the ciphertext corresponds to an access control structure.A unique identity representing the user's identity is introduced in the generation of the user's private key.When key exposure or key abuse happens,attribute authority can pinpoint the traitor's identity and revote his privileges.An efficient key insulated mechanism is introduced to provide forward and backward security and efficient key updating.(3)Research on ciphertext policy attribute based keyword searchThis section studies attribute based encryption and keyword search technology to build an efficient ciphertext policy attribute based keyword search scheme.To tackle the problem that most of the existing key word search schemes based on attribute based encryption lack the properties of key exposure protection and highly efficient key updating when key leakage happens,an efficient key insulated mechanism is introduced and the system life is divided into several periods.The public parameters of the cryptosystem remain unvaried during the whole lifespan,and users' private keys are refreshed termly.When key leakage occurs,a user's private key shall be updated in a timely fashion to minimize the damage brought by key exposure.We achieve flexible self-centric search management by utilizing a ciphertext policy attribute based encryption mechanism.The proposed scheme provides secure key exposure protection as well as both forward and backward security.(4)Research on signature scheme based on number theory research unit for mobile paymentThe traditional public key algorithm has higher requirements for hardware which is not suitable for mobile terminals of limited computing resources and these public key algorithms are vulnerable to quantum computing attacks.In addition,the probability of generating valid signature value of signature scheme based on number theory research unit(NTRU)lattice is not ideal.An improved signature scheme based on NTRU lattice is proposed for mobile payment,and the construction of the signature scheme is given as well as the security is proved.On this basis,the probability of generating valid signature value is analyzed,and the efficiency of the algorithm is improved by parameter selection.Then,we apply NTRU and the improved signature scheme based on NTRU in wireless public key infrastructure to design a new type of mobile payment scheme which achieves efficient encryption and signature,as well as the characteristic of against quantum attacks.