Research On Lattice-based Public Key Encryption With Keyword Search

With the advent of cloud storage,a great number of users choose to encrypt private data and upload it to the cloud server.Combined with searchable encryption technology,users can retrieve ciphertext data anytime and anywhere.Although the total amount of ciphertext data stored in cloud servers continues to grow,most of the existing public key encryption with keyword search(PEKS)schemes are based on heavy bilinear pairings,which take a long time to retrieve and will bring a worse experience for the users.Moreover,with the development of quantum computer technology,attackers can break through most of the current PEKS security system through quantum computing attack,so as to learn the user's query contents and private data.Therefore,PEKS schemes are called upon to have higher requirements for communication timeliness and ciphertext security.Hence,how to retrieve user's ciphertext data safely and efficiently has become a hot issue in cryptography research.In order to achieve a secure and efficient searchable encryption scheme in cloud computing environment,this thesis firstly constructs a public key encryption with conjunctive keyword search(PECKS)scheme based on learning with error(LWE)problem and then gives the security proof of ciphertext.Compared with PECKS scheme based on bilinear pairings,our scheme has higher computational efficiency and can be secure against quantum computing attack.To further enhance the security,we study the principle of keyword guessing attack(KGA)and its countermeasures.According to the advantages of designated test server public key encryption with keyword search(d PEKS)scheme and server-aided model,we design a d PEKS scheme which is particularly secure against KGA.Through trapdoor security analysis,we prove that our scheme can be secure against KGA from internal servers.The performance comparison with other scheme shows that the proposed scheme can guarantee superior retrieval efficiency.