Research On Data Encryption Scheme With Privacy Protection Characteristics

At present,data security and user privacy protection are currently hot research topic in the field of information security.Cryptography can guarantee the confidentiality,integrity and availability of data.Cryptography technology is an important foundation for achieving data security and privacy protection,as well as the theoretical and technical support for ensuring information security.It is very important to explore and study the cryptography technology to meet the needs of users and realize the privacy protection.Database encryption will break the data format constraint,and can increase the cost of modifying the database structure to adapt to the changes in the ciphertext.Format preserving encryption is one of the most important technologies to realize data privacy protection.This technology has the characteristic of "the data format and data length remain unchanged after encryption" most of the existing encryption schemes are based on symmetric cryptosystem,which has the problem of high cost of key management.Searchable encryption can not only save users' data in form of ciphertext,but also realize ciphertext keyword search,which can effectively solve the problem of user data privacy protection on the cloud server.However,existing searchable encryption technologies can not allow users to deny the act of providing data.Denial authentication encryption can enable the data user to authenticate the identity of the data sender,but cannot prove the fact to the third party,therefore the data sender can deny the fact that they provide the data,and then protecting the identity of the sender.Based on the privacy protection requirements of user data,this paper studies the format preserving encryption of identity and searchable denial authentication encryption technology,the detailed research content is as follows:(1)A private information format preserving encryption scheme based on identity public key cryptosystem is designed.In the context of identity-based public key cryptography,the encryption key and decryption key required for preserving encryption are generated by the key derivation function by means of mixed encryption.The scheme makes it unnecessary for the two parties to transfer the encrypted key directly which improves the security of the transmission of private information.The scheme satisfies the identity-based security and adaptability of pseudo-random permutation and ciphertext indistinguishability under chosen-ciphertext attack.(2)A keyword searchable deny authentication encryption scheme based on identity public key cryptosystem is constructed.Based on the advantages of denial authentication encryption and keyword searchable encryption,the scheme achieves the functions of keyword ciphertext search and denial authentication in the context of identity public key cryptography.The data sender in the scheme can retrieve the ciphertext data containing a certain keyword,and can deny the behavior in which it participates,effectively protecting the identity privacy of the sender.At the same time,under the Random Oracle Model,based on the difficulty problem of bilinear Diffie-Hellman,the scheme is proved to have the characteristics of unforgeability,deniability and ciphertext indistinguishability under chosen-ciphertext attack.