Research On A Revocable Attribute Based Encryption Scheme

Cloud computing and cloud storage are developing rapidly,Users store data on cloud servers.Data become more and more lightweight.At the same time,users pay attention to data security.In order to satisfy this realistic scenario,attribute-based encryption mechanism has been mentioned.This encryption method solves the problem of data security in cloud computing mode.When the attributes of users are consistent with the access structure of ciphertext,the data can be decrypted.Compared with the traditional public key encryption scheme,ABE is better.The attribute-based encryption mechanism of revocable storage is characterized by that when the user is revoked from the server,the cloud server updates the stored ciphertext through common parameters to achieve the purpose of revoking the user.This system achieves flexible access control,secure user revocation and efficient storage functions,so it has been widely concerned by the academic community.This thesis starts with the attribute-based encryption mechanism of ciphertext policy(CP-ABE),aiming at achieving fine-grained control revocation of users,studies the revocable storage scheme of CP-ABE,and mainly completes the following tasks:(1)This thesis combines Chinese Remainder Theorem and the idea of ciphertext updating,and achieves revocable storage CP-ABE based on the basic CP-ABE scheme.At the same time,in order to ensure the efficiency of the whole scheme,in the decryption phase,the part of the decryption operation is outsourced to a third-party server,which improves the efficiency of the whole scheme.By analyzing the security of the scheme,it is proved that the scheme can provide clear text security and analyze the performance of the scheme.On this basis,this paper also proposes a practical application scenario of the encryption scheme.(2)This thesis presents a verifiable revocable storage CP-ABE scheme.In the existing CP-ABE schemes for user revocation,the revocation server must be a trusted server.The verifiable revocation storage CP-ABE scheme proposed in this paper can support the revocation function on unreliable third-party servers and provide the correct verification of updates.In this thesis the construction process of the scheme is given,and the security analysis and proof of the scheme are given.