Research Of Attribute-based Encryption Scheme With Attribute Revocation And Keyword Search

With the development of cloud computing,outsourcing data to cloud servers attracted widespread attention.In order to ensure data storage security and implement fine-grained data access control,attribute-based encryption scheme has become a hot of the research for solving cloud storage security problems.Revocable attribute-based encryption is an extension and expansion of attribute encryption.It has important research value and practical meaning for solving user attributes change in actual applications.The keyword search encryption scheme enables users to quickly find out the data that they are interested in stored in the cloud server,and does not reveal information of the search keyword,thus enduring the security of user search.How to construct a cryptographic scheme based on attribute-based encryption that can support user attribute change and achieve keyword search has become a,valuable research topic.In this paper,we study the attribute-based encryption scheme with attribute revocation and keyword search form the purpose of practical application,and show the results as follow:(1)We construct an attribute-based encryption scheme with attribute update and keyword search in cloud storage.It is a ciphertext-policy attribute-based encryption scheme which adopts LSSS access policy.The scheme not only supports keywords search but also the user's attribute update.When a user's attribute need to be updated,only the user's secret key related with the attribute need to be updated,while other user's secret key and the ciphertexts related with this attribute need not to be updated with the help of the cloud server.In addition,we outsource the operation with high computation cost to cloud server to reduce the user's computational burden.Finally,our scheme is proven to be secure against chosen ciphertext-policy and chosen plaintext attack in the general bilinear group model.And our scheme is also proven to be secure under index indistinguilishability against chosen keyword attack under bilinear Diffie-Hellman(BDH)assumption.(2)We construct a multi authority attribute based encryption scheme with attribute revocation and keyword search.It is a ciphertext-policy attribute-based encryption scheme which adopts access tree.The scheme supports multi-users keywords search and user's attribute revocation.And to improve the efficiency,we outsource the operation with high computation cost of user decryption,secret key update and ciphertext update to cloud server.Finally,our scheme is proven to be secure against selective ciphertext-policy and chosen plaintext attack(IND-sCP-CPA)secure under the decision bilinear Diffie-Hellman(DBDH)assumption.And,our scheme is proven to be secure under index indistinguilishability against chosen keyword attack under decision bilinear Diffie-Hellman(DBDH)assumption.And,our scheme is also proven to be secure under trapdoor indistinguilishability against chosen keyword attack under decision Diffie-Hellman(DDH)assumption.