Identity Based Proxy Re-encryption With Keyword Search

Cloud computing technology is an important technology in the process of social information development.After entering the era of large data,more and more users choose to encrypt the data and save it in the cloud to get the huge storage capacity and high speed data processing ability of the cloud.But this makes it difficult for users to timely access to his files,and when the user wants to get a file containing a specific keyword,he must first download the ciphertext and decrypt it locally before he can find the file containing the specific keyword in plaintext.The appearance of the searchable encryption(SE)technology makes the above situation be solved well,it not only guarantees the data security,but also realizes the file retrieval function without involving decryption of ciphertext,saves a lot of local computing space for the user.This thesis focuses on the research of identity-based encryption with keyword search(IBEKS)schemes,introduces the proxy re-encryption technology creatively,and constructs the identity-based proxy re-encryption with keyword search(IBPKS)scheme,which can not only realize the keyword search in the ciphertext,but also realize the delegation of keyword search authority,and can be safely and efficiently achieved in cloud environment.The correctness of the IBPKS is verified by theoretical analysis and experimental simulation,and the security of the IBPKS is proved under the random oracle model.In addition,this thesis improves the IBPKS scheme,combines identity and attribute,and proposes an identity&attribute based proxy re-encryption with keyword search(IABPKS)scheme that supports a one-to-many user agent mode,which solves the problem that the search right sharing is not flexible in the IBPKS scheme.In the initial ciphertext phase,the identity based encryption(IBE)is used and the ciphertext-policy attribute based encryption(CP-ABE)is used in the re-encryption phase.A delegator can delegate his search right to more than one delegatee who satisfies the access structure.As long as the attribute in the trapdoor of the delegatee satisfies the access structure in the re-encrypted ciphertext,the delegatee can achieve the search right.The access structure of delegatees is created by the linear secret sharing scheme(LSSS),LSSS not only supports fine-grained access control,but also has high computational efficiency.The correctness of IABPKS is verified by theoretical analysis and experimental simulation,and the security of IABPKS is proved under the random oracle model.