KSF-OABE: Outsourced Attribute-Based Encryption with Keyword Search Function for Cloud Storage

Abstract— Cloud computing becomes increasingly popular for data owners to outsource their data to public cloud servers while allowing intendeddata users to retrieve these data stored in cloud. This kind of computing model brings challenges to the security and privacy of data stored in cloud. Attribute-based encryption (ABE) technology has beenusedto design fine-grained access control system, which provides one good method to solve the security issuesin cloud setting. However, the computation cost and ciphertext size in most ABE schemes grow with the complexity of the access policy. Outsourced ABE(OABE) with fine-grained access control system can largely reduce the computation cost for users who want to access encrypted data stored in cloud by outsourcing the heavy computation to cloud service provider (CSP). However, as the amountof encrypted files stored in cloud is becomingvery huge, which will hinder efficient query processing. To deal withabove problem, we presenta new cryptographic primitive called attribute-based encryption scheme with outsourcing key-issuing and outsourcing decryption, which can implement keyword search function (KSF-OABE). The proposed KSF-OABE scheme isprovedsecure against chosen-plaintext attack (CPA). CSP performs partial decryption task delegated by data user without knowing anything about the plaintext. Moreover,the CSP can perform encrypted keyword search without knowing anything about the keywords embeddedin trapdoor. < final year projects >