A Study Of Attribute-based Public Key Encryption With Keyword Search

With the rapid development of cloud computing technology, more and more companies and individuals choose to outsource their data to the cloud service provider. In order to protect its security and user’s privacy, the data file is encrypted before storing in the cloud server. However,considering the real application, it brings a big challenge for searching operation in the ciphertext format. It is of great value about how effectively and securely to search the encrypted data in the cloud server. Searchable encryption technology came into being, it not only accomplishes the ciphertext search, but also ensures the confidentiality of the data. Searchable encryption can be divided into symmetric searchable encryption and public key encryption with keyword search.Compared with the symmetric searchable encryption, public key encryption with keyword search not only allows data users to search directly for the ciphertext without interacting with the data owner. It is necessary to verify the searched result because of the cloud server’s untrustworthiness. Besides,achieving fine-grained access control is also of great importance.However, most of the existing public key encryption schemes with keyword search neither verify the searched results nor achieve fine-grained access. As an extremely attractive cryptographic primitives,Attribute-based encryption mechanism can be particularly applied in cloud storage and can realize fine-grained access control based on the client’s attributes. The access control policy is specified by the data owner. The ciphertext which encrypted by the data owner can be decrypted if and only if the user’s attributes satisfy the access policy which embed in the ciphertext. The combination of the Attribute-based encryption mechanism with public key encryption with keyword search can realize the ciphertext search function and fine fine-grained access control. Furthermore, with the digital signatures, Bloom filters and other technology, the verification operation can be made to avoid receiving the mistake or incomplete searched result. It is of great value about this research.This paper mainly discuss the security and verifiability of the public key encryption scheme with keyword search. Our contributions as follows:1. Propose a verifiable public key encryption scheme with keyword search. It can verify the searched results returned by the cloud server based on the ELGamal algorithm. This can effectively prevent receiving an incorrect result. Our scheme is more efficient and securable by the comparison.2. Make an improvement for the verifiable attribute-based public key encryption scheme with keyword search. The secure channel which exists in the original scheme is removed and a novel method is proposed to verify the searched results. The simulation expresses that our scheme is more efficient and practical.