The Design And Research Of Generic Construction Of Publicly Verifiable Predicate Encryption

The predicate encryption is a hotspot in the area of the searchable encryption, providing a function of ciphertext search for outsourced data. In predicate encryption, it is assumed that the outsourcing party(like the cloud server) can execute the query algorithms correctly. Then the cloud server will return the real results of this query to the user. However, cloud service providers are likely to refuse to provide the correct query results in order to achieve certain purposes. So the query results returned by cloud service providers are not necessarily fully trusted in real life. For this reason, how to verify cloud ciphertext query results has become a serious problem.This paper presents a general publicly verifiable predicate encryption(PVPE) scheme, providing a new method for solving the problem of verifying the results of ciphertext query. This scheme expands the predicate encryption, achieve the verification of correctness, integrity and credibility of the query results based on the ciphertext query function of predicate encryption. In this scheme, any authorized user can publicly verify the query results returned by server, and doesn't have to interact with the server again. Also the PVPE is a general scheme means that any specific predicate encryption algorithm with attribute-hiding can expand to the PVPE.The general publicly verifiable predicate encryption scheme combines the predicate encryption and the verifiable computation protocol. This scheme adds authentication(Verify) algorithm. On the stage of encryption, the data owner encrypting two mutually exclusive ciphertext C0 and C1 respectively which associate with attribute value x and x. In normal situation, whether user's secret key associate with the attribute value x satisfies the predicate or not, there must be one of ciphertext can be encrypted by secret key but the other can't. When the secret key satisfies the predicate, the ciphertext C0 can be decrypted and C1 can't. Otherwise, the ciphertext C1 can be decrypted and C0 can't. In stage of verification, users can verify the correctness, integrity and credibility of the return results. In the aspect of safety, this paper proposed a security model for verifiable predicate encryption. Also reduced the security of the scheme to the hiding specific properties of predicate encryption. Because the attribute-hiding has proved to be safe, the adversary can only break the general publicly verifiable predicate encryption scheme with a negligible probability. So it can be sure that this scheme is safe. Then on the basis, we present a improved public verifiable predicate encryption scheme combined with practical application. The scheme improve the above scheme by combined the bloom filter. It reduces the amount of users and users' computing and improved the user's verification efficiency.At last, combining the database of general public verifiable predicate encryption scheme to achieve it. Then simulate the predicate verifiable encryption scheme in practical environment. This scheme laid a solid foundation for the practical application of universal public verifiable predicate encryption scheme.