Revocable Public Key Encryption with Equality Test without Pairing in Cloud Storage

Public key encryption with equality test (PKEET) plays an important role in the cloud storage. It allows a third party to test whether two ciphertexts contain the same message without decryption. Since the third party is not fully trusted, it is sometimes necessary to prevent the third party from testing the ciphertexts all the time. To this end, we propose the notion of revocable public key encryption with equality test (R-PKEET). We give the construction of R-PKEET in the random oracle model, which employs time key to update trapdoor and partial ciphertexts. In details, our scheme enables a user to revoke the third party's test right by sending a time key to the cloud server, which is responsible for updating partial ciphertexts using the time key. Compared with related works, our scheme achieves both lightweight revocation and lower computational complexity by using Shamir's secret sharing and Lagrange interpolating polynomial.