Group Public Key Encryption With Equality Test for Dynamic Membership

Group public key encryption with equality test supports group granularity authorization, which allows a tester to perform equality test only on ciphertexts of group users. If two ciphertexts are encrypted by users from two different groups, they cannot be performed the equality test. Indeed, most of the existing works either only support users to join the group but do not support group members to leave the group, or are inefficient for all the ciphertexts need to be re-encrypted after each revocation operation. In this paper, we propose a group public key encryption with equality test for dynamic membership. Compared with the existing works, (1) our scheme supports efficient member revocation function. Once a group member has malicious behavior, it can be withdrawn from the group, which improves the security of the scheme, (2) our scheme supports the verification of ciphertext encryptors, that is, it verifies whether the ciphertext encryptors have been revoked and come from the same group before an equality test, which improves the efficiency of our scheme. Besides, we prove our scheme can achieve OW-CCA security against the Type-I adversary and IND-CCA security against the Type-II adversary in the random oracle model.