Anonymous Multireceiver Identity-Based Encryption against Chosen-Ciphertext Attacks with Tight Reduction in the Standard Model

Multireceiver identity-based encryption is a cryptographic primitive, which allows a sender to encrypt a message for multiple receivers efficiently and securely. In some applications, the receivers may not want their identities to be revealed. Motivated by this issue, in 2010, Fan et al. first proposed the concept of anonymous multireceiver identity-based encryption (AMRIBE). Since then, lots of literature studies in this field have been proposed. After surveying the existing works, however, we found that most of them fail to achieve provable anonymity with tight reduction. A security proof with tight reduction means better quality of security and better efficiency of implementation. In this paper, we focus on solving the open problem in this field that is to achieve the ANON-IND-CCA security with tight reduction by giving an AMRIBE scheme. The proposed scheme is proven to be IND-MID-CCA and ANON-MID-CCA secure with tight reduction under a variant of the DBDH assumption. To the best of our knowledge, this is the first scheme proven with tight reducible full CCA security in the standard model.