Data sharing technology plays an important role in sharing information on mobile devices, ensuring that users can preserve their privacy while guaranteeing secure data transmission. Matchmaking encryption is a novel cryptographic primitive that provides bilateral access control to maintain user trust and data integrity. However, this primitive faces a challenge in terms of achieving secure multi-receiver construction. In a multi-user environment, users need to encrypt the data many times, resulting in inefficiencies under this approach. To address this challenge, we focus on the underlying construction of identity-based broadcast matchmaking encryption (IBBME). This paper presents a new IBBME construction with DBDH andq-SDH assumptions under the standard model. Specifically, we propose a new approach that abandons the generalized transformations that already existed previously in multiple receivers. Specifically, we adopt the “two-level” method to guarantee privacy and authenticity, where the identity-based broadcast encryption (IBBE) level guarantees privacy, while the signature level guarantees authenticity. In addition, we present a strict security proof, which shows that our construction satisfies privacy and authenticity exactly. Moreover, we compare the existing ME constructions with our construction through theoretical and performance analysis. The analysis shows that the ciphertext size in our construction can be reduced to be independent of the number of receivers, which is more efficient.

Abstract ID-based encryption with equality test (IBEET) allows a tester to compare ciphertexts encrypted under different public keys for checking whether they contain the same message. In this paper, we first introduce group mechanism into IBEET and propose a new primitive, namely group ID-based encryption with equality test (G-IBEET). With the group mechanism: (1) group administrator can authorize a tester to make comparison between ciphertexts of group users, but it cannot compare their ciphertexts with any ciphertext of any user who is not in the group. Such group granularity authorization can make IBEET that adapts to group scenario; (2) for the group granularity authorization, only one trapdoor, named group trapdoor, should be issued to the tester, which can greatly reduce the cost of computation, transmission and storage of trapdoors in traditional IBEET schemes; (3) G-IBEET can resist the insider attack launched by the authorized tester, which is an open problem in IBEET. We give definitions for G-IBEET and propose a concrete construction with an efficient test algorithm. We then give its security analysis in the random oracle model.