Paper 2025/1297 Original: eprint.iacr.org/2025/1297 ↗

On the Relations between Matchmaking Public Key Encryption and Public Key Authenticated Encryption with Keyword Search

Abstract

Ateniese et al. (CRYPTO 2019/JoC 2021) introduced a cryptographic primitive which they call matchmaking encryption (ME), and Identity-based ME (IB-ME) is its identity-based variant. IB-ME supports an equality matching where a sender (encryptor) indicates a receiver's (decryptor's) identity (rcv) in addition to their own ID ($\sigma$), and a receiver indicates a sender's identity (snd) in addition to the own identity ($\rho$). A ciphertext is decrypted if $(\sigma,\rho)=$(snd,rcv). In this paper, we pay attention to the search condition of public key authenticated encryption with keyword search (PAEKS) (Huang-Li, Information Sciences 2017) is reminiscent of the equality matching. We introduce a public key variant of ME which we call PK-ME, and propose a generic construction of PK-ME from PAEKS. As a conceptual contribution, our work lies in revealing a connection between ME and public key searchable encryption, which were independently researched so far. Due to the generic construction of PAEKS (Li-Boyen, IACR CiC 2024), we can instantiate the proposed generic construction from pairings or lattices. We also introduce a weaker version of authenticity and show that it can be instantiated from several complexity assumptions. Finally, we discuss the advantage/disadvantage of PK-ME compared to IB-ME.