On the construction of a leakage-resilient certificate-based encryption with equality test scheme

Abstract

With the rapid development of cloud computing, the need for data privacy and encrypted data applications has become increasingly important. Although traditional certificate-based encryption (CBE) can ensure the confidentiality of data, it lacks the equality test property which is crucial for the comparison of encrypted data. Indeed, the existing CBE with equality test (CBEET) scheme has solved this limitation. The equality test property is important because it allows users to determine whether two encrypted data are identical without decryption, which plays a critical role in applications such as cloud storage, data retrieval, and deduplication. However, encryption schemes that support equality test may be vulnerable to side-channel attacks. Such attacks exploit additional information leaked during system operations, such as power consumption, electromagnetic emissions, or computation time, to extract sensitive keys or intermediate computation results without breaking the mathematical security of the cryptographic algorithm. Therefore, when designing encryption schemes with equality test, it is essential to also account for their resistance to side-channel attacks to ensure the overall security of the system. To overcome this challenge, this paper proposes the first leakage-resilient CBEET (LR-CBEET) scheme under a continual leakage model, which enhances the defense against side-channel attacks by integrating key update technology. The proposed LR-CBEET scheme is rigorously analyzed under the generic bilinear group model. The scheme achieves indistinguishability under chosen ciphertext attacks (IND-CCA) and one-way security under chosen ciphertext attacks (OW-CCA). We also compare the performance with existing schemes. Our proposed scheme not only maintains the original performance but also provides the ability to resist side-channel attacks.