Leakage-Resilient Certificate-based Key Encapsulation Scheme Resistant to Continual Leakage

Abstract

In the past, the security of most public-key encryption or key encapsulation schemes is shown in an ideal model, where private keys, secret keys and random values are assumed to be absolutely secure to adversaries. However, this ideal model is not practical due to side-channel attacks in the sense that adversaries could gain partial information of these secret values involved in decryption operations by perceiving energy consumption or execution timing. In such a case, these schemes under the ideal model could suffer from side-channel attacks. Recently, leakage-resilient cryptography resistant to side-channel attacks is an emerging research topic. Certificatebased encryption (CBE) or certificate-based key encapsulation (CB-KE) schemes are a class of important public-key encryption. However, little work addresses the design of leakageresilient CBE (LR-CBE) or leakage-resilient CB-KE (LR-CB-KE) schemes. In this paper, we present the first LR-CB-KE scheme with overall unbounded leakage property which permits adversaries to continuously gain partial information of the system secret key of a trusted certificate authority (CA), the private keys and certificates of users, and random values. In the generic bilinear group model, formal security analysis is made to prove that the proposed LR-CB-KE scheme is secure against chosen ciphertext attacks.

Fully Continuous Leakage-Resilient Certificate-Based Signcryption Scheme for Mobile Communications

“…The CA uses its own secret key CSK to compute the member's certificate CTF m using the member ID m 's identity information and public key, and returns it back to the member ID m . By combining the adversary models of both the LR certificate-based signature (LR-CBS) scheme (Wu et al, 2019) and the LR certificate-based encryption (LR-CBE) scheme (Wu et al, 2020a), we define the adversary model of the FCLR-CBSC scheme. In this adversary model, there are two types of adversaries that include an uncertified member and the honest-but-curious CA.…”

“…Based on the frameworks of both the LR-CBS (Wu et al, 2019) and the LR-CBE (Wu et al, 2020a) schemes, a new framework of FCLR-CBSC schemes is defined as follows.…”

“…To resist such leakage attacks, researchers offer leakage-resilient cryptography as a solution. In the past, numerous leakage-resilient signature (LRS) schemes (Galindo and Virek, 2013;Wu et al, 2019;Tseng et al, 2020;Wu et al, 2020b), leakage-resilient encryption (LRE) schemes (Kiltz and Pietrzak, 2010;Galindo et al, 2016;Wu et al, 2018Wu et al, , 2020aTseng et al, 2022), and leakage-resilient authenticated key agreement protocols (Tseng et al, 2021;Peng et al, 2021;Tsai et al, 2022) under various PKS settings have been published in the literature.…”

CBEET: Constructing Certificate-based Encryption with Equality Test in the CB-PKS

“…To remove the key escrow problem, certificate-based public key system (CB-PKS) was proposed by Gentry [8], which not only eliminates the key escrow problem in the ID-PKS, but also avoids the construction of PKI in traditional public key systems. Based on the CB-PKS, a large number of certificate-based encryption (CBE) schemes have been published in the literature [7,9,19,25,29,30] to protect the confidentiality of private data. Research related to CBE continues to be explored to this day.…”

“…To the best of our knowledge, there is no related work on equality test of ciphertexts in the CB-PKS. Table 1 lists the comparisons between the PKE scheme [31], the PKEET scheme [6], IBE scheme [23], IBEET scheme [13], CBE scheme [25] and our CBEET scheme in terms of public key setting, eliminating PKI construction, avoiding key escrow problem and possessing equality test property. After comparing with other existing schemes, we attempt to propose the first CBEET scheme that provides the equality test of ciphertexts in the CB-PKS.…”