A collaborative team of international researchers from the Universidade de S\u00e3o Paulo in Brazil and Nanyang Technological University (NTU) in Singapore has published a significant new study highlighting hidden vulnerabilities in prominent post-quantum cryptographic schemes. The research paper, designated as Paper 2026\/2492 on the Cryptology ePrint Archive, focuses on sophisticated hardware-level security threats against two major code-based key encapsulation mechanisms (KEMs): HQC and BIKE.<\/p>\n
Authored by Thales B. Paiva, Lucas C. Cardoso, Keerthi Kamalakshan, Hariprasad Valsaraj Kelassery, Marcos A. Simplicio Jr., and Shivam Bhasin, the study demonstrates that fault injection attacks can successfully bypass traditional security measures. Specifically, the researchers show that attackers can penetrate systems even when defenses against manipulation of the widely scrutinized Fujisaki-Okamoto transform are firmly in place. <\/p>\n
As the global cybersecurity landscape prepares for the advent of quantum computing\u2014which threatens to break much of the public-key cryptography currently securing the internet\u2014cryptographers have raced to develop quantum-resistant alternatives. Code-based cryptography, which relies on the hardness of decoding random linear codes, has emerged as one of the most promising avenues for standardization by organizations like the National Institute of Standards and Technology (NIST). Among these, HQC (Hamming Quasi-Cyclic) and BIKE (Bit Flipping Key Encapsulation) stand out as leading contenders designed to withstand attacks from both classical and quantum computers.<\/p>\n
To protect these cryptographic schemes from physical tampering, developers have traditionally focused heavily on securing the Fujisaki-Okamoto (FO) transform. The FO transform is a mathematical wrapper applied to public-key encryption schemes and KEMs to convert them into secure ciphertexts that resist chosen-ciphertext attacks. Because security analyses of physical implementations have historically concentrated on this transformation layer, many modern hardware and software implementations incorporate countermeasures specifically designed to detect or prevent faults occurring during the FO verification step.<\/p>\n
However, the new research from the Brazilian and Singaporean teams demonstrates that relying exclusively on these established defenses leaves a dangerous blind spot. By shifting their focus away from the Fujisaki-Okamoto verification process, the researchers successfully identified and exploited less obvious instructions nested deep within the decapsulation phase of both HQC and BIKE.<\/p>\n
To prove the viability of their theoretical findings, the research team put their hypotheses to the test using physical hardware. The attacks were experimentally validated on an STM32H7 microcontroller, a widely used embedded processor common in secure devices and Internet of Things (IoT) hardware. Utilizing laser fault injection\u2014a precise physical attack method where a focused laser beam temporarily alters the electrical state of a semiconductor chip to flip bits or disrupt instruction execution\u2014the researchers demonstrated that their methods are highly repeatable and practical in real-world scenarios.<\/p>\n
The implications of the study are profound for the security guarantees of NIST Level 1 parameters, which represent the baseline security tier for post-quantum standards. According to the findings, the proposed attack methodologies achieve full cryptographic key recovery using only valid ciphertexts. This is a critical detail, as using valid ciphertexts allows an attacker to blend their malicious queries seamlessly into normal network or device traffic, making detection significantly more difficult for system administrators and intrusion detection systems.<\/p>\n
The efficiency of the attacks varies between the two schemes but remains well within feasible bounds for a determined adversary with physical access to a target device. For HQC, the researchers successfully achieved full key recovery requiring 17,392 decapsulation queries. For BIKE, the process required approximately 3 million decapsulation queries. While the higher number of queries for BIKE reflects the distinct mathematical structure of its underlying quasi-cyclic code and error-correcting decoder, both figures demonstrate that vulnerabilities extend deeply into the internal mechanics of the decapsulation algorithms rather than remaining isolated to the verification boundary.<\/p>\n
Beyond demonstrating the vulnerabilities of HQC and BIKE, the study introduces a broader, systematic approach to identifying effective fault locations within cryptographic implementations. Finding where a device is susceptible to fault injection has traditionally been a tedious process of trial and error, often relying on exhaustive searches or deep intuition regarding specific instruction sets. <\/p>\n
The team from Universidade de S\u00e3o Paulo and NTU Singapore circumvented this hurdle by analyzing how error-correcting decoders behave under perturbed conditions. By systematically observing how the decoder reacts when internal states are disturbed, the researchers developed a general methodology for pinpointing vulnerable instructions that handle intermediate data during the decoding process. This analytical framework not only streamlines the discovery of new attack vectors on HQC and BIKE but also provides a template for evaluating other cryptographic schemes currently under consideration for post-quantum standards.<\/p>\n
The authors note that these revelations expose a considerably broader attack surface than previously acknowledged in the academic literature. As industries prepare to transition their digital infrastructure to post-quantum algorithms, securing the mathematical purity of an algorithm on paper is only half the battle. Hardware implementations must also account for physical side-channel and fault injection threats that target internal decoding and decapsulation logic.<\/p>\n
By laying bare these vulnerabilities, the research provides a vital foundation for future work in hardware security, empowering cryptographers and hardware engineers to design more comprehensive countermeasures that extend far beyond the Fujisaki-Okamoto transform. The complete research paper, detailing the mathematical foundations, experimental setups, and BibTeX citation data for academic reference, is publicly accessible via the Cryptology ePrint Archive under paper identifier 2026\/2492.<\/p>\n","protected":false},"excerpt":{"rendered":"
A collaborative team of international researchers from the Universidade de S\u00e3o Paulo in Brazil and Nanyang Technological University (NTU) in Singapore has published a significant new study highlighting hidden vulnerabilities in prominent post-quantum cryptographic schemes. The research paper, designated as Paper 2026\/2492 on the Cryptology ePrint Archive, focuses on sophisticated hardware-level security threats against two<\/p>\n","protected":false},"author":19,"featured_media":1685,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[672],"tags":[674,423,1619,1618,603,1621,1616,1617,673,244,704,214,1164,1620,630,202],"class_list":["post-1686","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-cryptography-math","tag-algorithms","tag-attacks","tag-beyond","tag-bike","tag-cryptography","tag-defenses","tag-fault","tag-injection","tag-math","tag-post","tag-quantum","tag-research","tag-reveals","tag-standard","tag-target","tag-vulnerabilities"],"_links":{"self":[{"href":"https:\/\/wyominginvest.com\/index.php?rest_route=\/wp\/v2\/posts\/1686","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wyominginvest.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wyominginvest.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wyominginvest.com\/index.php?rest_route=\/wp\/v2\/users\/19"}],"replies":[{"embeddable":true,"href":"https:\/\/wyominginvest.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1686"}],"version-history":[{"count":0,"href":"https:\/\/wyominginvest.com\/index.php?rest_route=\/wp\/v2\/posts\/1686\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/wyominginvest.com\/index.php?rest_route=\/wp\/v2\/media\/1685"}],"wp:attachment":[{"href":"https:\/\/wyominginvest.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1686"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wyominginvest.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1686"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wyominginvest.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1686"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}