Projects per year
Abstract
The isogeny-based post-quantum digital signature algorithm SQIsign offers the most compact key and signature sizes among all candidates in the ongoing NIST call for additional post-quantum signature algorithms. To the best of our knowledge, we present the first Simple Power Analysis (SPA) side-channel attack on SQIsign, demonstrating its feasibility for key recovery.
Our attack specifically targets secret-dependent computations within Cornacchia's algorithm, a fundamental component of SQIsign's quaternion module. At the core of this algorithm, a secret-derived yet ephemeral exponent is used in a modular exponentiation subroutine. By performing SPA on the modular exponentiation, we successfully recover this ephemeral exponent. We then develop a method to show how this leaked exponent can be exploited to ultimately reconstruct the secret signing key of SQIsign.
Our findings emphasize the critical need for side-channel-resistant implementations of SQIsign, highlighting previously unexplored vulnerabilities in its design.
Our attack specifically targets secret-dependent computations within Cornacchia's algorithm, a fundamental component of SQIsign's quaternion module. At the core of this algorithm, a secret-derived yet ephemeral exponent is used in a modular exponentiation subroutine. By performing SPA on the modular exponentiation, we successfully recover this ephemeral exponent. We then develop a method to show how this leaked exponent can be exploited to ultimately reconstruct the secret signing key of SQIsign.
Our findings emphasize the critical need for side-channel-resistant implementations of SQIsign, highlighting previously unexplored vulnerabilities in its design.
Original language | English |
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Title of host publication | Africacrypt 2025 |
Publication status | Accepted/In press - 2025 |
Event | 16th International Conference on Cryptology, Progress in Cryptology - AFRICACRYPT 2025 - Rabat, Morocco Duration: 21 Jul 2025 → 23 Jul 2025 |
Conference
Conference | 16th International Conference on Cryptology, Progress in Cryptology - AFRICACRYPT 2025 |
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Abbreviated title | AFRICACRYPT 2025 |
Country/Territory | Morocco |
City | Rabat |
Period | 21/07/25 → 23/07/25 |
Fields of Expertise
- Information, Communication & Computing
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FWF - ISOCrystals - Secure and Efficient Isogeny-based Cryptography in Hardware
Sinha Roy, S. (Co-Investigator (CoI))
3/06/24 → 2/12/27
Project: Research project