Side-Channel Analysis of Arithmetic Encodings for Post-Quantum Cryptography: Cautionary Notes with Application to Kyber
(2024) 15th International Conference on Cryptology in Africa — Location: Douala, Cameroon (10.July.2024)
Files
Side-ChannelAnalysisofArithmetic.pdf
Open Access - Adobe PDF
- 1.39 MB
Details
- Authors
- Abstract
- The unprotected implementations of Kyber and Dilithium have recently been shown to offer a variety of side-channel attack paths. These attacks have in turn triggered the investigation of secure and effi- cient masked implementations. In this paper, we observe that the design and evaluation of such masked implementations come with new chal- lenges, due to the manipulation of small and non-uniform secrets that is common in post-quantum encryption algorithms, which may hinder their good understanding. On the one hand, we show that using the Signal- to-Noise Ratio (SNR) per share to select Points-of-Interest (POIs) in leakage traces, as it is common in symmetric cryptography, can lead to confusing outcomes where leakage samples that correspond to the ma- nipulation of another share than the targeted one are detected. On the other hand, we show that the arithmetic encoding of small and non- uniform secrets leads to representation-dependencies so that summing or subtracting shares leads to different amounts of information leakage. We apply these observations to Kyber and show that they essentially vanish when increasing the number of shares. Incidentally, we also dis- cuss the attack strategies to recover small and non-uniform secrets with side-channel attacks efficiently. We hope these observations can help im- plementers and evaluators to better interpret their security claims.
- Affiliations
Citations
Pay, T. M. D., & Standaert, F.-X. (2024). Side-Channel Analysis of Arithmetic Encodings for Post-Quantum Cryptography: Cautionary Notes with Application to Kyber. Progress in Cryptology - {AFRICACRYPT} 2024. Published. 15th International Conference on Cryptology in Africa, Douala, Cameroon. https://doi.org/10.1007/978-3-031-64381-1_12