Arithmetic recodings for ECC cryptoprocessors with protections against side-channel attacks

• Main Author: Chabrier, Thomas
• Language: ENG
• Published: Université Rennes 1 2013
• Subjects: [INFO:INFO_OH] Computer Science/Other; [INFO:INFO_OH] Informatique/Autre; Elliptic curve; Cryptography; Attack by observation; Side channel attack; Arithmetic recoding; Protection; Counter measure; Fpga; Asic; Hardware implementation
• Online Access: http://tel.archives-ouvertes.fr/tel-00910879; http://tel.archives-ouvertes.fr/docs/00/92/97/00/PDF/CHABRIER_Thomas.pdf

This PhD thesis focuses on the study, the hardware design, the theoretical and practical validation, and eventually the comparison of different arithmetic operators for cryptosystems based on elliptic curves (ECC). Provided solutions must be robust against some side-channel attacks, and efficient at a hardware level (execution speed and area). In the case of ECC, we want to protect the secret key, a large integer, used in the scalar multiplication. Our protection methods use representations of numbers, and behaviour of algorithms to make more difficult some attacks. For instance, we randomly change some representations of manipulated numbers while ensuring that computed values are correct. Redundant representations like signed-digit representation, the double- (DBNS) and multi-base number system (MBNS) have been studied. A proposed method provides an on-the-fly MBNS recoding which operates in parallel to curve-level operations and at very high speed. All recoding techniques have been theoretically validated, simulated extensively in software, and finally implemented in hardware (FPGA and ASIC). A side-channel attack called template attack is also carried out to evaluate the robustness of a cryptosystem using a redundant number representation. Eventually, a study is conducted at the hardware level to provide an ECC cryptosystem with a regular behaviour of computed operations during the scalar multiplication so as to protect against some side-channel attacks.