Search

Code-based public-key cryptosystems are promising candidates for standardization as quantum-resistant public-key cryptographic algorithms. Their security is based on the hardness of the syndrome decoding problem. Computing the syndrome in a finite field, usually \(\mathbb {F}_{2}\), guarantees the security of the constructions. We show in this article that the problem becomes considerably easier to solve if the syndrome is computed in \(\mathbb {N}\) instead. By means of laser fault injection, we illustrate how to compute the matrix-vector product in \(\mathbb {N}\) by corrupting specific instructions, and validate it experimentally. To solve the syndrome decoding problem in \(\mathbb {N}\), we propose a reduction to an integer linear programming problem. We leverage the computational efficiency of linear programming solvers to obtain real-time message recovery attacks against the code-based proposal to the NIST Post-Quantum Cryptography standardization challenge. We perform our attacks in the worst-case scenario, i.e. considering random binary codes, and retrieve the initial message within minutes on a desktop computer.

International audience; Microcontrollers storing valuable data or using security functions are vulnerable to fault injection attacks. Among the various types of faults, instruction skips induced at runtime proved to be effective against identification routines or encryption algorithms. Until recently, most research works assessed a fault model that consists in a single instruction skip, i.e. the ability to prevent one chosen instruction in a program from being executed. We question this fault model for EM fault injection on experimental basis and report the possibility to induce several consecutive instructions skips. Such an extended fault model proved to be effective against a duplication-based software countermeasure as our experiments revealed.

Laser injection is a powerful fault injection technique with a high spatial accuracy which allows an adversary to efficiently extract the secret information from an electronic device. The control and the repeatability of faults requires the attacker to understand the relation of the fault model to the setup (notably the laser spot size) and the process node of the target device. Most studies on laser fault injection report fault models resulting from a photo-electric current in CMOS transistors. This study provides a black-box analysis of the effect of a photo-electric current in floating-gate transistors of two embedded NOR Flash memories from two different manufacturers. Experimental results demonstrate that single-bit bit-set faults can be injected in code and data without corrupting the Flash memory, even with a laser spot of more than 20 µm in diameter, which is several orders of magnitude larger than the process node of the floating-gate transistors in the experiments. This article also presents the specifics of performing a "safe-error" attack on AES, leveraging the previously detailed single-bit bit-set fault model.

International audience; Microcontrollers storing valuable data or using security functions are vulnerable to fault injection attacks. Among the various types of faults, instruction skips induced at runtime proved to be effective against identification routines or encryption algorithms. Until recently, most research works assessed a fault model that consists in a single instruction skip, i.e. the ability to prevent one chosen instruction in a program from being executed. We question this fault model for EM fault injection on experimental basis and report the possibility to induce several consecutive instructions skips.

International audience; Fault injection techniques allow an attacker to alter the behavior of an electronic device in order to extract confidential information or be granted unauthorized privileges. To this end, local electromagnetic fault injections (EMFI) are commonly used to corrupt or prevent the execution of instructions.However, little attention is devoted to practical data corruption. This article investigates the local effects of EMFI on data transfer from the Flash memory to the 128-bit data buffer of a cortex-M microcontroller. We demonstrate that the corrupted bits are closely related to the location of the injection probe, allowing us to set or reset from 0 to 128 bits with a byte- level precision. Moreover, the spatial and temporal accuracy of the injection technique allowed us to target the data prefetch mechanism without corrupting the code execution.We highlight the efficiency of the derived fault model with three practical case studies. Firstly, we demonstrate precise key- zeroing and key-setting capability, with further extension to a DFA on the secret key of a cipher from Biham and Shamir, that was never implemented practically. Next, we report practical persistent faults on ARM microcontroller, which allows an attacker to retrieve the secret key of a cipher with a single successful injection.