Extending Glitch-Free Multiparty Protocols to Resist Fault Injection Attacks

Side channel analysis and fault attacks are two powerful methods to analyze and break cryptographic implementations. Recently, secure multiparty computation has been applied to prevent side channel attacks. While multiparty computation is known to be fault resistant as well, the particular schemes popular for side channel protection do not currently offer this feature. In this paper we introduce a new secure multiparty circuit to prevent both fault attacks and side channel analysis. The new scheme builds on an existing side channel countermeasure and extends it to preserve errors and propagate them until the end of the circuit. A new recombination operation ensures randomization of the output in the case of an error, ensuring that nothing can be learned from the faulty output. After introducing the new secure multiparty circuit, we show how it can be applied to AES and present the performance and security analysis

Cryptographic Fault Diagnosis using VerFI

Historically, fault diagnosis for integrated circuits has singularly dealt with reliability concerns. In contrast, a cryptographic circuit needs to be primarily evaluated concerning information leakage in the presence of maliciously crafted faults. While Differential Fault Attacks (DFAs) on symmetric ciphers have been known for over 20 years, recent developments have tried to structurally classify the attackers’ capabilities as well as the properties of countermeasures. Correct realization of countermeasures should still be manually verified, which is error-prone and infeasible for even moderate-size real-world designs. Here, we introduce the concept of Cryptographic Fault Diagnosis, which revises and shapes the notions of fault diagnosis in reliability testing to the needs of evaluating cryptographic implementations. Additionally, we present VerFI, which materializes the idea of Cryptographic Fault Diagnosis. It is a fully automated, open-source fault detection tool processing the gate-level representation of arbitrary cryptographic implementations. By adjusting the bounds of the underlying adversary model, VerFI allows us to rapidly examine the desired fault detection/correction capabilities of the given implementation. Among several case studies, we demonstrate its application on an implementation of LED cipher with combined countermeasures against side-channel analysis and fault-injection attacks (published at CRYPTO 2016). This experiment revealed general implementation flaws and undetectable faults leading to successful DFA on the protected design with full-key recovery

Extending Glitch-Free Multiparty Protocols to Resist Fault Injection Attacks

Side channel analysis and fault attacks are two powerful methods to analyze and break cryptographic implementations. At CHES 2011, Roche and Prouff applied secure multiparty computation to prevent side-channel attacks. While multiparty computation is known to be fault-resistant as well, the particular scheme used for side-channel protection does not currently offer this feature. This work introduces a new secure multiparty circuit to prevent both fault injection attacks and sidechannel analysis. The new scheme extends the Roche and Prouff scheme to make faults detectable. Arithmetic operations have been redesigned to propagate fault information until a new secrecy-preserving fault detection can be performed. A new recombination operation ensures randomization of the output in the case of a fault, ensuring that nothing can be learned from the faulty output. The security of the new scheme is proved in the ISW probing model, using the reformulated t-SNI security notion. Besides the new scheme and its security proof, we also present an extensive performance analysis, including a proof-of-concept, software-based AES implementation featuring the masking technique to resist both fault and side-channel attacks at the same time. The performance analysis for different security levels are given for the ARM-M0+ MCU with its memory requirements. A comprehensive leakage analysis shows that a careful implementation of the scheme achieves the expected security level