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Side-channel attacks that leak sensitive information through a computing device's interaction with its physical environment have proven to be a severe threat to devices' security, particularly when adversaries have unfettered physical access to the device. Traditional approaches for leakage detection measure the physical properties of the device. Hence, they cannot be used during the design process and fail to provide root cause analysis. An alternative approach that is gaining traction is to automate leakage detection by modeling the device. The demand to understand the scope, benefits, and limitations of the proposed tools intensifies with the increase in the number of proposals. In this SoK, we classify approaches to automated leakage detection based on the model's source of truth. We classify the existing tools on two main parameters: whether the model includes measurements from a concrete device and the abstraction level of the device specification used for constructing the model. We survey the proposed tools to determine the current knowledge level across the domain and identify open problems. In particular, we highlight the absence of evaluation methodologies and metrics that would compare proposals' effectiveness from across the domain. We believe that our results help practitioners who want to use automated leakage detection and researchers interested in advancing the knowledge and improving automated leakage detection. 

The design of software countermeasures against active and passive adversaries is a challenging problem that has been addressed by many authors in recent years. The proposed solutions adopt a theoretical foundation (such as a leakage model) but often do not offer concrete reference implementations to validate the foundation. Contributing to the experimental dimension of this body of work, we propose a customized processor called SKIVA that supports experiments with the design of countermeasures against a broad range of implementation attacks. Based on bitslice programming and recent advances in the literature, SKIVA offers a flexible and modular combination of countermeasures against power-based and timing-based side-channel leakage and fault injection. Multiple configurations of side-channel protection and fault protection enable the programmer to select the desired number of shares and the desired redundancy level for each slice. Recurring and security-sensitive operations are supported in hardware through custom instruction-set extensions. The new instructions support bitslicing, secret-share generation, redundant logic computation, and fault detection. We demonstrate and analyze multiple versions of AES from a side-channel analysis and a fault-injection perspective, in addition to providing a detailed performance evaluation of the protected designs. To our knowledge, this is the first validated end-to-end implementation of a modular bitslice-oriented countermeasure. 

Lightweight cryptography offers viable security solutions for resource constrained Internet of Things (IoT) devices. However, IoT devices have implementation vulnerabilities such as side channel attacks (SCA), where observation of physical phenomena associated with device operations can reveal sensitive internal contents. The U.S. National Institute of Standards and Technology has called for lightweight cryptographic solutions to process authenticated encryption with associated data (AEAD), and is evaluating candidates for suitability in a Lightweight Cryptography (LWC) Standardization Process. Two Round 2 candidate variants, COMET-CHAM and SCHWAEMM, use Addition-Rotation-XOR (ARX) primitives. However, ARX ciphers are known to be costly to protect against certain SCA. In this work we implement side channel protected versions of COMET-CHAM and SCHWAEMM using register transfer level design. Identical protection schemes consisting of a threshold implementation (TI)-protected Kogge-Stone adder are adopted. Resistance to power side channel analysis is verified on an Artix-7 FPGA target device. Implementations comply with the Hardware API for Lightweight Cryptography, and use a custom-designed extension of the Development Package for the Hardware API for Lightweight Cryptography which enables test and evaluation of side channel resistant designs. We compare side channel protection costs of the two candidates against each other, against their unprotected counterparts, and against previous side channel protected AEAD implementations. COMET-CHAM is shown to consume less area and power, while SCHWAEMM has higher throughput and throughput to area ratio, and is more energy efficient. On average, the costs of protecting these ciphers against SCA are 32% more in area and 38% more in power, compared to the average protection costs for a large selection of previously-evaluated ciphers of similar implementation. Our results highlight the costs involved in implementing side channel protected ARX-ciphers, and help to inform NIST LWC late round and final portfolio selections.