What a lovely hat

A partial key exposure attack is a key recovery attack where an adversary obtains a priori partial knowledge of the secret key, e.g., through side-channel leakage. While for a long time post-quantum cryptosystems, unlike RSA, have been believed to be resistant to such attacks, recent results by Esser, May, Verbel, and Wen (CRYPTO ’22), and by Kirshanova and May (SCN ’22), have refuted this belief. In this work, we focus on partial key exposure attacks in the context of rank-metric-based...

Side-channel analysis is a powerful technique to extract secret data from cryptographic devices. However, this task heavily relies on experts and specialized tools, particularly in the case of simple power analysis (SPA). Meanwhile, ChatGPT, a leading example of large language models, has attracted great attention and been widely applied for assisting users with complex tasks. Despite this, ChatGPT’s capabilities for fully automated SPA, where prompts and traces are input only once, have yet...

Cryptography secures our online interactions, transactions, and trust. To achieve this goal, not only do the cryptographic primitives and protocols need to be secure in theory, they also need to be securely implemented by cryptographic library developers in practice. However, implementing cryptographic algorithms securely is challenging, even for skilled professionals, which can lead to vulnerable implementations, especially to side-channel attacks. For timing attacks, a severe class of...

The so-called Gaussian template attacks (TA) is one of the optimal Side-Channel Analyses (SCA) when the measurements are captured with normal noise. In the SCA literature, several optimizations of its implementation are introduced, such as coalescence and spectral computation. The coalescence consists of averaging traces corresponding to the same plaintext value, thereby coalescing (synonymous: compacting) the dataset. Spectral computation consists of sharing the computational workload...

Recent work proposed by Bernstein et al. (from EPRINT 2024) identified two timing attacks, KyberSlash1 and KyberSlash2, targeting ML-KEM decryption and encryption algorithms, respectively, enabling efficient recovery of secret keys. To mitigate these vulnerabilities, correctives were promptly applied across implementations. In this paper, we demonstrate a very simple side-channel-assisted power analysis attack on the patched implementations of ML-KEM. Our result showed that original timing...

The CRYSTALS-Dilithium digital signature scheme, selected by NIST as a post-quantum cryptography (PQC) standard under the name ML-DSA, employs a public key compression technique intended for performance optimization. Specifically, the module learning with error instance $({\bf A}, {\bf t})$ is compressed by omitting the low-order bits ${\bf t_0}$ of the vector ${\bf t}$. It was recently shown that knowledge of ${\bf t_0}$ enables more effective side-channel attacks on Dilithium...

The Gentry-Peikert-Vaikuntanathan (GPV) framework is utilized for constructing digital signatures, which is proven to be secure in the classical/quantum random-oracle model. Falcon is such a signature scheme, recognized as a compact and efficient signature among NIST-standardized signature schemes. Although a signature scheme based on the GPV framework is theoretically highly secure, it could be vulnerable to side-channel attacks and hence further research on physical attacks is required to...

In this study, we present the first side-channel attack on the ARADI block cipher, exposing its vulnerabilities to physical attacks in non-profiled scenarios. We propose a novel bitwise divide-and-conquer methodology tailored for ARADI, enabling key recovery. Furthermore, based on our attack approach, we present a stepwise method for recovering the full 256-bit master key. Through experiments on power consumption traces from an ARM processor, we demonstrate successful recovery of target key...

This paper investigates pseudorandom generation in the context of masked cryptographic implementation. Although masking and pseudorandom generators (PRGs) have been distinctly studied for a long time, little literature studies how the randomness in the masked implementation should be generated. The lack of analysis on mask-bits generators makes the practical security of masked cryptographic implementation unclear, and practitioners (e.g., designer, implementer, and evaluator) may be confused...

Side-Channel Analysis (SCA) exploits physical vulnerabilities in systems to reveal secret keys. With the rise of Internet-of-Things, evaluating SCA attacks has become crucial. Profiling attacks, enhanced by Deep Learning-based Side-Channel Analysis (DLSCA), have shown significant improvements over classical techniques. Recent works demonstrate that ensemble methods outperform single neural networks. However, almost every existing ensemble selection method in SCA only picks the top few...

BAKSHEESH is a lightweight block cipher following up the well-known cipher GIFT-128, which uses a 4-bit SBox that has a non-trivial Linear Structure (LS). Also, the Sbox requires a low number of AND gates that makes BAKSHEESH stronger to resist the side channel attacks compared to GIFT-128. In this paper, we give the first third-party security analysis of BAKSHEESH from the traditional attacks perspective: integral, differential and linear attacks. Firstly, we propose a framework for...

Interconnected devices enhance daily life but introduce security vulnerabilities, new technologies enable malicious activities such as information theft. This article combines radio frequency (RF) side-channel attacks with software Trojans to create a hard-to-detect, stealthy method for extracting kilobytes of secret information per millisecond over record distances with a single measurement in the RF spectrum. The technique exploits Trojan-induced electrical disturbances in RF components...

Implementation-security vulnerabilities such as the power-based side-channel leakage and fault-injection sensitivity of a secure chip are hard to verify because of the sophistication of the measurement setup, as well as the need to generalize the adversary into a test procedure. While the literature has proposed a wide range of vulnerability metrics to test the correctness of a secure implementation, it is still up to the subject-matter expert to map these concepts into a working and...

In the face of escalating security threats in modern computing systems, there is an urgent need for comprehensive defense mechanisms that can effectively mitigate invasive, noninvasive and interactive security vulnerabilities in hardware and software domains. Individually, hardware and software weaknesses and probable remedies have been practiced but protecting a combined system has not yet been discussed in detail. This survey paper provides a comprehensive overview of the emerging...

In this paper, we present the first single trace side-channel attack that targets the MPC-in-the-Head (MPCitH) framework based on threshold secret sharing, also known as Threshold Computation in the Head (TCitH) in its original version. This MPCitH framework can be found in 5 of the 14 digital signatures schemes in the recent second round of the National Institute of Standards and Technology (NIST) call for digital signatures. In this work, we start by highlighting a side-channel...

Given the devastating security compromises caused by side-channel attacks on existing classical systems, can we store our private data encoded as a quantum state so that they can be kept private in the face of arbitrary side-channel attacks? The unclonable nature of quantum information allows us to build various quantum protection schemes for cryptographic information such as secret keys. Examples of quantum protection notions include copy-protection, secure leasing, and finally,...

The National Institute for Standards and Technology (NIST) initiated a standardization procedure for additional digital signatures and recently announced round-2 candidates for the PQ additional digital signature schemes. The multivariate digital signature scheme Unbalanced Oil and Vinegar (UOV) is one of the oldest post-quantum schemes and has been selected by NIST for Round 2. Although UOV is mathematically secure, several side-channel attacks (SCA) have been shown on the UOV or UOV-based...

During the past decade, Deep Neural Networks (DNNs) proved their value on a large variety of subjects. However despite their high value and public accessibility, the protection of the intellectual property of DNNs is still an issue and an emerging research field. Recent works have successfully extracted fully-connected DNNs using cryptanalytic methods in hard-label settings, proving that it was possible to copy a DNN with high fidelity, i.e., high similitude in the output predictions....

Side-channel attacks pose a serious risk to cryptographic implementations, particularly in embedded systems. While current methods, such as test vector leakage assessment (TVLA), can identify leakage points, they do not provide insights into their root causes. We propose ARCHER, an architecture-level tool designed to perform side-channel analysis and root cause identification for software cryptographic implementations on RISC-V processors. ARCHER has two main components: (1) Side-Channel...

In response to the quantum threat, new post-quantum cryptographic algorithms will soon be deployed to replace existing public-key schemes. MAYO is a quantum-resistant digital signature scheme whose small keys and signatures make it suitable for widespread adoption, including on embedded platforms with limited security resources. This paper demonstrates two single-trace side-channel attacks on a MAYO implementation in ARM Cortex-M4 that recover a secret key with probabilities of 99.9% and...

In this work, we propose the first hardware implementation of Classic McEliece protected with countermeasures against Side-Channel Attacks (SCA) and Fault Injection Attacks (FIA). Classic Mceliece is one of the leading candidates for Key Encapsulation Mechanisms (KEMs) in the ongoing round 4 of the NIST standardization process for post-quantum cryptography. In particular, we implement a range of generic countermeasures against SCA and FIA, particularly protected the vulnerable operations...

Multivariate cryptography currently centres mostly around UOV-based signature schemes: All multivariate round 2 candidates in the selection process for additional digital signatures by NIST are either UOV itself or close variations of it: MAYO, QR-UOV, SNOVA, and UOV. Also schemes which have been in the focus of the multivariate research community, but are broken by now - like Rainbow and LUOV - are based on UOV. Both UOV and the schemes based on it have been frequently analyzed regarding...

We present the protected hardware implementation of the Module-Lattice-Based Digital Signature Standard (ML-DSA). ML-DSA is an extension of Dilithium 3.1, which is the winner of the Post Quantum Cryptography (PQC) competition in the digital signature category. The proposed design is based on the existing high-performance Dilithium 3.1 design. We implemented existing Dilithium masking gadgets in hardware, which were only implemented in software. The masking gadgets are integrated with the...

We explore the use of microbenchmarks, small assembly code snippets, to detect microarchitectural side-channel leakage in CPU implementations. Specifically, we investigate the effectiveness of microbenchmarks in diagnosing the predisposition to side-channel leaks in two commonly used RISC-V cores: Picorv32 and Ibex. We propose a new framework that involves diagnosing side-channel leaks, identifying leakage points, and constructing leakage profiles to understand the underlying causes. We...

Evaluation of cryptographic implementations with respect to side-channels has been mandated at high security levels nowadays. Typically, the evaluation involves four stages: detection, modeling, certification and secret recovery. In pursuit of specific goal at each stage, inherently different techniques used to be considered necessary. However, since the recent works of Eurocrypt2022 and Eurocrypt2024, linear regression analysis (LRA) has uniquely become the technique that is well-applied...

In this paper, we introduce OT-PCA, a novel approach for conducting Plaintext-Checking (PC) oracle based side-channel attacks, specifically designed for Hamming Quasi-Cyclic (HQC). By calling the publicly accessible HQC decoder, we build offline templates that enable efficient extraction of soft information for hundreds of secret positions with just a single PC oracle call. Our method addresses critical challenges in optimizing key-related information extraction, including maximizing...

Falcon is one of the three postquantum signature schemes already selected by NIST for standardization. It is the most compact among them, and offers excellent efficiency and security. However, it is based on a complex algorithm for lattice discrete Gaussian sampling which presents a number of implementation challenges. In particular, it relies on (possibly emulated) floating-point arithmetic, which is often regarded as a cause for concern, and has been leveraged in, e.g., side-channel...

Classic McEliece is one of the three code-based candidates in the fourth round of the NIST post-quantum cryptography standardization process in the Key Encapsulation Mechanism category. As such, its decapsulation algorithm is used to recover the session key associated with a ciphertext using the private key. In this article, we propose a new side-channel attack on the syndrome computation in the decapsulation algorithm that recovers the private key, which consists of the private Goppa...

Masking schemes are key in thwarting side-channel attacks due to their robust theoretical foundation. Transitioning from Boolean to arithmetic (B2A) masking is a necessary step in various cryptography schemes, including hash functions, ARX-based ciphers, and lattice-based cryptography. While there exists a significant body of research focusing on B2A software implementations, studies pertaining to hardware implementations are quite limited, with the majority dedicated solely to creating...

Recently, deep learning-based side-channel analysis (DLSCA) has emerged as a serious threat against cryptographic implementations. These methods can efficiently break implementations protected with various countermeasures while needing limited manual intervention. To effectively protect implementation, it is therefore crucial to be able to interpret \textbf{how} these models are defeating countermeasures. Several works have attempted to gain a better understanding of the mechanics of these...

Masking is a sound countermeasure to protect against differential power analysis. Since the work by Balasch et al. in ASIACRYPT 2012, inner product masking has been explored as an alternative to the well known Boolean masking. In CARDIS 2017, Poussier et al. showed that inner product masking achieves higher-order security versus Boolean masking, for the same shared size, in the bit-probing model. Wang et al. in TCHES 2020 verified the inner product masking's security order amplification in...

Datasets of side-channel leakage measurements are widely used in research to develop and benchmarking side-channel attack and evaluation methodologies. Compared to using custom and/or one-off datasets, widely-used and publicly available datasets improve research reproducibility and comparability. Further, performing high-quality measurements requires specific equipment and skills, while also taking a significant amount of time. Therefore, using publicly available datasets lowers the barriers...

Passive (leakage exploitation) and active (fault injection) physical attacks pose a significant threat to cryptographic schemes. Although leakage-resistant cryptography is well studied, there is little work on mode-level security in the presence of joint faults and leakage exploiting adversaries. In this paper, we focus on integrity for authenticated encryption (AE). First, we point out that there is an inherent attack in the fault-resilience model presented at ToSC 2023. This shows how...

In Side-Channel Analysis (SCA), statistical or machine learning methods are employed to extract secret information from power or electromagnetic (EM) traces. In many practical scenarios, raw power/EM traces can span hundreds of thousands of features, with relevant leakages occurring over only a few small segments. Consequently, existing SCAs often select a small number of features before launching the attack, making their success highly dependent on the feasibility of feature selection....

The area of modern zero-knowledge proof systems has seen a significant rise in popularity over the last couple of years, with new techniques and optimized constructions emerging on a regular basis. As the field matures, the aspect of implementation attacks becomes more relevant, however side-channel attacks on zero-knowledge proof systems have seen surprisingly little treatment so far. In this paper we give an overview of potential attack vectors and show that some of the underlying...

The see-in-the-middle (SITM) attack combines differential cryptanalysis and the ability to observe differential patterns in the side-channel leakage traces to reveal the secret key of SPN-based ciphers. While SITM presents a fresh perspective to side-channel analysis and allows attacks on deeper cipher rounds, there are practical difficulties that come with this method. First, one must realize a visual inspection of millions of power traces. Second, there is a strong requirement to reduce...

AES implementation has been vastly analysed against side-channel attacks in the last two decades particularly targeting resource-constrained microcontrollers. Still, less research has been conducted on AES implementations on advanced hardware platforms. In this study, we examine the resilience of AES on an ARM Cortex A72 processor within the Raspberry Pi 4B model. Unlike their microcontroller counterparts, these platforms operate within the complex ecosystem of an operating system (OS),...

Secure elements are small microcontrollers whose main purpose is to generate/store secrets and then execute cryptographic operations. They undergo the highest level of security evaluations that exists (Common Criteria) and are often considered inviolable, even in the worst-case attack scenarios. Hence, complex secure systems build their security upon them. FIDO hardware tokens are strong authentication factors to sign in to applications (any web service supporting FIDO); they often embed...

To be competitive with other signature schemes, the MLWE instance $\bf (A,t)$ on which Dilithium is based is compressed: the least significant bits of $\bf t$, which are denoted $\textbf{t}_0$, are considered part of the secret key. Knowing $\bf t_0$ does not provide any information about the other data in the secret key, but it does allow the construction of much more efficient side-channel attacks. Yet to the best of our knowledge, there is no kown way to recover $\bf t_0$ from Dilithium...

Due to the ubiquitous requirements and performance leap in the past decade, it has become feasible to execute garbling and secure computations in settings sensitive to side-channel attacks, including smartphones, IoTs and dedicated hardwares, and the possibilities have been demonstrated by recent works. To maintain security in the presence of a moderate amount of leaked information about internal secrets, we investigate {\it leakage-resilient garbling}. We augment the classical privacy,...

This short note describes an update to the sca25519 library, an ECC implementation computing the X25519 key-exchange protocol on the Arm Cortex-M4 microcontroller. The sca25519 software came with extensive mitigations against various side-channel and fault attacks and was, to our best knowledge, the first to claim affordable protection against multiple classes of attacks that are motivated by distinct real-world application scenarios. This library is protected against various passive and...

Key distribution plays a fundamental role in cryptography. Currently, the quantum scheme stands as the only known method for achieving unconditionally secure key distribution. This method has been demonstrated over distances of 508 and 1002 kilometers in the measurement-device-independent and twin-field configurations, respectively. However, quantum key distribution faces transmission distance issues and numerous side channel attacks since the basic physical picture requires the use of...

Robust message authentication codes (MACs) and authenticated encryption (AE) schemes that provide authenticity in the presence of side-channel leakage are essential primitives. These constructions often rely on primitives designed for strong leakage protection, among others including the use of strong-unpredictable (tweakable) block-ciphers. This paper extends the strong-unpredictability security definition to the versatile and new forkcipher primitive. We show how to construct secure and...

Side-channel analysis on complex SoC devices with high-frequency microprocessors and multitasking operating systems presents significant challenges in practice due to the high costs of trace acquisition and analysis, generally involving tens of thousands to millions of traces. This work uses a cryptographic execution process on a Broadcom 2837 SoC as a case study to explore ways to reduce costs in electromagnetic side-channel analysis. In the data acquisition phase, we propose an efficient...

Side-channel attacks (SCAs) remain a significant threat to the security of cryptographic systems in modern embedded devices. Even mathematically secure cryptographic algorithms, when implemented in hardware, inadvertently leak information through physical side-channel signatures such as power consumption, electromagnetic (EM) radiation, light emissions, and acoustic emanations. Exploiting these side channels significantly reduces the attacker’s search space. In recent years, physical...

This paper presents Raccoon, a lattice-based signature scheme submitted to the NIST 2022 call for additional post-quantum signatures. Raccoon has the specificity of always being masked. Concretely, all sensitive intermediate values are shared into 𝑑 parts. The main design rationale of Raccoon is to be easy to mask at high orders, and this dictated most of its design choices, such as the introduction of new algorithmic techniques for sampling small errors. As a result, Raccoon achieves a...

Masking has become a widely applied and heavily researched method to protect cryptographic implementations against SCA attacks. The success of masking is primarily attributed to its strong theoretical foundation enabling it to formally prove security by modeling physical properties through so-called probing models. Specifically, the robust $d$-probing model enables us to prove the security for arbitrarily masked hardware circuits, manually or with the assistance of automated tools, even when...

Considering side-channel analysis (SCA) security for cryptographic devices, the mitigation of electromagnetic leakage and electromagnetic interference (EMI) between modules poses significant challenges. This paper presents a comprehensive review and deep analysis of the utilization of EMI shielding materials, devised for reliability purposes and standards such as EMI/EMC, as a countermeasure to enhance EM-SCA security. We survey the current landscape of EMI-shields materials, including...

HAWK is a lattice-based signature scheme candidate to the fourth call of the NIST's Post-Quantum standardization campaign. Considered as a cousin of Falcon (one of the future NIST post-quantum standards) one can wonder whether HAWK shares the same drawbacks as Falcon in terms of side-channel attacks. Indeed, Falcon signature algorithm and particularly its Gaussian sampler, has shown to be highly vulnerable to power-analysis attacks. Besides, efficiently protecting Falcon's signature...

A prominent countermeasure against side channel attacks, the hiding countermeasure, typically involves shuffling operations using a permutation algorithm. Especially in the era of Post-Quantum Cryptography, the importance of the hiding coun- termeasure is emphasized due to computational characteristics like those of lattice and code-based cryptography. In this context, swiftly and securely generating permutations has a critical impact on an algorithm’s security and efficiency. The widely...

By introducing collision information, the existing side-channel Correlation-Enhanced Collision Attacks (CECAs) performed collision-chain detection, and reduced a given candidate space to a significantly smaller collision-chain space, leading to more efficient key recovery. However, they are still limited by low collision detection speed and low success rate of key recovery. To address these issues, we first give a Collision Detection framework with Genetic Algorithm (CDGA), which exploits ...

Lattice-based cryptography is in the process of being standardized. Several proposals to deal with side-channel information using lattice reduction exist. However, it has been shown that algorithms based on Bayesian updating are often more favorable in practice. In this work, we define distribution hints; a type of hint that allows modelling probabilistic information. These hints generalize most previously defined hints and the information obtained in several attacks. We define two...

Compilers often weaken or even discard software-based countermeasures commonly used to protect programs against side-channel attacks; worse, they may also introduce vulnerabilities that attackers can exploit. The solution to this problem is to develop compilers that preserve such countermeasures. Prior work establishes that (a mildly modified version of) the CompCert and Jasmin formally verified compilers preserve constant-time, an information flow policy that ensures that programs are...

In recent years, formal verification has emerged as a crucial method for assessing security against Side-Channel attacks of masked implementations, owing to its remarkable versatility and high degree of automation. However, formal verification still faces technical bottlenecks in balancing accuracy and efficiency, thereby limiting its scalability. Former tools like maskVerif and CocoAlma are very efficient but they face accuracy issues when verifying schemes that utilize properties of...

The rapid evolution of post-quantum cryptography, spurred by standardization efforts such as those led by NIST, has highlighted the prominence of lattice-based cryptography, notably exemplified by CRYSTALS-Kyber. However, concerns persist regarding the security of cryptographic implementations, particularly in the face of Side-Channel Attacks (SCA). The usage of operations like the Number Theoretic Transform (NTT) in CRYSTALS-Kyber introduces vulnerabilities to SCA, especially single-trace...

Side-channel-analysis (SCA) resistance with cost optimization in AES hardware implementations remains a significant challenge. While traditional masking-based schemes offer provable security, they often incur substantial resource overheads (latency, area, randomness, performance, power consumption). Alternatively, the RAMBAM scheme introduced a redundancy-based approach to control the signal-to-noise ratio, and achieves exponential leakage reduction as redundancy increases. This method...

As a prominent category of side-channel attacks (SCAs), plaintext-checking (PC) oracle-based SCAs offer the advantages of generality and operational simplicity on a targeted device. At TCHES 2023, Rajendran et al. and Tanaka et al. independently proposed the multiple-valued (MV) PC oracle, significantly reducing the required number of queries (a.k.a., traces) in the PC oracle. However, in practice, when dealing with environmental noise or inaccuracies in the waveform classifier, they...

In side-channel testing, the standard timing analysis works when the vendor can provide a measurement to indicate the execution time of cryptographic algorithms. In this paper, we find that there exists timing leakage in power/electromagnetic channels, which is often ignored in traditional timing analysis. Hence a new method of timing analysis is proposed to deal with the case where execution time is not available. Different execution time leads to different execution intervals, affecting...

In this work, we introduce enhanced high-order masking techniques tailored for Dilithium, the post-quantum signature scheme recently standardized by NIST. We improve the masked generation of the masking vector $\vec{y}$, based on a fast Boolean-to-arithmetic conversion modulo $q$. We also describe an optimized gadget for the high-order masked rejection sampling, with a complexity independent from the size of the modulus $q$. We prove the security of our gadgets in the classical ISW...

Oblivious Transfer (OT) is a fundamental cryptographic primitive, becoming a crucial component of a practical secure protocol. OT is typically implemented in software, and one way to accelerate its running time is by using hardware implementations. However, such implementations are vulnerable to side-channel attacks (SCAs). On the other hand, protecting interactive protocols against SCA is highly challenging because of their longer secrets (which include inputs and randomness), more...

In this work, we use some recent developments in lattice-based cryptanalytic tools to revisit a fault attack on RSA-CRT signatures based on the Partial Approximate Common Divisor (PACD) problem. By reducing the PACD to a Hidden Number Problem (HNP) instance, we decrease the number of required faulted bits from 32 to 7 in the case of a 1024-bit RSA. We successfully apply the attack to RSA instances up to 8192-bit and present an enhanced analysis of the error-tolerance in the Bounded Distance...

Measuring the fluctuations of the clock phase of a target was identified as a leakage source on early electromagnetic side-channel investigations. Despite this, only recently was directly measuring the clock phase (or jitter) of digital signals from a target connected to being a source of exploitable leakage. As the phase of a clock output will be related to signal propagation delay through the target, and this propagation delay is related to voltage, this means that most digital devices...

Anticipating the advent of large quantum computers, NIST started a worldwide competition in 2016 aiming to define the next cryptographic standards. HQC is one of these post-quantum schemes still in contention, with three others already standardized. In 2022, Guo et al. introduced a timing attack that exploited an inconsistency in HQC rejection sampling function to recover its secret key in 866,000 calls to an oracle. The authors of HQC updated its specification by applying an algorithm to...

With concerns about data privacy growing in a connected world, cryptography researchers have focused on fully homomorphic encryption (FHE) for promising machine learning as a service solutions. Recent advancements have lowered the computational cost by several orders of magnitude, but the latency of fully homomorphic neural networks remains a barrier to adoption. This work proposes using multi-exit neural networks (MENNs) to accelerate the FHE inference. MENNs are network architectures that...

In order to challenge the security of cryptographic systems, Side-Channel Attacks exploit data leaks such as power consumption and electromagnetic emissions. Classic Side-Channel Attacks, which mainly focus on mono-channel data, fail to utilize the joint information of multi-channel data. However, previous studies of multi-channel attacks have often been limited in how they process and adapt to dynamic data. Furthermore, the different data types from various channels make it difficult to use...

It is fundamental that executing cryptographic software must not leak secrets through side-channels. For software-visible side-channels, it was long believed that "constant-time" programming would be sufficient as a systematic countermeasure. However, this belief was shattered in 2018 by attacks exploiting speculative execution—so called Spectre attacks. Recent work shows that language support suffices to protect cryptographic code with minimal overhead against one class of such attacks,...

Garbled circuits (GC) are a secure multiparty computation protocol that enables two parties to jointly compute a function using their private data without revealing it to each other. While garbled circuits are proven secure at the protocol level, implementations can still be vulnerable to side-channel attacks. Recently, side-channel analysis of GC implementations has garnered significant interest from researchers. We investigate popular open-source GC frameworks and discover that the AES...

While passive side-channel attacks and active fault attacks have been studied intensively in the last few decades, strong attackers combining these attacks have only been studied relatively recently. Due to its simplicity, most countermeasures against passive attacks are based on additive sharing. Unfortunately, extending these countermeasures against faults often leads to quite a significant performance penalty, either due to the use of expensive cryptographic operations or a large number...

Mathematically secured cryptographic implementations leak critical information in terms of power, EM emanations, etc. Several circuit-level countermeasures are proposed to hinder side channel leakage at the source. Circuit-level countermeasures (e.g., IVR, STELLAR, WDDL, etc) are often preferred as they are generic and have low overhead. They either dither the voltage randomly or attenuate the meaningful signature at $V_{DD}$ port. Although any digital implementation has two generic ports,...

There exists a mismatch between the theory and practice of cryptography in the presence of leakage. On the theoretical front, the bounded leakage model, where the adversary learns bounded-length but noiseless information about secret components, and the random probing model, where the adversary learns some internal values of a leaking implementation with some probability, are convenient abstractions to analyze the security of numerous designs. On the practical front, side-channel attacks...

In this work, we present various hardware implementations for the lightweight cipher ASCON, which was recently selected as the winner of the NIST organized Lightweight Cryptography (LWC) competition. We cover encryption + tag generation and decryption + tag verification for the ASCON AEAD and also the ASCON hash function. On top of the usual (unprotected) implementation, we present side-channel protection (threshold countermeasure) and triplication/majority-based fault protection. To the...

Masking is a widely adopted countermeasure against side-channel analysis (SCA) that protects cryptographic implementations from information leakage. However, current masking schemes often incur significant overhead in terms of electronic cost. RAMBAM, a recently proposed masking technique that fits elegantly with the AES algorithm, offers ultra-low latency/area by utilizing redundant representations of finite field elements. This paper presents a comprehensive generalization of RAMBAM and...

Resilience against side-channel attacks is an important consideration for cryptographic implementations deployed in devices with physical access to the device. However, noise in side-channel measurements has a significant impact on the complexity of these attacks, especially when an implementation is protected with masking. Therefore, it is important to assess the ability of an attacker to deal with noise. While some previous works have considered approaches to remove (some) noise from...

The Learning with Errors problem (LWE) and its variants are among the most popular assumptions underlying lattice-based cryptography. The Learning with Rounding problem (LWR) can be thought of as a deterministic variant of LWE. While lattice-based cryptography is known to enable many advanced constructions, constructing Fully Homomorphic Encryption schemes based on LWR remains an under-explored part of the literature. In this work, we present a thorough study of Somewhat Homomorphic...

Software based cryptographic implementations provide flexibility but they face performance limitations. In contrast, hardware based cryptographic accelerators utilize application-specific customization to provide real-time security solutions. Cryptographic instruction-set extensions (CISE) combine the advantages of both hardware and software based solutions to provide higher performance combined with the flexibility of atomic-level cryptographic operations. While CISE is widely used to...

We present a novel approach to small area and low-latency first-order masking in hardware. The core idea is to separate the processing of shares in time in order to achieve non-completeness. Resulting circuits are proven first-order glitch-extended PINI secure. This means the method can be straightforwardly applied to mask arbitrary functions without constraints which the designer must take care of. Furthermore we show that an implementation can benefit from optimization through EDA tools...

There has been significant progress over the past seven years in model reverse engineering (RE) for neural network (NN) hardware. Although there has been systematization of knowledge (SoK) in an overall sense, however, the treatment from the hardware perspective has been far from adequate. To bridge this gap, this paper systematically categorizes the types of NN hardware used prevalently by the industry/academia, and also the model RE attacks/defenses published in each category. Further, we...

Side channel attacks, and in particular timing attacks, are a fundamental obstacle to obtaining secure implementation of algorithms and cryptographic protocols, and have been widely researched for decades. While cryptographic definitions for the security of cryptographic systems have been well established for decades, none of these accepted definitions take into account the running time information leaked from executing the system. In this work, we give the foundation of new cryptographic...

Masking is one of the most popular countermeasures to protect implementations against power and electromagnetic side channel attacks, because it offers provable security. Masking has been shown secure against d-threshold probing adversaries by Ishai et al. at CRYPTO'03, but this adversary's model doesn't consider any physical hardware defaults and thus such masking schemes were shown to be still vulnerable when implemented as hardware circuits. To addressed these limitations glitch-extended...

Despite masking being a prevalent protection against passive side-channel attacks, implementing it securely in hardware remains a manual, challenging, and error-prone process. This paper introduces INDIANA, a comprehensive security verification tool for hardware masking. It provides a hardware verification framework, enabling a complete analysis of simulation-based security in the glitch-extended probing model, with cycle-accurate estimations for leakage probabilities in the random...

In this paper, we study the robustness of Kyber, the Learning With Errors (LWE)-based Key Encapsulation Mechanism (KEM) chosen for standardization by NIST, against key mismatch attacks. We demonstrate that Kyber's security levels can be compromised with a few mismatch queries by striking a balance between the parallelization level and the cost of lattice reduction for post-processing. This highlights the imperative need to strictly prohibit key reuse in CPA-secure Kyber. We further...

Over the last two decades, microarchitectural side channels have been the focus of a large body of research on the development of new attack techniques, exploiting them to attack various classes of targets and designing mitigations. One line of work focuses on increasing the speed of the attacks, achieving higher levels of temporal resolution that can allow attackers to learn finer-grained information. The most recent addition to this line of work is Prime+Scope [CCS '21], which only...

In our highly digitalized world, an adversary is not constrained to purely digital attacks but can monitor or influence the physical execution environment of a target computing device. Such side-channel or fault-injection analysis poses a significant threat to otherwise secure cryptographic implementations. Hence, it is important to consider additional adversarial capabilities when analyzing the security of cryptographic implementations besides the default black-box model. For side-channel...

In this paper, we present efficient protected software implementations of the authenticated cipher Ascon, the recently announced winner of the NIST standardization process for lightweight cryptography. Our implementations target theoretical and practical security against second-order power analysis attacks. First, we propose an efficient second-order extension of a previously presented first-order masking of the Keccak S-box that does not require online randomness. The extension...

FALCON is candidate for standardization of the new Post Quantum Cryptography (PQC) primitives by the National Institute of Standards and Technology (NIST). However, it remains a challenge to define efficient countermeasures against side-channel attacks (SCA) for this algorithm. FALCON is a lattice-based signature that relies on rational numbers which is unusual in the cryptography field. While recent work proposed a solution to mask the addition and the multiplication, some roadblocks...

Fault Injection (FI) attacks, which involve intentionally introducing faults into a system to cause it to behave in an unintended manner, are widely recognized and pose a significant threat to the security of cryptographic primitives implemented in hardware, making fault tolerance an increasingly critical concern. However, protecting cryptographic hardware primitives securely and efficiently, even with well-established and documented methods such as redundant computation, can be a...

In white-box cryptography, early protection techniques have fallen to the automated Differential Computation Analysis attack (DCA), leading to new countermeasures and attacks. A standard side-channel countermeasure, Ishai-Sahai-Wagner's masking scheme (ISW, CRYPTO 2003) prevents Differential Computation Analysis but was shown to be vulnerable in the white-box context to the Linear Decoding Analysis attack (LDA). However, recent quadratic and cubic masking schemes by Biryukov-Udovenko...

This paper endeavors to securely implement a Physical Unclonable Function (PUF) for private data generation within Field-Programmable Gate Arrays (FPGAs). SRAM PUFs are commonly utilized due to their use of memory devices for generating secret data, particularly in resource constrained devices. However, their reliance on memory access poses side-channel threats such as data remanence decay and memory-based attacks, and the time required to generate secret data is significant. To address...

We study the hardness of the Syndrome Decoding problem, the base of most code-based cryptographic schemes, such as Classic McEliece, in the presence of side-channel information. We use ChipWhisperer equipment to perform a template attack on Classic McEliece running on an ARM Cortex-M4, and accurately classify the Hamming weights of consecutive 32-bit blocks of the secret error vector. With these weights at hand, we optimize Information Set Decoding algorithms. Technically, we show how to...

Side-Channel Attacks target the recovery of key material in cryptographic implementations by measuring physical quantities such as power consumption during the execution of a program. Simple Power Attacks consist in deducing secret information from a trace using a single or a few samples, as opposed to differential attacks which require many traces. Software cryptographic implementations now all contain a data-independent execution path, but often do not consider variations in power...

Software solutions to address computational challenges are ubiquitous in our daily lives. One specific application area where software is often used is in embedded systems, which, like other digital electronic devices, are vulnerable to side-channel analysis attacks. Although masking is the most common countermeasure and provides a solid theoretical foundation for ensuring security, recent research has revealed a crucial gap between theoretical and real-world security. This shortcoming stems...

Side-channel analysis is an important part of the security evaluations of hardware components and more specifically of those that include cryptographic algorithms. Profiling attacks are among the most powerful attacks as they assume the attacker has access to a clone device of the one under attack. Using the clone device allows the attacker to make a profile of physical leakages linked to the execution of algorithms. This work focuses on the characteristics of this profile and the...

Analyzing user data while protecting the privacy of individuals remains a big challenge. Trusted execution environments (TEEs) are a possible solution as they protect processes and Virtual Machines (VMs) against malicious hosts. However, TEEs can leak access patterns to code and to the data being processed. Furthermore, when data is stored in a TEE database, the data volume required to answer a query is another unwanted side channel that contains sensitive information. Both types of...

Cache side-channels are a major threat to cryptographic implementations, particularly block ciphers. Traditional manual hardening methods transform block ciphers into Boolean circuits, a practice refined since the late 90s. The only existing automatic approach based on Boolean circuits achieves security but suffers from performance issues. This paper examines the use of Lookup Tables (LUTs) for automatic hardening of block ciphers against cache side-channel attacks. We present a novel method...

As we enter 2024, the post-quantum cryptographic algorithm Dilithium, which emerged from the National Institute of Standards and Technology post-quantum cryptography competition, has now reached the deployment stage. This paper focuses on the practical security of Dilithium. We performed practical attacks on Dilithium2 on an STM32F4 platform. Our results indicate that an attack can be executed with just two signatures within five minutes, with a single signature offering a 60% probability of...

Here is a potential way to create a SLH-DSA-like\cite{DraftFIPS205} key generation/signer that aspires to be resistant to DPA side channel attacks. We say that it is “SLH-DSA-like”, because it does not follow the FIPS 205 method of generating signatures (in particular, it does not have the same mapping from private key, messages, opt\_rand to signatures), however it does generate public keys and signatures that are compatible with the standard signature verification method, and with the...

Soft Analytical Side Channel Attacks (SASCA) are a powerful family of Side Channel Attacks (SCA) that allows the recovery of secret values with only a small number of traces. Their effectiveness lies in the Belief Propagation (BP) algorithm, which enables efficient computation of the marginal distributions of intermediate values. Post-quantum schemes such as Kyber, and more recently, Hamming Quasi-Cyclic (HQC), have been targets of SASCA. Previous SASCA on HQC focused on Reed-Solomon (RS)...

Side-channel attacks pose a significant threat to the security of cryptographic hardware implementations and Threshold Implementation (TI) is a well-established countermeasure to mitigate those attacks. In 2023, Piccione et al. proposed a general construction of (first-order) TIs that is universal for S-boxes that are bijective vectorial Boolean function (functions from a binary vector space $\mathbb{F}_{2}^n$ into itself). This paper presents a novel approach to TI by addressing a broader...

Side-channel analysis has become a cornerstone of modern hardware security evaluation for cryptographic accelerators. Recently, these techniques are also being applied in fields such as AI and Machine Learning to investigate possible threats. Security evaluations are reliant on standard test setups including commercial and open-source evaluation boards such as, SASEBO/SAKURA and ChipWhisperer. However, with shrinking design footprints and overlapping tasks on the same platforms, the quality...

A recent work from Eurocrypt 2023 suggests that prime-field masking has excellent potential to improve the efficiency vs. security tradeoff of masked implementations against side-channel attacks, especially in contexts where physical leakages show low noise. We pick up on the main open challenge that this seed result leads to, namely the design of an optimized prime cipher able to take advantage of this potential. Given the interest of tweakable block ciphers with cheap inverses in many...