Is it possible to comprehensively destroy a piece of quantum information, so that nothing is left behind except the memory of that one had it at some point? For example, various works, most recently Morimae, Poremba, and Yamakawa (TQC '24), show how to construct a signature scheme with certified deletion where a user who deletes a signature on $m$ cannot later produce a signature for $m$. However, in all of the existing schemes, even after deletion the user is still able keep irrefutable...

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...

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...

Privacy-preserving graph analysis allows performing computations on graphs that store sensitive information while ensuring all the information about the topology of the graph, as well as data associated with the nodes and edges, remains hidden. The current work addresses this problem by designing a highly scalable framework, $\mathsf{Graphiti}$, that allows securely realising any graph algorithm. $\mathsf{Graphiti}$ relies on the technique of secure multiparty computation (MPC) to design a...

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...

Software watermarking allows for embedding a mark into a piece of code, such that any attempt to remove the mark will render the code useless. Provably secure watermarking schemes currently seems limited to programs computing various cryptographic operations, such as evaluating pseudorandom functions (PRFs), signing messages, or decrypting ciphertexts (the latter often going by the name ``traitor tracing''). Moreover, each of these watermarking schemes has an ad-hoc construction of its...

The existence of pseudorandom unitaries (PRUs)---efficient quantum circuits that are computationally indistinguishable from Haar-random unitaries---has been a central open question, with significant implications for cryptography, complexity theory, and fundamental physics. In this work, we close this question by proving that PRUs exist, assuming that any quantum-secure one-way function exists. We establish this result for both (1) the standard notion of PRUs, which are secure against any...

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...

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...

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....

We propose waterlogs, a new direction to detect and trace synthetic text outputs from large language models based on transparency logs. Waterlogs offer major categorical advantages over watermarking: it (1) allows for the inclusion of arbitrary metadata to facilitate tracing, (2) is publicly verifiable by third parties, and (3) operates in a distributed manner while remaining robust and efficient. Waterlogs rely on a verifiable Hamming distance index, a novel data structure that we...

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),...

Recently, Geraud-Stewart and Naccache proposed two trapdoors based on matrix products. In this paper, we answer the call for cryptanalysis. We explore how using the trace and determinant of a matrix can be used to attack their constructions. We fully break their first construction in a polynomial-time attack. We show an information leak in the second construction using characteristic polynomials, and provide an attack using traces that decreases the bit security by about half.

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...

Delegatable anonymous credentials (DACs) enable a root issuer to delegate credential-issuing power, allowing a delegatee to take a delegator role. To preserve privacy, credential recipients and verifiers should not learn anything about intermediate issuers in the delegation chain. One particularly efficient approach to constructing DACs is due to Crites and Lysyanskaya (CT-RSA '19). In contrast to previous approaches, it is based on mercurial signatures (a type of equivalence-class...

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...

We show that the Chunka-Banerjee-Goswami authentication and key agreement scheme [Wirel. Pers. Commun., 117, 1361-1385, 2021] fails to keep user anonymity, not as claimed. It only keeps pseudonymity. Anonymous actions are designed to be unlinkable to any entity, but pseudonymous actions can be traced back to a certain entity. We also find the scheme is insecure against offline dictionary attack.

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...

Hyperledger Fabric, an open-source, enterprise-grade consortium platform, employs an endorsement policy wherein a set of endorsers signs transaction proposals from clients to confirm their authenticity. The signatures from endorsers constitute the core component of endorsement. However, when dealing with dynamic transactions with high timeliness and frequent updates (e.g., stock trading, real-time ad delivery, news reporting, etc.), the current endorsement process somewhat slows down the...

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...

Traceable Receipt-free Encryption (TREnc) is a verifiable public-key encryption primitive introduced at Asiacrypt 2022. A TREnc allows randomizing ciphertexts in transit in order to remove any subliminal information up to a public trace that ensures the non-malleability of the underlying plaintext. A remarkable property of TREnc is the indistinguishability of the randomization of chosen ciphertexts against traceable chosen-ciphertext attacks (TCCA). This property can support applications...

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...

We show that the scalar product protocol [IEEE Trans. Parallel Distrib. Syst. 2023, 1060-1066] is insecure against semi-honest server attack, not as claimed. Besides, its complexity increases exponentially with the number $n$, which cannot be put into practice.

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...

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,...

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...

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...

In onion routing, a message travels through the network via a series of intermediaries, wrapped in layers of encryption to make it difficult to trace. Onion routing is an attractive approach to realizing anonymous channels because it is simple and fault tolerant. Onion routing protocols provably achieving anonymity in realistic adversary models are known for the synchronous model of communication so far. In this paper, we give the first onion routing protocol that achieves anonymity in...

We use pairings over elliptic curves to give a collusion-resistant traitor tracing scheme where the sizes of public keys, secret keys, and ciphertexts are independent of the number of users. Prior constructions from pairings had size $\Omega(N^{1/3})$. An additional consequence of our techniques is general result showing that attribute-based encryption for circuits generically implies optimal traitor tracing.

We introduce and formally define Multivariate Multi-Polynomial (MMP) commitment, a commitment scheme on multiple multivariate polynomials, and illustrate the concept with an efficient construction, which enjoys constant commitment size and logarithmic proof size. We further enhance our MMP scheme to achieve the zero-knowledge property. Additionally, combined with a novel zero-knowledge range proof for Pedersen subvector commitment, we present a Zero-Knowledge Range Proof (ZKRP) for MMP...

The universal composability (UC) model provides strong security guarantees for protocols used in arbitrary contexts. While these guarantees are highly desirable, in practice, schemes with a standalone proof of security, such as the Groth16 proof system, are preferred. This is because UC security typically comes with undesirable overhead, sometimes making UC-secure schemes significantly less efficient than their standalone counterparts. We establish the UC security of Groth16 without any...

Traceable threshold secret sharing schemes, introduced by Goyal, Song and Srinivasan (CRYPTO'21), allow to provably trace leaked shares to the parties that leaked them. The authors give the first definition and construction of traceable secret sharing schemes. However, the size of the shares in their construction are quadratic in the size of the secret. Boneh, Partap and Rotem (CRYPTO'24) recently proposed a new definition of traceable secret sharing and the first practical constructions. In...

We study watermarking schemes for language models with provable guarantees. As we show, prior works offer no robustness guarantees against adaptive prompting: when a user queries a language model more than once, as even benign users do. And with just a single exception (Christ and Gunn, 2024), prior works are restricted to zero-bit watermarking: machine-generated text can be detected as such, but no additional information can be extracted from the watermark. Unfortunately, merely detecting...

Fully Homomorphic Encryption (FHE) is a transformative technology that enables computations on encrypted data without requiring decryption, promising enhanced data privacy. However, its adoption has been limited due to significant performance overheads. Recent advances include the proposal of domain-specific, highly-parallel hardware accelerators designed to overcome these limitations. This paper introduces PICA, a comprehensive compiler framework designed to simplify the programming of...

This work proposes a new white-box attack technique called filtering, which can be combined with any other trace-based attack method. The idea is to filter the traces based on the value of an intermediate variable in the implementation, aiming to fix a share of a sensitive value and degrade the security of an involved masking scheme. Coupled with LDA (filtered LDA, FLDA), it leads to an attack defeating the state-of-the-art SEL masking scheme (CHES 2021) of arbitrary degree and number of...

Introduced by Kohlweiss, Lysyanskaya, and Nguyen (Eurocrypt'23), an $f$-privacy-preserving blueprint (PPB) system allows an auditor with secret input $x$ to create a public encoding of the function $f(x,\cdot)$ that verifiably corresponds to a commitment $C_x$ to $x$. The auditor will then be able to derive $f(x,y)$ from an escrow $Z$ computed by a user on input the user's private data $y$ corresponding to a commitment $C_y$. $Z$ verifiably corresponds to the commitment $C_y$ and reveals...

We present two techniques to improve the computational and/or communication costs of STARK proofs: packing and modular split-and-pack. Packing allows to generate a single proof of the satisfiability of several constraints. We achieve this by packing the evaluations of all relevant polynomials in the same Merkle leaves, and combining all DEEP FRI functions into a single randomized validity function. Our benchmarks show that packing reduces the verification time and proof size compared...

We propose GraphOS, a system that allows a client that owns a graph database to outsource it to an untrusted server for storage and querying. It relies on doubly-oblivious primitives and trusted hardware to achieve a very strong privacy and efficiency notion which we call oblivious graph processing: the server learns nothing besides the number of graph vertexes and edges, and for each query its type and response size. At a technical level, GraphOS stores the graph on a doubly-oblivious data...

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...

Third-party private set intersection (PSI) enables two parties, each holding a private set to compute their intersection and reveal the result only to an inputless third party. In this paper, we present an efficient third-party PSI protocol requiring only 3 communication rounds, while significantly lowering the computational workload compared to prior work. Our work is motivated by real-world applications such as contact tracing whereby expedition is essential while concurrently preserving...

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...

Cryptographic protocols are hard to design and prove correct, as witnessed by the ever-growing list of attacks even on protocol standards. Symbolic models of cryptography enable automated formal security proofs of such protocols against an idealized cryptographic model, which abstracts away from the algebraic properties of cryptographic schemes and thus misses attacks. Computational models of cryptography yield rigorous guarantees but support at present only interactive proofs and/or...

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...

Private messaging platforms provide strong protection against platform eavesdropping, but malicious users can use privacy as cover for spreading abuse and misinformation. In an attempt to identify the sources of misinformation on private platforms, researchers have proposed mechanisms to trace back the source of a user-reported message (CCS '19,'21). Unfortunately, the threat model considered by initial proposals allowed a single user to compromise the privacy of another user whose...

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)...

This paper presents SNOW-SCA, the first power side-channel analysis (SCA) attack of a 5G mobile communication security standard candidate, SNOW-V, running on a 32-bit ARM Cortex-M4 microcontroller. First, we perform a generic known-key correlation (KKC) analysis to identify the leakage points. Next, a correlation power analysis (CPA) attack is performed, which reduces the attack complexity to two key guesses for each key byte. The correct secret key is then uniquely identified utilizing...

Suppose Alice uses a $t$-out-of-$n$ secret sharing to store her secret key on $n$ servers. Her secret key is protected as long as $t$ of them do not collude. However, what if a less-than-$t$ subset of the servers decides to offer the shares they have for sale? In this case, Alice should be able to hold them accountable, or else nothing prevents them from selling her shares. With this motivation in mind, Goyal, Song, and Srinivasan (CRYPTO 21) introduced the concept of {\em traceable secret...

We report on efficient and secure hardware implementation techniques for the FIPS 205 SLH-DSA Hash-Based Signature Standard. We demonstrate that very significant overall performance gains can be obtained from hardware that optimizes the padding formats and iterative hashing processes specific to SLH-DSA. A prototype implementation, SLotH, contains Keccak/SHAKE, SHA2-256, and SHA2-512 cores and supports all 12 parameter sets of SLH-DSA. SLotH also supports side-channel secure PRF computation...

Attribute-based cryptography allows fine-grained control on the use of the private key. In particular, attribute-based signature (ABS) specifies the capabilities of the signer, which can only sign messages associated to a policy that is authorized by his set of attributes. Furthermore, we can expect signature to not leak any information about the identity of the signer. ABS is a useful tool for identity-preserving authentication process which requires granular access-control, and can...

LoPher brings, for the first time, cryptographic security promises to the field of logic locking in a bid to break the game of cat-and-mouse seen in logic locking. Toward this end, LoPher embeds the circuitry to lock within multiple rounds of a block cipher, by carefully configuring all the S-Boxes. To realize general Boolean functionalities and to support varying interconnect topologies, LoPher also introduces additional layers of MUXes between S-Boxes and the permutation operations. The...

We uncover a critical side-channel vulnerability in the Hamming Quasi-Cyclic (HQC) round 4 optimized implementation arising due to the use of the modulo operator. In some cases, compilers optimize uses of the modulo operator with compile-time known divisors into constant-time Barrett reductions. However, this optimization is not guaranteed: for example, when a modulo operation is used in a loop the compiler may emit division (div) instructions which have variable execution time depending on...

Vehicle-to-grid (V2G) provides effective charging services, allows bidirectional energy communication between the power grid and electric vehicle (EV), and reduces environmental pollution and energy crises. Recently, Sungjin Yu et al. proposed a PUF-based, robust, and anonymous authentication and key establishment scheme for V2G networks. In this paper, we show that the proposed protocol does not provide user anonymity and is vulnerable to tracing attack. We also found their scheme is...

In recent years, decentralized computing has gained popularity in various domains such as decentralized learning, financial services and the Industrial Internet of Things. As identity privacy becomes increasingly important in the era of big data, safeguarding user identity privacy while ensuring the security of decentralized computing systems has become a critical challenge. To address this issue, we propose ADC (Anonymous Decentralized Computing) to achieve anonymity in decentralized...

CRYSTALS-Dilithium is a post-quantum secure digital signature algorithm currently being standardised by NIST. As a result, devices making use of CRYSTALS-Dilithium will soon become generally available and be deployed in various environments. It is thus important to assess the resistance of CRYSTALS-Dilithum implementations to physical attacks. In this paper, we present an attack on a CRYSTALS-Dilithium implementation in hedged mode in ARM Cortex-M4 using fault injection. Voltage glitching...

In this paper, we propose a leakage-resilient pseudo-random number generator (PRNG) design that leverages the rekeying techniques of the PSV-Enc encryption scheme and the superposition property of the Superposition-Tweak-Key (STK) framework. The random seed of the PRNG is divided into two parts; one part is used as an ephemeral key that changes every two calls to a tweakable block cipher (TBC), and the other part is used as a static long-term key. Using the superposition property, we show...

Equivalence class signatures (EQS; Asiacrypt '14), sign vectors of elements from a bilinear group. Anyone can transform a signature on a vector to a signature on any multiple of that vector; signatures thus authenticate equivalence classes. A transformed signature/message pair is indistinguishable from a random signature on a random message. EQS have been used to efficiently instantiate (delegatable) anonymous credentials, (round-optimal) blind signatures, ring and group signatures,...

Traitor-tracing systems allow identifying the users who contributed to building a rogue decoder in a broadcast environment. In a traditional traitor-tracing system, a key authority is responsible for generating the global public parameters and issuing secret keys to users. All security is lost if the \emph{key authority itself} is corrupt. This raises the question: Can we construct a traitor-tracing scheme, without a trusted authority? In this work, we propose a new model for...

Side-Channel Analysis (SCA) is critical in evaluating the security of cryptographic implementations. The search for hyperparameters poses a significant challenge, especially when resources are limited. In this work, we explore the efficacy of a multifidelity optimization technique known as BOHB in SCA. In addition, we proposed a new objective function called $ge_{+ntge}$, which could be incorporated into any Bayesian Optimization used in SCA. We show the capabilities of both BOHB and...

Kyber KEM, the NIST selected PQC standard for Public Key Encryption and Key Encapsulation Mechanisms (KEMs) has been subjected to a variety of side-channel attacks, through the course of the NIST PQC standardization process. However, all these attacks targeting the decapsulation procedure of Kyber KEM either require knowledge of the ciphertexts or require to control the value of ciphertexts for key recovery. However, there are no known attacks in a blind setting, where the attacker does not...

In side-channel analysis (SCA), the success of an attack is largely dependent on the dataset sizes and the number of instances in each class. The generation of synthetic traces can help to improve attacks like profiling attacks. However, manually creating synthetic traces from actual traces is arduous. Therefore, automating this process of creating artificial traces is much needed. Recently, diffusion models have gained much recognition after beating another generative model known as...

The conversion between arithmetic and Boolean masking representations (A2B \& B2A) is a crucial component for side-channel resistant implementations of lattice-based (post-quantum) cryptography. In this paper, we first propose novel $d$-order algorithms for the secure addition (SecADDChain$_q$) and B2A (B2X2A). Our secure adder is well-suited for repeated ('chained') executions, achieved through an improved method for repeated masked modular reduction. The optimized B2X2A gadget removes a...

Most multivariate proof systems require, at some point, an algebraic check against the rows of the trace. One popular protocol for this is known as zerocheck which is a sumcheck based protocol which proves a constraint function is zero over the $n$-dimensional Boolean hypercube. One of the drawbacks of running zerocheck over a small field, is that it usually involves a large number of evaluations of the constraint polynomial over a cryptographically large extension field $\mathbb{G}$. ...

This paper questions the side-channel security of central reduction technique, which is widely adapted in efficient implementations of Lattice-Based Cryptography (LBC). We show that the central reduction leads to a vulnerability by creating a strong dependency between the power consumption and the sign of sensitive intermediate values. We exploit this dependency by introducing the novel absolute value prediction function, which can be employed in higher-order non-profiled multi-query...

NIST released the draft standard for ML-KEM, and we can expect its widespread use in the embedded world in the near future. Several side-channel attacks have been proposed, and one line of research has focused on attacks against the comparison step of the FO-transform. A work published at TCHES 2022 stressed the need for secure higher-order masked comparisons beyond the $t$-probing model and proposed a higher-order masked comparison method. Subsequently, D'Anvers, Van Beirendonck, and...

Side-channel analysis based on machine learning, especially neural networks, has gained significant attention in recent years. However, many existing methods still suffer from certain limitations. Despite the inherent capability of neural networks to extract features, there remains a risk of extracting irrelevant information. The heavy reliance on profiled traces makes it challenging to adapt to remote attack scenarios with limited profiled traces. Besides, attack traces also contain...

As the message recovery-based attack poses a serious threat to lattice-based schemes, we conducted a study on the side-channel secu- rity of parallel implementations of lattice-based key encapsulation mech- anisms. Initially, we developed a power model to describe the power leakage during message encoding. Utilizing this power model, we pro- pose a multi-ciphertext message recovery attack, which can retrieve the required messages for a chosen ciphertext attack through a suitable mes- sage...

We present a general method to simplify soundness proofs under certain conditions. Given an adversary $\mathcal{A}$ able to break a scheme $S$ with non-negligible probability $t$, we define the concept of $\textit{trace}$ of a $\textit{winning configuration}$, which is already implicitly used in soundness proofs. If a scheme can be constructed that (1) takes a random configuration $e$, being the inputs and execution environment of $\mathcal{A}$, (2) "guesses" a trace, (3) modifies $e$ based...

The splitting field $F$ of the polynomial $Y^n-2$ is an extension over $\mathbb{Q}$ generated by $\zeta_n=\exp(2 \pi \sqrt{-1} /n)$ and $\sqrt[n]{2}$. In this paper, we lay the foundation for applying the Order-LWE in the integral ring $\mathcal{R}=\mathbb{Z}[\zeta_n, \sqrt[n]{2}]$ to cryptographic uses when $n$ is a power-of-two integer. We explicitly compute the Galois group $\text{Gal}\left(F/\mathbb{Q} \right)$ and the canonical embedding of $F$, based on which we study the properties of...

We present a side-channel attack on CRYSTALS-Dilithium, a post-quantum secure digital signature scheme, with two variants of post-processing. The side-channel attack exploits information leakage in the secret key unpacking procedure of the signing algorithm to recover the coefficients of the polynomials in the secret key vectors ${\bf s}_1$ and ${\bf s}_2$ by profiled deep learning-assisted power analysis. In the first variant, one half of the coefficients of ${\bf s}_1$ and ${\bf s}_2$ is...

Software for various post-quantum KEMs has been submitted by the KEM design teams to the SUPERCOP testing framework. The ref/*.c and ref/*.h files together occupy, e.g., 848 lines for ntruhps4096821, 928 lines for ntruhrss701, 1316 lines for sntrup1277, and 2633 lines for kyber1024. It is easy to see that these numbers overestimate the inherent complexity of software for these KEMs. It is more difficult to systematically measure this complexity. This paper takes these KEMs as case...

In recent years, deep learning-based side-channel analysis (DLSCA) has become an active research topic within the side-channel analysis community. The well-known challenge of hyperparameter tuning in DLSCA encouraged the community to use methods that reduce the effort required to identify an optimal model. One of the successful methods is ensemble learning. While ensemble methods have demonstrated their effectiveness in DLSCA, particularly with AES-based datasets, their efficacy in analyzing...

During the standardisation process of post-quantum cryptography, NIST encourages research on side-channel analysis for candidate schemes. As the recommended lattice signature scheme, CRYSTALS-Dilithium, when implemented on hardware, has only been subjected to the side-channel attack presented by Steffen et al. in IACR ePrint 2022. This attack is not complete and requires excessive traces. Therefore, we investigate the leakage of an FPGA (Kintex7) implementation of CRYSTALS-Dilithium using...

In 2022, NIST selected Kyber and Dilithium as post-quantum cryptographic standard algorithms. The Number Theoretic Transformation (NTT) algorithm, which facilitates polynomial multiplication, has become a primary target for side-channel attacks. In this work, we embed the NTT transformation matrix in Dilithium and Kyber into the SIS search problem, and further, we propose a divide and conquer strategy for dimensionality reduction of the SIS problem by utilizing the properties of NTT, and...

Deep Learning (DL) based Side-Channel Analysis (SCA) has been extremely popular recently. DL-based SCA can easily break implementations protected by masking countermeasures. DL-based SCA has also been highly successful against implementations protected by various trace desynchronization-based countermeasures like random delay, clock jitter, and shuffling. Over the years, many DL models have been explored to perform SCA. Recently, Transformer Network (TN) based model has also been introduced...

CRYSTALS-Kyber is a key-encapsulation mechanism, whose security is based on the hardness of solving the learning-with-errors (LWE) problem over module lattices. As in its specification, Kyber prescribes the usage of the Number Theoretic Transform (NTT) for efficient polynomial multiplication. Side-channel assisted attacks against Post-Quantum Cryptography (PQC) algorithms like Kyber remain a concern in the ongoing standardization process of quantum-computer-resistant cryptosystems. Among the...

As NIST is putting the final touches on the standardization of PQC (Post Quantum Cryptography) public key algorithms, it is a racing certainty that peskier cryptographic attacks undeterred by those new PQC algorithms will surface. Such a trend in turn will prompt more follow-up studies of attacks and countermeasures. As things stand, from the attackers’ perspective, one viable form of attack that can be implemented thereupon is the so-called “side-channel attack”. Two best-known...

A $t$-out-of-$n$ threshold decryption system assigns key shares to $n$ parties so that any $t$ of them can decrypt a well-formed ciphertext. Existing threshold decryption systems are not secure when these parties are rational actors: an adversary can offer to pay the parties for their key shares. The problem is that a quorum of $t$ parties, working together, can sell the adversary a decryption key that reveals nothing about the identity of the traitor parties. This provides a risk-free...

In Crypto 94, Chor, Fiat, and Naor first introduced the traitor tracing (TT) systems, which aim at helping content distributors identify pirates. Since its introduction, many traitor tracing schemes have been proposed. However, we observe until now almost all the traitor tracing systems using probabilistic public key (and secret key) encryption as the the content distribution algorithm, they do not consider this basic fact: the malicious encrypter can plant some trapdoor in the randomness...

The global lockdown imposed during the Covid-19 pandemic has resulted in significant social and economic challenges. In an effort to reopen economies and simultaneously control the spread of the disease, the implementation of contact tracing and digital vaccine passport technologies has been introduced. While contact tracing methods have been extensively studied and scrutinized for security concerns through numerous publications, vaccine passports have not received the same level of...

Power analysis of public-key algorithms is a well-known approach in the community of side-channel analysis. We usually classify operations based on the differences in power traces produced by different basic operations (such as modular exponentiation) to recover secret information like private keys. The more accurate the segmentation of power traces, the higher the efficiency of their classification. There exist two commonly used methods: one is equidistant segmentation, which requires a...

Masking, as a common countermeasure, has been widely utilized to protect cryptographic implementations against power side-channel attacks. It significantly enhances the difficulty of attacks, as the sensitive intermediate values are randomly partitioned into multiple parts and executed on different times. The adversary must amalgamate information across diverse time samples before launching an attack, which is generally accomplished by feature extraction (e.g., Points-Of-Interest (POIs)...

Ascon is a recently standardized suite of symmetric cryptography for authenticated encryption and hashing algorithms designed to be lightweight. The Ascon scheme has been studied since it was introduced in 2015 for the CAESAR competition, and many efforts have been made to transform this hardware-oriented scheme to work with any embedded device architecture. Ascon is designed with side-channel resistance in mind and can also be protected with countermeasures against side-channel...

This paper presents practicable single trace attacks against the Hamming Quasi-Cyclic (HQC) Key Encapsulation Mechanism. These attacks are the first Soft Analytical Side-Channel Attacks (SASCA) against code-based cryptography. We mount SASCA based on Belief Propagation (BP) on several steps of HQC's decapsulation process. Firstly, we target the Reed-Solomon (RS) decoder involved in the HQC publicly known code. We perform simulated attacks under Hamming weight leakage model, and reach...

Last year CRYSTALS-Kyber was chosen by NIST as a new, post-quantum secure key encapsulation mechanism to be standardized. This makes it important to assess the resistance of CRYSTALS-Kyber implementations to physical attacks. Pure side-channel attacks on post-quantum cryptographic algorithms have already been well-explored. In this paper, we present an attack on a masked and shuffled software implementation of CRYSTALS-Kyber that combines fault injection with side-channel analysis. First, a...

This paper formally analyzes two major non-profiled deep-learning-based side-channel attacks (DL-SCAs): differential deep-learning analysis (DDLA) by Timon and collision DL-SCA by Staib and Moradi. These DL-SCAs leverage supervised learning in non-profiled scenarios. Although some intuitive descriptions of these DL-SCAs exist, their formal analyses have been rarely conducted yet, which makes it unclear why and when the attacks succeed and how the attack can be improved. In this paper, we...

Zero-Knowledge Virtual Machines (ZKVMs) have gained traction in recent years due to their potential applications in a variety of areas, particularly blockchain ecosystems. Despite tremendous progress on ZKVMs in the industry, no formal definitions or security proofs have been established in the literature. Due to this lack of formalization, existing protocols exhibit significant discrepancies in terms of problem definitions and performance metrics, making it difficult to analyze and compare...

The application of masking, widely regarded as the most robust and reliable countermeasure against Side-Channel Analysis (SCA) attacks, has been the subject of extensive research across a range of cryptographic algorithms, especially AES. However, the implementation cost associated with applying such a countermeasure can be significant and even in some scenarios infeasible due to considerations such as area and latency overheads, as well as the need for fresh randomness to ensure the...

Committing security has gained considerable attention in the field of authenticated encryption (AE). This can be traced back to a line of recent attacks, which entail that AE schemes used in practice should not only provide confidentiality and authenticity, but also committing security. Roughly speaking, a committing AE scheme guarantees that ciphertexts will decrypt only for one key. Despite the recent research effort in this area, the finalists of the NIST lightweight cryptography...

This study delves into secure computations for set intersections using fully homomorphic encryption (FHE) within the semi-honest setting. Our protocols facilitate joint computations between two parties, each holding a set of inputs denoted as $N_s$ and $N_r$ in size, respectively. The primary objective is to determine various functionalities, such as intersection size and sum, while maintaining data confidentiality. These functionalities extend the classic private set intersection (PSI) and...

This paper offers a mathematical introduction to fully homomorphic encryption, a concept that enables computation on encrypted data. We trace the historical development of FHE, describe Fully Homomorphic Encryption over the Torus (TFHE) and how it performs certain mathematical operations, and explore bootstrapping and the possibility for adjusting computational depth. This paper equips readers with a brief understanding of FHE's evolution and the essential mechanisms facilitating practical...

FIDO2 is currently the main initiative for passwordless authentication in web servers. It mandates the use of secure hardware authenticators to protect the authentication protocol’s secrets from compromise. However, to ensure that only secure authenticators are being used, web servers need a method to attest their properties. The FIDO2 specifications allow for authenticators and web servers to choose between different attestation modes to prove the characteristics of an authenticator,...

We introduce a novel side-channel-based reverse engineering technique capable of reconstructing a procedure solely from inputs, outputs, and traces of execution. Beyond generic restrictions, we do not assume any prior knowledge of the procedure or the chip it operates on. These restrictions confine our analysis to 8-bit RISC constant-time software implementations. Specifically, we demonstrate the feasibility of reconstructing a symmetric cryptographic cipher, even in scenarios where...

User privacy is becoming increasingly important in our digital society. Yet, many applications face legal requirements or regulations that prohibit unconditional anonymity guarantees, e.g., in electronic payments where surveillance is mandated to investigate suspected crimes. As a result, many systems have no effective privacy protections at all, or have backdoors, e.g., stored at the operator side of the system, that can be used by authorities to disclose a user’s private information...

Side-channel analysis certification is a process designed to certify the resilience of cryptographic hardware and software implementations against side-channel attacks. In certain cases, third-party evaluations by external companies or departments are necessary due to limited budget, time, or even expertise with the penalty of a significant exchange of sensitive information during the evaluation process. In this work, we investigate the potential of Homomorphic Encryption (HE) in...

Vehicle-to-grid (V2G) networks, as an emerging smart grid paradigm, can be integrated with renewable energy resources to provide power services and manage electricity demands. When accessing electricity services, an electric vehicle(EV) typically provides authentication or/and payment information containing identifying data to a service provider, which raises privacy concerns as malicious entities might trace EV activity or exploit personal information. Although numerous anonymous...

In this work, we propose a novel single-trace key recovery attack targeting side-channel leakage from the key-generation and encryption procedure of Kyber KEM. Our attack exploits the inherent nature of the Module-Learning With Errors (Module-LWE) problem used in Kyber KEM. We demonstrate that the inherent reliance of Kyber KEM on the Module-LWE problem results in higher number of repeated and secret key-related computations, referred to as STAMPs appearing on a single side channel trace,...

Side-channel attacks against cryptographic implementations are mitigated by the application of masking and hiding countermeasures. Hiding countermeasures attempt to reduce the Signal-to-Noise Ratio of measurements by adding noise or desynchronization effects during the execution of the cryptographic operations. To bypass these protections, attackers adopt signal processing techniques such as pattern alignment, filtering, averaging, or resampling. Convolutional neural networks have shown the...