What a lovely hat

In pairing-based cryptography, final exponentiation with a large fixed exponent is crucial for ensuring unique outputs in Tate and optimal Ate pairings. While optimizations for elliptic curves with even embedding degrees have been well-explored, progress for curves with odd embedding degrees, particularly those divisible by $3$, has been more limited. This paper presents new optimization techniques for computing the final exponentiation of the optimal Ate pairing on these curves. The first...

This paper presents a novel single-trace side-channel attack on FALCON—a lattice-based post-quantum digital signature protocol recently approved for standardization by NIST. We target the discrete Gaussian sampling operation within the FALCON key generation scheme and use a single power measurement trace to succeed. Notably, negating the ‘shift right 63-bit’ operation (for 64-bit values) leaks critical information about the ‘-1’ vs. ‘0’ assignments to intermediate coefficients. These leaks...

The U.S. National Institute of Standards and Technology recently standardized the first set of post-quantum cryptography algo- rithms. These algorithms address the quantum threat, but also present new challenges due to their larger memory and computational footprint. Three of the four standardized algorithms are lattice based, offering good performance but posing challenges due to complex implementation and intricate security assumptions. A more conservative choice for quantum- safe...

Dynamic Decentralized Functional Encryption (DDFE) is a generalization of Functional Encryption which allows multiple users to join the system dynamically without interaction and without relying on a trusted third party. Users can independently encrypt their inputs for a joint evaluation under functions embedded in functional decryption keys; and they keep control on these functions as they all have to contribute to the generation of the functional keys. In this work, we present new...

This paper presents a novel single-trace side-channel attack on FALCON---a lattice-based post-quantum digital signature protocol recently approved for standardization by NIST. We target the discrete Gaussian sampling operation within the FALCON key generation scheme and use a single power measurement trace to succeed. Notably, negating the 'shift right 63-bit' operation (for 64-bit values) leaks critical information about the '-1' vs. '0' assignments to intermediate coefficients. These leaks...

The use of secure computation protocols within production software systems and applications is complicated by the fact that such protocols sometimes rely upon -- or are most compatible with -- unusual or restricted models of computation. We employ the features of a contemporary and widely used programming language to create an embedded domain-specific language for working with user-defined functions as binary matrices that operate on one-hot vectors. At least when working with small finite...

To provide safe communication across an unprotected medium such as the internet, network protocols are being established. These protocols employ public key techniques to perform key exchange and authentication. Transport Layer Security (TLS) is a widely used network protocol that enables secure communication between a server and a client. TLS is employed in billions of transactions per second. Contemporary protocols depend on traditional methods that utilize the computational complexity of...

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...

We present techniques for constructing zero-knowledge argument systems from garbled circuits, extending the GC-to-ZK compiler by Jawurek, Kerschbaum, and Orlandi (ACM CCS 2023) and the GC-to-Σ compiler by Hazay and Venkitasubramaniam (J. Crypto, 2020) to the following directions: - Our schemes are hybrid, commit-and-prove zero-knowledge argument systems that establish a connection between secrets embedded in algebraic commitments and a relation represented by a Boolean circuit. - Our...

Large polynomial multiplication is one of the computational bottlenecks in fully homomorphic encryption implementations. Usually, these multiplications are implemented using the number-theoretic transformation to speed up the computation. State-of-the-art GPU-based implementation of fully homomorphic encryption computes the number theoretic transformation in two different kernels, due to the necessary synchronization between GPU blocks to ensure correctness in computation. This can be a...

Embedded systems are flexible and cost-effective and thus have found a use case in almost every part of our daily lives. Due to their widespread use, they have also become valuable targets for cyber attacks. However, translating cutting-edge cyber security from servers and desktops to the embedded realm can be challenging due to the limited computational power and memory of embedded devices. Although quantum computing is still in early research and development, it threatens to break...

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...

The recent works of Ananth et al. (ITCS 2022) and Bartusek et al. (Eurocrypt 2023) initiated the study of pre-constrained cryptography which achieves meaningful security even against the system authority. In this work we significantly expand this area by defining several new primitives and providing constructions from simple, standard assumptions as follows. - Pre-Constrained Encryption. We define a weaker notion of pre-constrained encryption (PCE), as compared to the work of Ananth et...

We introduce Compass, a semantic search system over encrypted data that offers high accuracy, comparable to state-of-the-art plaintext search algorithms while protecting data, queries and search results from a fully compromised server. Additionally, Compass enables privacy-preserving RAG where both the RAG database and the query are protected. Compass contributes a novel way to traverse the Hierarchical Navigable Small Worlds (HNSW) graph, a top-performing nearest neighbor search index, over...

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...

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...

Blockchain technology ensures accountability, transparency, and redundancy in critical applications, includ- ing IoT with embedded systems. However, the reliance on public-key cryptography (PKC) makes blockchain vulnerable to quantum computing threats. This paper addresses the urgent need for quantum-safe blockchain solutions by integrating Post- Quantum Cryptography (PQC) into blockchain frameworks. Utilizing algorithms from the NIST PQC standardization pro- cess, we aim to fortify...

Physical attacks, and among them fault injection attacks, are a significant threat to the security of embedded systems. Among the means of fault injection, laser has the significant advantage of being extremely spatially accurate. Numerous state-of-the-art studies have investigated the use of lasers to inject faults into a target at run-time. However, the high precision of laser fault injection comes with requirements on the knowledge of the implementation and exact execution time of the...

The use of Internet of Things (IoT) devices in embedded systems has become increasingly popular with advancing technologies. These devices become vulnerable to cyber attacks as they gain popularity. The cryptographic operations performed for the purpose of protection against cyber attacks are crucial to yield fast results in open networks and not slow down network traffic. Therefore, to enhance communication security, studies have been conducted in the literature on using asymmetric...

Many lattice-based crypstosystems employ ideal lattices for high efficiency. However, the additional algebraic structure of ideal lattices usually makes us worry about the security, and it is widely believed that the algebraic structure will help us solve the hard problems in ideal lattices more efficiently. In this paper, we study the additional algebraic structure of ideal lattices further and find that a given ideal lattice in a polynomial ring can be embedded as an ideal into infinitely...

One of the most promising avenues for realizing scalable proof systems relies on the existence of 2-cycles of pairing-friendly elliptic curves. Such a cycle consists of two elliptic curves E/GF(p) and E'/GF(q) that both have a low embedding degree and also satisfy q = #E and p = #E'. These constraints turn out to be rather restrictive; in the decade that has passed since 2-cycles were first proposed for use in proof systems, no new constructions of 2-cycles have been found. In this paper,...

Generative pre-trained transformers (GPT's) are a type of large language machine learning model that are unusually adept at producing novel, and coherent, natural language. Notably, these technologies have also been extended to computer programming languages with great success. However, GPT model outputs in general are stochastic and not always correct. For programming languages, the exact specification of the computer code, syntactically and algorithmically, is strictly required in order to...

Existing oblivious systems offer robust security by concealing memory access patterns, but they encounter significant scalability and performance challenges. Recent efforts to enhance the practicality of these systems involve embedding oblivious computation, e.g., oblivious sorting and shuffling, within Trusted Execution Environments (TEEs). For instance, oblivious sort has been heavily utilized: in Oblix (S&P'18), when oblivious indexes are created and accessed; in Snoopy's high-throughput...

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...

Imagine being able to deploy a small, battery-powered device nearly anywhere on earth that humans frequent and having it be able to send data to the cloud without needing to provision a network—without buying a physical gateway, setting up WiFi credentials, or acquiring a cellular SIM. Such a capability would address one of the greatest bottlenecks to deploying the long-tail of small, embedded, and power-constrained IoT devices in nearly any setting. Unfortunately, decoupling the device...

In this paper, we study two problems: oblivious compression and decompression of ciphertexts. In oblivious compression, a server holds a set of ciphertexts with a subset of encryptions of zeroes whose positions are only known to the client. The goal is for the server to effectively compress the ciphertexts obliviously, while preserving the non-zero plaintexts and without learning the plaintext values. For oblivious decompression, the client, instead, succinctly encodes a sequence of...

Battery-operated applications have been ubiquitous all over the world ranging from power-intensive electric cars down to low-power smart terminals and embedded devices. Meanwhile, serious incidents around batteries such as swelling, fire, and explosion have been witnessed, which resulted in horribly huge financial and even life loss. People used to attribute such aftermaths to unintentional design mistakes or insufficient quality inspection of original battery manufacturers. However, this is...

High-performance crypto-engines have become crucial components in modern System-On-Chip (SoC) architectures across platforms, from servers to edge-IoTs’. Alas, their secure operation faces a significant obstacle caused by information-leakage accessed through Side-Channel Analysis (SCA). Adversaries exploit statistical-analysis techniques on measured (e.g.,) power and timing signatures generated during (e.g.,) encryption, extracting secrets. Mathematical countermeasures against such attacks...

Embedded Multimedia Cards (eMMCs) provide a protected memory area called the Replay Protected Memory Block (RPMB). eMMCs are commonly used as storage media in modern smartphones. In order to protect these devices from unauthorized access, important data is stored in the RPMB area in an authenticated manner. Modification of the RPMB data requires a pre-shared authentication key. An unauthorized user cannot change the stored data. On modern devices, this pre-shared key is generated and used...

Learning with Errors (LWE) is a hard math problem underlying post-quantum cryptography (PQC) systems for key exchange and digital signatures, recently standardized by NIST. Prior work [Wenger et al., 2022; Li et al., 2023a;b] proposed new machine learning (ML)-based attacks on LWE problems with small, sparse secrets, but these attacks require millions of LWE samples to train on and take days to recover secrets. We propose three key methods—better pre-processing, angular embeddings and model...

Number theoretic transform (NTT) has been a very useful tool in computations for number theory, algebra and cryptography. Its performance affects some post-quantum cryptosystems. In this paper, we discuss the butterfly operation of NTT. This basic module of NTT requires heavy modular arithmetics. Montgomery reduction is commonly used in this setting. Recently several variants of Montgomery have been proposed for the purpose of speeding up NTT. We observe that the Chinese remainder...

We optimize the number-theoretic transforms (NTTs) in Dilithium — a digital signature scheme recently standardized by the National Institute of Standards and Technology (NIST) — on Cortex-M3 and 8-bit AVR. The core novelty is the exploration of micro-architectural insights for modular multiplications. Recent work [Becker, Hwang, Kannwischer, Yang and Yang, Volume 2022 (1), Transactions on Cryptographic Hardware and Embedded Systems, 2022] found a correspondence between Montgomery and Barrett...

In this work, we introduce FANNG-MPC, a versatile secure multi-party computation framework capable to offer active security for privacy preserving machine learning as a service (MLaaS). Derived from the now deprecated SCALE-MAMBA, FANNG is a data-oriented fork, featuring novel set of libraries and instructions for realizing private neural networks, effectively reviving the popular framework. To the best of our knowledge, FANNG is the first MPC framework to offer actively secure MLaaS in the...

Fault injection attacks represent an effective threat to embedded systems. Recently, Laurent et al. have reported that fault injection attacks can leverage faults inside the microarchitecture. However, state-of-the-art counter-measures, hardware-only or with hardware support, do not consider the integrity of microarchitecture control signals that are the target of these faults. We present MAFIA, a microarchitecture protection against fault injection attacks. MAFIA ensures integrity of...

Deploying cryptography on embedded systems requires security against physical attacks. At CHES 2019, M&M was proposed as a combined countermeasure applying masking against SCAs and information-theoretic MAC tags against FAs. In this paper, we show that one of the protected AES implementations in the M&M paper is vulnerable to a zero-value SIFA2-like attack. A practical attack is demonstrated on an ASIC board. We propose two versions of the attack: the first follows the SIFA approach to...

Efficient power management is critical for embedded devices, both for extending their lifetime and ensuring safety. However, this can be a challenging task due to the unpredictability of the batteries commonly used in such devices. To address this issue, dedicated Integrated Circuits known as "fuel gauges" are often employed outside of the System-On-Chip. These devices provide various metrics about the available energy source and are highly accurate. However, their precision can also be...

We show how to embed a covert key exchange sub protocol within a regular TLS 1.3 execution, generating a stealth key in addition to the regular session keys. The idea, which has appeared in the literature before, is to use the exchanged nonces to transport another key value. Our contribution is to give a rigorous model and analysis of the security of such embedded key exchanges, requiring that the stealth key remains secure even if the regular key is under adversarial control. Specifically...

We present HAETAE (Hyperball bimodAl modulE rejecTion signAture schemE), a new lattice-based signature scheme. Like the NIST-selected Dilithium signature scheme, HAETAE is based on the Fiat-Shamir with Aborts paradigm, but our design choices target an improved complexity/compactness compromise that is highly relevant for many space-limited application scenarios. We primarily focus on reducing signature and verification key sizes so that signatures fit into one TCP or UDP datagram while...

In a vertical federated learning (VFL) system consisting of a central server and many distributed clients, the training data are vertically partitioned such that different features are privately stored on different clients. The problem of split VFL is to train a model split between the server and the clients. This paper aims to address two major challenges in split VFL: 1) performance degradation due to straggling clients during training; and 2) data and model privacy leakage from clients’...

In this work we are interested in evaluating the possibility of extracting information from radio-enabled embedded-systems from a long distance. That is, our focus is capturing information from sources in the micrometer to tens of centimeters scale, such as intra- or inter- device busses, board-level routing traces etc. Moreover, we focus on distances in the range of millimeters to tens of centimeters from the (on-chip or on-board) embedded-system Tx Antenna to the signal source....

Post-Quantum cryptography (PQC), in the past few years, constitutes the main driving force of the quantum resistance transition for security primitives, protocols and tools. TLS is one of the widely used security protocols that needs to be made quantum safe. However, PQC algorithms integration into TLS introduce various implementation overheads compared to traditional TLS that in battery powered embedded devices with constrained resources, cannot be overlooked. While there exist several...

As part of the responses to the ongoing ``crypto wars,'' the notion of {\em Anamorphic Encryption} was put forth [Persiano-Phan-Yung Eurocrypt '22]. The notion allows private communication in spite of a dictator who (in violation of the usual normative conditions under which Cryptography is developed) is engaged in an extreme form of surveillance and/or censorship, where it asks for all private keys and knows and may even dictate all messages. The original work pointed out efficient ways...

In this short note, we describe a few implementation techniques that allow performing key pair generation for the Falcon and Hawk lattice-based signature schemes, and for the BAT key encapsulation scheme, in a fully constant-time way and without any use of floating-point operations. Our new code is faster than previously published implementations, especially when running on small embedded systems, and uses less RAM.

Falcon is one of the three post-quantum signature schemes selected for standardization by NIST. Due to its low bandwidth and high efficiency, Falcon is seen as an attractive option for quantum-safe embedded systems. In this work, we study Falcon's side-channel resistance by analysing its Gaussian samplers. Our results are mainly twofold. The first result is an improved key recovery exploiting the leakage within the base sampler investigated by Guerreau et al. (CHES 2022). Instead of...

We introduce a new transparent zero-knowledge argument system based on the novel direct computation concept. Our protocol converts input parameters into a format that the verifier can process directly, so the output of the polynomial representing a circuit can be directly computed by the verifier, allowing us to significantly reduce the size of the polynomial evaluation needed to be evaluated.  In the default setting, the prover runtime cost for group exponentiation operations is only the...

FrodoKEM is a lattice-based Key Encapsulation Mechanism (KEM) based on unstructured lattices. From a security point of view this makes it a conservative option to achieve post-quantum security, hence why it is favored by several European authorities (e.g., German BSI and French ANSSI). Relying on unstructured instead of structured lattices (e.g., CRYSTALS-Kyber) comes at the cost of additional memory usage, which is particularly critical for embedded security applications such as smart...

Because of the rapid growth of Internet of Things (IoT), embedded systems have become an interesting target for experienced attackers. ESP32~\cite{tech-ref-man} is a low-cost and low-power system on chip (SoC) series created by Espressif Systems. The firmware extraction of such embedded systems is a real threat to the manufacturer as it breaks its intellectual property and raises the risk of creating equivalent systems with less effort and resources. In 2019,...

Embedded systems are a cornerstone of the ongoing digitization of our society, ranging from expanding markets around IoT and smart-X devices over to sensors in autonomous driving, medical equipment or critical infrastructures. Since a vast amount of embedded systems are safety-critical (e.g., due to their operation site), security is a necessity for their operation. However, unlike mobile, desktop, and server systems, where adversaries typically only act have remote access, embedded systems...

TLS is ubiquitous in modern computer networks. It secures transport for high-end desktops and low-end embedded devices alike. However, the public key cryptosystems currently used within TLS may soon be obsolete as large-scale quantum computers, once realized, would be able to break them. This threat has led to the development of post-quantum cryptography (PQC). The U.S. standardization body NIST is currently in the process of concluding a multi-year search for promising post-quantum...

A recent area of interest in cryptography is recursive composition of proof systems. One of the approaches to make recursive composition efficient involves cycles of pairing-friendly elliptic curves of prime order. However, known constructions have very low embedding degrees. This entails large parameter sizes, which makes the overall system inefficient. In this paper, we explore $2$-cycles composed of curves from families parameterized by polynomials, and show that such cycles do not...

The paper " An energy and area efficient, all digital entropy source compatible with modern standards based on jitter pipelining", by Peetermans and Verbauwhede, IACR Transactions on Cryptographic Hardware and Embedded Systems, Aug. 2022, 88-109, suggests a pipelined TRNG design and a stochastic model for it. The stochastic model is shown to be inadequate and other problems of the TRNG design are identified. Possible fixes for the problems are considered.

Decentralized Multi-Client Functional Encryption (DMCFE) extends the basic functional encryption to multiple clients that do not trust each other. They can independently encrypt the multiple inputs to be given for evaluation to the function embedded in the functional decryption key. And they keep control on these functions as they all have to contribute to the generation of the functional decryption keys. Dynamic Decentralized Functional Encryption (DDFE) is the ultimate extension...

A broadcast, trace and revoke system generalizes broadcast encryption as well as traitor tracing. In such a scheme, an encryptor can specify a list $L \subseteq N$ of revoked users so that (i) users in $L$ can no longer decrypt ciphertexts, (ii) ciphertext size is independent of $L$, (iii) a pirate decryption box supports tracing of compromised users. The ``holy grail'' of this line of work is a construction which resists unbounded collusions, achieves all parameters (including public and...

We consider the problem of proving in zero-knowledge the existence of vulnerabilities in executables compiled to run on real-world processors. We demonstrate that it is practical to prove knowledge of real exploits for real-world processor architectures without the need for source code and without limiting our consideration to narrow vulnerability classes. To achieve this, we devise a novel circuit compiler and a toolchain that produces highly optimized, non-interactive zero-knowledge proofs...

Bilinear pairings have been used in different cryptographic applications and demonstrated to be a key building block for a plethora of constructions. In particular, some Succinct Non-interactive ARguments of Knowledge (SNARKs) have very short proofs and very fast verifi- cation thanks to a multi-pairing computation. This succinctness makes pairing-based SNARKs suitable for proof recursion, that is proofs veri- fying other proofs. In this scenario one requires to express efficiently a...

Physical attacks can compromise the security of cryptographic devices. Depending on the attack’s requirements, adversaries might need to (i) place probes in the proximity of the integrated circuits (ICs) package, (ii) create physical connections between their probes/wires and the system’s PCB, or (iii) physically tamper with the PCB’s components, chip’s package, or substitute the entire PCB to prepare the device for the attack. While tamper-proof enclosures prevent and detect physical access...

We consider a federated representation learning framework, where with the assistance of a central server, a group of $N$ distributed clients train collaboratively over their private data, for the representations (or embeddings) of a set of entities (e.g., users in a social network). Under this framework, for the key step of aggregating local embeddings trained at the clients in a private manner, we develop a secure embedding aggregation protocol named SecEA, which provides...

Homomorphic encryption (HE), which allows computation over encrypted data, has often been used to preserve privacy. However, the computationally heavy nature and complexity of network topologies make the deployment of HE schemes in the Internet of Things (IoT) scenario difficult. In this work, we propose CARM, the first optimized GPU implementation that covers BGV, BFV and CKKS, targeting for accelerating homomorphic multiplication using GPU in heterogeneous IoT systems. We offer...

MPC-in-the-head based zero-knowledge proofs allow one to prove knowledge of a preimage for a circuit defined over a finite field F. In recent proofs the soundness depends on the size F, and small fields require more parallel repetitions, and therefore produce larger proofs. In this paper we develop and systematically apply lifting strategies to such proof protocols in order to increase soundness and reduce proof size. The strategies are (i) lifting parts of the protocol to extension fields...

The protection of cryptographic software implementations against power-analysis attacks is critical for applications in embedded systems. A commonly used algorithmic countermeasure against these attacks is masking, a secret-sharing scheme that splits a sensitive computation into computations on multiple random shares. In practice, the security of masking schemes relies on several assumptions that are often violated by microarchitectural side-effects of CPUs. Many past works address this...

We present a much-improved practical protocol, based on the hardness of Module-SIS and Module-LWE problems, for proving knowledge of a short vector $s$ satisfying $As=t\bmod q$. The currently most-efficient technique for constructing such a proof works by showing that the $\ell_\infty$ norm of $s$ is small. It creates a commitment to a polynomial vector $m$ whose CRT coefficients are the coefficients of $s$ and then shows that (1) $A\cdot \mathsf{CRT}(m)=t\bmod\,q$ and (2) in the case that...

The NIST standardization process for post-quantum cryptography has been drawing the attention of researchers to the submitted candidates. One direction of research consists in implementing those candidates on embedded systems and that exposes them to physical attacks in return. The Classic McEliece cryptosystem, which is among the four finalists of round 3 in the Key Encapsulation Mechanism category, builds its security on the hardness of the syndrome decoding problem, which is a classic...

Intellectual property (IP) cores are essential to creating modern system-on-chips (SoCs). Protecting the IPs deployed in modern SoCs has become more difficult as the IP houses have been established across the globe over the past three decades. The threat posed by IP piracy and overuse has been a topic of research for the past decade or so and has led to creation of a field called watermarking. IP watermarking aims of detecting unauthorized IP usage by embedding excess, nonfunctional...

Transport Layer Security (TLS) constitutes one of the most widely used protocols for securing Internet communications and has also found broad acceptance in the Internet of Things (IoT) domain. As we progress toward a security environment resistant to quantum computer attacks, TLS needs to be transformed to support post-quantum cryptography. However, post-quantum TLS is still not standardised, and its overall performance, especially in resource-constrained, IoT-capable, embedded devices, is...

In 2016, the National Institute of Standards and Technology (NIST) initiated a standardization process among the post-quantum secure algorithms. Forming part of the alternate group of candidates after Round 2 of the process is the Supersingular Isogeny Key Encapsulation (SIKE) mechanism which attracts with the smallest key sizes offering post-quantum security in scenarios of limited bandwidth and memory resources. Even further reduction of the exchanged information is offered by the...

Large-scale quantum computers will be able to efficiently solve the underlying mathematical problems of widely deployed public key cryptosystems in the near future. This threat has sparked increased interest in the field of Post-Quantum Cryptography (PQC) and standardization bodies like NIST, IETF, and ETSI are in the process of standardizing PQC schemes as a new generation of cryptography. This raises the question of how to ensure a fast, reliable, and secure transition to upcoming PQC...

Deep learning (DL)-based profiled attack has been proved to be a powerful tool in side-channel analysis. A variety of multi-layer perception (MLP) networks and convolutional neural networks (CNN) are thereby applied to cryptographic algorithm implementations for exploiting correct keys with a smaller number of traces and a shorter time. However, most attacks merely focus on small datasets, in which their points of interest are well-trimmed for attacks. Countermeasures applied in embedded...

Zero-Knowledge Proofs (ZKPs) are cryptographic primitives allowing a party to prove to another party that the former knows some information while keeping it secret. Such a premise can lead to the development of numerous privacy-preserving protocols in different scenarios, like proving knowledge of some credentials to a server without leaking the identity of the user. Even when the applications of ZKPs were endless, they were not exploited in the wild for a couple of decades due to the fact...

Shannon mutual information is an effective method to analyze the information interaction in a point-to-point communication system. However, it cannot solve the problem of channel capacity in graph structure communication system. This problem make it impossible to use traditional mutual information (TMI) to detect the real information and to measure the information embedded in the graph structure. Therefore, measuring the interaction of graph structure and the degree of privacy leakage has...

This paper introduces the concept of information with a foreseeable lifespan and explains who to achieve this primitive via a new method for encoding and storing information in DNA-RNA sequences. The storage process can be divided into three time-frames. Within the first (life), we can easily read out the stored data with high probability. The second time-frame (agony) is a parameter-dependent state of uncertainty; the data is not easily accessible, but still cannot be guaranteed to be...

Side-channel analysis (SCA) attacks pose a major threat to embedded systems due to their ease of accessibility. Realising SCA resilient cryptographic algorithms on embedded systems under tight intrinsic constraints, such as low area cost, limited computational ability, etc., is extremely challenging and often not possible. We propose a seamless and effective approach to realise a generic countermeasure against SCA attacks. XDIVINSA, an extended diversifying instruction agent, is introduced...

ChaCha is a high-throughput stream cipher designed with the aim of ensuring high-security margins while achieving high performance on software platforms. RISC-V, an emerging, free, and open Instruction Set Architecture (ISA) is being developed with many instruction set extensions (ISE). ISEs are a native concept in RISC-V to support a relatively small RISC-V ISA to suit different use-cases including cryptographic acceleration via either standard or custom ISEs. This paper proposes a...

Oblivious Transfer (OT) is a fundamental primitive in cryptography, supporting protocols such as Multi-Party Computation and Private Set Intersection (PSI), that are used in applications like contact discovery, remote diagnosis and contact tracing. Due to its fundamental nature, it is utterly important that its execution is secure even if arbitrarily composed with other instances of the same, or other protocols. This property can be guaranteed by proving its security under the Universal...

Advances in cryptography have enabled the features of confidentiality, security, and integrity on small embedded devices such as IoT devices. While mathematically strong, the platform on which an algorithm is implemented plays a significant role in the security of the final product. Side-channel attacks exploit the variations in the system’s physical characteristics to obtain information about the sensitive data. In our scenario, a software implementation of a cryptographic algorithm is...

As the Internet of Things (IoT) rolls out today to devices whose lifetime may well exceed a decade, conservative threat models should consider attackers with access to quantum computing power. The SUIT standard (specified by the IETF) defines a security architecture for IoT software updates, standardizing the metadata and the cryptographic tools---namely, digital signatures and hash functions---that guarantee the legitimacy of software updates. While the performance of SUIT has...

The framework of interactive oracle proofs (IOP) has been used with great success to construct a number of efficient transparent zk-SNARKs in recent years. However, these constructions are based on Reed-Solomon codes and can only be applied directly to statements given in the form of arithmetic circuits or R1CS over large fields $\mathbb{F}$ since their soundness error is at least $1/|\mathbb{F}|$. This motivates the question of what is the best way to apply these IOPs to statements that...

Despite a long history of research and wide-spread applications to censorship resistant systems, practical steganographic systems capable of embedding messages into realistic communication distributions, like text, do not exist. We identify two primary impediments to deploying universal steganography: (1) prior work leaves the difficult problem of finding samplers for non-trivial distributions unaddressed, and (2) prior constructions have impractical minimum entropy requirements. We...

Today's microprocessors often rely on microcode updates to address issues such as security or functional patches. Unfortunately, microcode update flexibility opens up new attack vectors through malicious microcode alterations. Such attacks share many features with hardware Trojans and have similar devastating consequences for system security. However, due to microcode's opaque nature, little is known in the open literature about the capabilities and limitations of microcode Trojans. We...

Lattice-based structures offer considerable possibilities for post-quantum cryptography. Recently, many algorithms have been built on hard lattice problems. The three of the remaining four in the final round of the post-quantum cryptography standardization process use lattice-based methods. Especially in embedded systems, these algorithms should be operated effectively. In this study, the potential of transport triggered architecture is examined in this sense. We try to compare open source...

ECIES has been widely used in many cryptographic devices and systems to ensure the confidentiality of communication data. Hence, researching its security of implementation is essential. It is generally considered that the embedded point validation towards the input point $Q$ during decryption is enough to resist most of the existing fault attacks and small subgroup attacks. Even many open source algorithm libraries (e.g., OpenSSL and BouncyCastle) only employ the embedded point validation...

In this paper, we contribute a comprehensive resource analysis for widely used cryptographic primitives across different off-the-shelf IoT platforms, and quantify the performance impact of crypto-hardware. This work builds on the newly designed crypto-subsystem of the IoT operating system RIOT, which provides seamless crypto support across software and hardware components. Our evaluations show that (i) hardware-based crypto outperforms software by considerably over 100 %, which is crucial...

Contemporary libraries and frameworks that make it possible to incorporate secure multi-party computation protocols and capabilities into production software systems and applications must sometimes deliver underlying capabilities (such as logical circuit synthesis) to new kinds of environments (such as web browsers or serverless cloud computing platforms). In order to illustrate some of the benefits of addressing this challenge by building a solution from the ground up that leverages the...

EPID systems are anonymous authentication protocols where a device can be revoked by including one of its signatures in a revocation list. Such protocols are today included in the ISO/IEC 20008-2 standard and are embedded in billions of chips, which make them a flagship of advanced cryptographic tools. Yet, their security analysis is based on a model that suffers from several important limitations, which either questions the security assurances EPID can provide in the real world or prevents...

With every new generation, high-end FPGAs are becoming richer in features and resources, making the usage model of single-user per FPGA decreasingly cost-efficient. Although virtualized FPGAs enable multiple users to share the same FPGA, this multi-tenancy is not employed in practice because of potential security threats, such as voltage attacks. These attacks use power-wasting circuits to exercise excessive switching activity on the target FPGA to cause extreme voltage fluctuations, which...

Anonymous attestation for secure hardware platforms leverages tailored group signature schemes and assumes the hardware to be trusted. Yet, there is an ever increasing concern on the trustworthiness of hardware components and embedded systems. A subverted hardware may, for example, use its signatures to exfiltrate identifying information or even the signing key. In this paper we focus on Enhanced Privacy ID (EPID)---a popular anonymous attestation scheme used in commodity secure hardware...

Point randomization is an important countermeasure to protect Elliptic Curve Cryptography (ECC) implementations against side-channel attacks. In this paper, we revisit its worst-case security in front of advanced side-channel adversaries taking advantage of analytical techniques in order to exploit all the leakage samples of an implementation. Our main contributions in this respect are the following: first, we show that due to the nature of the attacks against the point randomization (which...

The protection of cryptographic implementations against power analysis attacks is of critical importance for many applications in embedded systems. The typical approach of protecting against these attacks is to implement algorithmic countermeasures, like masking. However, implementing these countermeasures in a secure and correct manner is challenging. Masking schemes require the independent processing of secret shares, which is a property that is often violated by CPU microarchitectures in...

The side-channel community recently investigated a new approach, based on deep learning, to significantly improve profiled attacks against embedded systems. Compared to template attacks, deep learning techniques can deal with protected implementations, such as masking or desynchronization, without substantial pre-processing. However, important issues are still open. One challenging problem is to adapt the methods classically used in the machine learning field (e.g. loss function, performance...

Personal data exchange and disclosure prevention are widespread problems in our digital world. There are a couple of information technologies embedded in the commercial and government processes. People need to exchange their personal information while using these technologies. And therefore, It is essential to make this exchange is secure. Despite many legal regulations, there are many cases of personal data breaches that lead to undesirable consequences. Reasons for personal data leakage...

Cryptographic primitives have been designed to be secure against mathematical attacks in a black-box model. Such primitives can be implemented in a way that they are also secure against physical attacks, in a grey-box model. One of the most popular techniques for this purpose is masking. The increased security always comes with a high price tag in terms of implementation cost. In this work, we look at how the traditional design principles of symmetric primitives can be at odds with the...

It is known that attackers can exfiltrate data from air-gapped computers through their speakers via sonic and ultrasonic waves. To eliminate the threat of such acoustic covert channels in sensitive systems, audio hardware can be disabled and the use of loudspeakers can be strictly forbidden. Such audio-less systems are considered to be \textit{audio-gapped}, and hence immune to acoustic covert channels. In this paper, we introduce a technique that enable attackers leak data acoustically...

The design of software countermeasures against active and passive adversaries is a challenging problem that has been addressed by many authors in recent years. The proposed solutions adopt a theoretical foundation (such as a leakage model) but often do not offer concrete reference implementations to validate the foundation. Contributing to the experimental dimension of this body of work, we propose a customized processor called SKIVA that supports experiments with the design of...

An important selling point for the RISC-V instruction set is the separation between ISA and the implementation of the ISA, leading to flexibility in the design. We argue that for secure implementations, this flexibility is often a vulnerability. With a hardware attacker, the side-effects of instruction execution cannot be ignored. As a result, a strict separation between the ISA interface and implementation is undesirable. We suggest that secure ISA may require additional implementation...

Side-channel analysis (SCA) attacks – especially power analysis – are powerful ways to extract the secrets stored in and processed by cryptographic devices. In recent years, researchers have shown interest in utilizing on-chip measurement facilities to perform such SCA attacks remotely. It was shown that simple voltage-monitoring sensors can be constructed from digital elements and put on multi-tenant FPGAs to perform remote attacks on neighbouring cryptographic co-processors. A similar...

Mathematically-secure cryptographic algorithms leak significant side-channel information through their power supplies when implemented on a physical platform. These side-channel leakages can be exploited by an attacker to extract the secret key of an embedded device. The existing state-of-the-art countermeasures mainly focus on the power balancing, gate-level masking, or signal-to-noise (SNR) reduction using noise injection and signature attenuation, all of which suffer either from the...

We present our integration of post-quantum cryptography (PQC), more specifically of the post-quantum KEM scheme Kyber for key establishment and the post-quantum signature scheme SPHINCS$^+$, into the embedded TLS library mbed TLS. We measure the performance of these post-quantum primitives on four different embedded platforms with three different ARM processors and an Xtensa LX6 processor. Furthermore, we compare the performance of our experimental PQC cipher suite to a classical TLS variant...

To maintain the availability of industrial control systems (ICS), it is important to robustly detect malware infection that spreads within the ICS network. In ICS, a host often communicates with the determined hosts; for instance, a supervisory control host observes and controls the same devices routinely via the network. Therefore, a communication request to the unused internet protocol (IP) address space, i.e. darknet, in the ICS network is likely to be caused by malware in the compromised...

This paper explores the design space of secure communication in ultra-low-energy IoT devices based on Micro-Controller Units (MCUs). It tries to identify, evaluate and compare security-related design choices in a Commercial-Off-The-Shelf (COTS) embedded IoT system which contribute in the energy consumption. We conduct a study over a large group of software-implemented crypto algorithms: symmetric, stream, hash, AEAD, MAC, digital signature and key exchange. A comprehensive report of the...

We introduce a new technique for building multivariate encryption schemes based on random linear codes. The construction is versatile, naturally admitting multiple modifications. Among these modifications is an interesting embedding modifier--- any efficiently invertible multivariate system can be embedded and used as part of the inversion process. In particular, even small scale secure multivariate signature schemes can be embedded producing reasonably efficient encryption schemes. Thus...

In a traitor tracing (TT) system for $n$ users, every user has his/her own secret key. Content providers can encrypt messages using a public key, and each user can decrypt the ciphertext using his/her secret key. Suppose some of the $n$ users collude to construct a pirate decoding box. Then the tracing scheme has a special algorithm, called $Trace$, which can identify at least one of the secret keys used to construct the pirate decoding box. Traditionally, the trace algorithm output only...