In this work, we present a systematic study of Side-Channel Attacks (SCA) and Fault Injection Attacks (FIA) on structured lattice-based schemes, with main focus on Kyber Key Encapsulation Mechanism (KEM) and Dilithium signature scheme, which are leading candidates in the NIST standardization process for Post-Quantum Cryptography (PQC). Through our study, we attempt to understand the underlying similarities and differences between the existing attacks while classifying them into different categories. Given the wide variety of reported attacks, simultaneous protection against all the attacks requires to implement customized protections/countermeasures for both Kyber and Dilithium. We therefore present a range of customized countermeasures, capable of providing defenses/mitigations against existing SCA/FIA, and incorporate several SCA and FIA countermeasures within a single design of Kyber and Dilithium. Among the several countermeasures discussed in this work, we present novel countermeasures that offer simultaneous protection against several SCA- and FIA-based chosen-ciphertext attacks for Kyber KEM. We implement the presented countermeasures within two well-known public software libraries for PQC: (1) pqm4 library for the ARM Cortex-M4-based microcontroller and (2) liboqs library for the Raspberry Pi 3 Model B Plus based on the ARM Cortex-A53 processor. Our performance evaluation reveals that the presented custom countermeasures incur reasonable performance overheads on both the evaluated embedded platforms. We therefore believe our work argues for usage of custom countermeasures within real-world implementations of lattice-based schemes, either in a standalone manner or as reinforcements to generic countermeasures such as masking.

Large-scale quantum computers that can execute practical quantum algorithms have the potential to solve complex problems that are currently challenging for classical computers. This involves converting these problems into a form that can be processed by quantum circuits, a crucial process that requires minimizing quantum resources like qubit count, gate count, and circuit depth. Our work focuses on implementing and optimizing the foundational task of quantum finance, known as option pricing, as a quantum circuit. This enables the utilization of quantum computing benefits, within the financial domain. Specifically, we implement and optimize the function fK(S) = max(S−K, 0). Taking into consideration the significant trade-offs between qubit count and circuit depth, we have developed quantum circuits for the optimized implementation of the fK(S). Our work incorporates various optimization techniques for the circuit, such as selecting the optimal adder, optimizing the S−K operation, parallelization, and qubit reuse. Furthermore, we offer various versions of our quantum circuits for the fK(S), each featuring different adders and Toffoli decompositions, thereby providing flexibility for a wide range of use cases.

Side Channel Analysis (SCA) is among the newly emerged threats to small scale devices performing a cryptographic operation. While such analysis is well studied against the block ciphers, we observe that the stream cipher counterpart is not that much explored. We propose novel modelling that can work with a number of stream ciphers and related constructions. We show practical state/key recovery attacks on the lightweight ciphers, LIZARD, PLANTLET and GRAIN-128-AEAD. We consider the software platform (where the Hamming weight leakage is available) as well as the hardware platform (where the Hamming distance leakage is available). Through the modelling of Satisfiability Modulo Theory (SMT), we show that the solution can be obtained in a matter of seconds in most cases. In a handful of cases, however, the entire state/key recovery is not feasible in a practical amount of time. For those cases, we show full recovery is possible when a small number of bits are guessed. We also study the effect of increasing/decreasing the number of keystream bits on the solution time. Following a number of literature, we initially assume the traces that are obtained are noiseless. Later, we show how an extension of our model can deal with the noisy traces (which is a more general assumption).

In the current world of the Internet-of-things and edge computing, computations are increasingly performed locally on small connected systems. As such, those devices are often vulnerable to adversarial physical access, enabling a plethora of physical attacks which is a challenge even if such devices are built for security. As cryptography is one of the cornerstones of secure communication among devices, the pertinence of fault attacks is becoming increasingly apparent in a setting where a device can be easily accessed in a physical manner. In particular, two recently proposed fault attacks, Statistical Ineffective Fault Attack (SIFA) and the Fault Template Attack (FTA) are shown to be formidable due to their capability to bypass the common duplication based countermeasures. Duplication based countermeasures, deployed to counter the Differential Fault Attack (DFA), work by duplicating the execution of the cipher followed by a comparison to sense the presence of any effective fault, followed by an appropriate recovery procedure. While a handful of countermeasures are proposed against SIFA, no such countermeasure is known to thwart FTA to date. In this work, we propose a novel countermeasure based on duplication, which can protect against both SIFA and FTA. The proposal is also lightweight with only a marginally additional cost over simple duplication based countermeasures. Our countermeasure further protects against all known variants of DFA, including Selmke, Heyszl, Sigl's attack from FDTC 2016. It does not inherently leak side-channel information and is easily adaptable for any symmetric key primitive. The validation of our countermeasure has been done through gate-level fault simulation.

Symmetric key cryptography is one of the cornerstones of security in the modern era of electronic communication. The symmetric key algorithms, known as the ciphers, are to satisfy certain requirements in order to be considered secure, which are broadly classified as classical attack and physical attack. We show new results in context of both the classical and physical attacks to advance the state-of-the-art [1].

This paper presents the first practical fault attack on the ChaCha family of addition-rotation-XOR (ARX)-based stream ciphers. ChaCha has recently been deployed for speeding up and strengthening HTTPS connections for Google Chrome on Android devices. In this paper, we propose differential fault analysis attacks on ChaCha without resorting to nonce misuse. We use the instruction skip and instruction replacement fault models, which are popularly mounted on microcontroller-based cryptographic implementations. We corroborate the attack propositions via practical fault injection experiments using a laser-based setup targeting an Atmel AVR 8-bit microcontroller-based implementation of ChaCha. Each of the proposed attacks can be repeated with 100% accuracy in our fault injection setup, and can recover the entire 256 bit secret key using 5-8 fault injections on an average.

Quantum computing necessitates the design of circuits via reversible logic gates. Efficient reversible circuit can be constructed by achieving low ancilla count, reducing logical depth and lowering Quantum costs. Generalized Peres gates have recently been realized with very low Quantum Cost (QC) by utilizing Quantum rotation gates. This is utilized in recent literature for efficient reversible circuit constructions for symmetric Boolean functions. In this paper, we extend this line of construction further by demonstrating efficient realization of adder circuits. In particular, we revisit the adder construction of Vedral, Barenco and Eckert to show that improvement of gate count and QC is achievable by exploiting a construction based only on Peres gates. We also report improved constructions of symmetric Boolean functions by following an approach recently proposed in the context of Boolean function complexity analysis.