Algorithmes quantiques pour la cryptanalyse et cryptographie symétrique post-quantique

Modern cryptography relies on the notion of computational security. The level of security given by a cryptosystem is expressed as an amount of computational resources required to break it. The goal of cryptanalysis is to find attacks, that is, algorithms with lower complexities than the conjectural bounds.With the advent of quantum computing devices, these levels of security have to be updated to take a whole new notion of algorithms into account. At the same time, cryptography is becoming widely used in small devices (smart cards, sensors), with new cost constraints.In this thesis, we study the security of secret-key cryptosystems against quantum adversaries.We first build new quantum algorithms for k-list (k-XOR or k-SUM) problems, by composing exhaustive search procedures. Next, we present dedicated cryptanalysis results, starting with a new quantum cryptanalysis tool, the offline Simon's algorithm. We describe new attacks against the lightweight algorithms Spook and Gimli and we perform the first quantum security analysis of the standard cipher AES.Finally, we specify Saturnin, a family of lightweight cryptosystems oriented towards post-quantum security. Thanks to a very similar structure, its security relies largely on the analysis of AES.La cryptographie moderne est fondée sur la notion de sécurité computationnelle. Les niveaux de sécurité attendus des cryptosystèmes sont exprimés en nombre d'opérations ; une attaque est un algorithme d'une complexité inférieure à la borne attendue. Mais ces niveaux de sécurité doivent aujourd'hui prendre en compte une nouvelle notion d'algorithme : le paradigme du calcul quantique. Dans le même temps,la délégation grandissante du chiffrement à des puces RFID, objets connectés ou matériels embarqués pose de nouvelles contraintes de coût.Dans cette thèse, nous étudions la sécurité des cryptosystèmes à clé secrète face à un adversaire quantique.Nous introduisons tout d'abord de nouveaux algorithmes quantiques pour les problèmes génériques de k-listes (k-XOR ou k-SUM), construits en composant des procédures de recherche exhaustive.Nous présentons ensuite des résultats de cryptanalyse dédiée, en commençant par un nouvel outil de cryptanalyse quantique, l'algorithme de Simon hors-ligne. Nous décrivons de nouvelles attaques contre les algorithmes Spook et Gimli et nous effectuons la première étude de sécurité quantique du chiffrement AES. Dans un troisième temps, nous spécifions Saturnin, une famille de cryptosystèmes à bas coût orientés vers la sécurité post-quantique. La structure de Saturnin est proche de celle de l'AES et sa sécurité en tire largement parti

Analyse et Conception d'Algorithmes de Chiffrement Légers

The work presented in this thesis has been completed as part of the FUI Paclido project, whose aim is to provide new security protocols and algorithms for the Internet of Things, and more specifically wireless sensor networks. As a result, this thesis investigates so-called lightweight authenticated encryption algorithms, which are designed to fit into the limited resources of constrained environments. The first main contribution focuses on the design of a lightweight cipher called Lilliput-AE, which is based on the extended generalized Feistel network (EGFN) structure and was submitted to the Lightweight Cryptography (LWC) standardization project initiated by NIST (National Institute of Standards and Technology). Another part of the work concerns theoretical attacks against existing solutions, including some candidates of the nist lwc standardization process. Therefore, some specific analyses of the Skinny and Spook algorithms are presented, along with a more general study of boomerang attacks against ciphers following a Feistel construction.Les travaux présentés dans cette thèse s’inscrivent dans le cadre du projet FUI Paclido, qui a pour but de définir de nouveaux protocoles et algorithmes de sécurité pour l’Internet des Objets, et plus particulièrement les réseaux de capteurs sans fil. Cette thèse s’intéresse donc aux algorithmes de chiffrements authentifiés dits à bas coût ou également, légers, pouvant être implémentés sur des systèmes très limités en ressources. Une première partie des contributions porte sur la conception de l’algorithme léger Lilliput-AE, basé sur un schéma de Feistel généralisé étendu (EGFN) et soumis au projet de standardisation international Lightweight Cryptography (LWC) organisé par le NIST (National Institute of Standards and Technology). Une autre partie des travaux se concentre sur des attaques théoriques menées contre des solutions déjà existantes, notamment un certain nombre de candidats à la compétition LWC du NIST. Elle présente donc des analyses spécifiques des algorithmes Skinny et Spook ainsi qu’une étude plus générale des attaques de type boomerang contre les schémas de Feistel

New results on Gimli: full-permutation distinguishers and improved collisions

International audienceGimli is a family of cryptographic primitives (both a hash function and an AEAD scheme) that has been selected for the second round of the NIST competition for standardizing new lightweight designs. The candidate Gimli is based on the permutation Gimli, which was presented at CHES 2017. In this paper, we study the security of both the permutation and the constructions that are based on it. We exploit the slow diffusion in Gimli and its internal symmetries to build, for the first time, a distinguisher on the full permutation of complexity 2 64. We also provide a practical distinguisher on 23 out of the full 24 rounds of Gimli that has been implemented. Next, we give (full state) collision and semi-free-start collision attacks on Gimli-Hash, reaching respectively up to 12 and 18 rounds. On the practical side, we compute a collision on 8-round Gimli-Hash. In the quantum setting, these attacks reach 2 more rounds. Finally, we perform the first study of linear trails in the permutation, and we propose differential-linear cryptanalysis that reach up to 17 rounds of Gimli

White-Box Block Cipher Implementation Based on LS-Design

Protecting secret keys from malicious observers in untrusted environments is a critical security issue. White-box cryptography suggests software protection by hiding the key in the white-box setting. One method for hiding the key in the cipher code is through encoding methods. Unfortunately, encoding methods may be vulnerable to algebraic attacks and side-channel analysis. Another technique to hide the key is (M,Z)-space hardness approach that conceals the key into a large lookup table generated with a reliable small block cipher. In (M,Z)-space-hard algorithms, the key extraction problem in the white-box setting turns into a key recovery problem in the black-box setting. One of the problems for (M,Z)-space-hard algorithms is improving run-time performance. In this study, we aim to improve the run-time performance of the existing white-box implementations. We propose an LS-design based white-box algorithm with better run-rime performance than space-hard SPNbox algorithm. Moreover, an LS-design based table creation method is designed. When we compare the run-time performance of our method with the SPNbox algorithm, we obtain 28% improvement for white-box implementation and 27% for black-box implementation for 128-bit block size. The LS-design based method is also used for 256-bit block size in the white-box setting

A Comprehensive Survey on the Implementations, Attacks, and Countermeasures of the Current NIST Lightweight Cryptography Standard

This survey is the first work on the current standard for lightweight cryptography, standardized in 2023. Lightweight cryptography plays a vital role in securing resource-constrained embedded systems such as deeply-embedded systems (implantable and wearable medical devices, smart fabrics, smart homes, and the like), radio frequency identification (RFID) tags, sensor networks, and privacy-constrained usage models. National Institute of Standards and Technology (NIST) initiated a standardization process for lightweight cryptography and after a relatively-long multi-year effort, eventually, in Feb. 2023, the competition ended with ASCON as the winner. This lightweight cryptographic standard will be used in deeply-embedded architectures to provide security through confidentiality and integrity/authentication (the dual of the legacy AES-GCM block cipher which is the NIST standard for symmetric key cryptography). ASCON's lightweight design utilizes a 320-bit permutation which is bit-sliced into five 64-bit register words, providing 128-bit level security. This work summarizes the different implementations of ASCON on field-programmable gate array (FPGA) and ASIC hardware platforms on the basis of area, power, throughput, energy, and efficiency overheads. The presented work also reviews various differential and side-channel analysis attacks (SCAs) performed across variants of ASCON cipher suite in terms of algebraic, cube/cube-like, forgery, fault injection, and power analysis attacks as well as the countermeasures for these attacks. We also provide our insights and visions throughout this survey to provide new future directions in different domains. This survey is the first one in its kind and a step forward towards scrutinizing the advantages and future directions of the NIST lightweight cryptography standard introduced in 2023

Internal symmetries and linear properties: Full-permutation distinguishers and improved collisions on Gimli

Gimli is a family of cryptographic primitives (both a hash function and an AEAD scheme) that has been selected for the second round of the NIST competition for standardizing new lightweight designs. The candidate Gimli is based on the permutation Gimli, which was presented at CHES 2017. In this paper, we study the security of both the permutation and the constructions that are based on it. We exploit the slow diffusion in Gimli and its internal symmetries to build, for the first time, a distinguisher on the full permutation of complexity 2^64. We also provide a practical distinguisher on 23 out of the full 24 rounds of Gimli that has been implemented. Next, we give (full state) collision and semi-free start collision attacks on Gimli-Hash, reaching, respectively, up to 12 and 18 rounds. On the practical side, we compute a collision on 8-round Gimli-Hash. In the quantum setting, these attacks reach 2 more rounds. Finally, we perform the first study of linear trails in Gimli, and we find a linear distinguisher on the full permutation

Internal Symmetries and Linear Properties: Full-permutation Distinguishers and Improved Collisions on Gimli

International audienceGimli is a family of cryptographic primitives (both a hash function and an AEAD scheme) that has been selected for the second round of the NIST competition for standardizing new lightweight designs. The candidate Gimli is based on the permutation Gimli, which was presented at CHES 2017. In this paper, we study the security of both the permutation and the constructions that are based on it. We exploit the slow diffusion in Gimli and its internal symmetries to build, for the first time, a distinguisher on the full permutation of complexity 2 64. We also provide a practical distinguisher on 23 out of the full 24 rounds of Gimli that has been implemented. Next, we give (full state) collision and semi-free-start collision attacks on Gimli-Hash, reaching respectively up to 12 and 18 rounds. On the practical side, we compute a collision on 8-round Gimli-Hash. In the quantum setting, these attacks reach 2 more rounds. Finally, we perform the first study of linear trails in Gimli, and we find a linear distinguisher on the full permutation

Provably Minimum Data Complexity Integral Distinguisher Based on Conventional Division Property

Division property is an effective method for finding integral distinguishers for block ciphers, performing cube attacks on stream ciphers, and studying the algebraic degree of boolean functions. One of the main problems in this field is how to provably find the smallest input multiset leading to a balanced output. In this paper, we propose a new method based on division property for finding integral distinguishers with a provably minimum data complexity on permutation functions and block ciphers, in the conventional division property model. The new method is based on efficiently analyzing the algebraic normal form of the target output boolean function. We examine the proposed method on LBlock, TWINE, SIMON, Present, Gift, and Clyde-128 block ciphers. Although in most cases, the results are compliant with the distinguishers reported in the previous work, the proposed method proves the optimality of these results, in the conventional division property model. However, the proposed method can find distinguishers for 8-round Clyde-128 with a data complexity less than the previously reported one, based on conventional division property. The new method is also capable of determining the maximum number of balanced output bits in an integral distinguisher with a specified number of active bits. We propose an algorithm to exploit this capability and apply it to the studied ciphers. As a result, we determine the maximum number of balanced bits on integral distinguishers with minimum and non-minimum data complexities on the studied ciphers and report improved results on Gift-64, Present and SIMON64 in the conventional model