44 research outputs found
Analysis of AES, SKINNY, and Others with Constraint Programming
No full textInternational audienceSearch for different types of distinguishers are common tasks in symmetric-key cryptanalysis. In this work, we employ the constraint programming (CP) technique to tackle such problems. First, we show that a simple application of the CP approach proposed by Gerault et al. leads to the solution of the open problem of determining the exact lower bound of the number of active S-boxes for 6-round AES-128 in the related-key model. Subsequently, we show that the same approach can be applied in searching for integral distinguishers, impossible differentials, zero-correlation linear approximations, in both the single-key and related-(twea)key model. We implement the method using the open source constraint solver Choco and apply it to the block ciphers PRESENT, SKINNY, and HIGHT (ARX construction). As a result, we find 16 related-tweakey impossible differentials for 12-round SKINNY-64-128 based on which we construct an 18-round attack on SKINNY-64-128 (one target version for the crypto competition https://sites.google.com/site/skinnycipher announced at ASK 2016). Moreover, we show that in some cases, when equipped with proper strategies (ordering heuristic, restart and dynamic branching strategy), the CP approach can be very efficient. Therefore, we suggest that the constraint programming technique should become a convenient tool at hand of the symmetric-key cryptanalyst
Analyse de sécurité des protocoles de communication sans contact
No full textRésumé indisponible.Résumé indisponible
Differential Cryptanalysis with SAT, SMT, MILP, and CP: A Detailed Comparison for Bit-Oriented Primitives
No full textSAT, SMT, MILP, and CP, have become prominent in the
differential cryptanalysis of cryptographic primitives. In this paper, we
review the techniques for constructing differential characteristic search
models in these four formalisms. Additionally, we perform a system-
atic comparison encompassing over 20 cryptographic primitives and 16
solvers, on both easy and hard instances of optimisation, enumeration
and differential probability estimation problems
Distance bounding under different assumptions
No full textDistance-bounding protocols were introduced in 1993 as a countermeasure to relay attacks, in which an adversary fraudulently forwards the communication between a verifier and a distant prover. In the more than 40 different protocols that followed, assumptions were taken on the structure of distance-bounding protocols and their threat models. In this paper, we survey works disrupting these assumptions, and discuss the remaining challenges
Prise en charge pré-hospitalière des infarctus du myocarde par le SAMU de Rouen (étude de 260 cas sur deux ans)
No full textLa prise en charge pré-hospitalière des infarctus du myocarde par le SAMU-SMUR de Rouen est évaluée par une étude rétrospective du 1er mai 1997 au 30 avril 1999. Elle porte sur 314 dossiers d'infarctus évoqués par le SMUR de Rouen et sur 260 diagnostics confirmés secondairement. Cette étude montre que la prise en charge thérapeutique, et notamment en matière de désobstruction répond aux recommandations actuelles. Des points sont à améliorer en terme de régulation des appels pour douleur thoracique et dans le respect des critères d'inclusion dans les protocoles de désobstruction afin d'améliorer encore la qualité de prise en charge des patients avec infarctus du myocarde aigu.ROUEN-BU Médecine-Pharmacie (765402102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF
Related-Key Cryptanalysis of Midori
No full textInternational audienceMidori64 and Midori128 [2] are lightweight block ciphers, which respectively cipher 64-bit and 128-bit blocks. While several attack models are discussed by the authors of Midori, the authors made no claims concerning the security of Midori against related-key differential attacks. In this attack model, the attacker uses related-key differential characteristics, i.e., tuples (δP , δK , δC) such that a difference (generally computed as a XOR) of δP in the plaintext coupled with a difference δK in the key yields a difference δC after r rounds with a good probability. In this paper, we propose a constraint programming model to automate the search for optimal (in terms of probability) related-key differential characteristics on Midori. Using it, we build related-key distinguishers on the full-round Midori64 and Midori128, and mount key recovery attacks on both versions of the cipher with practical time complexity, respectively 2 35.8 and 2 43.7
A Cipher-Agnostic Neural Training Pipeline with Automated Finding of Good Input Differences
No full textNeural cryptanalysis is the study of cryptographic primitives through machine learning techniques. Following Gohr’s seminal paper at CRYPTO 2019, a focus has been placed on improving the accuracy of such distinguishers against specific primitives, using dedicated training schemes, in order to obtain better key recovery attacks based on machine learning. These distinguishers are highly specialized and not trivially applicable to other primitives. In this paper, we focus on the opposite problem: building a generic pipeline for neural cryptanalysis. Our tool is composed of two parts. The first part is an evolutionary algorithm for the search of good input differences for neural distinguishers. The second part is DBitNet, a neural distinguisher architecture agnostic to the structure of the cipher. We show that this fully automated pipeline is competitive with a highly specialized approach, in particular for SPECK32, and SIMON32. We provide new neural distinguishers for several primitives (XTEA, LEA, HIGHT, SIMON128, SPECK128) and improve over the state-of-the-art for PRESENT, KATAN, TEA and GIMLI
Using Constraint Programming to solve a Cryptanalytic Problem
No full textInternational audienceWe describe Constraint Programming (CP) models to solve a cryptanalytic problem: the chosen key differential attack against the standard block cipher AES. We show that CP solvers are able to solve these problems quicker than dedicated cryptanaly-sis tools, and we prove that a solution claimed to be optimal in two recent cryptanalysis papers is not optimal by providing a better solution
Using Constraint Programming to solve a Cryptanalytic Problem
No full textInternational audienceWe describe Constraint Programming (CP) models to solve a cryptanalytic problem: the chosen key differential attack against the standard block cipher AES. We show that CP solvers are able to solve these problems quicker than dedicated cryptanaly-sis tools, and we prove that a solution claimed to be optimal in two recent cryptanalysis papers is not optimal by providing a better solution
