Cryptanalyse Quantique de l'AES

National audienc

Block Ciphers that are Easier to Mask: How Far Can we Go?

The design and analysis of lightweight block ciphers has been a very active research area over the last couple of years, with many innovative proposals trying to optimize different performance figures. However, since these block ciphers are dedicated to low-cost embedded devices, their implementation is also a typical target for side-channel adversaries. As preventing such attacks with countermeasures usually implies significant performance overheads, a natural open problem is to propose new algorithms for which physical security is considered as an optimization criteria, hence allowing better performances again. We tackle this problem by studying how much we can tweak standard block ciphers such as the AES Rijndael in order to allow efficient masking (that is one of the most frequently considered solutions to improve security against side-channel attacks). For this purpose, we first investigate alternative S-boxes and round structures. We show that both approaches can be used separately in order to limit the total number of non-linear operations in the block cipher, hence allowing more efficient masking. We then combine these ideas into a concrete instance of block cipher called Zorro. We further provide a detailed security analysis of this new cipher taking its design specificities into account, leading us to exploit innovative techniques borrowed from hash function cryptanalysis (that are sometimes of independent interest). Eventually, we conclude the paper by evaluating the efficiency of masked Zorro implementations in an 8-bit microcontroller, and exhibit their interesting performance figures

Quantum Attacks without Superposition Queries: The Offline Simon's Algorithm

International audienc

Quantum linearization attacks

Recent works have shown that quantum period-finding can be used to break many popular constructions (some block ciphers such as Even-Mansour, multiple MACs and AEs...) in the superposition query model. So far, all the constructions broken exhibited a strong algebraic structure, which enables to craft a periodic function of a single input block. Recoverin

QCB: Efficient Quantum-secure Authenticated Encryption

It was long thought that symmetric cryptography was only mildly affected by quantum attacks, and that doubling the key length was sufficient to restore security. However, recent works have shown that Simon\u27s quantum period finding algorithm breaks a large number of MAC and authenticated encryption algorithms when the adversary can query the MAC/encryption oracle with a quantum superposition of messages. In particular, the OCB authenticated encryption mode is broken in this setting, and no quantum-secure mode is known with the same efficiency (rate-one and parallelizable). In this paper we generalize the previous attacks, show that a large class of OCB-like schemes is unsafe against superposition queries, and discuss the quantum security notions for authenticated encryption modes. We propose a new rate-one parallelizable mode named QCB inspired by TAE and OCB and prove its security against quantum superposition queries

QCB: Efficient Quantum-Secure Authenticated Encryption

International audienceIt was long thought that symmetric cryptography was only mildly affected by quantum attacks, and that doubling the key length was sufficient to restore security. However, recent works have shown that Simon's quantum period finding algorithm breaks a large number of MAC and authenticated encryption algorithms when the adversary can query the MAC/encryption oracle with a quantum superposition of messages. In particular, the OCB authenticated encryption mode is broken in this setting, and no quantum-secure mode is known with the same efficiency (rate-one and parallelizable). In this paper we generalize the previous attacks, show that a large class of OCB-like schemes is unsafe against superposition queries, and discuss the quantum security notions for authenticated encryption modes. We propose a new rate-one parallelizable mode named QCB inspired by TAE and OCB and prove its security against quantum superposition queries

Workflow-based data parallel applications on the EGEE production grid infrastructure

articleInternational audienceSetting up and deploying complex applications on a grid infrastructure is still challenging and the programming models are rapidly evolving. Efficiently exploiting grid parallelism is often not straight forward. In this paper, we report on the techniques used for deploying applications on the EGEE production grid through four experiments coming from completely different scientific areas: nuclear fusion, astrophysics and medical imaging. These applications have in common the need for manipulating huge amounts of data and all are computationally intensive. All the cases studied show that the deployment of data intensive applications require the development of more or less elaborated application-level workload management systems on top of the gLite middleware to efficiently exploit the EGEE grid resources. In particular, the adoption of high level workflow management systems eases the integration of large scale applications while exploiting grid parallelism transparently. Different approaches for scientific workflow management are discussed. The MOTEUR workflow manager strategy to efficiently deal with complex data flows is more particularly detailed. Without requiring specific application development, it leads to very significant speed-ups

La Cronología de las Necrópolis Neolíticas del NE Peninsular “Bòbila Madurell-Can Gambús” y “Camí de Can Grau” (Segunda mitad del V milenio cal.ANE- Primera mitad del IV milenio cal.ANE)

En esta comunicación se presentarán los resultados de diferentes análisis estadísticos y modelos bayesianos realizados para precisar la cronología de dos necrópolis neolíticas del Horizonte Cultural de los Sepulcres de Fossa: “Bòbila Madurell-Can Gambús”, con un total de 175 estructuras con restos humanos, y “Camí de Can Grau”, con un total de 25. Tradicionalmente el término Sepulcres de fossa ha sido acuñado para referirse a la recurrencia documentada de enterramientos en fosa o en cista con materiales exógenos depositados en sus ajuares durante este período en el NE de la península Ibérica. Entre estos materiales de origen foráneo suelen aparecer herramientas de sílex melado probablemente procedente del sureste de Francia, hachas y azuelas de jadeíta/eclogita procedentes de los Alpes, ornamentos de varicita extraída de la costa del NE de la península Ibérica, vasos cerámicos de tipo “boca cuadrada” parecidos a los encontrados en el norte de Italia (VBQ) y en algunas ocasiones, incluso, obsidiana sarda. Un patrón similar también ha sido identificado durante el mismo período en las prácticas funerarias de otros contextos europeos, como en la llamada cultura Chasséen en el centro y el sur de Francia, Cortaillod en Suiza o la Cultura dei Vasi a Bocca Quadrata en el norte de Italia. La documentación de estas similitudes entre estas prácticas funerarias ha dado lugar a hipótesis que plantean relaciones de intercambio a larga distancia entre estas comunidades como explicación del patrón. Sin embargo, las relaciones temporales entre estas prácticas funerarias todavía no han sido definidas del todo, por lo que no se ha descrito en profundidad el desarrollo cronológico de estas redes. En este trabajo pretendemos aclarar la cronología de “Bòbila Madurell-Can Gambús” y “Camí de Can Grau”, a través de análisis estadísticos y modelizaciones de enfoque bayesiano sobre más de 60 dataciones radiocarbónicas procedentes de distintas estructuras funerárias. La ida de fondo es aclarar la cronología de estas dos necrópolis teniendo en cuenta la sincronía/diacronía del conjunto de enterramientos en relación a la presencia y ausencia de las materias primas exógenas depositadas en sus ajuares. Entendemos este trabajo como una primera aproximación al desarrollo cronológico de estas redes de intercambio de materias primas en el NE de la Península Ibérica.Peer Reviewe

QCB: Efficient quantum-secure authenticated encryption

It was long thought that symmetric cryptography was only mildly affected by quantum attacks, and that doubling the key length was sufficient to restore security. However, recent works have shown that Simon’s quantum period finding algorithm breaks a large number of MAC and authenticated encryption algorithms when the adversary can query the MAC/encryption oracle with a quantum superposition of messages. In particular, the OCB authenticated encryption mode is broken in this setting, and no quantum-secure mode is known with the same efficiency (rate-one and parallelizable). In this paper we generalize the previous attacks, show that a large class of OCB-like schemes is unsafe against superposition queries, and discuss the quantum security notions for authenticated encryption modes. We propose a new rate-one parallelizable mode named QCB inspired by TAE and OCB and prove its security against quantum superposition queries

Disseminated tuberculosis and diagnosis delay during the COVID-19 era in a Western European country : a case series analysis

Disseminated tuberculosis is frequently associated with delayed diagnosis and a poorer prognosis. To describe case series of disseminated TB and diagnosis delay in a low TB burden country during the COVID-19 period. We consecutively included all patients with of disseminated TB reported from 2019 to 2021 in the reference hospital of the Northern Crown of the Metropolitan Area of Barcelona. We collected socio-demographic information, clinical, laboratory and radiological findings. We included all 30 patients reported during the study period-5, 9, and 16 in 2019, 2020, and 2021 respectively-20 (66.7%) of whom were male and whose mean age was 41 years. Twenty-five (83.3%) were of non-EU origin. The most frequent system involvement was central nervous system (N = 8; 26.7%) followed by visceral (N = 7; 23.3%), gastro-intestinal (N = 6, 20.0%), musculoskeletal (N = 5; 16.7%), and pulmonary (N = 4; 13.3%). Hypoalbuminemia and anemia were highly prevalent (72 and 77%). The median of diagnostic delay was 6.5 months (IQR 1.8-30), which was higher among women (36.0 vs. 3.5 months; p = 0.002). Central nervous system involvement and pulmonary involvement were associated with diagnostic delay among women. We recorded 24 cured patients, two deaths, three patients with post-treatment sequelae, and one lost-to-follow up. We observed a clustering effect of patients in low-income neighborhoods (p < 0.001). There was a substantial delay in the diagnosis of disseminated TB in our study region, which might impacted the prognosis with women affected more negatively. Our results suggest that an increase in the occurrence of disseminated TB set in motion by diagnosis delay may have been a secondary effect of the COVID-19 pandemic