FastCPA: Efficient Correlation Power Analysis Computation with a Large Number of Traces

International audienceCryptographic algorithm implementations need to be secured against side-channel attacks. Correlation Power Analysis (CPA) is an efficient technique for recovering secret key bytes of a cryptographic algorithm implementation by analyzing the power traces of its execution. Although CPA usually does not require a lot of traces to recover secret key bytes, it is no longer true in a noisy environment , for which the required number of traces can be very high. Computation time can then become a major concern for performing this attack and assessing the robustness of an implementation against it. This article introduces FastCPA, which is a correlation computation targeting the same goal as regular CPA, but based on power consumption vectors indexed by plaintext values. The main advantage of FastCPA is its fast execution time compared to the regular CPA computation, especially when the number of traces is high: for 100,000 traces, the speedup factor varies from 70 to almost 200 depending on the number of samples. An analysis of FastCPA accuracy is made, based on the number of correct key bytes found with an increasing noise. This analysis shows that FastCPA performs similarly as the regular CPA for a high number of traces. The minimum required number of traces to get the correct key guess is also computed for 100,000 noisy traces and shows that FastCPA obtains similar results to those of regular CPA. Finally, although FastCPA is more sensitive to plaintext values than the regular CPA, it is shown that this aspect can be neglected for a high number of traces

Estimation statistique et sécurité des cartes à puce (évaluation d'attaques DPA évoluées)

La première partie de la thèse comporte une étude approfondie sur les conditions nécessaires pour qu'une attaque DPA telle que décrite par Kocher permette de retrouver la clé. Cette étude permet aussi de construire un test sur le maximum de vraisemblance. L'utilisation du maximum de vraisemblance permet d'être plus robuste contre les variations temporelles de la variance du bruit.Dans une deuxième partie, trois différentes méthodes d'attaque permettant de tenir compte de plusieurs bits sont comparés: le DPA multibit, la méthode de corrélation empirique, et le maximum de vraisemblance par rapport à un modèle linéaire gaussien. La méthode de corrélation empirique converge le plus rapidement vers l'hypothèse correcte.Des travaux sur l'attaque DPA au second ordre sont présentés dans une troisième partie. Ces travaux ont pour but d'améliorer la mise en pratique de cette attaque. Dans un premier temps, on isole les variables susceptibles d'être attaquées par une attaque au second ordre. Enfin, une méthode multibit est utilisée pour accélérer la convergence de l'attaque.Dans la dernièr partie sont étudiés des attaques utilisant des messages choisis. Les messages choisis sont utilisés en premier lieu pour réduire le bruit algorithmique et diminuer le nombre de messages nécessaires pour la réussite d'une attaque. Les messages choisis sont aussi utilisés pour s'affranchir de certaines contre-mesures, notamment pour permettre à l'attaquant de viser des variables intermédiaires non protégées. Enfin, certaines valeurs sont prouvées dangereuses contre l'algorithme XTR si aucune contre-mesure n'est prévue contre l'apparition de zéro dans les variables initiales.The first part of the thesis deals with the necessary conditions for the success of the Differential Power Analysis (DPA). The study provide to the attacker a way to build a maximum likelihood test. This test is more robust to the time variation of the variance of noises.In a second part, three methods, which use several bits of a temporary variables inside the smartcards, are compared. The first method is the multibit DPA, the second is the Pearson correlation coefficient, the third is a method using the maximum likelihood with a gaussian linear model. Regarding the number of samples needed to retrieve the key, the second method is shown to be the best.Some works about second order DPA are presented in the third part. The investigations show how two temporary variables protected by the same random mask can be attacked by a difference of variances. A way to use several bits of the temporary results increase the efficiency of the attack.The last part deals with some specific attacks using chosen inputs. Chosen messages are initially used to decrease algorithmic noise. We show that chosen messages can be used to attack specific temporary variables which are not protected. Some variables which seem to require too much hypothesis on the key are not protected to save time. However with chosen messages, attacker can reduce the number of hypothesis and manage to set up an attack. Finally, chosen inputs can be used to reveal specific values of the temporary variables. In particular, some inputs of XTR create a serie of intermediate results equal to zero. As the use of zero in multiplication is very noticeable on power traces, these inputs can reveal the secret key.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Two Power Analysis Attacks Against One-Mask Methods

International audienc

Standards for the care of people with cystic fibrosis (CF); Planning for a longer life

This is the final of four papers updating standards for the care of people with CF. That this paper "Planning a longer life" was considered necessary, highlights how much CF care has progressed over the past decade. Several factors underpin this progress, notably increased numbers of people with CF with access to CFTR modulator therapy. As the landscape for CF changes, so do the hopes and aspirations of people with CF and their families. This paper reflects the need to consider people with CF not as a "problem" to be solved, but as a success, a potential and a voice to be heard. People with CF and the wider CF community have driven this approach, reflecting many of the topics in this paper. This exercise involved wide stakeholder engagement. People with CF are keen to contribute to research priorities and be involved in all stages of research. People with CF want healthcare professionals to respect them as individuals and consider the impact of our actions on the world around us. Navigating life presents challenges to all, but for people with CF these challenges are heightened and complex. In this paper we highlight the concerns and life moments that impact people with CF, and events that the CF team should aim to support, including the challenges around having a family. People with CF and their care teams must embrace the updated standards outlined in these four papers to enjoy the full potential for a healthier life.</p

Standards for the care of people with cystic fibrosis; establishing and maintaining health.

This is the second in a series of four papers updating the European Cystic Fibrosis Society (ECFS) standards for the care of people with CF. This paper focuses on establishing and maintaining health. The guidance is produced using an evidence-based framework and with wide stakeholder engagement, including people from the CF community. Authors provided a narrative description of their topic and statements, which were more directive. These statements were reviewed by a Delphi exercise, achieving good levels of agreement from a wide group for all statements. This guidance reinforces the importance of a multi-disciplinary CF team, but also describes developing models of care including virtual consultations. The framework for health is reinforced, including the need for a physically active lifestyle and the strict avoidance of all recreational inhalations, including e-cigarettes. Progress with cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy is reviewed, including emerging adverse events and advice for dose reduction and interruption. This paper contains guidance that is pertinent to all people with CF regardless of age and eligibility for and access to modulator therapy

Standards for the care of people with cystic fibrosis (CF); recognising and addressing CF health issues.

This is the third in a series of four papers updating the European Cystic Fibrosis Society (ECFS) standards for the care of people with CF. This paper focuses on recognising and addressing CF health issues. The guidance was produced with wide stakeholder engagement, including people from the CF community, using an evidence-based framework. Authors contributed sections, and summary statements which were reviewed by a Delphi consultation. Monitoring and treating airway infection, inflammation and pulmonary exacerbations remains important, despite the widespread availability of CFTR modulators and their accompanying health improvements. Extrapulmonary CF-specific health issues persist, such as diabetes, liver disease, bone disease, stones and other renal issues, and intestinal obstruction. These health issues require multidisciplinary care with input from the relevant specialists. Cancer is more common in people with CF compared to the general population, and requires regular screening. The CF life journey requires mental and emotional adaptation to psychosocial and physical challenges, with support from the CF team and the CF psychologist. This is particularly important when life gets challenging, with disease progression requiring increased treatments, breathing support and potentially transplantation. Planning for end of life remains a necessary aspect of care and should be discussed openly, honestly, with sensitivity and compassion for the person with CF and their family. CF teams should proactively recognise and address CF-specific health issues, and support mental and emotional wellbeing while accompanying people with CF and their families on their life journey

Wine microbiome : A dynamic world of microbial interactions

International audienceMost fermented products are generated by a mixture of microbes. These microbial consortia perform various biological activities responsible for the nutritional, hygienic, and aromatic qualities of the product. Wine is no exception. Substantial yeast and bacterial biodiversity is observed on grapes, and in both must and wine. The diverse microorganisms present interact throughout the winemaking process. The interactions modulate the hygienic and sensorial properties of the wine. Many studies have been conducted to elucidate the nature of these interactions, with the aim of establishing better control of the two fermentations occurring during wine processing. However, wine is a very complex medium making such studies difficult. In this review, we present the current state of research on microbial interactions in wines. We consider the different kinds of interactions between different microorganisms together with the consequences of these interactions. We underline the major challenges to obtaining a better understanding of how microbes interact. Finally, strategies and methodologies that may help unravel microbe interactions in wine are suggested