Efficient and Provable White-Box Primitives

International audienceIn recent years there have been several attempts to build white-box block ciphers whose implementations aim to be incompress-ible. This includes the weak white-box ASASA construction by Bouil-laguet, Biryukov and Khovratovich from Asiacrypt 2014, and the recent space-hard construction by Bogdanov and Isobe from CCS 2015. In this article we propose the first constructions aiming at the same goal while offering provable security guarantees. Moreover we propose concrete instantiations of our constructions, which prove to be quite efficient and competitive with prior work. Thus provable security comes with a surprisingly low overhead

Actuación en zonas antiguas de pueblos y ciudades

Actuación en zonas antiguas de pueblos y ciudade

Detecting Test Clones with Static Analysis

Large-scale software systems often have correspondingly complicated test suites, which are diffi cult for developers to construct and maintain. As systems evolve, engineers must update their test suite along with changes in the source code. Tests created by duplicating and modifying previously existing tests (clones) can complicate this task. Several testing technologies have been proposed to mitigate cloning in tests, including parametrized unit tests and test theories. However, detecting opportunities to improve existing test suites is labour intensive. This thesis presents a novel technique for etecting similar tests based on type hierarchies and method calls in test code. Using this technique, we can track variable history and detect test clones based on test assertion similarity. The thesis further includes results from our empirical study of 10 benchmark systems using this technique which suggest that test clone detection by our technique will aid test de-duplication eff orts in industrial systems

Formal Verification of Side-channel Countermeasures via Elementary Circuit Transformations

We describe a technique to formally verify the security of masked implementations against side-channel attacks, based on elementary circuit transforms. We describe two complementary approaches: a generic approach for the formal verification of any circuit, but for small attack orders only, and a specialized approach for the verification of specific circuits, but at any order. We also show how to generate security proofs automatically, for simple circuits. We describe the implementation of CheckMasks, a formal verification tool for side-channel countermeasures. Using this tool, we formally verify the security of the Rivain-Prouff countermeasure for AES, and also the recent Boolean to arithmetic conversion algorithm from CHES 2017

Childhood leukaemia and population movements in France, 1990–2003

In a national study, we investigated the incidence of childhood leukaemia (CL) over a 14-year period in France in relation to several measures based on the proportion of individuals who changed address between the last two national censuses. A positive association was found with the proportion of migrants who came from a distant place. The further the migrants came, the higher was the incidence of leukaemia, particularly among children aged 0–4 years in ‘isolated' communes at the time of diagnosis (RR=1.4, 95% CI: 1.1,1.8 in the highest category of migration distance). Although the role of the population density was less obvious, a more marked association was found above a certain threshold. No association with the proportion of commuters was observed

On lattice profile of the elliptic curve linear congruential generators

Lattice tests are quality measures for assessing the intrinsic structure of pseudorandom number generators. Recently a new lattice test has been introduced by Niederreiter and Winterhof. In this paper, we present a general inequality that is satisfied by any periodic sequence. Then, we analyze the behavior of the linear congruential generators on elliptic curves (EC-LCG) under this new lattice test and prove that the EC-LCG passes it up to very high dimensions. We also use a result of Brandstätter and Winterhof on the linear complexity profile related to the correlation measure of order k to present lower bounds on the linear complexity profile of some binary sequences derived from the EC-LCG

Theory and Practice of a Leakage Resilient Masking Scheme

A recent trend in cryptography is to formally prove the leakage resilience of cryptographic implementations - that is, one formally shows that a scheme remains provably secure even in the presence of side channel leakage. Although many of the proposed schemes are secure in a surprisingly strong model, most of them are unfortunately rather inefficient and come without practical security evaluations nor implementation attempts. In this work, we take a further step towards closing the gap between theoretical leakage resilient cryptography and more practice-oriented research. In particular, we show that masking countermeasures based on the inner product do not only exhibit strong theoretical leakage resilience, but moreover provide better practical security or efficiency than earlier masking countermeasures. We demonstrate the feasibility of inner product masking by giving a secured implementation of the AES for an 8-bit processor. © International Association for Cryptologic Research 2012.status: publishe