Deux métaplasies osseuses aux formes curieuses

Lombard Charles, Belgarric J., Roset J. Deux métaplasies osseuses aux formes curieuses. In: Bulletin de l'Académie Vétérinaire de France tome 116 n°4, 1963. pp. 167-169

Analysis and Improvements of the DPA Contest v4 Implementation

International audienc

Security Evaluation Against Side-Channel Analysis at Compilation Time

International audienceMasking countermeasure is implemented to thwart side-channel attacks. The maturity of high-order masking schemes has reached the level where the concepts are sound and proven. For instance, Rivain and Prouff proposed a full-fledged AES at CHES 2010. Some non-trivial fixes regarding refresh functions were needed though. Now, industry is adopting such solutions, and for the sake of both quality and certification requirements , masked cryptographic code shall be checked for correctness using the same model as that of the the theoretical protection rationale (for instance the probing leakage model). Seminal work has been initiated by Barthe et al. at EUROCRYPT 2015 for automated verification at higher orders on concrete implementations. In this paper, we build on this work to actually perform verification from within a compiler, so as to enable timely feedback to the developer. Precisely , our methodology enables to provide the actual security order of the code at the intermediate representation (IR) level, thereby identifying possible flaws (owing either to source code errors or to compiler optimizations). Second, our methodology allows for an exploitability analysis of the analysed IR code. In this respect, we formally handle all the symbolic expressions in the static single assignment (SSA) representation to build the optimal distinguisher function. This enables to evaluate the most powerful attack, which is not only function of the masking order d, but also on the number of leaking samples and of the expressions (e.g., linear vs non-linear leakages). This scheme allows to evaluate the correctness of a masked cryptographic code, and also its actual security in terms of number of traces in a given deployment context

Déjà Vu : Side-Channel Analysis of Mozilla's NSS

Recent work on Side Channel Analysis (SCA) targets old, well-known vulnerabilities, even previously exploited, reported, and patched in high-profile cryptography libraries. Nevertheless, researchers continue to find and exploit the same vulnerabilities in old and new products, highlighting a big issue among vendors: effectively tracking and fixing security vulnerabilities when disclosure is not done directly to them. In this work, we present another instance of this issue by performing the first library-wide SCA security evaluation of Mozilla's NSS security library. We use a combination of two independently-developed SCA security frameworks to identify and test security vulnerabilities. Our evaluation uncovers several new vulnerabilities in NSS affecting DSA, ECDSA, and RSA cryptosystems. We exploit said vulnerabilities and implement key recovery attacks using signals - -extracted through different techniques such as timing, microarchitecture, and EM - -and improved lattice methods.publishedVersionPeer reviewe

LadderLeak: Breaking ECDSA with Less than One Bit of Nonce Leakage

Although it is one of the most popular signature schemes today, ECDSA presents a number of implementation pitfalls, in particular due to the very sensitive nature of the random value (known as the nonce) generated as part of the signing algorithm. It is known that any small amount of nonce exposure or nonce bias can in principle lead to a full key recovery: the key recovery is then a particular instance of Boneh and Venkatesan’s hidden number problem (HNP). That observation has been practically exploited in many attacks in the literature, taking advantage of implementation defects or side-channel vulnerabilities in various concrete ECDSA implementations. However, most of the attacks so far have relied on at least 2 bits of nonce bias (except for the special case of curves at the 80-bit security level, for which attacks against 1-bit biases are known, albeit with a very high number of required signatures). In this paper, we uncover LadderLeak, a novel class of sidechannel vulnerabilities in implementations of the Montgomery ladder used in ECDSA scalar multiplication. The vulnerability is in particular present in several recent versions of OpenSSL. However, it leaks less than 1 bit of information about the nonce, in the sense that it reveals the most significant bit of the nonce, but with probability < 1. Exploiting such a mild leakage would be intractable using techniques present in the literature so far. However, we present a number of theoretical improvements of the Fourier analysis approach to solving the HNP (an approach originally due to Bleichenbacher), and this lets us practically break LadderLeak-vulnerable ECDSA implementations instantiated over the sect163r1 and NIST P-192 elliptic curves. In so doing, we achieve several significant computational records in practical attacks against the HNP.Diego F. Aranha, Felipe Rodrigues Novaes, Akira Takahashi, Mehdi Tibouchi, Yuval Yaro