Description
Caches leak information through timing measurements and so-called side-channel attacks. Several primitives exist with different requirements and trade-offs. Flush+Flush is a stealthy and fast cache attack primitive that uses the timing of the clflush instruction depending on the presence of a line in the cache. However, the CPU interconnect plays a bigger role than thought in these timings, and therefore in the error rate of Flush+Flush.
In this paper, we show that a naive implementation that does not take into account the topology of the interconnect yields very important error rates, especially on modern CPUs as the number of cores increases. We, therefore, reverse-engineer this topology and revisit the calibration phase of Flush+Flush for different attacker models to determine the correct threshold for clflush hits and misses. We evaluate that our method yields noiseless side-channel attacks by attacking the AES T-tables implementation of OpenSSL, and by building a covert channel. We obtain a maximal capacity of 3.15 Mbit/s with our improved method, compared to 1.4 Mbit/s with a naive implementation of Flush+Flush on an Intel Core i9-9900 CPU.
Prochains exposés
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HDL simulation for Masked Software Verification
Orateur : Quentin Meunier - Sorbonne Univ. Lip6
Masking is a countermeasure against Side-Channel Attacks (SCA) that aims to ensure that intermediate computations in an algorithm have secret-independent distributions through the use of random variables. This theoretically prevents SCAs, as power consumption is directly linked to the values manipulated by the program or hardware device. Designing a masking scheme is often non-trivial, and a[…]-
SemSecuElec
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Side-channel
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Étude, caractérisation et détection de verrouillage d'anneaux oscillants utilisés dans les générateurs de nombres aléatoires.
Orateur : Eloise Delolme - LabHC
Les générateurs de nombres aléatoires matériels basés sur des oscillateurs en anneau (RO-TRNGs) exploitent le jitter d’horloge comme source d’aléa afin de produire des séquences de bits aléatoires. Parmi ces architectures, le MURO-TRNG repose sur un modèle stochastique complexe qui suppose notamment l’indépendance des oscillateurs. Toutefois, dans la pratique, les oscillateurs en anneau sont[…]-
SemSecuElec
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TRNG
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Chamois: Formally verified compilation for optimisation and security
Orateur : David MONNIAUX - CNRS - Verimag
Embedded programs (including those on smart cards) are often developed in C and then compiled for the embedded processor. Sometimes they are modified by hand to incorporate countermeasures (fault attacks, etc.), but care must be taken to ensure that this does not disrupt normal program execution and that the countermeasure is actually adequate for blocking the attacks.In the process, it is[…]-
SemSecuElec
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Fault injection
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Formal methods
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Securing processor's microarchitecture against SCA in a post-quantum cryptography setting
Orateur : Vincent MIGLIORE - LAAS-CNRS
Hardware microarchitecture is a well-known source of side-channel leakages, providing a notable security reduction of standard cryptographic algorithms (e.g. AES) if not properly addressed by software or hardware. In this talk, we present new design approaches to harden processor's microarchitecture against power-based side-channel attacks, relying on configurable and cascadable building blocks[…]-
SemSecuElec
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Side-channel
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Micro-architectural vulnerabilities
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