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.
Next sessions
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Protection des processeurs modernes face à la vulnérabilité Spectre
Speaker : Herinomena ANDRIANATREHINA - Inria
Dans la quête permanente d'une puissance de calcul plus rapide, les processeurs modernes utilisent des techniques permettant d'exploiter au maximum leurs ressources. Parmi ces techniques, l'exécution spéculative tente de prédire le résultat des instructions dont l'issue n'est pas encore connue, mais dont dépend la suite du programme. Cela permet au processeur d'éviter d'être inactif. Cependant,[…]-
SemSecuElec
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Micro-architectural vulnerabilities
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Post-Quantum Cryptography Accelerated by a Superscalar RISC-V Processor
Speaker : Côme Allart - Inria
Two major changes are currently taking place in the embedded processor ecosystem: open source with the RISC-V instruction set, which could replace the ARM one, and post-quantum cryptography (PQC), which could replace classic asymmetric cryptography algorithms to resist quantum computers.In this context, this thesis investigates the improvement of embedded processor performance, generally for[…]-
SemSecuElec
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Implementation of cryptographic algorithm
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Chamois: Formally verified compilation for optimisation and security
Speaker : 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
Speaker : 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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