International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Benedikt Gierlichs

Publications

Year
Venue
Title
2022
TCHES
Semi-Automatic Locating of Cryptographic Operations in Side-Channel Traces
Locating a cryptographic operation in a side-channel trace, i.e. finding out where it is in the time domain, without having a template, can be a tedious task even for unprotected implementations. The sheer amount of data can be overwhelming. In a simple call to OpenSSL for AES-128 ECB encryption of a single data block, only 0.00028% of the trace relate to the actual AES-128 encryption. The rest is overhead. We introduce the (to our best knowledge) first method to locate a cryptographic operation in a side-channel trace in a largely automated fashion. The method exploits meta information about the cryptographic operation and requires an estimate of its implementation's execution time. The method lends itself to parallelization and our implementation in a tool greatly benefits from GPU acceleration. The tool can be used offline for trace segmentation and for generating a template which can then be used online in real-time waveform-matching based triggering systems for trace acquisition or fault injection. We evaluate it in six scenarios involving hardware and software implementations of different cryptographic operations executed on diverse platforms. Two of these scenarios cover realistic protocol level use-cases and demonstrate the real-world applicability of our tool in scenarios where classical leakage-detection techniques would not work. The results highlight the usefulness of the tool because it reliably and efficiently automates the task and therefore frees up time of the analyst. The method does not work on traces of implementations protected by effective time randomization countermeasures, e.g., random delays and unstable clock frequency, but is not affected by masking, shuffling and similar countermeasures.
2021
TCHES
My other car is your car: compromising the Tesla Model X keyless entry system 📺
Lennert Wouters Benedikt Gierlichs Bart Preneel
This paper documents a practical security evaluation of the Tesla Model X keyless entry system. In contrast to other works, the keyless entry system analysed in this paper employs secure symmetric-key and public-key cryptographic primitives implemented by a Common Criteria certified Secure Element. We document the internal workings of this system, covering the key fob, the body control module and the pairing protocol. Additionally, we detail our reverse engineering techniques and document several security issues. The identified issues in the key fob firmware update mechanism and the key fob pairing protocol allow us to bypass all of the cryptographic security measures put in place. To demonstrate the practical impact of our research we develop a fully remote Proof-of-Concept attack that allows to gain access to the vehicle’s interior in a matter of minutes and pair a modified key fob, allowing to drive off. Our attack is not a relay attack, as our new key fob allows us to start the car anytime anywhere. Finally, we provide an analysis of the update performed by Tesla to mitigate our findings. Our work highlights how the increased complexity and connectivity of vehicular systems can result in a larger and easier to exploit attack surface.
2020
TCHES
Dismantling DST80-based Immobiliser Systems 📺
Car manufacturers deploy vehicle immobiliser systems in order to prevent car theft. However, in many cases the underlying cryptographic primitives used to authenticate a transponder are proprietary in nature and thus not open to public scrutiny. In this paper we publish the proprietary Texas Instruments DST80 cipher used in immobilisers of several manufacturers. Additionally, we expose serious flaws in immobiliser systems of major car manufacturers such as Toyota, Kia, Hyundai and Tesla. Specifically, by voltage glitching the firmware protection mechanisms of the microcontroller, we extracted the firmware from several immobiliser ECUs and reverse engineered the key diversification schemes employed within. We discovered that Kia and Hyundai immobiliser keys have only three bytes of entropy and that Toyota only relies on publicly readable information such as the transponder serial number and three constants to generate cryptographic keys. Furthermore, we present several practical attacks which can lead to recovering the full 80-bit cryptographic key in a matter of seconds or permanently disabling the transponder. Finally, even without key management or configuration issues, we demonstrate how an attacker can recover the cryptographic key using a profiled side-channel attack. We target the key loading procedure and investigate the practical applicability in the context of portability. Our work once again highlights the issues automotive vendors face in implementing cryptography securely.
2020
TCHES
Revisiting a Methodology for Efficient CNN Architectures in Profiling Attacks 📺
This work provides a critical review of the paper by Zaid et al. titled “Methodology for Efficient CNN Architectures in Profiling attacks”, which was published in TCHES Volume 2020, Issue 1. This work studies the design of CNN networks to perform side-channel analysis of multiple implementations of the AES for embedded devices. Based on the authors’ code and public data sets, we were able to cross-check their results and perform a thorough analysis. We correct multiple misconceptions by carefully inspecting different elements of the model architectures proposed by Zaid et al. First, by providing a better understanding on the internal workings of these models, we can trivially reduce their number of parameters on average by 52%, while maintaining a similar performance. Second, we demonstrate that the convolutional filter’s size is not strictly related to the amount of misalignment in the traces. Third, we show that increasing the filter size and the number of convolutions actually improves the performance of a network. Our work demonstrates once again that reproducibility and review are important pillars of academic research. Therefore, we provide the reader with an online Python notebook which allows to reproduce some of our experiments1 and additional example code is made available on Github.2
2019
TCHES
Fast, Furious and Insecure: Passive Keyless Entry and Start Systems in Modern Supercars 📺
The security of immobiliser and Remote Keyless Entry systems has been extensively studied over many years. Passive Keyless Entry and Start systems, which are currently deployed in luxury vehicles, have not received much attention besides relay attacks. In this work we fully reverse engineer a Passive Keyless Entry and Start system and perform a thorough analysis of its security.Our research reveals several security weaknesses. Specifically, we document the use of an inadequate proprietary cipher using 40-bit keys, the lack of mutual authentication in the challenge-response protocol, no firmware readout protection features enabled and the absence of security partitioning.In order to validate our findings, we implement a full proof of concept attack allowing us to clone a Tesla Model S key fob in a matter of seconds with low cost commercial off the shelf equipment. Our findings most likely apply to other manufacturers of luxury vehicles including McLaren, Karma and Triumph motorcycles as they all use the same system developed by Pektron.
2017
ASIACRYPT
2017
CHES
Fast Leakage Assessment
Oscar Reparaz Benedikt Gierlichs Ingrid Verbauwhede
We describe a fast technique for performing the computationally heavy part of leakage assessment, in any statistical moment (or other property) of the leakage samples distributions. The proposed technique outperforms by orders of magnitude the approach presented at CHES 2015 by Schneider and Moradi. We can carry out evaluations that before took 90 CPU-days in 4 CPU-hours (about a 500-fold speed-up). As a bonus, we can work with exact arithmetic, we can apply kernel-based density estimation methods, we can employ arbitrary pre-processing functions such as absolute value to power traces, and we can perform information-theoretic leakage assessment. Our trick is simple and elegant, and lends itself to an easy and compact implementation. We fit a prototype implementation in about 130 lines of C code.
2015
EUROCRYPT
2015
CRYPTO
2015
CHES
2014
ASIACRYPT
2012
CHES
2012
ASIACRYPT
2011
CHES
2011
JOFC
2010
ASIACRYPT
2009
CHES
2008
CHES
2008
CHES
2007
CHES
2006
CHES

Program Committees

CHES 2022
CHES 2021
CHES 2020
Eurocrypt 2020
CHES 2019
CHES 2018
CHES 2017
CHES 2016
CHES 2015
CHES 2014
CHES 2013
CHES 2012
CHES 2011