Fault Template Attacks on Block Ciphers Exploiting Fault Propagation

Abstract

Fault attacks (FA) are one of the potent practical threats to modern cryptographic implementations. Over the years the FA techniques have evolved, gradually moving towards the exploitation of devicecentric properties of the faults. In this paper, we exploit the fact that activation and propagation of a fault through a given combinational circuit (i.e., observability of a fault) is data-dependent. Next, we show that this property of combinational circuits leads to powerful Fault Template Attacks (FTA), even for implementations having dedicated protections against both power and fault-based vulnerabilities. The attacks found in this work are applicable even if the fault injection is made at the middle rounds of a block cipher, which are out of reach for most of the other existing fault analysis strategies. Quite evidently, they also work for a known-plaintext scenario. Moreover, the middle round attacks are entirely blind in the sense that no access to the ciphertexts (correct/faulty) or plaintexts are required. The adversary is only assumed to have the power of repeating an unknown plaintext several times. Practical validation over a hardware implementation of SCA-FA protected PRESENT, and simulated evaluation on a public software implementation of protected AES prove the efficacy of the proposed attacks.

Multi-source Fault Injection Detection Using Machine Learning and Sensor Fusion

“…In [20], the authors provide a ML-assisted technique to explore and characterize the fault attack space and use the knowledge of a known fault attack on a cipher in understanding new attack instances. Regarding detection of fault attacks, a recent work [19] is presented that evaluates fault induced leakages from noncryptographic peripheral components of a security module, targeting cipher implementations, using a Deep Neural Network (DNN) test. From the defensive side, while most fault analyses are based on the characterized faults from known attacks (like [6]), our work is based on a completely different approach of online identification of attacks using real-time sensors.…”

Faultless to a fault?

“…We consider a template building phase [20] wherein the faults are targeted at the registers storing the masks 3 0 and 1 2 . In order to build the templates for obtaining the various bits of a nibble of the PRESENT cipher we consider the following faults:…”

“…This often restricts the attacks to the starting or finishing rounds of the block cipher. Recently, the first profiled fault attack, called Fault Template Attack (FTA) was proposed [20]. FTA is based on fault propagation characteristic which is dependent on the inputs to a Boolean circuit and is defined in a fault template collected in a profiling phase.…”

How Practical Are Fault Injection Attacks, Really?

“…Nowadays, 25 years after these attacks were published, this area has become one of the major areas in hardware security, alongside the passive side-channel attacks (SCA) [3]. Many analysis methods have been published to date, to mention the most prominent ones apart from the DFA: statistical ineffective fault analysis (SIFA) [4], persistent fault attack (PFA) [5], fault sensitivity analysis (FSA) [6], fault template attacks (FTA) [7], and FIA combined with SCA [8]. Aside from targeting cryptography, fault attacks have been used for bypassing checking routines [9], [10], and even faulting neural network…”