Differential Fault Analysis Attacks Research Articles

Automatic Search of Meet-in-the-Middle Differential Fault Analysis on AES-like Ciphers

Fault analysis is a powerful technique to retrieve secret keys by exploiting side-channel information. Differential fault analysis (DFA) is one of the most powerful threats utilizing differential information between correct and faulty ciphertexts and can recover keys for symmetric-key cryptosystems efficiently. Since DFA usually targets the first or last few rounds of the block ciphers, some countermeasures against DFA only protect the first and last few rounds for efficiency. Therefore, to explore how many rounds DFA can affect is very important to make sure how many rounds to protect in practice. At CHES 2011, Derbez et al. proposed an improved DFA on AES based on MitM approach, which covers one more round than previous DFAs. To perform good (or optimal) MitM DFA on block ciphers, the good (or optimal) attack configurations should be identified, such as the location where the faults inject, the matching point with differential relationship, and the two independent computation paths where two independent subsets of the key are involved. In this paper, we formulate the essential ideas of the construction of the attack, and translate the problem of searching for the best MitM DFA into optimization problems under constraints in Mixed-Integer-Linear-Programming (MILP) models. With the models, we achieve more powerful and practical DFA attacks on SKINNY, CRAFT, QARMA, PRINCE, PRINCEv2, and MIDORI with faults injected in 1 to 9 earlier rounds than the best previous DFAs.

AFIA: ATPG-Guided Fault Injection Attack on Secure Logic Locking

The outsourcing of the design and manufacturing of integrated circuits has raised severe concerns about the piracy of Intellectual Properties and illegal overproduction. Logic locking has emerged as an obfuscation technique to protect outsourced chip designs, where the circuit netlist is locked and can only be functional once a secure key is programmed. However, Boolean Satisfiability-based attacks have shown to break logic locking, simultaneously motivating researchers to develop more secure countermeasures. In this paper, we present a novel fault injection-based attack to break any locking technique that relies on a stored secret key, and denote this attack as AFIA, ATPG-guided Fault Injection Attack. The proposed attack is based on sensitizing a key bit to the primary output while injecting faults at a few other key lines that block the propagation of the targeted key bit. AFIA is very effective in determining a key bit as there exists a stuck-at fault pattern that detects a stuck-at 1 (or stuck-at 0) fault at any key line. The average complexity of the number of injected faults for AFIA is linear with the key size \(\mathcal {K}\) and requires only \(\mathcal {K}\) test patterns to determine a secret key K. AFIA requires fewer injected faults to sensitize a bit to the primary output, compared to \(2\mathcal {K}-1\) faults for the differential fault analysis attack illustrated in our previous work.

Differential Fault Analysis on the Key Schedule of the LBlock Algorithm

In 2011,Wu and Zhang proposed a lightweight block cipher named LBlock, whose plaintext size and key size are 64 bits and 80 bits, respectively. As they said, LBlock can be efficiently implemented in constrained hardware environments, such as wireless sensor network. In this paper, we study the security of LBlock against the differential fault analysis (DFA) on its key scheduling. As far as we know, this is the first time the DFA on key schedule is used to analyze LBlock. More concretely, our DFA attack adopts the random nibble fault model. When the fault is injected in the subkeys in round 30 and 31, most bits of the subkeys in round 31 and 32 can be recovered, which leads to the leakage of the bits of master secret key according to the key scheduling. A quantitative analysis of the input-output differentials of the S-boxes in LBlock shows that our attack reduces the searching space of master key from 2⁸⁰ to 2²³. Then the exhaustive search of all 2²³ possible keys can uniquely determine the true master key. Finally, we also implement LBlock and simulate the DFA on its key scheduling. The experiment results show that our attack is effective.

QuadSeal: Quadruple Balancing to Mitigate Power Analysis Attacks with Variability Effects and Electromagnetic Fault Injection Attacks

Side channel analysis attacks employ the emanated side channel information to deduce the secret keys from cryptographic implementations by analyzing the power traces during execution or scrutinizing faulty outputs. To be effective, a countermeasure must remove or conceal as many as possible side channels. However, many of the countermeasures against side channel attacks are applied independently. In this article, the authors present a novel countermeasure (referred to as QuadSeal ) against Power Analysis Attacks and Electromagentic Fault Injection Attacks (FIAs), which is an extension of the work proposed in Reference [27]. The proposed solution relies on algorithmically balancing both Hamming distances and Hamming weights (where the bit transitions on the registers and gates are balanced, and the total number of 1s and 0s are balanced) by the use of four identical circuits with differing inputs and modified SubByte tables. By randomly rotating the four encryptions, the system is protected against variations, path imbalances, and aging effects. After generating the ciphertext, the output of each circuit is compared against each other to detect any fault injections or to correct the faulty ciphertext to gain reliability. The proposed countermeasure allows components to be switched off to save power or to run four executions in parallel for high performance when resistance against power analysis attacks is not of high priority, which is not available with the existing countermeasures (except software based where source code can be changed). The proposed countermeasure is implemented for Advanced Encryption Standard (AES) and tested against Correlation Power Analysis and Mutual Information Attacks attacks (for up to a million traces), and none of the secret keys was found even after one million power traces (the unprotected AES circuit is vulnerable for power analysis attacks within 5,000 power traces). A detection circuit (referred to as C-FIA circuit) is operated using the algorithmic redundancy presented in four circuits of QuadSeal to mitigate Electromagnetic Fault Injection Attacks. Using Synopsys PrimeTime, we measured the power dissipation of QuadSeal registers and XOR gates to test the effectiveness of Quadruple balancing methodology. We tested the QuadSeal countermeasure with C-FIA circuit against Differential Fault Analysis Attacks up to one million traces; no bytes of the secret key were found. This is the smallest known circuit that is capable of withstanding power-based side channel attacks when electromagnetic injection attack resistance, process variations, path imbalances, and aging effects are considered.

Fault Attack on SKINNY Cipher

SKINNY is a family of tweakable lightweight block ciphers, proposed in CRYPTO 2016. The proposal of SKINNY describes two block size variants of 64 and 128 bits as well as three options for tweakey. In this paper, we present fault attacks (FA) on all SKINNY variants. In the first part of the paper, we propose differential fault analysis (DFA) attacks on SKINNY variants keeping the tweak fixed. The attack model of tweakable block ciphers allows the access and full control of the tweak by the attacker. Respecting this attack model, we assume a fixed tweak for the attack window. With this assumption, extraction of the master key of SKINNY requires about 10 random nibble fault injections on average for 64-bit versions of the cipher, whereas the 128-bit versions require roughly 21 byte-fault-injections. In the later part of this work, we relax this assumption and perform fault attacks under known but randomly varying tweaks. It is found that pairs of bit faults at the input and output of the S-Boxes allow complete key recovery under random tweak. Moreover, explicit access to ciphertexts is not required in our attack, and key recovery is possible only by knowing if the ciphertext is correct or faulty. This property of the attack allows key recovery even at the presence of simple redundancy-based FA countermeasures. Both the DFA and paired fault-based attacks were validated through extensive simulation. To the best of authors’ knowledge, these are the first instances of FAs reported on SKINNY tweakable block cipher family.

An automated framework for exploitable fault identification in block ciphers

Faults have been practically exploited on several occasions to compromise the security of mathematically robust cryptosystems at the implementation level. However, not every possible fault within a cryptosystem is exploitable for fault attack. Comprehensive knowledge about the exploitable part of the fault space is thus imperative for both the algorithm designer and the implementer in order to invent precise countermeasures and robust algorithms. This paper addresses the problem of exploitable fault characterization in the context of differential fault analysis attacks on block ciphers. A generic and automated framework has been proposed, which can determine the exploitability of fault instances from any given block cipher in a fast and scalable manner. Such automation is supposed to work as the core engine for analysing the fault spaces, which are, in general, difficult to characterize with manual effort due to their formidable size and the complex structural features of the ciphers. Our framework significantly outperforms another recently proposed one as reported by Khanna et.al. (in: DAC, ACM, pp. 1–6, 2017), in terms of attack class coverage and automation effort. Evaluation of the framework on AES and PRESENT establishes the efficacy of it as a potential tool for exploitable fault analysis.

Fully Automated Differential Fault Analysis on Software Implementations of Block Ciphers

Differential Fault Analysis (DFA) is considered as the most popular fault analysis method. While there are techniques that provide a fault analysis automation on the cipher level to some degree, it can be shown that when it comes to software implementations, there are new vulnerabilities, which cannot be found by observing the cipher design specification.This work bridges the gap by providing a fully automated way to carry out DFA on assembly implementations of symmetric block ciphers. We use a customized data flow graph to represent the program and develop a novel fault analysis methodology to capture the program behavior under faults. We establish an effective description of DFA as constraints that are passed to an SMT solver. We create a tool that takes assembly code as input, analyzes the dependencies among instructions, automatically attacks vulnerable instructions using SMT solver and outputs the attack details that recover the last round key (and possibly the earlier keys). We support our design with evaluations on lightweight ciphers SIMON, SPECK, and PRIDE, and a current NIST standard, AES. By automated assembly analysis, we were able to find new efficient DFA attacks on SPECK and PRIDE, exploiting implementation specific vulnerabilities, and previously published DFA on SIMON and AES. Moreover, we present a novel DFA on multiplication operation that has never been shown for symmetric block ciphers before. Our experimental evaluation also shows reasonable execution times that are scalable to current cipher designs and can easily outclass the manual analysis. Moreover, we present a method to check the countermeasure-protected implementations in a way that helps implementers to decide how many rounds should be protected. We note that this is the first work that automatically carries out DFA on cipher implementations without any plaintext or ciphertext information and therefore, can be generally applied to any input data to the cipher.

CRAFT: Lightweight Tweakable Block Cipher with Efficient Protection Against DFA Attacks

Traditionally, countermeasures against physical attacks are integrated into the implementation of cryptographic primitives after the algorithms have been designed for achieving a certain level of cryptanalytic security. This picture has been changed by the introduction of PICARO, ZORRO, and FIDES, where efficient protection against Side-Channel Analysis (SCA) attacks has been considered in their design. In this work we present the tweakable block cipher CRAFT: the efficient protection of its implementations against Differential Fault Analysis (DFA) attacks has been one of the main design criteria, while we provide strong bounds for its security in the related-tweak model. Considering the area footprint of round-based hardware implementations, CRAFT outperforms the other lightweight ciphers with the same state and key size. This holds not only for unprotected implementations but also when fault-detection facilities, side-channel protection, and their combination are integrated into the implementation. In addition to supporting a 64-bit tweak, CRAFT has the additional property that the circuit realizing the encryption can support the decryption functionality as well with very little area overhead.

CRAFT: Lightweight Tweakable Block Cipher with Efficient Protection Against DFA Attacks

Traditionally, countermeasures against physical attacks are integrated into the implementation of cryptographic primitives after the algorithms have been designed for achieving a certain level of cryptanalytic security. This picture has been changed by the introduction of PICARO, ZORRO, and FIDES, where efficient protection against Side-Channel Analysis (SCA) attacks has been considered in their design. In this work we present the tweakable block cipher CRAFT: the efficient protection of its implementations against Differential Fault Analysis (DFA) attacks has been one of the main design criteria, while we provide strong bounds for its security in the related-tweak model. Considering the area footprint of round-based hardware implementations, CRAFT outperforms the other lightweight ciphers with the same state and key size. This holds not only for unprotected implementations but also when fault-detection facilities, side-channel protection, and their combination are integrated into the implementation. In addition to supporting a 64-bit tweak, CRAFT has the additional property that the circuit realizing the encryption can support the decryption functionality as well with very little area overhead.

White-Box Cryptography: Don’t Forget About Grey-Box Attacks

Despite the fact that all current scientific white-box approaches of standardized cryptographic primitives have been publicly broken, these attacks require knowledge of the internal data representation used by the implementation. In practice, the level of implementation knowledge required is only attainable through significant reverse-engineering efforts. In this paper, we describe new approaches to assess the security of white-box implementations which require neither knowledge about the look-up tables used nor expensive reverse-engineering efforts. We introduce the differential computation analysis (DCA) attack which is the software counterpart of the differential power analysis attack as applied by the cryptographic hardware community. Similarly, the differential fault analysis (DFA) attack is the software counterpart of fault injection attacks on cryptographic hardware. For DCA, we developed plugins to widely available dynamic binary instrumentation (DBI) frameworks to produce software execution traces which contain information about the memory addresses being accessed. For the DFA attack, we developed modified emulators and plugins for DBI frameworks that allow injecting faults at selected moments within the execution of the encryption or decryption process as well as a framework to automate static fault injection. To illustrate the effectiveness, we show how DCA and DFA can extract the secret key from numerous publicly available non-commercial white-box implementations of standardized cryptographic algorithms. These approaches allow one to extract the secret key material from white-box implementations significantly faster and without specific knowledge of the white-box design in an automated or semi-automated manner.

FPGAhammer: Remote Voltage Fault Attacks on Shared FPGAs, suitable for DFA on AES

With each new technology generation, the available resources on Field Programmable Gate Arrays increase, making them more attractive for partial access from multiple users. They get increasingly adopted as accelerators in various application domains, embedded in shared Systems on Chip or remote cloud services. Thus, some recent works have already explored Denial-of-Service and side-channel attacks, where an FPGA fabric is shared among multiple users. In this work, we show how fault attacks can be launched within an FPGA, through software-provided bitstreams alone. Excessive voltage drops can be generated from legitimate logic mapped into the FPGA to cause timing faults, reaching from spatially and logically isolated partitions of one to another user of the FPGA fabric. To cause this voltage drop, we first show how specific patterns to activate Ring Oscillators can cause timing failures in simple test designs on various FPGA boards. Subsequently, we analyze and adapt an existing fault model for the Advanced Encryption Standard to match the accuracy of our fault attack. In the same multi-user scenario, we show as a proof-of-concept how a successful Differential Fault Analysis attack on an AES module can be launched. We perform experiments on three FPGA boards of the same model and confirm that the attack adapts to all systems and is successful under process variation, but with different susceptibility to faults. The paper is concluded by validating the attack on another platform, and analyzing the vulnerability based on a timing analysis, proving the applicability to different devices.

Towards Optimized DFA Attacks on AES under Multibyte Random Fault Model

Differential Fault Analysis (DFA) is one of the most practical methods to recover the secret keys from real cryptographic devices. In particular, DFA on Advanced Encryption Standard (AES) has been massively researched for many years for both single-byte and multibyte fault model. For AES, the first proposed DFA attack requires 6 pairs of ciphertexts to identify the secret key under multibyte fault model. Until now, the most efficient DFA under multibyte fault model proposed in 2017 can complete most of the attacks within 3 pairs of ciphertexts. However, we note that the attack is not fully optimized since no clear optimization goal was set. In this work, we introduce two optimization goals as the fewest ciphertext pairs and the least computational complexity. For these goals, we manage to figure out the corresponding optimized key recovery strategies, which further increase the efficiency of DFA attacks on AES. A more accurate security assessment of AES can be completed based on our study of DFA attacks on AES. Considering the variations of fault distribution, the improvement to the attack has been analyzed and verified.

Improving DFA attacks on AES with unknown and random faults

Differential fault analysis (DFA) aiming at the advanced encryption standard (AES) hardware implementations has become a widely research topic. Unlike theoretical model, in real attack scenarios, popular and practical fault injection methods like supply voltage variation will introduce faults with random locations, unknown values and multibyte. For analyzing this kind of faults, the previous fault model needed six pairs of correct and faulty ciphertexts to recover the secret round-key. In this paper, on the premise of accuracy, a more efficient DFA attack with unknown and random faults is proposed. We introduce the concept of theoretical candidate number in the fault analysis. Based on this concept, the correct round-key can be identified in advance, so the proposed attack method can always use the least pairs of correct and faulty ciphertexts to accomplish the DFA attacks. To further support our opinion, random fault attacks based on voltage violation were taken on an FPGA board. Experiment results showed that about 97.3% of the attacks can be completed within 3 pairs of correct and faulty ciphertexts. Moreover, on average only 2.17 pairs of correct and faulty ciphertexts were needed to find out the correct round-key, showing significant advantage of efficiency compared with previous fault models. On the other hand, less amount of computation in the analyses can be realized with a high probability with our model, which also effectively improves the time efficiency in DFA attacks with unknown and random faults.

A Silicon-Level Countermeasure Against Fault Sensitivity Analysis and Its Evaluation

In this paper, we present an efficient countermeasure against fault sensitivity analysis (FSA) based on configurable delay blocks (CDBs). FSA is a new type of fault attack, which exploits the relationship between fault sensitivity (FS) and secret information. Previous studies reported that it could break cryptographic modules equipped with conventional countermeasures against differential fault analysis (DFA), such as redundancy calculation, masked and–or, and wave dynamic differential logic. The proposed countermeasure can thwart both DFA and FSA attacks based on setup time violation faults. The proposed ideas are to use a CDB as a time base for detection and to combine the technique with Li’s countermeasure concept that removes the dependency between FSs and secret data. The postmanufacture configuration of the CDBs allows minimization of the overhead in operating frequency that comes from manufacture variability. In this paper, we also present an implementation of the proposed countermeasure in application-specified integrated circuit, and describe its configuration method. We then investigate the hardware overhead of the proposed countermeasure for an advanced encryption standard processor and demonstrate its validity through an experiment.

Construction of RSBFs with improved cryptographic properties to resist differential fault attack on grain family of stream ciphers

In recent literature, the differential fault analysis (DFA) on Grain family of stream ciphers has been shown to exploit the low algebraic degree of the derivative of the nonlinear combining function h of the stream cipher, h(x) ? h(x ? ?). The low algebraic degree allows the DFA adversary to create a linearly independent system of equations generated from the faulty and fault-free keystreams and use these equations to extract the initial state of the NFSR and LFSR stages in the stream cipher. In this paper, we propose a construction scheme for rotation symmetric Boolean functions (RSBFs) h(x) along with an orbit-tuple flip based iterative hill-climbing based construction algorithm for balanced RSBFs with high nonlinearity, low absolute indicator value of global avalanche characteristics (GAC), and high algebraic degree of h(x) ? h(x ? ?). The construction algorithm is scalable for higher input variables like n = 9,10,11 as shown in the paper. We find some interesting autocorrelation spectra and Walsh spectra properties for the class of RSBFs and then use them in the construction of RSBFs with improved cryptographic properties. We present the cryptographic properties of the RSBFs constructed for high input variables which can be used to make DFA attack harder using the existing techniques.

Information-Theoretic Approach to Optimal Differential Fault Analysis

This paper presents a comprehensive analysis of differential fault analysis (DFA) attacks on the Advanced Encryption Standard (AES) from an information-theoretic perspective. Injecting faults into cryptosystems is categorized as an active at tack where attackers induce an error in operations to retrieve the secret internal information, e.g., the secret key of ciphers. Here, we consider DFA attacks as equivalent to a special kind of passive attack where attackers can obtain leaked information without measurement noise. The DFA attacks are regarded as a conversion process from the leaked information to the secret key. Each fault model defines an upper bound for the amount of leaked information. The optimal DFA attacks should be able to exploit fully the leaked information in order to retrieve the secret key with a practical level of complexity. This paper discusses a new DFA methodology to achieve the optimal DFA attack by deriving the amount of the leaked information for various fault models from an information-theoretic perspective. We review several previous DFA at tacks on AES variants to check the optimality of their attacks. We also propose improved DFA attacks on AES-192 and AES-256 that reach the theoretical limits.

Differential Fault Analysis on SMS4 using a single fault

Differential Fault Analysis (DFA) attack is a powerful cryptanalytic technique that could be used to retrieve the secret key by exploiting computational errors in the encryption (decryption) procedure. In this paper, we propose a new DFA attack on SMS4 using a single fault. We show that if a random byte fault is induced into either the second, third, or fourth word register at the input of the 28-th round, the 128-bit key could be recovered with an exhaustive search of 22.11 bits on average. The proposed attack makes use of the characteristic of the cipher's structure and its round function. Furthermore, it can be tailored to any block cipher employing a similar structure and an SPN-style round function as that of SMS4.