Improving and Evaluating Differential Fault Analysis on LED with Algebraic Techniques

Algebraic fault analysis (AFA), which combines algebraic cryptanalysis with fault attacks, has represented serious threats to the security of lightweight block ciphers. Inspired by an earlier framework for the analysis of side-channel attacks presented at EUROCRYPT 2009, a new generic framework is proposed to analyze and evaluate algebraic fault attacks on lightweight block ciphers. We interpret AFA at three levels: the target, the adversary, and the evaluator. We describe the capability of an adversary in four parts: the fault injector, the fault model describer, the cipher describer, and the machine solver. A formal fault model is provided to cover most of the current fault attacks. Different strategies of building optimal equation set are also provided to accelerate the solving process. At the evaluator level, we consider the approximate information metric and the actual security metric. These metrics can be used to guide adversaries, cipher designers, and industrial engineers. To verify the feasibility of the proposed framework, we make a comprehensive study of AFA on an ultra-lightweight block cipher called LBlock. Three scenarios are exploited which include injecting a fault to encryption, to key scheduling, or modifying the round number or counter. Our best results show that a single fault injection is enough to recover the master key of LBlock within the affordable complexity in each scenario.

An optimized lightweight Hardware Trojan (HT)based fault attack is proposed, especially for those resource-constrained environments such as IoT networks. Firstly, Algebraic fault analysis (AFA)is introduced to evaluate different fault models and search for the optimal one. Next, considering the limited resource, a lightweight HT is carefully designed which only flips one bit of the circuit in IoT device. Finally, AFA is applied again to exploit the fault and recover the secret key. An illustrative attack is demonstrated on DES implemented on an FPGA platform, SASEBO-GII. This paper shows that, for single bit fault injection at different rounds or different indexes in the same round, the reduced key search space of DES varies. The proposed technique can search for the optimal fault model, guide the lightweight Hardware Trojan design and automatically recover the secret key. Only one fault is required to recover the secret key of DES, which improves the stealthiness of the designed Hardware Trojan in IoT networks. The entire attack framework can also be applied to other block ciphers such as AES and PRESENT.

In the 1970s researchers noticed that radioactive particles produced by elements naturally present in packaging material could cause bits to flip in sensitive areas of electronic chips. Research into the effect of cosmic rays on semiconductors, an area of particular interest in the aerospace industry, led to methods of hardening electronic devices designed for harsh environments. Ultimately various mechanisms for fault creation and propagation were discovered, and in particular it was noted that many cryptographic algorithms succumb to so-called fault attacks. Preventing fault attacks without sacrificing performance is nontrivial and this is the subject of this book. Part I deals with side-channel analysis and its relevance to fault attacks. The chapters in Part II cover fault analysis in secret key cryptography, with chapters on block ciphers, fault analysis of DES and AES, countermeasures for symmetric-key ciphers, and countermeasures against attacks on AES. Part III deals with fault analysis in public key cryptography, with chapters dedicated to classical RSA and RSA-CRT implementations, elliptic curve cryptosystems and countermeasures using fault detection, devices resilient to fault injection attacks, lattice-based fault attacks on signatures, and fault attacks on pairing-based cryptography. Part IV examines fault attacks on stream ciphers and how faults interact with countermeasures used to prevent power analysis attacks. Finally, Part V contains chapters that explain how fault attacks are implemented, with chapters on fault injection technologies for microprocessors, and fault injection and key retrieval experiments on a widely used evaluation board. This is the first book on this topic and will be of interest to researchers and practitioners engaged with cryptographic engineering.

Differential fault analysis (DFA) finds the key of a block cipher using differential information between correct and faulty ciphertexts obtained by inducing faults during the computation of ciphertexts. Among many ciphers, advanced encryption standard (AES) has been the main target of DFA due to its popularity. The naive implementation of AES is known to be vulnerable to DFA, which can be split into two categories depending on the fault location: the DFA on the State and the DFA on the Key Schedule. For the first category, much research has been done and very efficient methods were devised. However, there is still a lack of research in the second category. The advantage of DFA on the Key Schedule is that it can even defeat some fault-protected AES implementations. Research on DFA has been diversified into several directions: reducing the number of required faults, changing fault models (from one-byte fault to multibyte fault and vise versa), extending to AES-192 and AES-256, and exploiting faults induced at an earlier round. This paper deals with all these directions together in DFA on AES Key Schedule. We introduce new attacks that find the AES-128 key with two faults in a one-byte fault model without exhaustive search and the AES-192 and the AES-256 keys with six and four faults, respectively.

Stream ciphers are highly frequent in the realm of secret key cryptography because of their low-computational complexity and latency. Though variety of attack models for testing the robustness of various stream ciphers are available, the differential fault analysis (DFA) model is the most popular. DFA is used not only to disclose the identity of any unknown cipher but also to recover the secret KEY and the cipher’s internal state. Deep learning approaches extract patterns from large amounts of cryptographic data, which aids in crypt-analysis. Here, single bit and multi-bit faults are injected into the internal register of trivium cipher, and artificial neural network (ANN) is used to identify the injected fault location without any handcrafted features of keystream unlike other existing state-of-the-art fault analysis techniques. In order to enhance the speed of fault analysis, we have used system on chip (SoC) platform where ANN-based classifier has been placed in the programmable logic area as an accelerator. This enhances the speed of fault analysis by 9% for single bit fault, 12% for two adjacent bit faults, and 13% for three adjacent bit faults compared to their software models. To the best of the author’s knowledge, this is the first of kind research where ANN-based hardware accelerator has been used for fault location identification on SoC platform.

Literature on Differential Fault Analysis (DFA) on AES-128 shows that it is more difficult to attack AES when the fault is induced in the key schedule, than when it is injected in the intermediate states. Recent research shows that DFA on AES key schedule still requires two faulty cipher texts, while it requires only one faulty cipher text and a brute-force search of $2^8$ AES-128 keys when the fault is injected inside the round of AES. The present paper proposes a DFA on AES-128 key schedule which requires only one single byte fault and a brute-force search of $2^8$ keys, showing that a DFA on AES key schedule is equally dangerous as a fault analysis when the fault is injected in the intermediate state of AES. Further, the fault model of the present attack is a single byte fault. This is more realistic than the existing fault model of injecting three byte faults in a column of the AES key which has a less chance of success. To the best of our knowledge the proposed attack is the best known DFA on AES key schedule and requires minimum number of faulty cipher text. The simulated attack, running on 3GHz Intel Core 2 Duo desktop machine with 2GB RAM, takes around 35 minutes to reveal the secret key.

Fault injection attacks (FIAs) are becoming a serious threat to the security of integrated circuits (ICs). Circuit designers need a simple and effective method to evaluate the ability of their IC designs against the FIAs at design stage. To address the need, this paper based on FPGA emulation proposes a method, which mimics FIAs on a circuit design implemented on a FPGA by instantiating a uniform architecture which can generate different fault models and span the space of faults and inserting fault injection logic into the design. After the circuit design is submitted to the emulation platform, the fault generation and injection are executed automatically, and a report about the ability of the IC design against the FIAs is generated. The method works at the circuit netlist level, leaves the source codes of the circuit design unmodified, and makes the evaluation a transparent process to the designers. The experiment with various fault models and differential fault analysis on AES-128 encryption circuit shows the effectiveness of the method.

Differential fault analysis on the contracting UFN structure, with application to SMS4 and MacGuffin

We present a fault analysis study of the ChaCha and Salsa families of stream ciphers. We first show that attacks like differential fault analysis that are common in the block cipher setting are not applicable against these families of stream ciphers. Then we propose two novel fault attacks that can be used against any variant of the ciphers. We base our attacks on two different fault models: the stuck-at fault model and the biased fault model. Each of them is exploited differently by the attacker. If the attacker knows the plaintexts and the ciphertexts both fault models can be successfully exploited. If the ciphers operate on fixed yet unknown plaintexts only the biased fault model can be successfully exploited. We evaluate exemplary attacks using both models in simulation. Their low complexity confirms that they are practical. To the best of our knowledge these are the first fault attacks against ChaCha and Salsa that do not require faults in the control flow (e.g. instruction skip).

Side channel analysis(SCA) focuses on attacking cryptographic algorithm implementations by collecting leaked information and analyzing the correlation between the leaked and key information in the cryptographic system. Currently, SCA is the main threat to cryptographic implementations, with DPA (differential power analysis) and DFA (differential fault analysis) being two of the most threatening types of SCA. However, the existing countermeasures against DPA and DFA have shortcomings and can hardly protect cipher designs perfectly. Based on a comprehensive analysis of DPA and DFA, this paper proposes a new idea of using an evolutionary cipher (EVOC) against DPAs based on the model proposed by Kocher, and several different new types of DFAs. In fact, an EVOC is a kind of dynamic cipher designing method. Moreover, combined with intelligent searching algorithms and cryptography design policies, EVOCs utilize the dynamic and unpredictable properties of TRNG (a truly random number generator) to ensure cipher design at a high level of security. Therefore, with an EVOC we could design cryptography algorithms with high security to resist mathematical analysis as well as DPAs and DFAs. This paper analyzes and proves the security, efficiency, cost, and original features of EVOCs against DPA and DFA both theoretically and experimentally. Compared with existing countermeasures against SCAs, EVOCs use dynamic non-linear operations to destroy the bases of DPA and DFA. At the algorithm level, EVOCs are more efficient than other resistance methods. Based on the theory and experiments, this paper proposes certain modifications to the EVOC in the AES (advanced encryption standard) algorithm, which can be referenced by other dynamic designs of cryptographic algorithms.

The development of differential fault analysis (DFA) techniques and mechanisms to inject faults into cryptographic circuits brings with it the need to use protection mechanisms that guarantee the expected level of security. The AES cipher, as a standard, has been the target of numerous DFA techniques, where its security has been compromised through different formulations and types of fault injections. These attacks have shown vulnerabilities of different AES implementations and building blocks. Consequently, several solutions have been proposed that provide additional protection to cover the identified vulnerabilities. In this paper, an extensive analysis has been carried out covering the existing fault injection techniques, the types of faults, and the requirements needed to apply DFA. Additionally, an analysis of the countermeasures reported in the literature is also presented, considering the protection provided, the type of faults considered, and the coverage against fault attacks. The eight different types of fault that allow us to perform DFAs on the AES cipher have been differentiated, as well as the vulnerabilities of the cipher. On the other hand, two comparisons have been made considering frequency penalty vs. area and fault coverage vs. area and frequency overhead. A metric has been proposed to compare the fault coverage of all the proposed solutions. To conclude, a final analysis is presented discussing the key aspects when choosing a particular solution and the possible development of new countermeasures to provide further protection against DFA.

This work analyzes the strength of NIST Lightweight Cryptography (LWC) Round 1 Candidate SIV-Rijndael256 in light of Differential Fault Attacks (DFA). It is observed that SIV-Rijndael256 presents an interesting case for DFA due to its large state-size which has been capitalized in this work to contribute to the state-of-the-art in DFA on AES-like ciphers. We first study the differential properties over three rounds of the cipher and then use it to mount a DFA that uses a classical strategy in conjunction with the properties of the key-schedule. The nonce-misuse property of SIV-Rijndael256 facilitates the use of DFA and is exploited to reduce the key-space from 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">128</sup> to just one using only a single random byte fault in the internal state. Moreover, the support for the release of unverified plaintexts which have been shown in literature as a vulnerability to DFA, makes the decryption also vulnerable to the same attack. Finally, the ability to uniquely retrieve the key using just a single fault makes the attack, reported here, an optimal DFA. To the best of our knowledge, this is the first differential fault analysis of any candidate in the NIST LWC competition.

Differential fault analysis (DFA) has already been applied to attack many block ciphers with the help of inducing some faults at the last few rounds of block ciphers. Currently, a general countermeasure against DFA is to protect the last few rounds of block ciphers by means of redundancy. In this paper, we present a new fault attack on block ciphers called linear fault analysis (LFA), in which linear characteristics for some consecutive rounds of a block cipher will be utilized instead of exploiting differential distributions of S-Boxes within the block cipher in DFA. Basically, the new approach can handle the case that faults are induced several rounds earlier compared to DFA, thus leading to a threat to the protected implementations (against DFA) of block ciphers. For the purpose of illustration, we mount an effective attack on SERPENT by adopting LFA and achieve a good cryptanalytic result on SERPENT. We hope that our work enriches the picture on the applicability of fault attacks to block ciphers and could be beneficial to the security evaluation of block ciphers.

PRESENT is a hardware-optimized 64-bit lightweight block cipher which supports 80- and 128-bit secret keys. In this paper, we propose a differential fault analysis (DFA) on PRESENT-80/128. The proposed attack is based on a 2-byte random fault model. In detail, by inducing several 2-byte random faults in input registers after 28 rounds, our attack recovers the secret key of the target algorithm. From simulation results, our attacks on PRESENT-80/128 can recover the secret key by inducing only two and three 2-byte random faults, respectively. These are superior to known DFA results on them.

Differential fault analysis (DFA) was introduced by Biham and Shamir. It is a powerful analysis technique to retrieve the secret key by injecting fault into an internal state and utilizing the differences between the correct ciphertexts and the faulty ciphertexts. Based on the idea of meet-in-the-middle, some differential characters can help to recover the key of some symmetric ciphers. At CHES 2011, this technique was utilized to give analyses on AES. In this article, we propose several DFA schemes on ITUbee, a software-oriented block symmetric cipher for resource-constrained devices based on the meet-in-the-middle idea. Our attacks are efficient enough and more powerful than previous works. Furthermore, the attacks in this article break the protection countermeasure, meaning we have to review the protection method on devices for ITUbee.