# Hardware Countermeasures Benchmarking against Fault Attacks
## 1 Introduction  
Nowadays, determining and minimizing vulnerabilities in cryptographic devices has become a scientific challenge. This is mainly due to the constant development and improvement of analysis techniques and attacks that are able to exploit the vulnerabilities of existing implementations in order to access the device secret information. In addition to this, there has been a large increase in the number of applications that require the use of devices with significant resource and power constraints. An example of this is the increasing usage of the Internet of Things (IoT). In [1], the authors describe the importance of analysing security in the IoT, considering recent research work on the different stages of the IoT security solution. Finally, ref. [2] discusses the risks that exist if attacks on embedded applications used in this area are not considered. Although different techniques exist to compromise the security of the cryptographic devices, herein we will focus on the so-called active attacks. Active attacks have been extensively studied since the paper presented by [PERSON] et al. [3], where the authors presented a fault injection attack on the Rivest-Shamir-Adleman (RSA) cryptosystem. These types ofattack can compromise the security of cryptographic devices by comparing the relationship between the correct and the faulty output of the circuit when a fault is injected during its operations. On the one hand, fault injection is carried out by means of Fault Injection Attack (FIA) techniques such as non-invasive (the device is not modified such as glitch induction in the clock signal) or invasive (the device is manipulated such as stripping of the circuit using a laser beam). On the other hand, the analysis between the correct and faulty output of the circuit is performed by means of Differential Fault Analysis (DFA). This analysis allows attackers to obtain information related to the secret key by comparing the correct and faulty ciphertexts of the circuit. This technique has been used successfully in different cryptographic algorithms. Among the block ciphers presented over the years, the Advanced Encryption Standard (AES) [4] cipher has received the most attention because it is the standard chosen by the National Institute of Standards and Technology (NIST), it is widely used, and it is implemented as a standard in a large number of technologies. This cipher has been subjected to numerous differential analyses and attacks with the aim of compromising its security [5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17]. Since fault attacks and differential analysis studies are numerous, so are fault detection schemes. A large number of related works focus on the AES cipher, as in the case of this work. This paper aims to analyze the different fault injection techniques and the types of fault they can produce, to analyze the characteristics of the DFAs presented on the AES cipher, to summarize the most relevant protection schemes, and to analyze them considering fault coverage, resource consumption, and throughput. To this end, the different FIA techniques are analyzed to meet the requirements of the DFAs, considering the fault level, requirements for a successful attack, and the fault location control. A complete and detailed classification of the different DFA methods on the AES cipher has been carried out, defining weaknesses, requirements, and attacks times. To compare all countermeasures as a whole, it is necessary to consider that the attacker is capable of achieving any type of fault, being the most powerful attacker. This makes it possible to determine whether the countermeasures studied offer an appropriate level of protection depending on the types of fault that may occur in relation to those that they are able to detect. This analysis is a guide for choosing among the many proposals, depending on the level of protection required for a given application and environment.