# Hardware Countermeasures Benchmarking against Fault Attacks
## 1 Introduction
Note that in this paper, we focus on analysing attacks on physical implementations of private key encryption algorithms and on proposed hardware solutions to detect such attacks and prevent secret encrypted and exchanged information from being compromised. To this end, attackers must have access to the devices that implement the encryption algorithms in hardware. There are some reviews about differential analysis and countermeasures in hardware implementations such as [18; 19; 20] or software such as [21]. In the case of [18] an analysis of security issues and possible countermeasures in IoT applications is carried out. In this work, the main weaknesses in IoT environments are analysed, and the application of encryption algorithms such as AES, Data Encryption Standard (DES), or Rivest-Shamir-Adleman (RSA) are proposed as countermeasures. However, this work does not consider the vulnerabilities that are present in this type of algorithms, such as the AES cipher, the possible attacks or solutions that allow them to be detected. In [19], an extensive analysis of the different types of DFA applied to the AES cipher is presented and some of the solutions proposed to detect flaws are presented. In this work, some of the DFAs reported in the literature on the AES cipher are considered, considering single bit, single byte and multiple byte fault types. However, the analysis of attack types by fault insertion is not considered, as well as the comparison between fault coverage and occupied area of the physical implementations. The comparison between the most relevant solutions against attacks is not presented, considering only a few solutions. A comparison of cost versus security of countermeasures against fault attacks is presented in [20]. In this work, different solutions based on the use of redundant spaces for fault detection are analysed. However, the comparison of fault types, attack techniques, DFAs and fault coverage analysis versus delay and area is not carried out. Finally, an analysis of countermeasures applied on the AES cipher from the software point of view is carried out in [21]. Different solutions and their comparisons are presented, but it should be considered that they are not comparable to those studied in this work because they do not deal with attacks on physical implementations or hardware countermeasures. The rest of the paper is organized as follows. Section 2 presents a study of the different FIA techniques through which it is possible to achieve the requirements needed to be able to apply the DFA on the AES. Section 3 presents in summary form a description of the AES cipher, a classification of the types of faults useful for DFAs is presented, and the vulnerabilities of the AES cipher against DFAs are described in detail. Section 4 presents the different countermeasures considered, performing a classification of all of them, and making a comparison between implementation costs and fault coverage. Section 5 presents a comparison between the different protection schemes and the current state of the art according to the security level. Section 6 presents a discussion from the point of view of security and resource trade-offs. Finally, Section 7 presents the conclusions.