Securisation of implementations of cryptographic algorithms in the context of embedded systems

Overview & Synopsis

Embedded systems are ubiquitous and they have more and more applications. Most actual industrial fields rely on embedded systems for accomplishing specific tasks, sometimes highly sensitive. Currently, the deployment of embedded systems is even more increasing by the birth of the "Internet of Things", which is expected to revolutionize our digital world.An embedded system is an electronic and informatic system in control of a specific part of a larger system. Numerous constraints, in particular regarding its size, must be taken into account during its conception. Consequently, an embedded system is usually low cost, consume low power and has limited computational resources.For accomplishing its specific tasks, an embedded system collect, manipulate and exchange data that are usually sensitive. Moreover, such a system can often be directly accessible physically. This particularity can then be exploited by an unauthorized entity in order to control, extract or alter sensitive data manipulated by such systems.In this context, it is mandatory to develop well-suited security mechanisms. In particular, it is crucial to prevent direct physical access to the device but also to protect sensitive data manipulated or stored by the device.Cryptography is the science of secrets and offers numerous ways to mitigate the risks that face electronic devices. However, in such a context, some physical characteristics of the electronics of embedded systems vary during the execution of the implementations of cryptographic algorithms guaranteeing the security of information. In particular, the power consumption of a device or its electromagnetic radiations depend on the manipulated data as well as of the choices made for implementing the cryptographic algorithms. These physical characteristics can also be measured if physical access to the device is possible. The exploitation of these measurements has led to devastating attacks called "Side-Channel attacks". Mounting this kind of attacks enables to extract sensitive data stored or manipulated by an electronic device, usually without much effort.Special countermeasures have to be implemented to mitigate the security risks that face the implementations of cryptographic algorithms without deteriorating too much their performances in practice. Masking is a well-known solution, but its correct implementation requires a thorough analysis of algorithmic solutions it provides, especially in the context just described where devices have limited resources.