Security of Block Ciphers

Chapter 7Countermeasures against Side-Channel Analysis and Fault Analysis

In order to overcome the side-channel attacks and the fault attacks introduced in Chapters 5 and 6, this chapter explains several countermeasures. There exist many possible countermeasures depending on the abstraction level in cryptosystems. Figure 7.1 describes the hierarchy of the cryptosystem, and the position of logic-level countermeasures for hardware implementations.

Figure 7.1 Countermeasures for side-channel analysis and fault analysis

The hardware device can counteract the side-channel attack if the countermeasure is appropriately implemented in the lowest abstraction level, that is, in the logic level. Such a logic-level countermeasure not only protects the logical gates but also helps to enhance the security of cryptographic algorithm and protocol against side-channel attacks, which is one of the most advantageous points of applying the countermeasure to the logic level. In general, the side-channel countermeasure tends to be more ineffective if implementing it in a higher level because higher level countermeasures cannot take care of all leakage sources that exist all over the circuits consisting of logical gates. Therefore, this chapter mainly explains the logic-level countermeasure using hiding logics and masking logics. The concept of higher level countermeasures is also explained especially ...