Security analysis on dummy based side-channel countermeasures—Case study: AES with dummy and shuffling

Abstract

Side-channel analysis is a serious type of attack that can break mathematically secure cryptographic algorithms. Many studies have designed countermeasures against side-channel analysis, such as masking and hiding schemes. Frequently, designers employ combined countermeasures that use both a first-order masking scheme and a hiding scheme to provide sufficient security and efficiency.Random insertion of dummy operations scheme, which is one of the hiding schemes, randomly changes the execution time of the operation to be attacked by inserting dummy operations. However, if the dummy operations can be distinguished from real ones, attackers could extract secret information with lower complexity than the intended attack complexity with the designer inserting the dummy operations. In this paper, we present a novel vulnerability that can enable dummy and real operations to be distinguished for various implementation methods using C language on the XMEGA128D4 microprocessor. This novel vulnerability occurs regardless of the four methods of implementation of dummy operations and the compile levels. We also present a new countermeasure against this vulnerability and demonstrate the security through practical experimentation.