Secure Double Rate Registers as an RTL Countermeasure Against Power Analysis Attacks

Abstract

Power analysis attacks (PAAs), a class of side-channel attacks based on power consumption measurements, are a major concern in the protection of secret data stored in cryptographic devices. In this paper, we introduce the secure double rate registers (SDRRs) as a register-transfer level (RTL) countermeasure to increase the security of cryptographic devices against PAAs. We exploit the SDRR in a conventional advanced encryption standard (AES)-128 architecture, improving the immunity of the cryptographic hardware to the state-of-the-art PAAs. In the AES-128 exploiting SDRR, the combinational path evaluates random data throughout the entire clock cycle, and the interleaved processing of random and real data ensures the protection of both combinational and sequential logics. Our technique does not require the duplication of the combinational path to process the random data, thus limiting area overhead, unlike previous RTL countermeasures. The proposed approach is validated by means of PAAs based on real measurements on a field-programmable gate array implementation and on a 65-nm CMOS prototype chip. The protected implementation shows a strongly reduced correlation coefficient for the correct key, and more than three orders of magnitude increase in the measurements to disclosure with respect to the unprotected AES-128.