Comparison of cost of protection against differential power analysis of selected authenticated ciphers

Abstract

Authenticated ciphers are vulnerable to side-channel attacks, including differential power analysis (DPA). Test Vector Leakage Assessment (TVLA) using Welch's t-test has been used to verify improved resistance of block ciphers to DPA after application of countermeasures. However, extension of this methodology to authenticated ciphers is non-trivial, since this requires additional input and output conditions, complex interfaces, and long test vectors interlaced with protocol necessary to describe authenticated cipher operations. In this research we augment an existing side-channel analysis architecture (FOBOS) with TVLA for authenticated ciphers. We use this capability to show that implementations in the Spartan-6 FPGA of the CAESAR Round 3 candidates ACORN, ASCON, CLOC (AES and TWINE), SILC (AES, PRESENT, and LED), JAMBU (AES and SIMON), and Ketje Jr., as well as AES-GCM, are potentially vulnerable to 1st order DPA. We then implement versions of the above ciphers, protected against 1st order DPA, using threshold implementations. TVLA is used to verify improved resistance to 1st order DPA of the protected cipher implementations. Finally, we benchmark unprotected and protected cipher implementations in the Spartan-6 FPGA, and compare the costs of 1st order DPA protection in terms of area, frequency, throughput, throughput-to-area (TP/A) ratio, power, and energy per bit. Our results show that ACORN is the most energy efficient, has the lowest area (in LUTs), and has the highest TP/A ratio of DPA-resistant implementations. However, Ketje Jr. has the highest throughput.