Effectiveness of Variable Bit-Length Power Analysis Attacks on SHA-3 Based MAC.

Keccak is the hash function selected by NIST as the new SHA-3 standard. Keccak is built on sponge construction, and it provides a new keyed Message Authentication Code (MAC) function called MAC-Keccak. The focus of this work was to apply the power analysis attacks that use Correlation Power Analysis (CPA) technique to extract the secret key. Our attack methodology utilizes simulated power consumption waveforms and is applied to the Keccak high-speed core hardware design from the SHA-3 competition. 1-bit, 2-bit, 4-bit, 8-bit, and 16-bit CPA selection function key guess size attacks are performed on the waveforms to compare and analyze computational effort of successful key extraction on MAC-Keccak. Our experiments confirm that the larger the selection function key guess size is used, the better the fewer traces are needed to retrieve the key, but using more computation time.