FACE–LIGHT: Fast AES–CTR Mode Encryption for Low-End Microcontrollers

Abstract

In this paper, we revisited the previous Fast AES–CTR mode Encryption (FACE) method for high-end processors and tailored the method to the microcontrollers, namely FACE–LIGHT. We targeted the 32-bit counter mode of operation for AES in constant timing. This optimized technique pre-computes the 2 Add-RoundKey, 2 Sub-Bytes, 2 Shift-Rows and 1 Mix-Columns operations. The FACE–LIGHT is implemented on the representative low-end microcontrollers (e.g. 8-bit AVR). The execution timing of AES–CTR algorithm for 128-bit and 256-bit security levels achieved the 2,218 and 3,184 clock cycles, respectively. This is faster than previous works by 22 % for 128-bit security level. The FACE–LIGHT can be used to extend the FACE to round 3. The AES is also implemented to be secure against the CPA (Correlation Power Analysis).