Improvement in Resilience of AES Design With Reconfigured CFB Mode Against Power Attacks

Advanced encryption standard (AES) is used to secure the communication process on the Internet-of-Things (IoT) hardware. It is implementable in various 128-bit modes, such as electronic code book (ECB), cipher block chaining (CBC), cipher feedback (CFB), output feedback (OFB), and counter (CTR), to facilitate parallel processing of data. The noninvasive nature of power analysis attacks (PAAs) to retrieve secret information off a physical device renders such hardware to be unsafe from the adversaries. Also, the assessment of the aforementioned modes for security remains obscured, which is undertaken by this work as a novel attempt. In addition, this work proposes a novel 64-bit version of CFB mode, which provides the highest security with respect to other modes and several unprotected AES designs. PAAs are performed on ASIC platform utilizing UMC 65-nm technology node and a hardware experimental setup using side-channel attack security evaluation board (SASEBO), both at 16-MHz AES frequency and traces sampled at the rate of 1 GSa/s. The measurements to disclose (MTDs) of >1 000 000 provided by the proposed CFB-64 are significantly more than that provided by usual unprotected AES designs. It also offers the highest MTD, and least signal-to-noise ratio (SNR) and mutual information (MI) among other modes, indicating the highest security. The proposed CFB-64 acts as a countermeasure upon integration with an unprotected AES.