An embedded low-overhead PLL-based countermeasure against DPA side channel attack

Side channels attacks are considered among physical, noninvasive methods employed to obtain private key of cryptographic devices such as smart cards. In this paper, a new approach for countermeasure against Differential Power Analysis (DPA) with an extremely low-area and -power overhead is proposed. The proposed method employs a Phase Locked Loop (PLL) which is placed in the power path of an Advanced Encryption Standard (AES) based encryption system. This method suppresses the power characteristic of the encryption system through both masking and hiding the private key information. Moreover, the proposed method is successful in maintaining high frequency operation of the encryption engine. The proposed method is implemented in TSMC CMOS 65nm technology. The protection circuit has only 5% area overhead, and 6% increase in power consumption, with frequency degradation of only 1%.