Biblio

Authentication and encryption within an embedded system environment using cameras, sensors, thermostats, autonomous vehicles, medical implants, RFID, etc. is becoming increasing important with ubiquitious wireless connectivity. Hardware-based authentication and encryption offer several advantages in these types of resource-constrained applications, including smaller footprints and lower energy consumption. Bitstring and key generation implemented with Physical Unclonable Functions or PUFs can further reduce resource utilization for authentication and encryption operations and reduce overall system cost by eliminating on-chip non-volatile-memory (NVM). In this paper, we propose a dynamic partial reconfiguration (DPR) strategy for implementing both authentication and encryption using a PUF for bitstring and key generation on FPGAs as a means of optimizing the utilization of the limited area resources. We show that the time and energy penalties associated with DPR are small in modern SoC-based architectures, such as the Xilinx Zynq SoC, and therefore, the overall approach is very attractive for emerging resource-constrained IoT applications.

A hardware Trojan (HT) detection method is presented that is based on measuring and detecting small systematic changes in path delays introduced by capacitive loading effects or series inserted gates of HTs. The path delays are measured using a high resolution on-chip embedded test structure called a time-to-digital converter (TDC) that provides approx. 25 ps of timing resolution. A calibration method for the TDC as well as a chip-averaging technique are demonstrated to nearly eliminate chip-to-chip and within-die process variation effects on the measured path delays across chips. This approach significantly improves the correlation between Trojan-free chips and a simulation-based golden model. Path delay tests are applied to multiple copies of a 90nm custom ASIC chip having two copies of an AES macro. The AES macros are exact replicas except for the insertion of several additional gates in the second hardware copy, which are designed to model HTs. Simple statistical detection methods are used to isolate and detect systematic changes introduced by these additional gates. We present hardware results which demonstrate that our proposed chip-averaging and calibration techniques in combination with a single nominal simulation model can be used to detect small delay anomalies introduced by the inserted gates of hardware Trojans.