FPGA Time-Bounded Unclonable Authentication

Abstract. This paper introduces a novel technique for extracting the unique tim-ing signatures of the FPGA configurable logic blocks in a digital form over the space of possible challenges. A new class of physical unclonable functions that enables inputs challenges such as timing, digital, and placement challenges can be built upon the delay signatures. We introduce a suite of new authentication protocols that take into account non-triviality of bitstream reverse-engineering in addition to the FPGA’s unprecedented speed in responding to challenges. Our technique is secure against various attacks and robust to fluctuations in opera-tional conditions. Proof of concept implementation of the signature extraction and evaluations of the proposed methods are demonstrated on Xilinx Virtex 5 FPGAs. Experimental results demonstrate practicality of the proposed techniques.

FPGA-based true random number generation using circuit metastability with adaptive feedback control

13th International Workshop, Nara, Japan, September 28 – October 1, 2011. ProceedingsThe paper presents a novel and efficient method to generate true random numbers on FPGAs by inducing metastability in bi-stable circuit elements, e.g. flip-flops. Metastability is achieved by using precise programmable delay lines (PDL) that accurately equalize the signal arrival times to flip-flops. The PDLs are capable of adjusting signal propagation delays with resolutions higher than fractions of a pico second. In addition, a real time monitoring system is utilized to assure a high degree of randomness in the generated output bits, resilience against fluctuations in environmental conditions, as well as robustness against active adversarial attacks. The monitoring system employs a feedback loop that actively monitors the probability of output bits; as soon as any bias is observed in probabilities, it adjusts the delay through PDLs to return to the metastable operation region. Implementation on Xilinx Virtex 5 FPGAs and results of NIST randomness tests show the effectiveness of our approach