μRNG: A 300-950 mV, 323 Gbps/W All-Digital Full-Entropy True Random Number Generator in 14 nm FinFET CMOS

This paper describes mu RNG, an ultra-lightweight all-digital full-entropy true-random number generator (TRNG), fabricated in 14 nm high-k/metal-gate FinFET CMOS, targeted for on-die generation of cryptographic keys in energy-constrained IoT and wearable platforms. The mu RNG combines the entropy of multiple independent sources to generate an output bit-stream that is indistinguishable from an ideal unbiased entropy source. Three independent self-calibrating all-digital entropy sources, coupled with XOR feedback shift-register based correlation suppressors and an in-line compact Barak-Impagliazzo-Wigderson (BIW) extractor enable ultra-low energy consumption of 3 pJ/full-entropy bit with a dense layout occupying 1008 mu m(2), while achieving: (i) 162.5 Mbps full-entropy throughput at 1.3 GHz operation, with total power consumption of 1.5 mW and leakage power component of 90 mu W, measured at 0.75 V, 25 degrees C, (ii) mutually uncorrelated raw bitstreams from the three entropy sources with phi-coefficient cross-correlation <0.003, (iii) extracted full-entropy bitstream that passes all 16 NIST RNG tests with measured Shannon entropy up to 0.9999999995, and lower-bound min-entropy H-infinity > 0.99, (iv) hysteresis-free extracted output for lags 1-1000, with ACF similar to 0 within 95% confidence bounds of a Gaussian distribution (mu = 0, sigma(2) = 0.002), (v) wide operating supply voltage range of 300-950 mV with throughput scaling to 225 Mbps at 950 mV and robust subthreshold voltage performance of 400 Kbps, 4 mu W, measured at 300 mV, 25 degrees C, (vi) peak energy-efficiency of 323 Gbps/Wat near-threshold voltage of 400 mV, with full-entropy throughput of 8.6 Mbps, total power consumption of 27 mu W, (vii) 6.5x reduction in gate count and 5.4x lower energy consumption compared to conventional AES-based entropy extractors.