New universal element with integrated PUF and TRNG capability

The paper presents a novel hardware block that can be used for simultaneous generation of random bits and PUF responses. The new element called Universal Transition Effect Ring Oscillator (UTERO) is based on the TERO loop presented at CHES 2010. The PUF response bit corresponds to the output value of the TERO loop that converges to a state determined by the manufacturing process. The random bit is obtained by counting the number of oscillations and by taking the least significant bit of the counter. Although both outputs are generated by the same hardware (the TERO loop), the two output signals are mutually independent. The proposed structure is scalable and it can be easily implemented in FPGAs and in ASICs. Its performance and robustness is demonstrated on a UTERO cluster implemented in Actel Fusion FPGA. The cluster is composed of 216 UTERO elements generating simultaneously over 75 % of highly stable PUF response bits and 900 kbits/s of true random data that pass FIPS and NIST statistical tests.