Characterization and Verification of Assignment and Routing of RO-Based TRNG Using the Randomness Test

Ryoichi Sato, Yasuyuki Nogami, Yuta Kodera

This study focused on a ring oscillator-based true random number generator (RO-based TRNG) on an FPGA. We verify the randomness of the effect of elements in an RO and the correlation of the respective places of ROs. In this paper, two verifications are presented in an RO-based RNG with 32 ROs: (1) correlation of the gap of each RO and randomness and (2) the effect of placement optimization on randomness. Regarding (1), we design an RO circuit assigned to one SLICE and then place it with and without a space of one blank SLICE. Regarding (2), we design an RO-based RNG without deciding on the elements and SLICEs. These random sequences were tested using NIST Special Publication 800-22 (SP 800-22) and 800-90B. Consequently, we confirmed that the assignment in an RO-based TRNG has a small on randomness. Concurrently, we observed common characteristic in all results.

2026 10th International Conference on Cryptography, Security and Privacy (CSP 2026)