A High-Entropy True Random Number Generator with Keccak Conditioning for FPGA

Any cryptographic system strongly relies on randomness to ensure robust encryption and masking methods. True Random Number Generators play a fundamental role in this context. The National Institute of Standards and Technology (NIST) and the Bundesamt für Sicherheit in der Informationstechnik (BSI) provide guidelines for designing reliable entropy sources to fuel cryptographic Random Bit Generators. This work presents a highly parameterized, open-source implementation of a TRNG based on ring oscillators, complemented by an optimized Keccak conditioning unit. The design process is accompanied by a thorough study of the relevant literature and standards, specifying the requirements for reliable entropy sources in cryptographic systems. The design of the TRNG proposed in this paper aims to strike a balance between area, throughput, power consumption, and entropy, while adhering to these guidelines. The proposed design has undergone extensive testing and validation and has successfully passed the NIST SP 800-22, NIST SP 800-90B, and BSI AIS-31 tests, achieving a min-entropy per bit of 0.9982 (NIST) and 0.9998 (BSI).