TY - JOUR

T1 - Energy-Efficient Post-Processing Technique Having High Extraction Efficiency for True Random Number Generators

AU - Zhang, Ruilin

AU - Wang, Xingyu

AU - Shinohara, Hirofumi

N1 - Funding Information:
This work is supported by ROHM Co., Ltd. The authors would like to thank Mr. Koichi Takanashi from ROHM Co., Ltd. for technical supports during the back-end ASIC design process.
Publisher Copyright:
© 2021 Institute of Electronics, Information and Communication, Engineers, IEICE. All rights reserved.

PY - 2021/7/1

Y1 - 2021/7/1

N2 - In this paper, we describe a post-processing technique having high extraction efficiency (ExE) for de-biasing and de-correlating a random bitstream generated by true random number generators (TRNGs). This research is based on the N-bit von Neumann (VN N) post-processing method. It improves the ExE of the original von Neumann method close to the Shannon entropy bound by a large N value. However, as the N value increases, the mapping table complexity increases exponentially (2N), which makes VN N unsuitable for low-power TRNGs. To overcome this problem, at the algorithm level, we propose a waiting strategy to achieve high ExE with a small N value. At the architectural level, a Hamming weight mapping-based hierarchical structure is used to reconstruct the large mapping table using smaller tables. The hierarchical structure also decreases the correlation factor in the raw bitstream. To develop a technique with high ExE and low cost, we designed and fabricated an 8-bit von Neumann with waiting strategy (VN 8W) in a 130-nm CMOS. The maximum ExE of VN 8W is 62.21%, which is 2.49 times larger than the ExE of the original von Neumann. NIST SP 800-22 randomness test results proved the debiasing and de-correlation abilities of VN 8W. As compared with the stateof-the-Art optimized 7-element iterated von Neumann, VN 8W achieved more than 20% energy reduction with higher ExE. At 0.45V and 1 MHz, VN 8W achieved the minimum energy of 0.18 pJ/bit, which was suitable for sub-pJ low energy TRNGs.

AB - In this paper, we describe a post-processing technique having high extraction efficiency (ExE) for de-biasing and de-correlating a random bitstream generated by true random number generators (TRNGs). This research is based on the N-bit von Neumann (VN N) post-processing method. It improves the ExE of the original von Neumann method close to the Shannon entropy bound by a large N value. However, as the N value increases, the mapping table complexity increases exponentially (2N), which makes VN N unsuitable for low-power TRNGs. To overcome this problem, at the algorithm level, we propose a waiting strategy to achieve high ExE with a small N value. At the architectural level, a Hamming weight mapping-based hierarchical structure is used to reconstruct the large mapping table using smaller tables. The hierarchical structure also decreases the correlation factor in the raw bitstream. To develop a technique with high ExE and low cost, we designed and fabricated an 8-bit von Neumann with waiting strategy (VN 8W) in a 130-nm CMOS. The maximum ExE of VN 8W is 62.21%, which is 2.49 times larger than the ExE of the original von Neumann. NIST SP 800-22 randomness test results proved the debiasing and de-correlation abilities of VN 8W. As compared with the stateof-the-Art optimized 7-element iterated von Neumann, VN 8W achieved more than 20% energy reduction with higher ExE. At 0.45V and 1 MHz, VN 8W achieved the minimum energy of 0.18 pJ/bit, which was suitable for sub-pJ low energy TRNGs.

KW - low-power

KW - post-processing techniques

KW - true random number generator

KW - von Neumann entropy extractor

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U2 - 10.1587/transele.2020CDP0006

DO - 10.1587/transele.2020CDP0006

M3 - Article

AN - SCOPUS:85108991589

SP - 300

EP - 308

JO - IEICE Transactions on Electronics

JF - IEICE Transactions on Electronics

SN - 0916-8524

IS - 7

ER -