Ring Oscillator TRNG Sampling for Faster Entropy Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ring oscillator-based true random number generators (TRNGs) are relatively slow compared to other entropy generation methods, necessitating a faster TRNG that maintains or exceeds the same level of entropy.
Innovation Solution
A ring oscillator-based TRNG that samples the complete state of the oscillator, incorporating a second ring oscillator for generating a sampling pulse, synchronization circuits, and a compression circuit to reduce output size while handling metastability, thereby increasing speed and entropy extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a ring oscillator is used as an entropy source for a TRNG, then the device complexity is reduced and ease of manufacture is improved, but the generation speed is relatively slow
Solution Approach 1:
The patent divides the ring oscillator into multiple stages (e.g., 9 stages) and uses multiple sampling circuits (e.g., 3 sampling circuits) to simultaneously sample different stages. This segmentation allows parallel entropy extraction, significantly increasing the generation speed while maintaining the digital inverter-based simple structure that ensures ease of manufacture.
2Device complexity
If a ring oscillator-based TRNG samples only a single output state, then the device complexity is minimized, but the entropy extraction efficiency is insufficient
Solution Approach 1:
The patent transitions from sampling a single output state (one-dimensional) to sampling multiple stages simultaneously (multi-dimensional). By using multiple sampling circuits connected to different stages of the ring oscillator, the system extracts entropy from multiple dimensions of the oscillator state, dramatically improving entropy extraction efficiency while adding only minimal complexity through additional sampling circuits.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A true random number generator circuit includes a ring oscillator and a plurality of sampling circuits. The ring oscillator includes a plurality of series-connected stages coupled together in a ring. An output of a last stage of the ring oscillator is coupled to an input of a first stage of the ring oscillator. A sampling circuit of the plurality of sampling circuits has an input coupled to a node located between two adjacent stages of the plurality of series-connected stages. Every node of the ring oscillator is coupled to a corresponding sampling circuit of the plurality of sampling circuits. In another embodiment, a method for generating a random number is provided.