Ring Oscillator Correlation Detection for TRNG Interference
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Solution Overview
Problem
Ring oscillators used as entropy sources in computer systems are vulnerable to interference, which can lead to synchronization and destruction of randomness, allowing unauthorized access and compromising information security, as existing solutions are expensive, fragile, and difficult to evaluate or design.
Innovation Solution
Employing multiple ring oscillators with different oscillation frequencies, equipped with counters to detect correlations in their outputs, generating notifications when interference is detected above a predefined threshold, thereby preventing harm to information security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ring oscillators are used as entropy sources to generate true random numbers, then information security is improved, but the system becomes vulnerable to interference that can synchronize the oscillators and destroy randomness
Solution Approach 1:
The system divides the single entropy source into multiple ring oscillators (at least two) operating in parallel. Each oscillator serves as an independent entropy source, and their outputs are combined through XOR operations. This segmentation ensures that if one oscillator is affected by interference, the others can still provide randomness, thereby maintaining information security while reducing interference sensitivity.
Solution Approach 2:
The system continuously monitors the phase drift correlation between multiple ring oscillators. When the correlation exceeds a threshold indicating potential synchronization due to interference, the system detects this through feedback mechanisms and can switch to alternative entropy sources or alert security systems, preventing compromise of information security.
2Reliability
If physical protection such as shields or filters is used to reduce interference sensitivity, then reliability is improved, but the system becomes expensive and fragile
Solution Approach 1:
The patent replaces physical protection mechanisms (shields, filters) with a logical/mathematical approach using multiple ring oscillators and XOR operations. This substitution eliminates the need for expensive and fragile physical components while achieving the same goal of interference resistance through computational methods.
Solution Approach 2:
Instead of using expensive physical protection, the system employs multiple inexpensive ring oscillator circuits that can be easily manufactured and integrated into standard CMOS technology. These digital logic-based oscillators are cost-effective and non-fragile compared to physical shields or filters.
3Reliability
If logic gates that are less sensitive to interference are used, then reliability is improved, but the system becomes slower and harder to evaluate or design
Solution Approach 1:
The system maintains the use of standard ring oscillator circuits with typical logic gates but changes the operational parameters by running multiple oscillators in parallel and combining their outputs. This approach preserves the speed characteristics of standard logic gates while achieving interference resistance through the statistical properties of multiple independent oscillators, avoiding the speed penalty of specialized low-sensitivity gates.
Data Source
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AI summary
A system (100) for providing security in a computer system (110) is provided. The system includes a plurality of ring oscillators (102) and one or more logic circuits (101, 103, 104, 105). The ring oscillators are equipped with a respective plurality of counters (not shown) to count impulses of oscillating outputs of the ring oscillators. The one or more logic circuits (101, 13, 104, 105) start (enable) and stop (clear) the respective plurality of counters over repeated counting periods, and select (103) a group of ring oscillators from the plurality of ring oscillators (102). The one or more logic circuits (104) also determine a correlation between oscillating outputs of the group of ring oscillators. The one or more logic circuits (105) further generate a notification indicating interference in the group of ring oscillators (102) and thereby the plurality of ring oscillators when the correlation is above a predefined threshold correlation.