Ring Oscillator Random Number Generation via Startup Metastability
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Solution Overview
Problem
Solid State Drives (SSDs) lack physical entropy sources due to their lack of moving parts, making it difficult to generate high-entropy random numbers necessary for secure cryptographic algorithms, which can compromise security if poor random number generation processes are used.
Innovation Solution
A method and circuit that utilize the metastable properties of ring oscillator circuits to generate random numbers by capturing entropic properties from the unpredictable switching of inverter components during oscillation startup, allowing parallel generation of multiple bits and addressing the lack of physical entropy sources in SSDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical entropy sources are used for random number generation, then high-entropy random numbers can be generated, but SSDs lack moving parts and therefore lack physical entropy sources
Solution Approach 1:
The patent replaces the need for mechanical entropy sources with an electronic solution. Instead of relying on physical entropy sources like mechanical noise or thermal effects that require moving parts, the invention uses a ring oscillator circuit to generate random numbers through electronic means, specifically by capturing entropic properties during the startup transient phase when the oscillator is settling into its stable oscillation pattern.
Solution Approach 2:
The patent exploits parameter changes that occur during the startup transient phase of the ring oscillator. During this transient period, the oscillator transitions from an initial state to its stable oscillation pattern, creating measurable entropic properties in the signal. By capturing these entropic properties during the transient phase and using them to generate random numbers, the system achieves high-entropy random number generation without requiring physical entropy sources.
2Reliability
If ring oscillator circuits are used to generate random numbers, then high-entropy random numbers can be generated without moving parts, but the circuit must be designed to capture entropic properties during transient startup
Solution Approach 1:
The patent performs preliminary action by capturing entropic properties during the transient startup phase before the ring oscillator reaches its stable oscillation pattern. The circuit is designed to sample and store the entropic properties of the oscillator signal during this transient period, which occurs automatically when the system is powered on or reset. This preliminary capture of entropy during the transient phase enables subsequent random number generation without requiring continuous complex circuitry.
3Productivity
If multiple bits are generated in parallel from entropic properties, then random number generation efficiency is improved, but the circuit requires multiple entropic capture circuits operating in parallel
Solution Approach 1:
The patent segments the random number generation process by using multiple independent entropic capture circuits, each tasked with capturing entropic properties from different points in the ring oscillator circuit. Each capture circuit operates independently and contributes to the overall random number generation output. This segmentation allows parallel processing of entropy capture operations, improving the generation rate while maintaining the security properties of the random numbers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a reliable and cost-effective source of high-entropy random numbers, enhancing the security of SSDs and other applications by ensuring unpredictability and meeting standards like FIPS PUB 140-2, while avoiding security risks associated with stored random number generator states.
Implementation Method 1
A ring oscillator circuit is provided with a common start signal that causes the ring oscillator circuit to enter a metastable mode. At least a first bit and a second bit of a random number are both generated in parallel. The parallel generation of the bits involves the generation of the first bit from entropic properties of a signal of a first one of the plurality of inverter components and the generation of the second bit from entropic properties of a signal of a second one inverter components.
Data Source
AI summary
Random numbers are generated according to a variety of solutions. A particular solution relates to a method for generating the random number. A common start signal is provided to each of a plurality of inverter components of a ring oscillator circuit. This causes the ring oscillator circuit to enter a metastable mode. At least a first bit and a second bit of a random number are both generated in parallel. The parallel generation of the bits involves the generation of the first bit from entropic properties of a signal of a first one of the plurality of inverter components and the generation of the second bit from entropic properties of a signal of a second one inverter components.