Solid-State Imaging Device Random Seed Generation
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Solution Overview
Problem
Current technologies for generating random numbers for electronic signatures lack effectiveness in utilizing the characteristics of solid-state imaging devices for enhanced security and randomness, particularly in protecting image data output from these devices.
Innovation Solution
A solid-state imaging device is designed with a pixel array unit on a first substrate and a processing unit on a second substrate, stacked such that the processing unit generates a seed value for random numbers based on pixel values from target pixels, improving randomness and security by leveraging inherent noise in the imaging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If random numbers are generated using conventional methods for electronic signatures, then security protection is provided, but the randomness and security effectiveness are insufficient
Solution Approach 1:
The patent converts the inherent noise and variability in pixel data, which is typically considered harmful or unwanted information, into a beneficial source of high-quality randomness for cryptographic key generation. By utilizing the natural variations in pixel values from the imaging sensor, the system transforms what would be signal degradation into a security advantage, creating unpredictable random numbers that enhance cryptographic security.
2Loss of information
If pixel data is processed to generate seed values, then randomness is improved, but device complexity increases due to stacked substrate configuration
Solution Approach 1:
The patent implements multi-functionality by enabling the pixel array unit to serve dual purposes: traditional image capture and random number generation for cryptography. The same pixel sensors and readout circuits are utilized for both imaging and entropy collection, eliminating the need for separate random number generation hardware and reducing overall device complexity despite the stacked configuration.
Solution Approach 2:
The patent segments the device into distinct functional layers on different substrates: the first substrate contains the pixel array unit for data collection, while the second substrate contains the processing unit for seed value generation. This segmentation allows independent optimization of each function and simplifies the design by separating sensing from processing operations.
3Productivity
If target pixels are selected from the pixel array, then processing efficiency is improved, but measurement precision may be affected by selective sampling
Solution Approach 1:
The patent changes the parameter being measured from traditional image quality metrics to cryptographic entropy metrics. By selecting target pixels based on their contribution to randomness rather than image fidelity, the system optimizes for cryptographic strength. The selection criteria and processing methods are specifically designed to maximize entropy while maintaining sufficient processing efficiency.
Data Source
AI summary
A seed value of a random number is generated in a more preferable manner by utilizing characteristics of a solid-state imaging device. A solid-state imaging device includes a pixel array unit in which a plurality of pixels is arrayed, and a processing unit that generates a seed value of a random number on the basis of each pixel value of predetermined one or more target pixels of the plurality of pixels, in which the pixel array unit is arranged on a first substrate, the processing unit is arranged on a second substrate, and a plurality of substrates including at least the first substrate and the second substrate is stacked so that the second substrate is located in a lower layer than the first substrate.