Unstable Memory Cell Read for Pseudorandom Number Generator Seed
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Solution Overview
Problem
Conventional pseudorandom number generators in smart cards and cryptographic devices face challenges in creating non-recalculatable random numbers due to the need for true random number generators, which are time-consuming and expensive to implement, and pseudorandom number generators can be predictable with a known starting value.
Innovation Solution
A device and method that unstably read out memory cell values to determine a starting value for a pseudorandom number generator, using a reading circuit and determining circuit within a chip, without requiring analog units, by iteratively varying the read reference or cell voltage/current to create an unstable read state, which is then used to generate a random starting value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a true random number generator is used to create a starting value, then the randomness and security are improved, but the implementation complexity and cost increase
Solution Approach 1:
The patent replaces the complex analog true random number generator with a digital memory cell reading system. Instead of using physical noise sources (thermal noise, shot noise) that require analog circuitry, the invention uses digital memory cells that can be read in an unstable state to generate starting values for pseudorandom number generators. This substitution of analog mechanisms with digital ones reduces implementation complexity while maintaining security requirements.
Solution Approach 2:
The patent changes the reading parameters of the memory cell by varying the read reference voltage or cell voltage/current to create an unstable reading state. By dynamically adjusting these parameters, the system generates random starting values without requiring true random number generators. This parameter variation approach allows the same digital memory cell to produce entropy for security purposes.
2Device complexity
If a pseudorandom number generator with a known starting value is used, then the implementation simplicity is improved, but the security and predictability deteriorate
Solution Approach 1:
The patent performs a preliminary action by generating a starting value in advance using the unstable memory cell reading method before the pseudorandom number generation begins. This preliminary starting value is created through deliberate unstable reading of memory cells, ensuring it is unknown to manufacturers and outsiders. Once generated, this starting value seeds the pseudorandom number generator, combining the simplicity of digital implementation with the security of an unknown seed.
3Measurement precision
If conventional memory cells are read stably, then the reading accuracy is improved, but the randomness and security of the starting value deteriorate
Solution Approach 1:
The patent introduces dynamics into the memory cell reading process by deliberately creating an unstable reading state. Instead of reading memory cells in a stable, deterministic state, the system varies the read reference voltage or cell voltage/current during the reading process. This dynamic approach causes the reading outcome to be unpredictable and random, while still extracting usable information from the memory cell state for generating secure starting values.
Data Source
AI summary
Method and device for creating a starting value for a pseudorandom number generator, having a reader configured to unstably read out an output value from a memory cell and a determiner configured to determine the starting value on the basis of the output value of the memory cell.