Transponder Random Number Generation Using Dual Automata Seeds
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Solution Overview
Problem
Existing methods for generating random numbers in passive transponders, such as those used in RFID systems, face challenges in achieving high quality, low power consumption, and minimal area requirements due to the impracticality of long linear feedback shift registers and the predictability of generated numbers, which are also vulnerable to attacks.
Innovation Solution
A method utilizing three automata, where two seeds with different statistical properties are used to preload a central feedback shift register, improving the quality of the generated random numbers without requiring long shift registers, and incorporating a physical random number source and chaotic oscillators to enhance randomness and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If long linear feedback shift registers are used to generate high-quality pseudorandom numbers, then the periodicity and quality of random numbers improve, but power consumption and area requirements increase significantly
Solution Approach 1:
The invention divides the random number generation process into two independent segments: a long-period LFSR that generates candidate sequences and a cryptographic hash function that processes these sequences. This segmentation allows the LFSR to maintain long periodicity with minimal register length, while the hash function ensures high-quality random number generation, thereby reducing power consumption compared to using a single long LFSR.
Solution Approach 2:
The cryptographic hash function serves as an intermediary between the LFSR and the final random number output. The LFSR generates intermediate sequences that are then processed by the hash function to produce high-quality random numbers. This intermediary approach allows the system to achieve high randomness quality without requiring the LFSR itself to be extremely long, thus reducing power consumption.
2Reliability
If long linear feedback shift registers are used to generate high-quality pseudorandom numbers, then the periodicity and quality of random numbers improve, but the area occupied by the register increases
Solution Approach 1:
The invention segments the random number generation functionality between a compact LFSR and a cryptographic hash function. The LFSR uses minimal registers (e.g., 16-32 bits) to generate long-period sequences, while the hash function provides the additional entropy and quality assurance. This segmentation achieves long periodicity without requiring a large-area LFSR.
Solution Approach 2:
The invention replaces the traditional mechanical/digital LFSR approach with a hybrid system that incorporates cryptographic processing. Instead of relying solely on the LFSR's inherent periodicity properties, the system uses the hash function's mathematical properties to ensure both long periodicity and high randomness quality, thereby reducing the area requirement for the register portion.
3Device complexity
If standard LFSR with fixed feedback polynomial is used, then the structure is simple and area is minimized, but the generated numbers become predictable and reproducible
Solution Approach 1:
The invention introduces dynamic elements to the traditionally static LFSR system. The feedback polynomial is no longer fixed but is dynamically selected or modified based on the hash function's processing of the LFSR output. This dynamic approach prevents predictability while maintaining relatively simple LFSR structure, as the complexity is shifted to the cryptographic processing layer.
Solution Approach 2:
The invention implements a feedback mechanism where the output of the hash function influences the LFSR's operation. The hash function processes the LFSR sequence and feeds back information that affects subsequent LFSR states or polynomial selection. This feedback loop ensures that the system remains unpredictable and non-reproducible, even though the basic LFSR structure remains simple.
Data Source
AI summary
A method and a device are provided, in particular a transponder, for generating a random number by a linear feedback shift register, wherein a first seed is generated by means of a first automaton, a second seed is generated by means of a second automaton, the first and second automata operate using different functional principles, so that the first and second seeds have different properties, and the shift register is reloaded with the first and/or second seed.