LFSR Random Number Generator Seedless Startup
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Solution Overview
Problem
Conventional random number generators face challenges in providing low power consumption and fast response times while maintaining sufficient randomness, particularly during startup and shutdown processes, due to the need for seed number storage and retrieval, which increases power consumption and introduces time delays.
Innovation Solution
A random number generator based on a linear feedback shift register (LFSR) is enhanced by incorporating a second input coupled with a combinatorial cell to modify the feedback line, allowing for improved randomness without the need for seed storage, using various sources such as oscillators or sensors to influence the sequence generation, and enabling transient modifications to the feedback polynomial.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If seed number storage in memory is used during shutdown and startup, then sufficient randomness is provided, but power consumption increases and time delay is introduced
Solution Approach 1:
The invention extracts the randomness generation function from the memory-based seed storage approach and implements it using a linear feedback shift register (LFSR) circuit. The LFSR generates random numbers through its inherent feedback mechanism without requiring external memory storage, thereby eliminating the power consumption and time delay associated with read/write operations while maintaining sufficient randomness for security applications
Solution Approach 2:
The LFSR circuit is designed to be self-sufficient by using its own internal state and feedback polynomial to generate random sequences. The circuit automatically initializes upon startup without requiring external seed input from memory, and continuously generates random numbers through its clocked operation, making the system self-starting and eliminating dependency on memory-based seed retrieval
2Reliability
If seed number storage in memory is used during shutdown and startup, then sufficient randomness is provided, but time delay is introduced
Solution Approach 1:
The LFSR circuit is pre-configured with its feedback polynomial and tap connections during manufacturing, so that upon startup it can immediately begin generating random numbers without requiring time-consuming seed retrieval from memory. The circuit is designed to be in a ready-to-operate state, eliminating initialization delays
Solution Approach 2:
The invention removes the memory-based seed storage and retrieval mechanism entirely, replacing it with an LFSR that generates randomness through its inherent feedback logic. This extraction of the randomness generation function from memory operations eliminates the time delay associated with read/write procedures while maintaining sufficient randomness
3Reliability
If LFSR feedback polynomial is modified via second input, then randomness is improved, but device complexity increases
Solution Approach 1:
The second input of the LFSR is designed with multi-functionality, serving both to improve randomness when activated and to maintain compatibility with standard LFSR operation when inactive. The feedback polynomial modification mechanism can be selectively enabled or disabled, allowing the same circuit structure to adapt to different randomness requirements without requiring separate circuits for each mode
Solution Approach 2:
The invention changes the feedback polynomial parameters of the LFSR dynamically through the second input, allowing optimization of randomness characteristics. By modifying the feedback polynomial coefficients based on the second input signal, the circuit can adjust its randomness properties without changing its fundamental structure, achieving improved randomness with minimal additional complexity
Data Source
AI summary
The random number generator comprises a linear feedback shift register (10), which comprises a series of storage elements (14(1), 14(2), . . . , 14(n)), a first input (11) to receive a clock signal from a clock oscillator (28), a feedback line (20) connecting the output of a last storage element (14(n)) with an input of at least a first storage element (14(1)), a second input (22) coupled with the feedback line (20) via at least one cell (15) and wherein the output of the cell (15) is coupled to an input of at least one of the storage elements (14(1), 14(2), . . . , 14(n)).