SRAM PUF Authentication via Cell Read Speed Comparison
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Solution Overview
Problem
Conventional physically unclonable functions (PUFs) based on power-on states of static random-access memory (SRAM) devices face issues with power consumption and reliability due to environmental parameter dependencies, leading to inefficient signature generation and limited throughput.
Innovation Solution
The proposed solution generates a PUF signature by comparing the reading speeds of adjacent memory cells in a memory device, eliminating the need for power cycling and reducing environmental parameter influence, thus enhancing reliability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PUFs use power-on states of SRAM devices for authentication, then signature generation can be performed, but power consumption increases and reliability decreases due to environmental parameter dependencies
Solution Approach 1:
The patent extracts the PUF signature generation process from the power-on state dependency by using read operations at stable operating conditions. Instead of relying on the power-on state of SRAM cells which is influenced by environmental parameters, the invention extracts timing information from read operations that can be performed repeatedly under controlled conditions, thereby eliminating the need for power cycling and reducing sensitivity to environmental variations.
Solution Approach 2:
The patent performs preliminary characterization of memory cell read speeds during manufacturing or initial operation. The measured read speeds are stored and used as reference values for subsequent authentication operations. This preliminary action eliminates the need to perform power-on state measurements during actual authentication, reducing both power consumption and environmental parameter dependencies while maintaining signature reliability.
2Productivity
If conventional PUFs use power-on states of SRAM devices for authentication, then signature generation can be performed, but signature generation speed decreases and throughput is limited
Solution Approach 1:
The patent enables continuous authentication operations by eliminating the power cycling requirement. Instead of requiring the device to power on and measure SRAM states (which is a discrete, time-consuming operation), the invention allows multiple authentication operations to be performed continuously by simply reading memory cells at different addresses. This continuous operation mode significantly increases throughput and reduces the time loss associated with repeated power-on events.
Solution Approach 2:
The patent performs preliminary measurement and storage of read speeds for multiple memory cell locations. During authentication, pre-stored challenge-response pairs are retrieved and compared, eliminating the need for time-consuming real-time measurements during each authentication event. This preliminary characterization enables rapid authentication with high throughput.
3Reliability
If conventional PUFs use power-on states of SRAM devices, then authentication can be performed, but environmental parameter dependencies reduce reliability
Solution Approach 1:
The patent replaces the physical mechanism of power-on state measurement (which is highly sensitive to environmental parameters like temperature and voltage) with an electrical measurement of read operation timing. By measuring the time required to read data from memory cells at stable operating conditions, the invention substitutes a more stable electrical measurement for the environmentally sensitive physical state measurement, thereby improving reliability and reducing environmental parameter influence.
Data Source
AI summary
A memory device includes a memory cell array comprising a plurality of memory cells wherein each of the plurality of memory cells is configured to be in a data state, and a physically unclonable function (PUF) generator. The PUF generator further includes a first sense amplifier, coupled to the plurality of memory cells, wherein while the plurality of memory cells are being accessed, the first sense amplifier is configured to compare accessing speeds of first and second memory cells of the plurality of memory cells, and based on the comparison, provide a first output signal for generating a first PUF signature.