PUF Enrollment Using SRAM Segments and Anti-Aging
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Solution Overview
Problem
Conventional PUF systems face challenges in multiple enrollments and security access across separate secure areas without additional hardware, as manufacturing variations and physical semiconductor migration affect SRAM cell states, leading to security compromises.
Innovation Solution
A method for multiple enrollments of a PUF using a single SRAM segment, where a first and second PUF key are created by combining the PUF response with activation codes, applying error correction, and using a random number generator to generate secret strings, eliminating the need for extra dedicated hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple physical SRAM segments are used to implement multiple PUFs, then multiple parties can access separate secure areas, but hardware cost increases
Solution Approach 1:
The patent enables a single PUF segment to serve multiple functions by allowing multiple enrollment operations that generate different secret strings and helper data. The same physical PUF resource can authenticate different parties (manufacturer, customer, service center) and protect different secure areas, eliminating the need for multiple dedicated PUF instances
Solution Approach 2:
The patent segments the logical functionality into multiple enrollment instances within a single physical PUF segment. Each enrollment creates a separate authentication pathway with its own secret string and helper data, allowing the single PUF to be virtually divided into multiple functional units for different security domains
2Reliability
If PUF key is reconstructed frequently, then security is maintained without stored keys, but physical semiconductor migration affects SRAM cell states
Solution Approach 1:
The patent performs anti-aging procedures in advance during enrollment operations to compensate for future semiconductor migration effects. By pre-adjusting the helper data and secret strings to account for expected drift, the system maintains reliable key reconstruction despite frequent operations and physical degradation over time
Solution Approach 2:
The system incorporates error correction codes and verification mechanisms that provide feedback on PUF response quality. This allows the system to detect and correct deviations caused by semiconductor migration, maintaining security reliability even as physical conditions change over time
3Stability of the object's composition
If PUF response is preserved through anti-aging, then initial state is maintained, but additional processing steps are required
Solution Approach 1:
The patent combines the anti-aging compensation process with the enrollment operation itself. Rather than treating anti-aging as a separate post-processing step, the system integrates drift compensation into the secret string generation and helper data creation process, performing both functions in a unified enrollment procedure
Data Source
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AI summary
A data processing system having a PUF and method for providing multiple enrollments, or instantiations, of the PUF are provided. A PUF segment includes a plurality of SRAM cells on an integrated circuit. A PUF response from the PUF segment is used to create a first activation code and a first PUF key. A second PUF key may be created from the PUF response. Initially, during a second enrollment, the PUF response is combined with the first activation code to reproduce a codeword. The first secret string is reconstructed by encoding the codeword. The codeword is combined with the first activation code to reproduce the PUF response. Inverse anti-aging is applied to the PUF response. Then a second secret string is generated using a random number generator (RNG). The second secret string is encoded to produce a new codeword. The new codeword is combined with the recovered PUF response to create a second activation code. The second activation coded is hashed with the second secret string to provide a second PUF key.