Electronic physical unclonable functions
Inventors
Lewis, James M • Walther, Dane R • Horn, Paul H
Assignees
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Publication Number
US-9171144-B2
Publication Date
2015-10-27
Expiration Date
Abstract
An electronic asymmetric unclonable function applied to an electronic system being evaluated includes an electronic system and an AUF array electronically associated with the electronic system. The AUF array includes a plurality of non-identical cells. Each of the non-identical cells includes a test element representing a characteristic of the electronic system being evaluated and a measurement device evaluating the test element. A comparison unit processes an output of the measurement device to provide a multi-bit output value representing a magnitude of differences.
Core Innovation
The disclosed invention provides an electronic asymmetric unclonable function applied to an electronic system being evaluated, in which an integrated circuit is associated with an asymmetric unclonable function array. The array includes a plurality of non-identical cells of different constructions, where each cell includes a test element comprising an oscillator representing a characteristic of the electronic system being evaluated and a measurement device comprising a binary counter that evaluates the test element to provide an output value.
Each test element of the non-identical cells incorporates different arrangements of delay elements and routing structures, so that the cells are non-identical with different delay or different structural elements. The time interval over which the measurement device evaluates operation of the test element is adjusted based on temperature, voltage or age, and output values of the measurement device are processed by a comparison unit to provide a multi-bit output value for each test representing a magnitude of differences between the non-identical cells.
The multi-bit output values are applied in comparing integrated circuits to identify differences in the integrated circuits for identification of counterfeit or modified electronics. The described approach contrasts multi-bit output values with single-bit symmetric PUFs by using measurement outputs that represent magnitudes of differences, and it further supports generation and use of device-identification information derived from the scaled or compensated differences for authentication and cryptographic key derivation.
Claims Coverage
The document includes one independent claim defining the AUF-based authentication arrangement, plus multiple dependent claims that refine the implementation and environmental compensation/scaling aspects. Across the set, the inventive features are centered on an asymmetric non-identical-cell AUF with oscillator-based test elements, binary-counter measurement, time-interval adjustment based on temperature, voltage or age, and multi-bit comparison for counterfeit or modified electronics identification.
Asymmetric unclonable function array with non-identical cells
An asymmetric unclonable function array electronically associated with the integrated circuit, including a plurality of non-identical cells of different constructions including different delay or different structural elements, where each cell is built with different arrangements of delay elements and routing structures.
Oscillator test element with binary-counter measurement device
A test element comprising an oscillator representing a characteristic of the electronic system being evaluated and a measurement device comprising a binary counter evaluating the test element to provide an output value for each non-identical cell.
Time interval adjustment based on environmental factors
A time interval over which the measurement device evaluates operation of the test element that is adjusted based on temperature, voltage or age.
Comparison unit producing multi-bit magnitude-of-differences outputs
A comparison unit processing output values of the measurement device of the plurality of non-identical cells to provide a multi-bit output value for each test representing a magnitude of differences between the non-identical cells.
Multi-bit comparison for identifying counterfeit or modified electronics
Applying the multi-bit output value in comparing integrated circuits to identify differences in the integrated circuits for identification of counterfeit or modified electronics.
Measurement time interval adjustment with environmental compensation and scaling
Configuration in which the measurement device adjusts a measurement time interval using environmental compensation and further scales data.
Ring-oscillator test element
An oscillator configured as a ring oscillator as the test element.
Scaling by subtracting one evaluation output from another
Scaling of the measurement data by subtracting one evaluation output value from another evaluation output value (including subtraction used for scaling the data).
Reference cell including comparator and signal generating device
A reference cell in which a comparator and a signal generating device are included.
Overall, the claim set covers an AUF authentication approach that uses non-identical cells with oscillator-based test elements, binary-counter measurement, environmental adjustment of the evaluation time interval, and a comparison unit that outputs multi-bit magnitude-of-differences used to compare integrated circuits for counterfeit or modified electronics identification, with dependent refinements addressing environmental compensation, ring oscillators, scaling via subtraction, and reference-cell components such as a comparator and a signal generating device.
Stated Advantages
Enables identifying differences between integrated circuits for identification of counterfeit or modified electronics.
Uses multi-bit output values representing a magnitude of differences between non-identical cells.
Adjusts evaluation time interval based on temperature, voltage or age to account for environmental effects.
Documented Applications
Comparing integrated circuits for identification of counterfeit or modified electronics using the AUF outputs.
Device identification/authentication using scaled/compensated multi-bit differences derived from the AUF array.
Cryptographic key derivation using family characteristics and scaled data derived from the AUF measurements.
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