Stable probing-resilient physically unclonable function (PUF) circuit
First Claim
1. A physically unclonable function (PUF) circuit comprising:
- a bit node and a bit bar node;
a first inverter and a second inverter that are cross-coupled between the bit node and the bit bar node;
a first pre-charge transistor coupled between the bit node and a power supply rail;
a second pre-charge transistor coupled between the bit bar node and the power supply rail, the first and second pre-charge transistors to receive a clock signal via respective first and second clock paths;
a first delay chain disposed on the first clock path;
a second delay chain disposed on the second clock path; and
control circuitry to;
pass the clock signal to the first and second pre-charge transistors during a bit generation mode to generate a PUF bit at the bit node with a first value; and
write a second value to the bit node during a delay hardening mode, the second value being a logical inverse of the first value to provide a differential delay in the first and second clock paths.
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Accused Products
Abstract
Embodiments include apparatuses, methods, and systems for a physically unclonable function (PUF) circuit. The PUF circuit may include an array of PUF cells to generate respective PUF bits of an encryption code. Individual PUF cells may include first and second inverters cross-coupled between a bit node and a bit bar node. The individual PUF cells may further include a first pre-charge transistor coupled to the bit node and configured to receive a clock signal via a first clock path, and a second pre-charge transistor coupled to the bit bar node and configured to receive the clock signal via a second clock path. Features and techniques of the PUF cells are disclosed to improve the stability and/or bias strength of the PUF cells, to generate a dark bit mask for the array of PUF cells, and to improve resilience to probing attacks. Other embodiments may be described and claimed.
25 Citations
25 Claims
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1. A physically unclonable function (PUF) circuit comprising:
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a bit node and a bit bar node; a first inverter and a second inverter that are cross-coupled between the bit node and the bit bar node; a first pre-charge transistor coupled between the bit node and a power supply rail; a second pre-charge transistor coupled between the bit bar node and the power supply rail, the first and second pre-charge transistors to receive a clock signal via respective first and second clock paths; a first delay chain disposed on the first clock path; a second delay chain disposed on the second clock path; and control circuitry to; pass the clock signal to the first and second pre-charge transistors during a bit generation mode to generate a PUF bit at the bit node with a first value; and write a second value to the bit node during a delay hardening mode, the second value being a logical inverse of the first value to provide a differential delay in the first and second clock paths. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A physically unclonable function (PUF) circuit comprising:
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a bit node and a bit bar node; a first inverter and a second inverter that are cross-coupled between the bit node and the bit bar node; a first pre-charge transistor coupled between the bit node and a power supply rail; a second pre-charge transistor coupled between the bit bar node and the power supply rail, the first and second pre-charge transistors to receive a clock signal via respective first and second clock paths; a programmable delay chain disposed on the first clock path; and mask generation circuitry coupled to the programmable delay chain to; control the programmable delay chain to provide a series of different delay values on the first clock path, wherein the PUF circuit is to generate respective output bits associated with individual delay values of the series of delay values; and determine a bias strength of the PUF circuit based on the output bits. - View Dependent Claims (14, 15, 16, 17)
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18. An apparatus comprising:
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a clock terminal to receive a clock signal; a physically unclonable function (PUF) cell coupled to the clock terminal to receive the clock signal, the PUF cell to perform multiple instances of a bit generation process, responsive to the clock signal, to generate respective output bits at a bit node of the PUF cell; a counter coupled to the bit node to count a number of instances for which the output bit has a first logic value; and processing circuitry coupled to the bit node, the processing circuitry to; determine that a value of a PUF bit associated with the PUF cell is the first logic value if the counted number is above a first threshold; determine that the value of the PUF bit is a second logic value if the counted number is below a second threshold that is less than the first threshold; and mark the PUF bit as a dark bit if the counted number is between the first and second thresholds. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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Specification