Physically unclonable functions based on non-linearity of sub-threshold operation

摘要

An electronic circuit for implementing a physically unclonable function. The electronic circuit includes duplicate circuits, referred to as “circuit primitives,” that generate a first and a second output voltage based on the received input, referred to as a “challenge.” The electronic circuit further includes a comparator coupled to the circuit primitives and generates an output based on the difference between the first and second output voltages. While the circuit primitives contain duplicate circuitry, the circuit primitives may generate a different output voltage due to a particular set of transistors in the circuit primitives operating in the sub-threshold region whose gates are tied to ground and whose sub-threshold current, the magnitude of which is random based on the threshold voltage variation of the set of transistors, is used to affect the value of the output voltage.

主权项

1. An electronic circuit for implementing a Physically Unclonable Function (PUF), the electronic circuit comprising:
a first and a second circuit primitive configured to generate a first and a second output voltage, respectively, wherein said first and second circuit primitives are duplicates of one another; a challenge inputted to said first and second circuit primitives; and a comparator coupled to said first and second circuit primitives, wherein said comparator generates an output based on a difference between said first and second output voltages; wherein each of said first and second circuit primitives comprises:
one or more circuit blocks, wherein each of said one or more circuit blocks comprises:
a first plurality of series-connected transistors that operate in a sub-threshold region, wherein a gate of each of said first plurality of series-connected transistors is tied to ground or to an internal node, wherein a drain of a first transistor of said first plurality of series-connected transistors is coupled to an output node; anda second plurality of transistors that are in parallel to said first plurality of series-connected transistors, wherein a drain of a first transistor of said second plurality of transistors is coupled to said output node, wherein a gate of each of said second plurality of transistors receives a value of one bit of said challenge; a first transistor coupled to a source of a second transistor of said first plurality of series-connected transistors and coupled to a source of a second transistor of said second plurality of transistors in response to having two or more of said circuit blocks, wherein said first transistor is controlled by an input that corresponds to a logical operation of each value for each bit of said challenge; wherein each of said first and second output voltages of said first and second circuit primitives, respectively, is determined based on current that flows through said first plurality of series-connected transistors of said first and second circuit primitives, respectively, whose magnitude is random based on a threshold voltage variation of said first plurality of series-connected transistors.