BACKGROUND

The present invention generally relates to methods and system for integrated circuits (ICs), and more specifically, to methods and systems for secure chip identification using resistive processing units (RPUs) as a physically unclonable function.

A physical unclonable function (sometimes also called physically unclonable function), or PUF, is a physical object that for a given input and conditions (challenge), provides a physically-defined “digital fingerprint” output (response) that serves as a unique identifier, most often for a semiconductor device such as a microprocessor. A PUF is a physical entity embodied in a physical structure. PUFs are usually implemented in integrated circuits (ICs) and are typically used in applications with high security requirements. ICs (also referred to as a chip or a microchip) include a large number electronic devices that form the electronic circuits on the wafer. The wafer can be a semiconductor material, such as, for example, silicon or other materials.

SUMMARY

A non-limiting example of computer-implemented method for identification includes biasing, using a control system, a crossbar array of resistive processing units (RPUs) under a midrange condition, the midrange condition causing resistances of the RPUs to result in a random output of low values and high values in about equal proportions. The computer-implemented method includes reinforcing, using the control system, the low values and the high values of the random output by setting the resistances of the RPUs to a state that forces the low values and the high values having resulted from the midrange condition. Reinforcing the low values and the high values makes the random output permanent even when the crossbar array of the RPUs is not biased under the midrange condition. Also, the computer-implemented method includes recording, using the control system, a sequence of the low values and the high values of the random output responsive to reinforcing the low values and the high values of the random output.

A non-limiting example of computer program product includes a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to perform operations. The operations include biasing a crossbar array of resistive processing units (RPUs) under a midrange condition, the midrange condition causing resistances of the RPUs to result in a random output of low values and high values in about equal proportions. The operations include reinforcing the low values and the high values of the random output by setting the resistances of the RPUs to a state that forces the low values and the high values having resulted from the midrange condition. Reinforcing the low values and the high values makes the random output permanent even when the crossbar array of the RPUs is not biased under the midrange condition. Also, the operations include recording a sequence of the low values and the high values of the random output responsive to reinforcing the low values and the high values of the random output.

A non-limiting example of a system includes a memory having computer readable instructions, and one or more processors for executing the computer readable instructions, the computer readable instructions controlling the one or more processors to perform operations. The operations include biasing a crossbar array of resistive processing units (RPUs) under a midrange condition, the midrange condition causing resistances of the RPUs to result in a random output of low values and high values in about equal proportions. The operations include reinforcing the low values and the high values of the random output by setting the resistances of the RPUs to a state that forces the low values and the high values having resulted from the midrange condition. Reinforcing the low values and the high values makes the random output permanent even when the crossbar array of the RPUs is not biased under the midrange condition. The operations include recording a sequence of the low values and the high values of the random output responsive to reinforcing the low values and the high values of the random output.

Additional technical features and benefits are realized through the techniques of the present invention. Embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed subject matter. For a better understanding, refer to the detailed description and to the drawings.

