MEMS-based physically unclonable function (PUF) for mechanical trust extension

Abstract

To provide methods and systems that extend the reach and benefit of PUFs to other systems and environments.SOLUTION: A system 100 includes: a physically unclonable function (PUF) circuit having an input, an output, and an embedded microelectromechanical system (MEMS) device; and an interface 108 that is coupled to the PUF circuit and is coupled to a mechanical structure. The embedded MEMS device detects a parameter or characteristic associated with the mechanical structure and provides an input to the PUF circuit based on the detected parameter, whereby the PUF circuit uses the input from the embedded MEMS device to extend trust to the mechanical structure.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 516,949, filed Aug. 1, 2023, entitled "DUAL USE MICROELECTROMECHANICAL SYSTEM (MEMS) DEVICE," the contents of which are incorporated by reference in their entirety.

[0002] This application is a continuation of U.S. patent application Ser. No. 18 / 661,373 (Attorney Docket No. H232672-US2), entitled "DUAL USE MICROELECTROMECHANICAL SYSTEM (MEMS) DEVICE", filed on the same day as this application, U.S. patent application Ser. No. 18 / 661,400 (Attorney Docket No. H233692-US), entitled "CODEPENDENT PHYSICAL UNCLONABLE FUNCTION / RANDOM NUMBER GENERATOR PAIRING FOR PHYSICAL PROVENANCE", and U.S. patent application Ser. No. 18 / 661,426 (Attorney Docket No. H233694-US), entitled "ACTIVE TRANSISTOR PHYSICAL UNCLONABLE FUNCTION (PUF) CIRCUIT WITH MEMS No. 18 / 661,437, filed on the same day herewith, entitled "ACTIVE TRANSISTOR RANDOM NUMBER GENERATOR (RNG) CIRCUIT WITH MEMS ENTROPY," all of which are incorporated herein by reference in their entireties. [Background technology]

[0003] A Physically Unclonable Function (PUF) is a physical object that, for a given input and condition (challenge), provides a physically defined "digital fingerprint" output (response) that serves as a unique identifier. PUFs are commonly used with semiconductor devices such as microprocessors, field programmable gate arrays (FPGAs), and other integrated circuits. The digital fingerprint of a particular PUF is based on unique differences between devices that occur naturally during the semiconductor manufacturing process. PUFs are beneficial for applications with high security requirements such as cryptography, Internet of Things (IoT) devices, and privacy protection. However, there are many systems and structures that would benefit from PUF-like protection that are not conducive to working with traditional PUF circuits.

[0004] Thus, there is a need in the art for methods and systems that extend the reach and benefits of PUFs to other systems and environments. Summary of the Invention

[0005] A system is provided that includes a physical unclonable function (PUF) circuit having an input, an output, and an embedded microelectromechanical system (MEMS) device, and an interface configured to couple to the PUF circuit and to be coupled to a mechanical structure, where the embedded MEMS device is configured to detect a parameter or characteristic associated with the mechanical structure and provide an input to the PUF circuit based on the detected parameter, whereby the PUF circuit extends trust to the mechanical structure using the input from the embedded MEMS device. [Brief description of the drawings]

[0006] Embodiments of the present invention may be more readily understood, and further advantages and uses thereof may become more readily apparent, when considered in light of the description of the preferred embodiments and the following drawings. [Figure 1] FIG. 1 is a block diagram of one embodiment of a system including a physical unclonable function (PUF) circuit, the PUF circuit including an embedded microelectromechanical systems (MEMS) device for extending trust of the PUF circuit to an attached mechanical structure. [Diagram 2] FIG. 13 is a block diagram of another embodiment of a system including a PUF circuit with an embedded MEMS device that provides a security seal for a structure. [Diagram 3] FIG. 1 is a block diagram of another embodiment of a system having a mechanical assembly including a PUF circuit with embedded MEMS that can extend trust of the PUF circuit to the mechanical assembly. [Figure 4] FIG. 1 is a block diagram of another embodiment of a system including a PUF circuit having multiple embedded MEMS devices to extend trust of the PUF circuit to an attached mechanical structure. [Figure 5A] FIG. 2 is a perspective view of one embodiment of a PUF circuit having an embedded MES device, the PUF circuit having Swiss cheese pattern openings in the structure of the PUF circuit. [Figure 5B] FIG. 5B is a perspective view of the PUF circuit of FIG. 5A embedded in potting material and attached to a mechanical structure. [Figure 6] 1 is a flow chart of one embodiment of a method for extending trust of a physical unclonable function (PUF) circuit to a machine structure. [Figure 7] FIG. 1 is a block diagram of one embodiment of a system for providing secure communication between nodes implementing PUF circuits with embedded MEMS devices that extend trust to mechanical systems.

[0007] According to common practice, the various features described are not drawn to scale but are drawn to emphasize features relevant to the present invention. Reference characters denote like elements throughout the figures and text. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of example specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized, and that logical, mechanical, and electrical changes may be made without departing from the scope of the invention. Accordingly, the following detailed description is not to be taken in a limiting sense.

[0009] Embodiments of the present invention extend the trust associated with physical unclonable function (PUF) circuits to hardware as well as other systems and objects. These embodiments provide a solution embedded in a hardware system that can provide assurance of the identity of the physical hardware. This capability provides a means to improve the ability to meet and maintain network integrity, for example. Embodiments of the present invention provide a system that can be integrated into an electronic system via mounting, packaging, and potting that provides a unique digital identity to software such that the resulting digital identity permanently changes with any physical change. The identity can then be encoded into the cryptographic process of the hardware system. Embodiments of the present invention provide validation of the identity of the hardware such that changing the hardware changes the identifier.

[0010] The present invention is accomplished by creating a Micro-Electro-Mechanical System (MEMS) sensor or device designed to change its device RLC (resistance-capacitance-inductance) properties in response to a physical property (such as the physical stress of mounting). Based on the physical property, the present invention creates a unique output from a physical Unclonable Function (PUF) circuit that can uniquely identify the sensor instance. The present invention ensures that the output of the PUF circuit changes permanently based on the modification and that the output of the PUF circuit is unique to each instance. In addition, the PUF circuit provides a unique output and is unpredictable while producing a stable PUF output over the expected product environment including aging, temperature, movement, etc. The concept of extending trust stems from the concept that by using a MEMS device as a sensor that can be affected by the surface it is attached to, the identity of the surface to which the MEMS device is attached is protected since the MEMS device in the PUF circuit can detect changes to the surface.

[0011] 1 is a block diagram of one embodiment of a system 100 including a physical unclonable function (PUF) circuit 102. The PUF circuit 102 includes an embedded microelectromechanical system (MEMS) device 104 to extend trust of the PUF circuit 102 to a mechanical structure 106 attached to the PUF circuit 102 via an interface 108. By way of example and without limitation, the mechanical structure 106 may include an airframe or other component of an aircraft or other vehicle, a motor, an engine, a power plant, a flywheel or generator, a bearing, an electronic device, glass (windows), or any other structure having a property whose change in property can be detected by a MEMS device. The PUF circuit 102 extends trust to the mechanical structure 106, for example, by being able to detect failure of the structure, integrity of the structure, whether the structure has been tampered with, changes in the proximity of the structure, damage to the structure, or by sounding an alarm when the structure is moved without authorization. In some embodiments, the PUF circuit 102 incorporates aspects of the PUF circuits described in co-pending applications Ser. Nos. ________ and _________ (Attorney Docket Nos. H233692-US and H233694-US), both of which are incorporated by reference above.

[0012] The interface 108 includes any number of mechanisms for attaching the PUF circuit 102 to the mechanical structure 106. For example, the interface 108 includes different types of adhesives, potting materials, welding, and other conventional methods to establish a physical relationship between components or objects of the system with trust extended from the PUF circuit 102. In one embodiment, the PUF circuit 102 is designed to be embedded in a potting material. In this example, the PUF circuit 102 includes a structure having a Swiss cheese pattern as shown and described below with respect to Figures 5A and 5B, which has openings that allow the PUF circuit 102 to be embedded in contact with the sides, front, and back of the mechanical structure 106.

[0013] Advantageously, the PUF circuit 102 includes a MEMS device 104 that is sensitive to some characteristic or parameter of the environment of the mechanical structure 106 such that the MEMS device 104 can detect changes in the mechanical structure 106. Additionally, the MEMS device 104 may be sensitive to the physical placement and modification of the mechanical structure 106. For example, if the mechanical structure 106 is removed and replaced, the output of the MEMS device 104 will change, causing the output of the PUF circuit 102 to also change, indicating a problem with the mechanical structure 106.

[0014] In the embodiment shown in FIG. 1, a single PUF circuit 102 is shown attached to the mechanical structure 106. In other embodiments, multiple PUF circuits 102 may be attached to the mechanical structure 106 via an interface 108. Advantageously, by including a MEMS device 104 with each PUF circuit 102, an operator can later qualify an additional one of the PUFs 102 as being included in the family by verifying whether the output of the additional PUF circuit 102 and MEMS device 104 is the same as that previously displayed by the previous PUF circuit 102 / MEMS device 104 under the applied environmental influences. Note that this is information known only to the PUF / MEMS group user.

[0015] The PUF circuit 102 receives system inputs and generates a physical unclonable function output. In addition, the PUF circuit 102 receives inputs from the mechanical structure 106 via the MEMS device 104. The PUF circuit 102 provides the correct response as a PUF output if the mechanical structure 106 is attached to the PUF circuit 102, is unaltered, and is functioning properly from the perspective of the MEMS device 104. If the MEMS device 104 detects a change, the output of the PUF circuit 102 will also change, thereby indicating a problem with the mechanical structure 106.

[0016] By way of example, and not limitation, the MEMS device 104 may be sensitive to temperature, vibration, pressure, motion, or any other property or parameter of the mechanical structure 106. In such a case, the MEMS device 104 will create a unique output based on its response to a particular property, parameter, configuration, or modification of the mechanical structure 106.

[0017] In one non-limiting example, the MEMS device 104 is sensitive to vibrations and the PUF circuit 102 with the MEMS device 104 is mounted on a mechanical structure 106, such as an engine. In this embodiment, the MEMS device 104 will create a unique output based on the engine it is attached to. For example, if a spark plug or other component in the engine fails, the output of the MEMS device 104 will change as detected and reported by the PUF circuit 102. This is because the output of the MEMS device 104 will change from the perspective of the PUF circuit 102 due to data collected from the MEMS device 104. In other embodiments, the mechanical structure 106 can be any suitable mechanical component of a system that can benefit from PUF-like protection.

[0018] In another embodiment, the MEMS device 104 can generate a small mechanical signal, e.g., vibration, heat, or acoustic, and measure a response to the small mechanical signal from the mechanical structure 106. For example, the MEMS device 104 can initiate a vibration signal 110 that is injected into the mechanical structure 106. The mechanical structure 106 responds to the vibration signal 110 from the MEMS device 104. The MEMS device 104 further measures a response 112 to the vibration signal 110 as an input to the PUF circuit 102. The vibration signal 110 from the MEMS device 104 resonates differently based on the type of material, mass, and other mechanical properties of the mechanical structure 106 to have a discernible impact on the PUF result from the PUF circuit 102.

[0019] In other embodiments, the PUF circuit 102 is designed to couple to other circuits via a permanent or temporary electrical connection at an interface (I / F) 114. The interface 114 includes any suitable circuitry for providing communication between the PUF circuit 102 and an external system. Thus, the interface 114 includes one or more of capacitive coupling, inductive coupling, wired coupling, and radio frequency coupling. In one example, the PUF circuit 102 can be coupled to an RF ID tag to enable wireless reading of the PUF response to check the health of the machine structure 106. The PUF circuit 102 can be wired to a machine equipment, such as an example of an engine, where the PUF circuit 102 provides different states based on the engine's state. FIG. 6 also provides an example of an interface 114 in a system having multiple nodes associated with a PUF circuit with an embedded MEMS device.

[0020] 2 is a block diagram of another embodiment of a system 200 including a PUF circuit 202 with an embedded MEMS device 204 that provides a security seal for a structure 206. In this embodiment, the structure 206 is a package or other object that is sealed to protect its contents from disclosure to non-designated parties. The PUF circuit 202 validates the security seal status based on an input from the embedded MEMS device 204. The MEMS device 204 is selected to be capable of detecting an appropriate change in a characteristic or property of the security seal of the structure 206 to detect tampering or destruction of the seal on the structure 206. For example, the characteristic or property of the security seal may be a mechanical or electrical property of an adhesive or foil associated with the security seal that is detectable by the MEMS device 204.

[0021] The PUF circuit 202 generates a physical unclonable function output. By reading this output, the system 200 provides the status of the security seal. If the package is opened or tampered with, the output of the MEMS 204 changes and is reported to the PUF circuit 202. This in turn changes the output of the PUF circuit 202 when a challenge input is provided to the PUF circuit 202.

[0022] 3 is a block diagram of another embodiment of a system 300 for extending trust to a mechanical system having a mechanical assembly 301 including a PUF circuit 302 with an embedded MEMS device 303 capable of extending trust of the PUF circuit 302 to the mechanical assembly 301. In this example, the PUF circuit 302 is mounted to a chip device 306 via an interface 304. The chip device 306 is further mounted on a chip package 308, which is in turn mounted to a circuit board assembly 310. A heat spreader 312 is further mounted between the PUF circuit 302 and a heat bridge 314, thereby encapsulating the components of the system 300 to form the mechanical assembly 301. Once manufactured, pressure is applied to the components within the mechanical assembly 301 and sensed by the MEMS device 303.

[0023] In this embodiment, the PUF circuit 302 receives a system input (challenge) and generates a physically unclonable function output (response) indicating whether the mechanical assembly 301 has been tampered with based on the output from the MEMS device 303. For example, the MEMS device 303 may be pressure sensitive and may detect changes in the mechanical assembly 301, e.g., due to changes in pressure caused by changes to the mechanical assembly 301. Such changes are reflected in the output of the PUF circuit 302, such that the MEMS device 303 extends the trust provided by the PUF circuit 302 to the mechanical assembly 301.

[0024] In security applications, it may be desirable to be able to observe the challenge (system input) and response (PUF output) outside of the system 300. In such a case, the chip device 306 provides the challenge (system input 316) and receives the response (PUF output 318). This provides PUF validation at the hardware level to determine if the system 300 is good (uncompromised). For example, this embodiment can be used to verify that the system 300 is still under warranty because the assembly has not been opened.

[0025] 4 is a block diagram of another embodiment of a system 400 including a PUF circuit 402 with multiple embedded MEMS devices 404-1-404-N to extend the trust of the PUF circuit 402 to an attached mechanical structure 406. In this embodiment, the PUF circuit 402 operates on a large mechanical structure 406 that is attached to the PUF circuit 402 by an interface 408. The system 400 is similar to the system 100 of FIG. 1, except that the system 400 includes multiple MEMS devices 404-1-404-N. In this embodiment, the MEMS device 404-1 injects a small mechanical signal, e.g., a vibration signal 410, into the mechanical structure 406. Each MEMS device 402-1-402-N generates a PUF value based on the vibration signal 410 at a different point along the material that makes up the mechanical structure 406. If a change occurs to the mechanical structure 406, such as destroying the material forming the mechanical structure 406, the path of the vibrations responsive to the vibration signal 410 will also change, and therefore the PUF response from the associated MEMS sensors 402-1 to 402-N will also change, along with the output of the PUF circuit 402.

[0026] 5A and 5B illustrate another embodiment of a PUF circuit that extends trust to a mechanical structure. As described above with respect to FIG. 1, in this embodiment, FIG. 5A illustrates a PUF circuit 502 having a Swiss cheese structure that includes a number of openings 504 formed in the PUF circuit 502. As shown in FIG. 5B, the PUF circuit 502 is attached to the mechanical structure 508 using an adhesive or potting material 506 that surrounds the PUF circuit 502 and passes through the openings 504. In some embodiments, the adhesive or potting material 506 also covers the edges of the PUF circuit 502, such that the PUF circuit 502 is completely covered by the adhesive or potting material 506. Advantageously, the Swiss cheese pattern of openings 504 increases the complexity of the interface between the PUF circuit 502 with the embedded MEMS device and the mechanical structure 508. This structure makes it more difficult to tamper with or disrupt the operation of the PUF circuit 502, thereby improving the extension of trust from the PUF circuit 502 to the machine structure 508.

[0027] 6 is a flow chart of one embodiment of a method 600 for extending trust of a physical unclonable function (PUF) circuit to a machine structure. Method 600 may be implemented in any suitable PUF circuit, such as the PUF circuits shown and described above with respect to any one or more of FIGS. 1-4.

[0028] The method 600 begins at 601 with a PUF circuit including an embedded MEMS device. In one embodiment, the MEMS device is sensitive to one or more of temperature, vibration, pressure, or motion. In another embodiment, the MEMS device is sensitive to physical placement and modification of the mechanical structure. In a further embodiment, the MEMS device senses a response to a small mechanical signal injected into the mechanical structure. The embedded MEMS device detects a parameter or characteristic of the mechanical structure. At block 603, the method 600 receives a challenge at an input of the PUF circuit. At block 605, the PUF circuit generates a PUF output that is based on or influenced by the output of the MEMS device. If the MEMS device detects a change in the parameter or characteristic of the mechanical structure, the output of the MEMS device will change, and therefore the output of the PUF circuit will also change. Thus, a change in the output of the PUF circuit assisted by the MEMS device indicates that there has been a change in the underlying mechanical structure. Thus, the method 600 extends the trust of the PUF circuit to the mechanical structure by embedding the MEMS device in the PUF circuit. At block 607, method 600 optionally provides the response of the PUF circuit to an external system.

[0029] A system of nodes that extends trust to machine structures using PUFs with embedded MEMS devices 7 is a block diagram of a system 700 including secure communications between nodes 701 that use embedded MEMS devices to extend PUF-based trust to machine structures in an exclusive community over a network 703. Examples of systems that use embedded MEMS devices to provide PUF-based extension of trust to machine structures are described in more detail above with respect to FIGS.

[0030] In Figure 7, system 700 is illustrated having two nodes 701, labeled as node 701-A and node 701-B. It should be understood that system 700 is not limited to a system having two nodes 701, as system 700 may include any suitable number of nodes 701. Additionally, Figure 7 illustrates node 701-A coupled to node 701-B via network 703. It should be understood that network 703 may include one or more of wireless access points, communication links, a wide area network (WAN), a local area network (LAN) such as an Ethernet network, a group of cables, optical fibers, direct connections, or any other suitable system for communicatively coupling the nodes 701 of system 700.

[0031] In system 700, node 701-A and node 701-B each include similar components for secure communications and for PUF-based extension of trust to machine structures. Thus, for simplicity and clarity, only node 701-A will be detailed using reference numbers for each component followed by the designator "-A". It will be understood that similar components are also included in node 701-B, identified by the same reference numbers followed by the designator "-B".

[0032] Node 701-A includes a PUF circuit 702-A with an embedded MEMS device 704-A to support PUF-based extension of trust to machine structure 708-A via interface 706-A. As mentioned above, various embodiments of the PUF circuit are shown and described with respect to Figures 1, 2, 3, 4, 5A, 5B, and 6.

[0033] Node 701-A also includes a system 710-A having one or more processors and memory for storing software or instructions for implementing functions for secure communication for node 701-A. Thus, system 710-A enables PUF circuit 702-A to extend trust to machine structure 708-A by establishing a secure communication channel with another node over network 703. Through this secure communication channel, PUF circuit 702-A is able to receive a challenge input from the other node. Furthermore, through this secure communication channel, PUF circuit 702-A is able to securely transmit a response generated based in part on the output of MEMS 704-A, such that the trust created by PUF circuit 702-A is extended to machine structure 708-A by securely communicating the response over network 703 to node 701 that initiated the challenge to node 701-A.

[0034] The system 710-A includes a provenance function 712-A, a random number generator (RNG) 714-A, an encryption / decryption circuit 716-A, and a verification / validation function 718-A. The RNG 714-A uses random data to generate random numbers used by the encryption / decryption circuit 716-A to securely transmit and receive data over the network 703. Additionally, the provenance function 712-A uses unique data to implement a second physically unclonable function (PUF) for the node 701-A. The node 701-A also uses the provenance function 712-A in conjunction with the verification / validation function 718-A to implement authentication that data received or transmitted by the node 701-A is from an authorized node in the system 700. In one embodiment, RNG 714-A receives random data and provenance function 712-A receives unique data collected from a MEMS device, such as MEMS device 704-A, using the techniques described in co-pending application Ser. No. ________ (Attorney Docket No. H232672-US2), incorporated by reference above.

[0035] In FIG. 7, the system 700 also includes a master node 800 that is used to set up or manage trust relationships between the nodes 701 of the system 700 that are in the exclusive community. Specifically, in one embodiment, the system 700 uses registry entries to set up / manage the trust relationships. To do this, for example, each respective node 701 uses a provenance function 712 and unique data (such as that collected from a MEMS device as taught in the '672 application) to generate a number of registries (e.g., thousands or tens of thousands of registries). These registries uniquely identify the particular node 701 as part of the trusted system 700. The master node 800 takes the registries generated by each node 701, for example, upon node setup, and provides the registries to all other nodes 701 in the system 700. These registries are stored as part of the provenance function 712 of each node 701 in the exclusive community, and essentially become a library of authorized users within the exclusive community of the system 700. By using these registry values, a given node will only recognize data received from similarly equipped nodes. When data is received over the network 703, the receiving node uses the registry in the provenance function 712 along with the verification / validation function 718 to authenticate that the input originated from an authorized user. For example, the receiving node can verify that the node 701 sending the data generated an output of the provenance function 712 that corresponds to one of the registries provided by the master node 800 and included in its own provenance function 712.

[0036] Node 701-A also includes a transceiver 720-A that provides an interface for communicating with other nodes 701, such as node 701-B, over network 703. Although a single transceiver 720-A is shown in Figure 7, it should be understood that the single transceiver 720-A may be replaced with separate and distinct transmitter and receiver components.

[0037] In other embodiments, the master node 800 may use mechanisms other than registry values ​​to set up or manage trust relationships between nodes 701. For example, in another embodiment, the master node 800 acts as a certificate authority / certification authority (CA) for applications using asymmetric cryptography where the CA can issue digital certificates.

[0038] Glossary The following terms are defined for purposes of this specification and apply to the various embodiments described in more detail above.

[0039] Random Bit Generator (RBG): A device or algorithm that outputs a random sequence that is virtually indistinguishable from statistically independent and unbiased bits.

[0040] Deterministic Random Bit Generator (DRBG): A RBG that includes a DRBG mechanism and has (at least initially) access to a source of entropy input. A DRBG generates a sequence of bits from a secret initial value called a seed, along with other possible inputs. A DRBG is often called a pseudorandom number (or bit) generator.

[0041] Entropy Source: A combination of a noise source, a sanity test, and an optional tuning component that generates the random bit string used by the RBG.

[0042] Noise Source: A component of an entropy source that contains non-deterministic entropy generating activity (e.g., thermal noise or hard drive seek times).

[0043] True Random Number Generator: A device or algorithm that generates numbers by extracting randomness from physical phenomena.

[0044] Random Number Generator: A device or algorithm that produces sequences of numbers or symbols that cannot be reasonably predicted better than chance.

[0045] In various aspects, the system elements, method steps, or examples (e.g., devices, systems, or components thereof) described throughout this disclosure may be implemented on one or more computer systems, including central processing units (CPUs), graphics processing units (GPUs), field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), and / or similar devices with hardware to execute code to implement those elements, processes, or examples, which code is stored in non-transitory data storage devices. These devices include or function with software programs, firmware, or other computer-readable instructions to perform various method, process tasks, computations, and control functions.

[0046] These instructions are typically stored on any suitable non-transitory computer readable medium used for storing computer readable instructions or data structures. Computer readable media can be embodied as any available medium accessible by a general purpose or specialized computer or processor, or any programmable logic device. Suitable processor readable media can include storage or memory media such as magnetic or optical media. For example, storage or memory media may include volatile or non-volatile media such as conventional hard disks, Compact Disk-Read Only Memory (CD-ROM), Random Access Memory (RAM) (including but not limited to Synchronous Dynamic Random Access Memory (SDRAM), Double Data Rate (DDR) RAM, RAMBUS Dynamic RAM (RDRAM), Static RAM (SRAM), etc.), Read Only Memory (ROM), Electrically Erasable Programmable ROM (EEPROM), and Flash memory. Suitable processor-readable media may also include transmission media, such as electrical, electromagnetic, or digital signals conveyed over a communications medium, such as a network and / or wireless link.

[0047] The methods and techniques described herein may be implemented in part in digital electronic circuitry, or with a programmable processor (e.g., a special purpose processor or a general purpose processor such as a computer), firmware, software, or combinations thereof. Apparatus embodying these techniques may include suitable input and output devices, a programmable processor, and a storage medium tangibly embodying program instructions for execution by the programmable processor. Processes embodying these techniques may be implemented by a programmable processor executing a program of instructions to perform a desired function by operating on input data and generating appropriate output. The techniques may be advantageously implemented in one or more programs executable on a programmable system including at least one programmable processor coupled to receive data and instructions from and transmit data and instructions to a data storage system, at least one input device, and at least one output device. In general, the processor receives instructions and data from a read-only memory and / or a random access memory. Suitable storage devices for tangibly embodying computer program instructions and data include, by way of example, all forms of non-volatile memory, including semiconductor memory devices (EPROM, EEPROM, and Flash memory devices), magnetic disks (internal hard disk or removable disk), magneto-optical disks, and DVD disks. Any of the foregoing may be supplemented by, or incorporated in, specially-designed application-specific integrated circuits (ASICs).

[0048] Exemplary embodiments Although specific embodiments have been illustrated and described herein, those skilled in the art will recognize that any configuration that is expected to achieve the same purpose may be substituted for the specific embodiments shown. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.

[0049] Example 1 includes a system including a physical unclonable function (PUF) circuit having an input, an output, and an embedded microelectromechanical system (MEMS) device; and an interface configured to couple to the PUF circuit and to be coupled to a mechanical structure, where the embedded MEMS device is configured to detect a parameter or characteristic associated with the mechanical structure and provide an input to the PUF circuit based on the detected parameter, whereby the PUF circuit uses the input from the embedded MEMS device to extend trust to the mechanical structure.

[0050] Example 2 includes the system of example 1, where the implantable MEMS device has resistance, inductance, and capacitance (RLC) properties that change in response to parameters or characteristics of the mechanical structure.

[0051] Example 3 includes the system of any of examples 1 and 2, wherein the MEMS device comprises a MEMS sensor configured to detect a change in a surface of the mechanical structure.

[0052] Example 4 includes the system of any of Examples 1-3, wherein the interface includes an adhesive, a potting material, a weld, or other suitable method for establishing a physical relationship between the PUF circuitry and the mechanical structure.

[0053] Example 5 includes the system of any of examples 1-4, wherein the MEMS device comprises a MEMS sensor that is sensitive to physical placement and modification of the mechanical structure.

[0054] Example 6 includes the system of any of examples 1-5, wherein the MEMS device is sensitive to one or more of temperature, vibration, pressure, or motion.

[0055] Example 7 includes the system of any of Examples 1-6, wherein the MEMS device is configured to inject a small mechanical signal into the mechanical structure and is further configured to sense a response from the mechanical structure to the small mechanical signal.

[0056] Example 8 includes the system of any of Examples 1-7, further comprising an interface for providing communication between the PUF circuit and an external system.

[0057] Example 9 includes the system of any of examples 1-8, wherein the MEMS device is configured to detect a change in a characteristic or property of the security seal.

[0058] Example 10 includes a system described in any of Examples 1 to 9, wherein the PUF circuit includes a plurality of MEMS devices, one of the plurality of MEMS devices configured to inject a small mechanical signal into the mechanical structure, and each of the plurality of MEMS devices configured to sense a response from the mechanical structure to the small mechanical signal.

[0059] Example 11 includes a system comprising a chip device, a physical unclonable function (PUF) circuit having an input, an output, and an embedded microelectromechanical system (MEMS) device, an interface coupled between the PUF circuit and the chip device, a circuit board assembly, where the chip device is coupled to the circuit board assembly, a heat bridge coupled to the circuit board assembly and encapsulating the chip device, the interface, and the PUF circuit, where the circuit board assembly and the heat bridge form a mechanical assembly, and a heat spreader mounted between the PUF circuit and the heat bridge, where the PUF circuit receives a challenge at an input and generates a PUF response at an output, where the PUF response indicates whether the mechanical assembly has been tampered with based on the output of the MEMS device.

[0060] Example 12 includes the system of example 11, wherein the MEMS device comprises a MEMS sensor that senses pressure within the mechanical assembly.

[0061] Example 13 includes the system of any of examples 11 and 12, wherein the PUF response indicates that the mechanical assembly has been tampered with when the MEMS sensor detects a change in pressure on the mechanical assembly.

[0062] Example 14 includes the system of any of examples 11-13, wherein the response in the PUF output is communicated to a device external to the mechanical assembly.

[0063] Example 15 includes the system of any of examples 11-14, wherein the chip device is configured to provide a challenge to an input of the PUF circuit and receive a response from an output of the PUF circuit.

[0064] Example 16 includes a method for extending trust of a physical unclonable function (PUF) circuit to a mechanical structure, the method including detecting a parameter or characteristic of the mechanical structure using a microelectromechanical systems (MEMS) device embedded in the PUF circuit, the PUF circuit coupling to the mechanical structure via an interface, receiving a challenge at an input to the PUF circuit, and generating a response based on an output of the MEMS device that reflects the parameter or characteristic of the mechanical structure.

[0065] Example 17 includes the method of example 16, further comprising providing the response to an external system.

[0066] Example 18 includes a method as described in any of Examples 16-17, wherein detecting a parameter or characteristic of the mechanical structure includes detecting the characteristic or parameter using a MEMS device that is sensitive to one or more of temperature, vibration, pressure, or motion.

[0067] Example 19 includes the method of any of examples 16-18, wherein detecting a parameter or characteristic of the mechanical structure includes detecting the characteristic or parameter using a MEMS device that is sensitive to physical placement and modification of the mechanical structure.

[0068] Example 20 includes a method as described in any of examples 16-19, wherein detecting a parameter or characteristic of the mechanical structure includes injecting a small mechanical signal into the mechanical structure using a MEMS device and sensing a response from the mechanical structure to the small mechanical signal.

Claims

1. 1. A system comprising: A physical unclonable function (PUF) circuit (102) having an input, an output, and an embedded microelectromechanical system (MEMS) device (104); an interface (114) configured to couple to the PUF circuit and to couple to a machine structure (106); The system further comprises: an embedded MEMS device configured to detect a parameter or characteristic associated with the mechanical structure and provide an input to the PUF circuit based on the detected parameter, whereby the PUF circuit uses the input from the embedded MEMS device to extend trust to the mechanical structure.

2. The system of claim 1 , wherein the embedded MEMS device has resistance-inductance-capacitance (RLC) properties that change in response to the parameter or characteristic of the mechanical structure.

3. 1. A method for extending trust of a physical unclonable function (PUF) circuit to a machine structure, the method comprising: Detecting (601) a parameter or characteristic of the mechanical structure using a Micro-Electro-Mechanical System (MEMS) device embedded in the PUF circuit, the PUF circuit coupling to the mechanical structure via an interface; Receiving a challenge at an input to the PUF circuit (603); generating 605 a response based on an output of the MEMS device that reflects the parameter or characteristic of the mechanical structure.

Images