Quantum computing resources are now becoming easily accessible from various cloud providers. Although still in the Noisy Intermediate Scale Quantum regime, quantum computers hold promise to be able to execute novel algorithms and create invaluable data. However, just as with any other type of computing resource, they may be vulnerable to security attacks and should have defenses built into their design. This paper explores a particular threat of untrusted cloud providers, and how to protect user's quantum programs and data from the untrusted cloud provider. By leveraging trusted hardware in the quantum computer, a new obfuscation-based protection is developed based on switching of control pulses between different drive and control channels of the quantum computer. This work demonstrates that simple hardware modifications can enable dynamic, run-time pulse switching, which makes it extremely difficult for the cloud provider to decode what actual circuit is executed on the quantum computer. This work presents a basic architecture that employs pulse switching, and an extended architecture that includes use of dummy qubits for increased protection. The overhead of the proposed changes, as well as attack complexity for different types of user circuits and obfuscation levels is evaluated in this work.
Quantum computing resources are now becoming easily accessible from various cloud providers. Although still in the Noisy Intermediate Scale Quantum regime, quantum computers hold promise to be able to execute novel algorithms and create invaluable data. However, just as with any other type of computing resource, they may be vulnerable to security attacks and should have defenses built into their design. This paper explores a particular threat of untrusted cloud providers, and how to protect user's quantum programs and data from the untrusted cloud provider. By leveraging trusted hardware in the quantum computer, a new obfuscation-based protection is developed based on switching of control pulses between different drive and control channels of the quantum computer. This work demonstrates that simple hardware modifications can enable dynamic, run-time pulse switching, which makes it extremely difficult for the cloud provider to decode what actual circuit is executed on the quantum computer. This work presents a basic architecture that employs pulse switching, and an extended architecture that includes use of dummy qubits for increased protection. The overhead of the proposed changes, as well as attack complexity for different types of user circuits and obfuscation levels is evaluated in this work.
The cloud-based environments in which today's and future quantum computers will operate, raise concerns about the security and privacy of user's intellectual property. Quantum circuits submitted to cloud-based quantum computer providers represent sensitive or proprietary algorithms developed by users that need protection. Further, input data is hard-coded into the circuits, and leakage of the circuits can expose users' data. To help protect users' circuits and data from possibly malicious quantum computer cloud providers, this work presented the first hardware architecture for a trusted execution environment for quantum computers. To protect the user's circuits and data, the quantum computer control pulses are obfuscated with decoy control pulses. While digital data can be encrypted, analog control pulses cannot and this paper proposed the novel decoy pulse approach to obfuscate the analog control pulses. The proposed decoy pulses can easily be added to the software by users. Meanwhile, the hardware components of the architecture proposed in this paper take care of eliminating, i.e. attenuating, the decoy pulses inside the superconducting quantum computer's dilution refrigerator before they reach the qubits. The hardware architecture also contains tamper-resistant features to protect the trusted hardware and users' information. The work leverages a new metric of variational distance to analyze the impact and scalability of hardware protection. The variational distance of the circuits protected with our scheme, compared to unprotected circuits, is in the range of only 0.16 to 0.26. This work demonstrates that protection from possibly malicious cloud providers is feasible and all the hardware components needed for the proposed architecture are available today.
The cloud-based environments in which today's and future quantum computers will operate raise concerns about the security and privacy of user's intellectual property, whether code, or data, or both. Without dedicated security protections, quantum circuits submitted to cloud-based quantum computer providers could be accessed by the cloud provider, or malicious insiders working in the cloud provider's data centers. Furthermore, data embedded in these circuits can similarly be accessed as it is encoded using quantum gates inside the circuit. This study presents various hardware and architecture modifications that could be deployed in today's quantum computers, based on superconducting qubits, to protect both the code and data from potentially untrusted quantum computer providers or malicious insiders. Motivated by existing Trusted Execution Environments (TEEs) in classical computers, this study introduces the notion of Quantum Trusted Execution Environments (QTEEs) which leverage trusted hardware to hide or obfuscate quantum circuits executing on a remote, cloud-based quantum computer. This study presents multiple, different approaches to design of QTEEs and considers both hardware and architecture, as well as system software and operating system support necessary for realization of QTEEs. Overall, this study presents three hardware architectures, namely, QC-TEE, SoteriaQ, and CASQUE, that have been designed to protect users' circuits and data from potential threats originating from both malicious quantum computer cloud providers or insider attackers. This study further outlines a roadmap for other possible QTEEs that can be developed in the future, to account for different threat models or to support different types of quantum computer architectures.
Rapidly evolving research on quantum computers brings closer reality of practical quantum computers that can solve previously untractable problems. However, as these computers become more powerful, they will process and generate valuable data and intellectual property, making them targets of security attacks. As a result, there is a need to develop architectures for securing quantum computers and the computation. This work presents emerging ideas on design of a trusted quantum computer controller as a pivotal component in securing quantum computing systems. At its core, a trusted controller acts to protect the privacy and security of user's circuits executing on the quantum computer itself. In this work, the classical controller used to generate control pulses for quantum computers is augmented with trusted hardware. The trusted classical hardware can analyze and manipulate circuits and instructions before generating control pulses sent to the untrusted, quantum processing unit. This work analyzes the promises of trusted controller and presents ideas for design of secure cloud-based quantum computers.
Circuit cutting is a novel technique in the field of quantum computing that offers a promising approach for breaking up large quantum circuits into smaller ones that can be executed on smaller quantum computers. Circuit cutting offers a scalable and hybrid computing approach, by combining classical and quantum computers to run large quantum circuits. At the same time, quantum circuits represent the fundamental building blocks of quantum algorithms, and obfuscation techniques are crucial for protecting the sensitive information and intellectual property encoded in these circuits. This paper constitutes the first security analysis of circuit cutting techniques as a means to protect quantum circuits, and not just for cutting bigger quantum circuits to fit on smaller devices. As cloud providers are in control of quantum computers and give access to users, utilizing cloud-based quantum computers for executing quantum circuits involves considerable security risks. This work demonstrates that quantum circuits can be effectively obfuscated by using quantum circuit cutting techniques. If users are worried about an adversary who attempts to reverse-engineer the original quantum algorithm, circuit cutting can be used as a security measure. To further provide configurable obfuscation level, i.e. number of possible circuits that the cloud provider would have to guess, this work proposes a novel dummy-subcircuits technique. This technique introduces dummy subcircuits with additional qubit cut points to create more confusion for the cloud provider and further help to obfuscate the user's original circuits with limited cost.
We present the first architecture for a trusted execution environment for quantum computers. In the architecture, to protect the user's circuits, they are obfuscated with decoy control pulses added during circuit transpilation by the user. The decoy pulses are removed, i.e. attenuated, by the trusted hardware inside the superconducting quantum computer's fridge before they reach the qubits. This preliminary work demonstrates that protection from possibly malicious cloud providers is feasible with minimal hardware cost.
The rapidly growing interest in quantum computing also increases the importance of securing these computers from various physical attacks. Constantly increasing qubit counts and improvements to the fidelity of the quantum computers hold great promise for the ability of these computers to run novel algorithms with highly sensitive intellectual property. However, in today's cloud-based quantum computer setting, users lack physical control over the computers. Physical attacks, such as those perpetrated by malicious insiders in data centers, could be used to extract sensitive information about the circuits being executed on these computers. This work shows the first exploration and study of power-based side-channel attacks in quantum computers. The explored attacks could be used to recover information about the control pulses sent to these computers. By analyzing these control pulses, attackers can reverse-engineer the equivalent gate-level description of the circuits, and the algorithms being run, or data hard-coded into the circuits. This work introduces five new types of attacks, and evaluates them using control pulse information available from cloud-based quantum computers. This work demonstrates how and what circuits could be recovered, and then in turn how to defend from the newly demonstrated side-channel attacks on quantum computing systems.