The rapid expansion of cloud-based access to quantum computers has significantly democratized their usage, enabling a more diverse range of users to explore and utilize quantum computing technologies. However, this increased accessibility also introduces security and privacy concerns. Cloud-based access and sharing of quantum computers require secure means to isolate different users, such as through the use of reset operations. However, current reset operations, including direct thermalization and fast reset instructions, are vulnerable to information leakage due to imperfections in quantum computer operations. To counteract these vulnerabilities, our work proposes multiple implementations of the one-time pad (OTP) defense mechanism. These implementations, specifically random execution, dynamic circuit, and control gate, involve applying Pauli or control gates randomly before executing standard reset operations. We analyze and compare these implementations in detail, demonstrating their effectiveness in mitigating state leakage. This work offers innovative approaches to enhancing the security of reset operations and the safety of cloud-based quantum computers.
The rapid expansion of cloud-based access to quantum computers has significantly democratized their usage, enabling a more diverse range of users to explore and utilize quantum computing technologies. However, this increased accessibility also introduces security and privacy concerns. Cloud-based access and sharing of quantum computers require secure means to isolate different users, such as through the use of reset operations. However, current reset operations, including direct thermalization and fast reset instructions, are vulnerable to information leakage due to imperfections in quantum computer operations. To counteract these vulnerabilities, our work proposes multiple implementations of the one-time pad (OTP) defense mechanism. These implementations, specifically random execution, dynamic circuit, and control gate, involve applying Pauli or control gates randomly before executing standard reset operations. We analyze and compare these implementations in detail, demonstrating their effectiveness in mitigating state leakage. This work offers innovative approaches to enhancing the security of reset operations and the safety of cloud-based quantum computers.
The ability for users to access quantum computers through the cloud has increased rapidly in recent years. Despite still being Noisy Intermediate-Scale Quantum (NISQ) machines, modern quantum computers are now being actively employed for research and by numerous startups. Quantum algorithms typically produce probabilistic results, necessitating repeated execution to produce the desired outcomes. In order for the execution to begin from the specified ground state each time and for the results of the prior execution not to interfere with the results of the subsequent execution, the reset mechanism must be performed between each iteration to effectively reset the qubits. However, due to noise and errors in quantum computers and specifically these reset mechanisms, a noisy reset operation may lead to systematic errors in the overall computation, as well as potential security and privacy vulnerabilities of information leakage. To counter this issue, we thoroughly examine the state leakage problem in quantum computing, and then propose a solution by employing the classical and quantum one-time pads before the reset mechanism to prevent the state leakage, which works by randomly applying simple gates for each execution of the circuit. In addition, this work explores conditions under which the classical one-time pad, which uses fewer resources, is sufficient to protect state leakage. Finally, we study the role of various errors in state leakage, by evaluating the degrees of leakage under different error levels of gate, measurement, and sampling errors. Our findings offer new perspectives on the design of reset mechanisms and secure quantum computing systems.
The development of quantum computers has been advancing rapidly in recent years. As quantum computers become more widely accessible, potentially malicious users could try to execute their code on the machines to leak information from other users, interfere with or manipulate the results of other users, or reverse engineer the underlying quantum computer architecture and its intellectual property. Among different security threats, previous work has demonstrated information leakage across the reset operations, and it then proposed a secure reset operation could be an enabling technology that allows the sharing of a quantum computer among different users or different quantum programs of the same user. In this study, we delve deeper into the reset attack, aiming to augment its efficacy and capabilities and the countermeasure to protect from this attack. First, we propose a set of new extended reset attacks that could be more stealthy by hiding the intention of the attacker's circuit. This work shows various concealing circuits and how attackers can retrieve information from the execution of a previous shot of a circuit, even if the concealing circuit is used between the reset operation (of the victim, after the shot of the circuit is executed) and the measurement (of the attacker). Second, based on the uncovered new possible attacks, this work proposes a set of heuristic checks that could be applied at transpile time to check for the existence of malicious circuits that try to steal information via the attack on the reset operation. Unlike run-time protection or added secure reset gates, this work proposes a complimentary, compile-time security solution to the attacks on reset operation.
Enabling the sharing of quantum computers among different users requires a secure reset operation that can reset the state of a qubit to ground state |0> and prevent leakage of the state to a post-reset circuit. This work highlights that the existing reset operations available in superconducting qubit NISQ quantum computers are not fully secure. In particular, this work demonstrates for the first time a new type of higher-energy state attack. Although NISQ quantum computers are typically abstracted as working with only energy states |0> and |1>, this work shows that it is possible for unprivileged users to set the qubit state to |2 or |3>. By breaking the abstraction of a two-level system, the new higher-energy state attack can be deployed to affect the operation of circuits or for covert communication between circuits. This work shows that common reset protocols are ineffective in resetting a qubit from a higher-energy state. To provide a defense, this work proposes a new Cascading Secure Reset (CSR) operation. CSR, without hardware modifications, is able to efficiently and reliably reset higher-energy states back to |0>. CSR achieves a reduction in |3> -initialized state leakage channel capacity by between 1 and 2 orders of magnitude, and does so with a 25x speedup compared with the default decoherence reset.
A secure reset operation could be an enabling technology that allows sharing of a quantum computer among different users, or among different quantum programs of the same user. Today, the dominant method to erase the qubit state is a full system wipe, which effectively resets all the qubits at the same time. In today's superconducting qubit machines from IBM, for example, a full system wipe takes up to 1000 μs, and it fully erases all information in the system. However, with a full system wipe there is no means for only a few qubits to be cleared and assigned to a new user or program; everything has to be erased at the same time. A secure reset operation could allow resetting only a subset of qubits, and it could be built upon existing (insecure) reset operation available from superconducting qubit machines from IBM, for example. The (insecure) reset operation is available today, which can be used to reset the state of a qubit in a time on the order of 10 μs down to 1 μs. The reset operation is thus much faster than a full system wipe. However, as this work demonstrates, it is possible to leak some information across the (insecure) reset operation as it does not perfectly reset the qubit state between two users or programs who may be sequentially scheduled on the same qubit. Further, crosstalk-like effects are observed where reset behavior of one qubit can be inferred from an adjacent qubit. This work analyzes the existing (insecure) reset operation in order to understand how a secure reset operation could be built upon it. This work then describes the design, implementation, and evaluation of the proposed secure reset operation which can reset qubits without leaking information, and retains a factor of 300 speedup over a full system~wipe.
The rise of quantum computing/technology potentially introduces significant security challenges to cloud computing, necessitating quantum-resistant encryption strategies as well as protection schemes and methods for cloud infrastructures offering quantum computing time and services (i.e. quantum clouds). This research explores various options for securing quantum clouds and ensuring privacy, especially focussing on the integration of homomorphic encryption (HE) into Eclipse Qrisp, a high-level quantum computing framework, to enhance the security of quantum cloud platforms. The study addresses the technical feasibility of integrating HE with Qrisp, evaluates performance trade-offs, and assesses the potential impact on future quantum cloud architectures. The successful implementation and Qrisp integration of three post-quantum cryptographic (PQC) algorithms demonstrates the feasibility of integrating HE with quantum computing frameworks. The findings indicate that while the Quantum One-Time Pad (QOTP) offers simplicity and low overhead, other algorithms like Chen and Gentry-Sahai-Waters (GSW) present performance trade-offs in terms of runtime and memory consumption. The study results in an overall set of recommendations for securing quantum clouds, e.g. implementing HE at data storage and processing levels, developing Quantum Key Distribution (QKD), and enforcing stringent access control and authentication mechanisms as well as participating in PQC standardization efforts.
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.