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New Quantum Protocol Enables Secure Communication Among Multiple Users
Confirmed
In Short: This protocol, which utilizes Pauli-based computation, allows for secure communication among multiple users by reducing the necessary quantum server size to depend solely on the number of non-Clifford T gates present in the calculation.
Researchers at the University of Ottawa, in collaboration with international partners, have unveiled a new protocol for blind quantum computation that significantly reduces the demands on quantum hardware.
Previous blind quantum computation protocols required the quantum server’s size to increase proportionally with both the number of qubits in the circuit and the count of non-Clifford gates within it.
The new protocol introduces 'blindness' through secret rotations applied to the initial quantum state before server interaction begins, ensuring that the server cannot determine the computation being performed.
This advancement confirms that blind quantum computation functions even when standard computers cannot replicate it, expanding our understanding of its limitations.
The resulting protocol not only inherits established benefits like fault tolerance and qubit virtualization but also reveals that secure delegation is achievable even when classical simulation becomes impractical.
Furthermore, an entanglement-based dual protocol offers dramatically reduced execution costs for resource state computations.
The Signal Protocol, used by billions of people worldwide, has also advanced its security measures with the introduction of the Sparse Post Quantum Ratchet (SPQR), enhancing resilience against future quantum computing threats.
The NSF Quantum Leap Challenge Institutes, which collectively receive over $290 million in funding, are focused on solving the underlying scientific and technological challenges required for quantum devices to achieve high performance.
These institutes serve as a productive nexus between scientists, federal science agencies, quantum technology companies, and educational organizations.
The investment is an expansion of the NSF Quantum Leap Challenge Institutes program, which was created in 2020 as part of the agency's strategy to fulfill the 2018 National Quantum Initiative Act.
What this adds
The new protocol's ability to scale based solely on computational difficulty, rather than qubit number and non-Clifford gate count, represents a significant leap in quantum communication efficiency.
What's confirmed
- Researchers at the University of Ottawa, in collaboration with international partners, have unveiled a new protocol for blind quantum computation that significantly reduces the demands on quantum hardware.
- Previous blind quantum computation protocols required the quantum server’s size to increase proportionally with both the number of qubits in the circuit and the count of non-Clifford gates within it.
- The new protocol introduces 'blindness' through secret rotations applied to the initial quantum state before server interaction begins, ensuring that the server cannot determine the computation being performed.
- This advancement confirms that blind quantum computation functions even when standard computers cannot replicate it, expanding our understanding of its limitations.
- The resulting protocol not only inherits established benefits like fault tolerance and qubit virtualization but also reveals that secure delegation is achievable even when classical simulation becomes impractical.
- Furthermore, an entanglement-based dual protocol offers dramatically reduced execution costs for resource state computations.
- The Signal Protocol, used by billions of people worldwide, has also advanced its security measures with the introduction of the Sparse Post Quantum Ratchet (SPQR), enhancing resilience against future quantum computing threats.
- The NSF Quantum Leap Challenge Institutes, which collectively receive over $290 million in funding, are focused on solving the underlying scientific and technological challenges required for quantum devices to achieve high performance.
- These institutes serve as a productive nexus between scientists, federal science agencies, quantum technology companies, and educational organizations.
- The investment is an expansion of the NSF Quantum Leap Challenge Institutes program, which was created in 2020 as part of the agency's strategy to fulfill the 2018 National Quantum Initiative Act.
What's still developing
- This work addresses a key limitation of current BQC protocols, the substantial scaling of server resources alongside computational complexity, by utilising Pauli-based computation to create a system where server size correlates only with the number of non-Clifford gates required for a calculation.
- Researchers at University of Ottawa, in collaboration with University of Granada, Leibniz Universität Hannover, Bilkent University, and Johannes Kepler University, have demonstrated significant progress towards practical blind quantum computation.
- Previous methods needed the quantum computer’s capacity to grow proportionally with both calculation complexity and qubit number; this approach scales based solely on computational difficulty, specifically the count of non-Clifford gates within a circuit.
- Technical information on the Signal Protocol can be found in the specifications section of our docs site.
- In a previous blog post, we announced the first step towards advancing quantum resistance for the Signal Protocol: an upgrade called PQXDH that incorporates quantum-resistent cryptographic secrets when chat sessions are established in order to protect against harvest-now-decrypt-later attacks that could allow current chat sessions to become compromised if a sufficiently powerful quantum computer is developed in the future.
- Today, we are happy to announce the next step in advancing quantum resistance for the Signal Protocol: an additional regularly advancing post-quantum ratchet called the Sparse Post Quantum Ratchet, or SPQR.
- Mean ol’ Mallory records the entire (encrypted) communication, and really wants to know what Alice and Bob are talking about.
- Signal >> Blog >> Signal Protocol and Post-Quantum Ratchets Get Signal Help Blog Developers Careers Donate Signal Protocol and Post-Quantum Ratchets Graeme Connell and Rolfe Schmidt on 02 Oct 2025 We are excited to announce a significant advancement in the security of the Signal Protocol: the introduction of the Sparse Post Quantum Ratchet (SPQR).
- The Signal Protocol is a set of cryptographic specifications that provides end-to-end encryption for private communications exchanged daily by billions of people around the world.
- After its publication in 2013, the open source Signal Protocol was adopted not only by the Signal application but also by other major messaging products.
- However, the Signal Protocol isn’t just about protecting cryptographic material and keys at the beginning of a new chat or phone call; it’s also designed to minimize damage and heal from compromise as that conversation continues.
- On its own, SPQR provides secure messaging that provably achieves these FS and PCS guarantees in a quantum safe manner.