Signal takes another step in making the Signal Protocol quantum-resistant with the introduction of the Sparse Post Quantum Ratchet (SPQR). This upgrade protects your messages against the threat of future quantum computers.
As you know, everything on Signal is end-to-end encrypted by default, which means messages cannot be read by others. This is made possible by the Signal Protocol, known for its strong encryption that cannot be broken by conventional computers. In recent years, however, the development of quantum computers has accelerated. While the current generation poses no threat to Signal, experts expect that future quantum computers may eventually become powerful enough to break even today’s encryption.
That is why Signal has been working for years to make the Signal Protocol quantum-resistant. In 2023, Signal introduced the PQXDH upgrade as the first post-quantum update, providing better protection for chats against future quantum computers. Now, Signal announces the next major update: the Sparse Post Quantum Ratchet (SPQR).
Sparse Post Quantum Ratchet (SPQR)
The new update adds the Sparse Post Quantum Ratchet to the existing Double Ratchet, together forming the new Triple Ratchet, which ensures that messages remain encrypted in a quantum-safe way.
For users, nothing changes: conversations will automatically transition to the new quantum-resistant Signal Protocol as soon as it becomes available, keeping messages secure both now and in the future.
With this update, Signal remains prepared for the advent of quantum computers while continuing to guarantee user privacy and security.
In a detailed blog post, Graeme Connell and Rolfe Schmidt from Signal dive deeper into the technical details of the Sparse Post Quantum Ratchet (SPQR).
