Signal Braces For Quantum Age With SPQR Encryption Upgrade

BrianFagioli shares a report from NERDS.xyz: Signal has introduced the Sparse Post Quantum Ratchet (SPQR), a new upgrade to its encryption protocol that mixes quantum safe cryptography into its existing Double Ratchet. The result, which Signal calls the Triple Ratchet, makes it much harder for even future quantum computers to break private chats. The change happens silently in the background, meaning users do not need to do anything, but once fully rolled out it will make harvested messages useless even to adversaries with quantum power.

The company worked with researchers and used formal verification tools to prove the new protocol's security. Signal says the upgrade preserves its guarantees of forward secrecy and post compromise security while adding protection against harvest now, decrypt later attacks. The move raises a bigger question: will this be enough when large scale quantum computers arrive, or will secure messaging need to evolve yet again?

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