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Signal: Signal >> Blog >> Quantum Resistance and the Signal Protocol
SimpleX Chat: SimpleX blog: SimpleX Chat v5.6 (beta): adding quantum resistance to Signal double ratchet algorithm, since v5.7 quantum resistant end-to-end encryption with all contacts.
- unlike Signal design that only added quantum resistance to the initial key exchange by replacing X3DH key agreement scheme with post-quantum PQXDH, but did not improve Signal algorithm itself, our design added quantum-resistant key agreements inside double algorithm, making its break-in recovery property also quantum resistant.