PQC

Overview Signal has added post-quantum cryptography with a new protocol called the SPQR (Sparse Post-Quantum Ratchet). This combines with Signal’s existing Double Ratchet to form a Triple Ratchet system. Signal uses the quantum-secure Key-Encapsulation Mechanism (ML-KEM 768) algorithm alongside traditional elliptic curve cryptography, which means attackers need to break both elliptic curve and ML-KEM cryptography to read messages. Signal are rolling out this new protocol in multiple phases - initially allowing older non-SPQR clients to interact with up-to-date clients and for older sessions (which might last for years) to continue working. In their final phase (once Signal have determined that all clients support the new protocol) older sessions will be upgraded to use SPQR. These phases are being planned to ensure nothing changes from an end-user experience. ...

Preparing for the Quantum Future: A Practical Guide to Post-Quantum Cryptography TL;DR Advances in quantum processing capabilities are rapidly bringing forward the estimated date that a cryptographically relevant quantum computer (CRQC) will be available and previously strong encryption algorithms will be broken. With the recommended date for ceasing the use of traditional asymmetric cryptography now only years away in 2030, “Harvest now, decrypt later” attacks mean switching to Post-Quantum Cryptography (PQC) strong encryption algorithms is something to do today. ...