Apple Unveils PQ3 Protocol - Post-Quantum Encryption for iMessage

Apple announced PQ3, a post-quantum cryptographic protocol for iMessage that combines Kyber and ECC to achieve what the company calls Level 3 security, aiming to protect against future quantum-computing threats and harvest-now-decrypt-later attacks; PQ3 includes key-rotation limits (every 50 messages or at least once every seven days) to limit the impact of key compromise and is expected to begin rolling out with iOS 17.4, iPadOS 17.4, macOS 14.4, and watchOS 10.4. The report compares PQ3 to other vendor efforts (such as Signal’s PQXDH), notes broader industry adoption of PQC, and highlights potential implications for RCS message security.