iMessage with PQ3: The new state of the art in quantum-secure messaging at scale - Apple Security Research
security.apple.com/blog/imessage-pq3
What Jamie wrote
Someday we will or may have quantum computers and theoretically they will be able to brute force existing encryption methods. Apple is moving iMessage to a post-quantum encryption method now in preparation for that. Any solutions that use encryption heavily seem to be considering this change. Ethereum has a roadmap for a post-quantum approach for example.