Apple is introducing a 'groundbreaking' post-Quantum cryptographic protocol for iMessage

Apple has unveiled PQ3, a post-quantum cryptographic protocol for iMessage, marking a significant leap in cryptographic security for the platform. In its announcement, Apple noted that “With compromise-resilient encryption and extensive defenses against even highly sophisticated quantum attacks, PQ3 is the first messaging protocol to reach what we call Level 3 security — providing protocol protections that surpass those in all other widely deployed messaging apps.” and that “PQ3 has the strongest security properties of any at-scale messaging protocol in the world”.

This development aligns Apple with Signal and other messaging apps that have begun incorporating quantum resistance into their messaging protocols. Traditionally, messaging platforms have relied on classical public key cryptography, including RSA, Elliptic Curve signatures, and Diffie-Hellman key exchange. These algorithms are based on complex mathematical problems deemed too computationally intensive for computers to solve. However, the emergence of quantum computing potentially alters this scenario.

Even though quantum computers with such capabilities do not exist yet, highly resourced attackers could already be preparing for their potential arrival by leveraging the dramatic reduction in modern data storage costs. To counter threats from future quantum computers, the cryptographic community has been exploring post-quantum cryptography (PQC).

Apple plans to roll out support for PQ3 in iMessage with the public releases of iOS 17.4, iPadOS 17.4, macOS 14.4, and watchOS 10.4. The protocol is already included in the corresponding developer preview and beta releases. iMessage conversations between devices that support PQ3 will automatically transition to the post-quantum encryption protocol. As Apple gains more experience with PQ3 on the global scale of iMessage, it intends to fully replace the existing protocol within all supported conversations this year.