Edward Collins 
Feb 22, 2024
Apple is rolling out a new cryptographic protocol for iMessage that is aimed at protecting users from potential threats posed by quantum computers. This enhanced encryption protocol, named PQ3, is designed to safeguard encrypted conversations from being compromised by quantum-powered attacks in the future.
Notably, iMessage became the second messaging platform to adopt quantum-security cryptography, following Signal's introduction of the PQXDH protocol last year. By implementing PQ3, Apple aims to add an extra layer of security, particularly in scenarios where encryption keys may be compromised.
According to Gadgets360, Apple detailed the development of the PQ3 protocol for iMessage on Wednesday, ahead of its deployment across compatible iPhone, iPad, Mac, and Apple Watch models. PQ3 is engineered to resist attacks from quantum computers, which could potentially decrypt encrypted data stored over time.
While conventional public key cryptography used in messaging services like WhatsApp and Signal currently offers protection against powerful computers, quantum computers pose a future threat due to their ability to solve complex mathematical problems.
One notable risk addressed by PQ3 is the "Harvest Now, Decrypt Later" scenario, where encrypted data stored today could be decrypted in the future once quantum computers advance.
PQ3 mitigates this risk by regularly updating post-quantum keys, limiting exposure to potential breaches. Apple emphasizes that PQ3 will complement existing encryption methods, requiring attackers to overcome both traditional and post-quantum encryption layers to compromise iMessage conversations.
Apple's Security Engineering and Architecture (SEAR) teams have thoroughly reviewed PQ3, along with assessments from academic experts and third-party security consultancies.
The upcoming updates to iOS 17.4, iPadOS 17.4, macOS 14.4, and watchOS 10.4 will integrate support for PQ3, automatically applying the new encryption protocol to iMessage conversations on compatible devices. This phased rollout aims to upgrade all supported conversations to the PQ3 encryption standard within the year.
