Apple secures iMessage against threats from the future

Now the safest messaging app available, iMessage offers encryption so secure that even threats from the future won't be able to crack your conversations.
Written by Maria Diaz, Staff Writer
Maria Diaz/ZDNET

Quantum computing may still be an emerging technology, but Apple is two steps ahead of other tech giants by releasing quantum-secure messaging. The company introduced PQ3 for iMessage, bringing the iOS messaging app up to level 3 of cryptographic security, the highest level applied to a messaging app. 

Most other messaging apps are between levels 0 and 1, including WhatsApp, which offers end-to-end encryption without quantum security. iMessage with PQ3 is designed to withstand quantum attacks that may happen in the future -- years down the line. 

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But if quantum computers don't yet exist, why should this matter to you

"The premise is simple: Such attackers can collect large amounts of today's encrypted data and file it all away for future reference," noted Apple's Security Engineering and Architecture team in a blog post announcing the news. "Even though they can't decrypt any of this data today, they can retain it until they acquire a quantum computer that can decrypt it in the future."  

Apple plans to make today's iMessage exchanges secure against the computers and attackers of the future, particularly against attack scenarios known as  "Harvest Now, Decrypt Later." As described by the Apple team, these scenarios involve filing away data for years until a device is created that's advanced enough to crack it -- such as a quantum computer.

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While Apple claims iMessage is the only Level 3 messaging service, Signal with PQXDH, at Level 2 security, also offers post-quantum cryptography, the only quantum messaging service available. 

Level 2 only applies post-quantum cryptography to the initial key establishment, which means that if the key is compromised, an attacker could access all messages in a thread until the key is changed. 

With Level 3, the level to be offered in iMessage, advanced encryption methods are applied from the start of the conversation and maintained throughout, where digital keys change frequently and automatically. If a conversation were compromised, an attacker would only access a very small portion of it until the key changes again.

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Like WhatsApp, iMessage already offered Level 1 end-to-end encryption by default, which is not considered quantum secure. Other Level 1 messaging services include Line and Viber. Level 0 messaging services, including QQ, Skype, Telegram, and WeChat, offer no end-to-end encryption by default. 

Support for iMessage with PQ3 will roll out for general use with the public releases of iOS 17.4, iPadOS 17.4, macOS 14.4, and watchOS 10.4. It is already available in the corresponding beta releases.

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