Post-quantum encryption is arriving in your apps: what it means

First, what is encryption?

Encryption scrambles information so only the right person can read it. When you see a padlock in your browser, or send a message on a secure app, encryption is at work. It is like posting a letter inside a locked box: anyone can carry the box, but only someone with the right key can open it.

Today's encryption relies on maths problems that ordinary computers would take an impossibly long time to solve. That is what keeps your bank details safe as they travel across the internet.

Why quantum computers change things

A quantum computer works in a very different way from a normal one. For most jobs it is not faster, but for a few special maths problems it could be dramatically quicker, and some of those problems are exactly the ones that protect much of today's encryption.

No one has yet built a quantum computer big and reliable enough to do this, and experts disagree on when, or whether, one will exist. So why act now? Because of a tactic Apple and others describe as "harvest now, decrypt later": an attacker could record encrypted data today, store it, and wait until a quantum computer can unlock it. Medical records, state secrets or private messages could still matter in ten or twenty years.

The new standards

In August 2024 the US National Institute of Standards and Technology (NIST), which sets widely used security standards, published its first three finalised post-quantum standards. The main one for encrypting information is called ML-KEM. Two others, ML-DSA and SLH-DSA, are for digital signatures, which prove that a message or update really came from who it claims. NIST encouraged organisations to start moving to them straight away.

These new methods are built on different maths problems that, as far as experts know, quantum computers do not crack easily.

Where you will meet it

You will not see a new button. The change happens behind the scenes. Apple's published security guide gives a clear example of how this is rolling out:

• iMessage has used a quantum-secure design since iOS 17.4 in 2024.
• With iOS 26, iPadOS 26 and macOS 26, quantum-secure encryption is on by default for secure web connections made by the system and by apps that use Apple's standard networking tools.
• The same versions add it to Apple's built-in VPN support and to the link between an iPhone and an Apple Watch.

Apple uses what it calls a hybrid approach: the new quantum-safe method is combined with the trusted older one, so the connection is at least as strong as before. It is like fitting a second lock to your door rather than swapping the old one out. Apple also notes that the protection only applies when the website or server at the other end supports it too, so the change spreads gradually as services upgrade.

Other major browsers, operating systems and messaging apps are making similar moves, which is why this is a shift you will benefit from without noticing.

Do you need to do anything?

For most people, the answer is pleasingly short:

1. Keep your devices and apps updated. That is how the new encryption reaches you.
2. Replace devices that no longer get updates when you reasonably can, as they will not receive these improvements.
3. Keep doing the basics. Quantum-safe encryption protects data in transit. It does not stop you being tricked into typing a password into a fake site, so passkeys, strong passwords and scam awareness still matter.

Tip: Be wary of products that use "quantum" as a scary sales pitch. Your existing devices are getting this protection through normal updates. Want the technical version? Read our notes on cryptography and the CIA triad.