Quantum Computers & Encryption: What to Worry About (& What Not To)

Quantum computing isn’t about to break every lock on the internet - but it will change which keys we use.

Headlines love a scare story.

In reality, the first wave of impact from quantum computing will be about identity and handshakes (the “keys”), not the ciphers that protect your actual messages and files (the “locks”).

In other words, you could say the bigger risk is not that messages will suddenly become readable - it’s that people could lose confidence in the systems that keep them private.

Let me explain...

This guide decodes what to worry about - and what not to - across tools you use every day, from WhatsApp and FileVault to secure email solutions like Mailock.

The Big Picture

Let's think of the two main types of encryption as a safe and a set of keys that you exchange.

Symmetric encryption (for example, AES) is the safe - it locks your content so only someone with the right key can open it.

Asymmetric cryptography (RSA and ECC) is the key system we use to prove who we are and agree on session keys across the internet (for example, in TLS for email-in-transit or browsing).

TLS (Transport Layer Encryption) is the padlock your browser shows when data moves between services.

Quantum computing, when it arrives at a useful scale, threatens these key exchanges long before it threatens the safe.

What To Worry About (and What Not To)

Worry About: Internet “Keys” Changing - Certificates, Signatures, and Handshakes

To stay ahead of the risk to online "keys", independent expert organisations called standards bodies - such as the US-based National Institute of Standards and Technology (NIST) - have created new “post-quantum” algorithms (or, PQC), built to defend against future threats.

These approved standards - including Kyber (for establishing secure connections) and Dilithium (for digital signatures) - are already being adopted into web browsers, VPNs, and code signing.

In practical terms, this means the systems for proving who you are and connecting securely online are being modernised for the quantum era.

The encryption used to actually lock your messages, documents, or files - often known as content-level encryption, like AES-256 - remains strong.

Content-level encryption secures the information itself, making sure only authorised parties can read what’s inside emails, chats, or stored files, even if attackers get hold of them.

It's what we use to secure the content you send via our Mailock secure email platform.

Don’t Panic About: Strong “Safes” Like AES-256 (Content Encryption)

For symmetric ciphers used with content, such as AES-256, the current best-known quantum attack is a speed-up, not a shortcut.

In reality, the sheer number of possible combinations makes it practically impossible for anyone to successfully guess the key using brute force, even with advances in computing.

Your safe remains extremely hard to crack; it’s the keys and exchanges around the edges that will modernise with time.

That's why it's vitally important that your software is regularly updated and upgraded, especially those supporting critical systems.

Quick Look-Up: Your Channels, What’s Encrypted, and Quantum-Worry Level

Everyday Examples (in Plain English)

WhatsApp/iMessage: End-to-End “Safes” for Chats

Modern messengers lock your chat content with a strong symmetric cipher (think: a very strong safe).

Devices perform a short “handshake” to agree the keys.

Quantum-era changes will focus on upgrading that handshake - not necessarily on protecting the content of your old messages.

FileVault (Mac) and Similar Disk Encryption: The Whole Drive in a Safe

Disk encryption locks everything on your drive when the lid’s closed.

Quantum computers don’t help an attacker guess your long passcode or bypass your device’s built-in hardware security chip.

What helps attackers most is you: short passcodes, old OS versions, or malware capturing the screen when the drive is unlocked.

Email with TLS Only: Safer in Transit, but Not End-to-End

TLS is the tunnel that carries your email between providers.

It uses public key cryptography for the handshake - that’s the piece the world is upgrading to PQC (post-quantum cryptography).

Remember: TLS protects the journey, not the destination! Once the message lands, it may sit unencrypted in a mailbox unless you use end-to-end encryption.

Secure Email and Mailock: End-to-End with Identity Checks on Top

Mailock locks the content itself with AES-256 (the “safe”) and asks the recipient to prove who they are (the “key”).

In a quantum future, the safe stays strong; the industry simply swaps in PQC for the handshakes used elsewhere, like browser sessions and APIs.

Take a look at our practical guide to sending a secure email.

How To Plan Sensibly (Without Overreacting or Underreacting)

1) Keep Using Strong “Safes” for Content (AES-256) - You’re on Solid Ground

Files and messages protected with strong symmetric encryption remain best practice.

There’s no evidence of a practical quantum attack that would make brute-forcing AES-256 feasible.

2) Prioritise PQC for Keys, Certificates, and Signatures (the Parts Quantum Targets First)

Ask vendors about their PQC roadmap across TLS, device provisioning, code signing, and archives.

If a provider can, and plans to, rotate in new keys without upheaval, you should be sensibly future-proofed.

3) Design for Crypto-Agility and Good Key Hygiene (This Matters More than Hype)

Crypto-agility means you can upgrade locks and keys without rewriting everything.

Pair that with strong key management, MFA to reduce account takeover, and policy-based encryption that adapts to risk, and you’re ready to contend with most real-world attacks - quantum or not.

4) Mind “Harvest-Now, Decrypt-Later” for Sensitive Archives (but Don’t Conflate Risks)

If attackers can steal today and decrypt years later, prioritise PQC for long-lived secrets (certificates, signatures, key-exchange records), as those protected only by today's TLS handshakes are likely to become vulnerable.

For content already protected with strong symmetric ciphers, your biggest risks remain human and operational - mistaken sends, poor access controls, weak endpoints.

"Quantum won’t flip a switch on data privacy.

The real shift is operational: rotating internet keys and certificates to post-quantum standards while keeping proven content encryption - like AES-256 - right where it is."

Michael Wakefield, CTO, Beyond Encryption

FAQs

Can a Quantum Computer Break AES-256?

No practical method is known.

Quantum offers a theoretical speed-up, but even then the work factor is astronomically large, so AES-256 remains a strong choice for protection.

Will TLS Become “Quantum-Safe”?

Yes. TLS is migrating to PQC algorithms for its handshakes and certificates.

That work is already standardised and being rolled out.

Is WhatsApp Still Safe? What About FileVault?

Yes. They rely on strong symmetric encryption for content.

Quantum-era updates will focus on device identity and key agreement, not brute-forcing your archived chats or encrypted disks.

References

NIST Releases First Finalised Post-Quantum Encryption Standards, NIST, 2024

Post-Quantum Cryptography (PQC) Project, NIST, 2024

PQC FAQs (Symmetric Crypto and Grover), NIST, 2024

RFC 8446: TLS 1.3, IETF, 2018

WhatsApp Security Whitepaper, WhatsApp, 2024

Volume Encryption with FileVault, Apple, 2021

Apple Platform Security Guide, Apple, 2025

How to Send a Secure Email, Beyond Encryption, 2025

Reviewed by

Sam Kendall, 21.10.25