Quantum computing and security

A large quantum computer would break some of the encryption that protects today's data. This path explains which, why it matters now, and what replaces it. It needs no banking, regulatory or engineering background.

• Beginner to intermediate
• 5 steps, about 30 min
• Best after Foundations lesson 5

The path

Why a large quantum computer would break some of today's encryption, why data recorded now matters, and what replaces it. No banking or regulation needed.

1. What is public-key cryptography?3 minQuick answer · Two keys instead of one: the idea behind secure connections and signatures, and the part quantum computers threaten.
2. "Harvest now, decrypt later," explained7 minWhy data stolen today can become readable tomorrow, and who should worry.
3. Post-quantum cryptography for non-engineers14 minWhat ML-KEM and ML-DSA are in one sentence each, and what changes for your organisation.
4. QKD versus post-quantum cryptography3 minQuick answer · Physics versus maths: two very different answers to the quantum threat, and which one security agencies recommend.
5. What is crypto-agility?3 minQuick answer · The ability to change cryptography without rebuilding systems, and why it outlasts the quantum migration.

Try it on your own data

The Mosca calculator tests whether data you protect today could still need protecting when a large quantum computer arrives. It runs in your browser.

Going deeper at work

• Banking and payments

  From payment-message cryptography to the full readiness guide.

• Risk, audit and governance

  Threat indicators, Canadian guidance and what internal audit should test.