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Quantum-safe cryptography
Encryption designed to stay secure against future quantum computers.
What it means
Quantum-safe cryptography, also called post-quantum, is encryption built to survive a quantum computer large enough to break the mathematics under today's public key systems. NIST published the first standards in August 2024, among them FIPS 203 for key establishment, and browsers and cloud providers have begun shipping them.
The threat is specific rather than general. It is serious for the key exchange and signature schemes protecting connections and certificates, and much smaller for the symmetric encryption guarding stored data.
Why it matters
The reason this is not purely tomorrow's problem is the harvest now, decrypt later pattern. Encrypted traffic captured today can be stored and opened once the capability arrives. If what you send this year still needs to be secret in fifteen years, such as medical records, legal files or long contracts, the clock is already running.
For most businesses, though, this is not an emergency. Session cookies and order histories do not need to stay confidential for decades, and anybody calling it urgent for an ordinary web application is usually selling something.
How it shows up
The practical question is not which algorithm to adopt. It is whether you could change one at all. Cryptographic agility means knowing where encryption is used, replacing an algorithm without rewriting the application, and keeping key lengths and algorithm names out of code scattered across the repository.
A sensible position today has three parts. Work out which of your data has a long confidentiality life. Expect your cloud and browser vendors to carry most of the migration for connections. And avoid building anything that fixes one algorithm permanently in place.
Questions people ask
Quantum-safe cryptography, answered
Do we need to do anything about this now?
Most web applications, no. The migration for connections is arriving through TLS libraries, browsers and cloud providers rather than through your code.
What is worth doing now is knowing where you use cryptography and confirming you could change an algorithm without a rewrite.
What does harvest now, decrypt later mean?
An attacker records encrypted traffic today and stores it, waiting for the capability to open it. Nothing about the capture is visible to you.
It only matters for data that must stay secret long enough for that capability to exist, which is why confidentiality lifetime is the question to ask.
Which algorithms are actually standardised?
NIST released FIPS 203, 204 and 205 in August 2024, covering key encapsulation and two digital signature schemes, and has selected further algorithms for standardisation since.
If a vendor cannot tell you which standard they implement, that is your answer about how far along they are.
Does quantum computing break all encryption?
No. The serious problem is public key cryptography, which protects key exchange and certificates. Symmetric encryption is affected much less, and longer keys cover most of it.
So your stored data is in a different position from the connections carrying it.
Is this the same as quantum key distribution?
No, and the names get confused constantly. Quantum-safe cryptography is ordinary software running on ordinary computers, designed to resist quantum attack.
Quantum key distribution needs specialist hardware and dedicated links, and it is not what the published standards describe.
Sources
Where this comes from
Related
Terms that sit next to this one
Encryption in transit
Protecting data while it travels between a browser and your servers.
Encryption at rest
Stored data scrambled so a stolen disk is useless without the key.
Hashing
A one-way transformation, so a password can be checked but never read back.
Key rotation
Replacing a credential on a schedule so a leaked one has a short life.
HTTPS
The encrypted web protocol, and the minimum for anything with a login.
Worth worrying about yet?
Probably not before the everyday things are covered. Cyberlop tests the crypto handling your application relies on today, beside nine other classes. Start with one application and see.
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