Q-Day is the day a quantum computer becomes strong enough to break the cryptography we rely on today. Nobody knows exactly when it will happen, but in this video Jeff Crume of IBM Technology makes a clear case that the right time to prepare is now.
What breaks on Q-Day
Today's cryptography combines two types of algorithms:
- Symmetric encryption such as AES uses one key to encrypt and decrypt. It is fast and used for bulk data. A quantum computer running Grover's algorithm weakens it, but doubling the key length from 128 to 256 bits is enough to stay safe.
- Asymmetric encryption such as RSA uses a pair of keys. It handles key exchange, digital certificates and the whole public key infrastructure (PKI). Shor's algorithm breaks it completely, and longer keys do not help. These algorithms have to be replaced with post-quantum cryptography (PQC).
Why it matters
If that cryptography fails, three things we take for granted go with it:
- Confidentiality: health records, payment data and intellectual property stop being secret.
- Authentication: you can no longer be sure who you are dealing with.
- Integrity: digital signatures can no longer prove that a contract or document has not been changed.
When will it happen?
Most estimates put Q-Day five to ten years away. Governments and regulators are working towards deprecating today's algorithms between 2030 and 2035. It is also likely that whoever gets there first will keep quiet about it, so Q-Day may already have passed before anyone knows.
Why you can't wait
The video gives four reasons not to treat five to ten years as time to spare:
- Migration takes years. Organisations commonly have thousands of places where cryptography is used. Converting one a day would take more than a decade.
- Waiting makes it more expensive. As the deadline approaches, everyone will compete for the same scarce specialists.
- Breakthroughs can come early. Research claiming to break today's cryptography with current hardware has not held up so far, but it was a warning shot.
- Harvest now, decrypt later. Encrypted data copied today can be stored and decrypted once a strong enough quantum computer exists. For data that has already been intercepted, the damage is effectively done.
What to do now
Start with visibility: find out where cryptography is used in your applications, infrastructure and supply chain, and which data needs to stay protected the longest. From there you can prioritise and plan the migration step by step.
Want to know whether your data is already at risk? Try the Mosca calculator on our homepage, or plan your awareness workshop with our team.
Video: IBM Technology, "Q-Day Explained: How Quantum Computing Threatens Today's Cryptography".