Harvest now, decrypt later means that someone stores encrypted data today to unlock it later, when quantum computers can break the encryption.
Harvest now, decrypt later means store now and unlock later. It is a way of attacking where someone captures and stores encrypted data today. They cannot read it now. But they expect to unlock it in some years with a quantum computer.
Why is it a threat today?
Many think quantum computers only become a problem when they exist. But the threat starts when the data is stolen. If your encrypted mail is captured in 2026, it can be read in 2035. If the content still has value on that day, the damage is done.
Large players have enough storage to keep a lot of traffic. That is why authorities in both the US and the EU assume it is already happening.
Which data is at risk?
Mostly data that must stay secret for many years:
- Records about staff, salaries and health.
- Contracts, drawings, patents and plans for new products.
- Data about customers and citizens that is protected by GDPR.
- Information about the state, defence and critical infrastructure.
Data that is only secret for a few weeks is not the big problem. It is the long secrets that count.
What does it mean for HCL Notes?
Notes applications often hold data that is many years old and still in use. Mail and documents are encrypted with RSA keys from the user's Notes ID. Traffic for web and mail is secured with TLS, which is also built on RSA. In theory all of it can be stored today and read later.
What can you do?
The best defence is quantum safe encryption. Until it is ready in Domino, you can do three things. Find out which databases hold long secrets. Limit where that data is sent. And keep Notes and Domino up to date, so you get the new encryption as soon as it arrives. Read more in the article on quantum safe encryption in Notes 2027.