What Is Harvest Now, Decrypt Later, and Should You Worry?

[WWEPete45]

Harvest now, decrypt later means attackers collect encrypted data today and keep it in the hope that future tools will decrypt it. The worry is not that everything breaks immediately, but that sensitive data with a long shelf life may still matter when stronger attacks become available. Medical records, legal files, private messages, source code, and government data are the obvious examples, but small sites should still think about what they store and how long they keep it

[Northernah]

This is probably the clearest QDay topic because it explains why the threat starts before the quantum computer exists

[One-One-Five]

People forget that stolen encrypted data can sit in an archive for years waiting to become useful

[Kieron83]

For a normal forum, private messages and old database dumps are where I would start looking

[Forge45]

The hard part is deciding what data still matters ten or twenty years from now