What is Harvest now, decrypt later cyber attack?

I recently stumbled upon this concept called Harvest Now, Decrypt Later and the more I read, the more it feels like a ticking time bomb nobody’s talking about enough.

The idea is terrifyingly simple: hackers steal encrypted data today, even if they can’t break into it, and just store it away until their technology—most likely quantum computing—catches up so they can decrypt it later.

Currently, strong encryption makes most stolen data useless to hackers in the short term. But fast-forward 10 years or even earlier, and we might have quantum computers powerful enough to rip through today’s encryption standards in hours or even minutes.

And then what? All that secure information—government documents, classified military intelligence, corporate trade secrets, medical records, personal messages—could be suddenly exposed.

And the worst part? You can’t just go back and re-encrypt data that’s been stolen. Once it’s out there, it’s over. It’s not a hypothetical, sci-fi-level threat; even security agencies have been warning about it for years, and some nation-state hackers are hoarding encrypted data for this exact reason. It’s not just a privacy but a national security and economic issue; post-quantum cryptography is supposed to protect against this, but it’s not implemented by most organizations and honestly, most people have never heard of it.

The window to prepare is closing, and every year that passes, more future-compromisable data is being stolen and stockpiled.

Should we be pushing for post-quantum encryption now, even if quantum computers that powerful don’t exist yet? Is it a cause for panic at all?

And if you work in cybersecurity, are you already seeing signs that attackers are playing the long game here?