# What is harvest now, decrypt later?

Harvest now, decrypt later means storing encrypted data today in the hope of decrypting it once quantum computers are strong enough. Anything encrypted on a public blockchain is stored for good, so it is exposed to this by design.

Also called store now, decrypt later or HNDL.

## Why blockchains are a special case

A blockchain keeps every byte forever, and anyone can download it. Encrypted notes, memos or messages written to a chain with today’s public-key encryption could be opened years later by whoever holds the right machine.

## How privacy systems avoid it

The safe choices are to write nothing encrypted to the chain at all, or to encrypt only with keys that do not depend on elliptic curves.

## In Redacted

In bunker mode, nothing Redacted writes on chain is encrypted, so there is nothing stored there for a future computer to decrypt.

More: [Bunker mode](https://redacted.gg/docs/using-redacted/bunker-mode.md)

## Related terms

- [Post-quantum cryptography](https://redacted.gg/glossary/post-quantum-cryptography.md): Post-quantum cryptography is cryptography built to stay secure against quantum computers, which could break the elliptic curves and RSA that most wallets and websites rely on today.
- [Shielded pool](https://redacted.gg/glossary/shielded-pool.md): A shielded pool holds funds as private notes inside a smart contract. Deposits and withdrawals are public, but what happens inside is proved with zero-knowledge proofs and does not reveal who owns what.
- [Note](https://redacted.gg/glossary/note.md): A note is a sealed entry on-chain that records coins in Redacted’s Reserve and that only your keys can open. From the outside all notes look alike, whoever owns them and whatever they hold.
- [Viewing key](https://redacted.gg/glossary/viewing-key.md): A viewing key lets someone see the history of a private account without being able to spend from it, for example to show an accountant or an auditor exactly what happened.

Sources: [Harvest now, decrypt later, Wikipedia](https://en.wikipedia.org/wiki/Harvest_now,_decrypt_later)
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Page: https://redacted.gg/glossary/harvest-now-decrypt-later/