What Is a Hash?
A cryptographic hash function (like SHA-256) takes any input — a document, an image, a database row — and produces a fixed-length string of characters. This string is unique to that exact input. Change a single character, and the hash changes completely.
The Magic Property
Hashes are **one-way functions**. Given a hash, it is computationally impossible to determine the original input. This means:
- We can verify data integrity without seeing the data
- The blockchain stores only the hash, not your content
- Even if the blockchain is public, your data remains private
How Provn Uses This
- You compute the SHA-256 hash of your data (client-side)
- You send only the hash to Provncloud
- We anchor the hash to Solana
- You receive a timestamped proof of existence
GDPR Compliance
Under GDPR, personal data must be deletable. But blockchain data is immutable. Our hash-only architecture solves this paradox:
- We never store personal data
- The hash alone cannot identify an individual
- If you request deletion, we remove the association in our database
- The hash on the blockchain has no meaning without your original data
Verify for Yourself
You don't have to trust us. You can compute the hash yourself using any SHA-256 tool, then verify it matches the anchored hash on Solana. This is what we call **Sovereign Verification**.