What is proof of existence for a file?

What does a proof of existence actually prove?

A proof of existence shows that one specific file existed at or before a certain point in time. It works by creating a unique digital fingerprint of the file. If even one character changes later, the fingerprint will be completely different.

This means the proof is tied to the exact contents of the file — not just its name or folder. It’s concrete evidence, not a vague claim.

Why your file stays private

The key insight is that only the fingerprint is needed, not the file itself. Think of it like a seal on a letter — it proves the letter hasn’t been opened, without revealing what’s inside.

This means you can create the proof entirely on your own device. Only the fingerprint is saved to a public record, while your document stays with you.

• Your original file is never uploaded or shared.
• The proof can be checked later by anyone with the same file.
• It proves the file’s contents are unchanged, not just that a filename exists.

When is it useful?

Proof of existence is most valuable when timing matters: contracts, creative work, research notes, business records, photos, or anything you may need to prove existed before a certain date.

It’s best created before a dispute happens — not after one starts. Think of it as an insurance policy for your documents.