Cryptographic hash
What it is
A fingerprint for one exact file, computed with SHA-256.
What it does
Identifies this precise file and anchors timestamps and signed records. Even a tiny change produces a completely different hash.
What it doesn't do
It cannot recognize resized, recompressed, or edited versions — those are different files with different hashes.
What changes it can survive
Renaming. Nothing that changes the file’s bytes.
When we recommend it
Always. It’s the foundation of every record.
Does your original leave your device?
No. The hash is computed in your browser; only the hash (not the file) is stored in a record.
Is an external provider involved?
No, unless you add an independent timestamp, which sends only the hash.
Can you verify it without us?
Yes. Anyone can re-hash the file and compare it to the recorded hash.