Boundry — content authenticity demonstration

Step 1

Sign at source

Each item is hashed, and that hash — with its title, source and timestamp — is signed with the demo key. The signature and a registry entry are the output.

Step 2

Verify

Check an untouched copy, a tampered copy, or something that was never signed.

Run a check below — the verdict appears here.

Step 3

Try it with your own file

Nothing leaves this machine. The file is read locally, hashed, and signed with the same demo key.

Choose a file — or drop one here
any type; it is hashed, and nothing you upload is stored or logged

What this does and does not prove

The limits matter as much as the capability. Stated plainly, because an evaluator deserves it.

What it proves

That this exact item came from the holder of this key and has not been altered since.
Any later change, down to one byte, is detectable.
There is a permanent, append-only record that this item was signed, and when.

What it does not prove

That the content is true, accurate, or wise. A signature binds authorship and integrity, not truth.
Anything about copies you cannot see, or about what happened to an item before it was signed.
Anything at all about content that never passed through the signer. An item with no valid signature cannot be confirmed as genuine — which is not the same as being false.

The registry

An append-only, hash-chained log. Each entry carries the hash of the one before it, so removing or editing history breaks the chain.