What a HashMark is
A short record published on the Radiant blockchain. It carries a fingerprint of a file — not the file itself — and, in most cases, a signature. Publishing it puts that fingerprint in a block, and the further down the chain that block ends up, the harder its place in the order is to change.
What checking one can establish
That the fingerprint existed no later than the block that carried it, so whoever published it knew the file by then. If the record is signed and the signature checks out, that the holder of a particular key made that statement.
What it cannot establish
Not who wrote the file. Not who owns it. Not that they were first to it. Not where anyone was. And nothing whatever about whether what the file says is true.
Nothing here is uploaded
The record is read from a public blockchain server. If you check a file against it, the file is hashed inside this browser and never leaves this machine.
Getting ready — a one-time ~12 MB download, cached for next time…
Nothing to check yet?
This is a real signed mark on the Radiant main chain. Open it to see what the answers look like.
This page could not start
The check runs entirely in your browser, and the code it needs did not load. Nothing about the mark itself is implied by this.
If it keeps happening, please open an issue with the text above.