The notary's desk: prove two copies match
After any transfer — a beam, a USB stick, a download — the only real proof that nothing changed is a matching fingerprint. Drop the copies here and get a ruling.
drop it here or tap to choose
the copy you want to check
Everything is computed on your device — big files stream through the hash in 4 MB slices, so even multi-gigabyte videos get fingerprinted without leaving your disk or filling your memory.
What a fingerprint promises
SHA-256 reads every byte of a file and distills it into 64 hex characters. Change a single byte anywhere — one pixel, one comma — and the fingerprint changes beyond recognition. So if two copies produce the same fingerprint, they are the same file in every way that matters; no practical process can forge a second, different file with a matching one. It's the same check our file beam runs automatically on both ends of every transfer before it stamps verified ✓.
Handy in the wild: confirming a downloaded installer against the hash its publisher lists, checking a backup really equals the original, or settling whether two same-sized videos are actually the same cut.
Why only SHA-256 at this desk
Older stamps like MD5 and SHA-1 are still seen on download pages, but both have known collision attacks — two different files can be manufactured to share a fingerprint, which defeats the entire point of a notary. Rather than offer a weaker stamp next to a strong one and let habit pick wrong, this desk carries the one that still holds. If a publisher only lists an MD5, treat it as a hint, not a proof.
Moving the file between your own devices first? The beaming counter transfers it and verifies the fingerprints in one motion.