Verify a document
Drop a file to check whether its proof was recorded on the LKSCOIN blockchain, and when. The file is never uploaded — the fingerprint is computed inside your browser, and the checks below are recomputed there too.
Your document never leaves this device
The SHA-256 fingerprint is computed locally. All the server receives is 64 hexadecimal characters, from which the content cannot be reconstructed. Open your browser's developer tools, go to the Network tab and drop a file: you will see no upload.
…or paste a SHA-256 fingerprint or a certificate ID and press Enter
From your file to two independent blockchains
One record on LKSCOIN certifies thousands of documents; the same root is committed to Bitcoin, so the proof does not depend on this service.
The fingerprint
Your device computes the SHA-256 digest of the file: 64 characters that change completely if a single byte of the document is altered.
Aggregation
Incoming digests are combined into a Merkle tree. One blockchain record certifies thousands of documents, which keeps the cost negligible.
The record
The root of the tree is written into a LKSCOIN transaction as an unspendable output carrying 38 bytes of data. From that moment it is public and immutable.
The anchor
The same root is committed to Bitcoin through OpenTimestamps, so the proof outlives both this service and the LKSCOIN network.
What this proves — and what it does not
What happens to the document I upload?
You do not upload it. The file is read by your browser on your own device, its fingerprint is computed locally, and only that fingerprint reaches the server. No copy of your document exists in our systems and none can be reconstructed. The flip side: keeping the file is your responsibility. If you lose it, the certificate still proves that something with that fingerprint existed on that date, but it cannot tell you what.
What exactly does a certificate prove?
That this exact sequence of bytes already existed when it was recorded on the blockchain. It is a proof of anteriority and of integrity: change one character of the file and the fingerprint no longer matches. It does not prove who authored the document, nor that its contents are true.
Legal positioning. This is a simple electronic time stamp within the meaning of eIDAS — admissible evidence whose legal effect is assessed by the court — not a qualified time stamp, which only a qualified trust service provider on the EU Trusted List can issue. See the legal positioning.
Is the metadata I attach public?
Yes. The optional metadata field is stored and returned to anyone who looks up the certificate, because it is part of what gets certified. Use it for neutral references — a case number, a document type — and never for personal or confidential data. The fingerprint itself reveals nothing.
Do I have to trust you?
No, and that is the point. This page does not display the server's verdict: it recomputes the fingerprint, the Merkle leaf and the Merkle root in your browser, so a tampered record would fail in front of you. You can also repeat every check independently with the open lks-verify tool against any LKSCOIN node you choose — see the independent verifier.
What if this service shuts down?
The proofs remain. They are written on the LKSCOIN blockchain and attested on Bitcoin, both independent of us. The record format is public and every transaction carries the LKSN prefix, so anyone can scan the chain and find them without going through this site. Keep the certificate together with the document.
How long until the proof is final?
Three levels, on different timescales. The record reaches the LKSCOIN blockchain within minutes and is confirmed in the following block. Quorum finality through ChainLocks applies once quorums are active on the network. The Bitcoin attestation — the guarantee that does not depend on LKSCOIN at all — completes within a few hours. The certificate always shows which stage has been reached.