How to date-stamp a document permanently.

The short version

• Compute a SHA-256 fingerprint of the document on your own device.
• Submit the fingerprint through OpenTimestamps, the open public protocol that aggregates submissions into a single Bitcoin transaction.
• Keep the resulting receipt alongside the document. Any party can later verify that the document existed by the time of the recorded Bitcoin block.

What actually proves it

A document — a contract, a draft, a memo, a manuscript — is a sequence of bytes. A cryptographic hash function reduces those bytes to a short fixed-length fingerprint. Two documents that differ by even a single byte produce different fingerprints. The function is one-way: the fingerprint reveals nothing about the document, but any copy can be checked against it in seconds.

The Bitcoin chain is a public sequence of blocks. Every block carries a timestamp and a transaction-level commitment, and once a block is buried under additional blocks, rewriting it is for practical purposes impossible. When a document's fingerprint is committed to a specific block, that fingerprint — and by extension the document whose bytes produce it — is permanently associated with a public moment that no single party can backdate or revoke.

The mechanism that connects the two is OpenTimestamps. The protocol aggregates many fingerprints into a Merkle tree and commits only the root to the chain. A receipt is the small set of hash operations that, applied to the document's own fingerprint, reproduces the on-chain root. A verifier reads the receipt, reads the chain, and either agrees or does not.

The step-by-step

1. Save the final version of the document. PDF, DOCX, plain text, image, and source archive all work — what is anchored is the byte sequence, not the format.

2. Open the office at orphograph.com and drop the file onto the anchor area. The browser computes the fingerprint locally. The document itself does not leave the device.

3. The office submits the fingerprint through OpenTimestamps. Within roughly an hour, the protocol's calendars confirm a Bitcoin block has been mined containing the aggregate commitment.

4. Download the receipt. Store it with the document in any backup the document already lives in — drive, archive, evidence folder. The receipt is a small file; it can sit beside the document indefinitely.

5. When the date matters, hand the document and the receipt to any verifier. The independent verifier at /docs/verify.html reads both and returns a binary verdict: the recorded fingerprint matches the document, and the recorded Bitcoin block matches the public chain.

For a working set — a folder of contracts, exhibits, drafts, or workpapers — the same procedure applies once over the whole set using the folder extension at /method/folder-merkle.html. One receipt covers the entire set; any single document inside it can be later proven to belong without revealing the rest.

Common questions

Is a Bitcoin-anchored date admissible as evidence?

Electronic-records authentication is addressed in the federal rules of evidence, in the model state code adopted by most states, and in several explicit blockchain-evidence statutes. Bitcoin-anchored receipts have been used in real disputes to authenticate the date of a digital record. The landscape is described at /method/evidence-law.html. Admissibility in any specific forum is a question for that forum and the customer's counsel.

Does the office see the contents of the document?

No. The fingerprint is computed in the browser or the local command-line tool. Only the fingerprint, a short opaque string, is transmitted. The document itself stays on the customer's device. The architecture is described at /about-the-office.html.

What if the office is no longer operating?

The receipt continues to verify against the Bitcoin chain without any participation from the office. The open-source verifier and the underlying OpenTimestamps protocol are both free and public. The chain is the trust anchor; the office is the convenience layer.

How much does it cost?

The free tier covers a small number of anchors per day, which is enough for most personal and small-business use. Paid tiers cover higher volumes and folder anchoring for working sets. Pricing is on the homepage.

How long does the date last?

As long as the Bitcoin chain endures and the document's bytes are preserved. The receipt does not expire. There is no annual renewal. There is no central authority that can rescind the record.

What this does not prove

The receipt proves one narrow thing: the document existed in its present byte form by the recorded moment. It does not prove who wrote the document. It does not prove the contents are true. It does not prove the document was created lawfully or that the customer holds rights in it. It does not prove anything about events that occurred after the recorded moment. The receipt establishes a dated-existence floor; the broader claims belong to the customer and their counsel.

Try it

The office is at orphograph.com. A walk-through of a first anchor is at /docs/quickstart.html. The architectural method is at /method/folder-merkle.html. The independent verifier is at /docs/verify.html. The doctrinal grounding is at /method/evidence-law.html.