How to Independently Verify an OpenTimestamps (.ots) Receipt

The greatest advantage of decentralized notarization compared to traditional timestamping is neutrality. When you stamp a file on the blockchain, you do not need to trust the provider. If Verifybit goes out of business tomorrow, your proof of existence is still 100% valid and verifiable forever.

This is because the verification relies entirely on public, open-source standards and the Bitcoin network. This guide explains how to perform an independent verification of your notarized files using the official OpenTimestamps tools, without depending on Verifybit's servers.

1. What You Need for Verification

To verify a timestamp, you need two items:

1. The Original File: The exact file you uploaded (e.g., contract.pdf). Even if a single comma or byte has changed, the verification will fail.
2. The .ots Receipt File: The cryptographic receipt you downloaded from Verifybit (e.g., verifybit_contract.ots).

2. Under the Hood: How the Proof Works

An .ots file is not the document itself; it contains a set of instructions and cryptographic proofs (Merkle branches) that link your file's hash to a specific transaction in a Bitcoin block. The verification tool will:

• Calculate the SHA-256 hash of your original file.
• Follow the mathematical hashing path described in the .ots file up to the root hash.
• Check if that root hash matches a transaction confirmed on the public Bitcoin blockchain.

3. Option A: Verification via Web (Quick & Simple)

The easiest way to verify is to use the official OpenTimestamps web interface:

1. Go to the official OpenTimestamps verification page: verify.opentimestamps.org.
2. Drag and drop your original file first.
3. Drag and drop the corresponding .ots receipt file.
4. The website will process the math locally in your browser and check the Bitcoin blockchain. If successful, you will see a green confirmation message displaying the exact date, time, and Bitcoin block height where your footprint was anchored.

4. Option B: Verification via Command Line (Advanced & Developer-friendly)

For complete independence, you can install the official Python-based client on your own machine.

Step 1: Install Python and the client

Make sure you have Python installed, then run the following command in your terminal:

pip install opentimestamps-client

Step 2: Run the verification command

Place your original file and the .ots receipt in the same directory, then run:

ots verify contract.pdf.ots -f contract.pdf

The tool will compute the local hash, fetch block data from the public Bitcoin blockchain, and output a confirmation like:

Success! Timestamp is confirmed in Bitcoin block #845321

5. Option C: Verification using a Private Bitcoin Node

If you want the ultimate level of sovereignty, you can verify the proof without querying any third-party block explorers. You can run the command-line tool connected directly to your own local full Bitcoin node:

ots --bitcoin-node-url http://username:password@127.0.0.1:8332 verify contract.pdf.ots

By doing this, you are validating your timestamp completely offline/locally against your own copy of the Bitcoin ledger, ensuring 100% mathematical autonomy.