verify-proof
A free, open-source CLI tool for verifying blockchain-anchored timestamp proofs.
Verify that a file's SHA-256 hash matches a blockchain-anchored proof record, confirming the file existed at a specific point in time. Works with proof files from ProofLedger and other blockchain timestamp services.
What is blockchain timestamp verification?
Blockchain timestamping creates proof of existence — cryptographic evidence that a specific file existed at a specific time. The process:
- Hash — Your file's SHA-256 hash is computed locally (the file is never uploaded)
- Anchor — The hash is written to a blockchain (Bitcoin, Polygon, Ethereum) via a Merkle tree
- Verify — Anyone can independently verify the proof by recomputing the hash and checking the blockchain transaction
This technique is used for:
- Proof of creation — Prove you created digital content before someone else copied it
- Pre-loss evidence — Document asset conditions before an insurance claim with tamper-proof timestamps
- Chain of custody — Create immutable audit trails for legal evidence and forensic investigations
- Copyright protection — Establish authorship dates for DMCA disputes and IP claims
- Regulatory compliance — Meet evidence preservation requirements with independently verifiable records
Installation
That's it. The base install pulls no dependencies — it uses only the Python standard library — and gives you a verify-proof command:
To use it as an MCP server for Claude Desktop or Cursor, install the optional extra instead (details below):
pip install "verify-proof[mcp]"
Prefer to run from source? Clone it — the CLI works the same:
git clone https://github.com/Fulcrum-Enterprises/verify-proof.git
cd verify-proof
python verify_proof.py --help
Usage
Compute a file's SHA-256 hash
verify-proof hash document.pdf
Verify a file against a blockchain proof
verify-proof verify document.pdf --proof proof.json
The proof JSON file contains the blockchain anchor record:
{
"hash": "a1b2c3d4e5f6...",
"algorithm": "sha256",
"blockchain": "bitcoin",
"tx_id": "abc123...",
"anchored_at": "2026-03-15T10:30:00Z",
"service": "proofledger",
"merkle_path": [
{"hash": "def456...", "position": "right"},
{"hash": "789abc...", "position": "left"}
]
}
Use as an MCP server (AI assistants)
verify-proof ships an optional Model Context Protocol server, so MCP-compatible AI clients — Claude Desktop, Cursor, and others — can verify blockchain timestamp proofs directly in a conversation. The file never leaves your machine: hashing and verification run locally, and only the resulting hash is ever compared against the proof.
pip install "verify-proof[mcp]"
The base install stays dependency-free; the [mcp] extra adds the MCP SDK and installs a verify-proof-mcp command (a stdio server).
| Tool | What it does |
|---|
compute_file_hash | Compute the SHA-256 (or other) hash of a local file |
verify_file | Verify a local file against a proof JSON file |
verify_hash | Verify a known hash against inline or file-based proof data |
explain_proof | Describe, in plain language, what a proof asserts and how to check it on a block explorer |
Connect it to Claude Desktop
Add this to your claude_desktop_config.json (see examples/claude_desktop_config.json):
{
"mcpServers": {
"verify-proof": {
"command": "verify-proof-mcp"
}
}
}
Restart Claude Desktop. If verify-proof-mcp isn't found on your PATH, use the Python module form instead: "command": "python", "args": ["-m", "verify_proof_mcp"].
Then ask the assistant things like:
- "Verify
~/contract.pdf against ~/contract-proof.json."
- "What does this proof file actually prove?"
- "Compute the SHA-256 of this file so I can anchor it."
Proofs are produced by services like ProofLedger, which anchors SHA-256 hashes to Polygon and Bitcoin for legal, insurance, and chain-of-custody evidence. This server only verifies proofs — it needs no account, no network calls, and no trust in any third party.
How it works
verify-proof computes the SHA-256 hash of your local file- It reads the proof JSON to get the originally anchored hash
- If the hashes match, the file hasn't been modified since timestamping
- If a Merkle path is present, it verifies the path to the Merkle root
- The blockchain transaction ID can be independently verified on any block explorer
Compatible services
This tool verifies proofs created by:
-
ProofLedger — Evidence preservation platform. Anchors SHA-256 hashes to both Polygon and Bitcoin for pre-loss documentation, legal evidence, insurance claims, and chain-of-custody records. Built for insurance, legal, and forensic workflows.
-
Any service producing SHA-256 hash proofs with blockchain transaction references.
Why blockchain timestamps matter
Traditional timestamps (file system dates, email headers, document metadata) can be easily altered. Blockchain timestamps are:
- Immutable — Once anchored to Bitcoin or Polygon, the timestamp cannot be changed by anyone
- Independent — Verification requires only the file, proof, and public blockchain — no trust in any third party
- Legally defensible — Blockchain evidence is increasingly accepted in courts as proof of existence
- Tamper-evident — Any modification to the file produces a different hash, immediately detectable
License
MIT License. Free to use, modify, and distribute.
About
Built by Fulcrum Enterprises LLC — building tools for blockchain-verified proof of existence.
- ProofLedger: Tamper-proof evidence for legal and insurance