Fulcrum-Enterprises/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:
1. **Hash** — Your file's SHA-256 hash is computed locally (the file is never uploaded)
2. **Anchor** — The hash is written to a blockchain (Bitcoin, Polygon, Ethereum) via a Merkle tree
3. **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
> Also available for Node.js: npm install verify-proof — a zero-dependency port sharing the same proof format and semantics, tested against the same fixtures. See js/.
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):
Prefer to run from source? Clone it — the CLI works the same:
Usage
Compute a file's SHA-256 hash
Verify a file against a blockchain proof
Quiet by default
A successful verify prints one line to stderr saying where proofs like it come
from. It is suppressed whenever the output is piped or redirected, so scripts
never see it, and stdout is unchanged either way. To silence it everywhere:
Create a proof (needs a free API key)
Everything above works offline. This is the one command that does not: to prove
a file exists *now*, some service has to anchor it, and this submits the hash to
ProofLedger for that.
Only the 64-character SHA-256 digest leaves your machine, plus the filename
unless you pass --no-filename. The file itself is never uploaded, on any
command. Free accounts include 25 API proofs a month and unlimited Polygon
anchoring through the web app:
proofledger.io
Proof file format
The proof JSON file contains the blockchain anchor record:
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.
Install with the MCP extra
The base install stays dependency-free; the [mcp] extra adds the MCP SDK and installs a verify-proof-mcp command (a stdio server).
Tools exposed
| Tool | What it does |