stamp-verify

Open-source CLI to independently verify BA | Stamp blockchain timestamps.

No account needed. No dependency on bastamp.com. Just cryptographic math and a public blockchain.

What it does

1. Computes the SHA-256 hash of your file (or accepts a known hash)
2. Rebuilds the Merkle root from the hash + proof (keccak256, sortPairs)
3. Queries the Stamper smart contract on Polygon
4. Reports the on-chain timestamp if the root is anchored

Install

npm install -g stamp-verify

Or run without installing:

npx stamp-verify document.pdf --proof proof.json

Usage

Verify a file

stamp-verify document.pdf --proof proof.json

Verify using a known hash

stamp-verify --hash 0x3a7bd3e2... --proof proof.json

Just compute the SHA-256

stamp-verify hash document.pdf

JSON output

stamp-verify document.pdf --proof proof.json --json

Where to get the proof

The Merkle proof is included in every BA | Stamp certificate PDF (page 2). You can also download it from the public verification page:

https://bastamp.com/verify/<your-file-hash>

Save the proof array as a JSON file:

["0xabc123...", "0xdef456...", "0x789..."]

How it works

BA | Stamp batches document hashes into a Merkle tree and anchors the root on the Polygon blockchain. Each document gets a Merkle inclusion proof that links it to the on-chain root.

This tool reproduces the verification locally:

• SHA-256 — same algorithm used by BA | Stamp in the browser
• keccak256 + sortPairs — same Merkle tree construction as the Stamper contract
• On-chain query — reads timestamps(root) from the public smart contract

The Stamper contract is verified on Polygonscan. Anyone can inspect the source code.

Contract

| | | |---|---| | Address | 0x50ddee9a1afbe1a14f1cf01b379535f897b3ca3d | | Chain | Polygon (PoS) | | Verified source | Polygonscan |

Desktop app (GUI)

A Tauri-based desktop binary lives in gui/. Same verification logic as the CLI (via src/core/verify.ts), wrapped in a drag-a-file UI.

Run in browser (dev)

cd gui
npm install
npm run dev      # opens http://localhost:1420

Build the native binary

Requires Rust and, on Linux, Tauri's system dependencies:

# Ubuntu/Debian
sudo apt install libwebkit2gtk-4.1-dev build-essential curl wget file \
  libxdo-dev libssl-dev libayatana-appindicator3-dev librsvg2-dev pkg-config

# macOS: Xcode Command Line Tools (xcode-select --install)
# Windows: Microsoft Visual Studio C++ Build Tools + WebView2 (pre-installed on Win 11)

Then:

cd gui
npm run tauri:build   # produces .dmg / .msi / .AppImage under gui/src-tauri/target/release/bundle/

License

MIT — use it however you want.