WebScrapeHelper — Bitcoin ECDSA Signature Analyzer

A Flask-based research tool for inspecting Bitcoin transactions for textbook ECDSA weaknesses (low-S, repeated r/nonce reuse) and, when given real per-input message hashes, applying the standard nonce-reuse recovery formula x = (s·k − z) / r mod n.

Status & honest caveats

• The transaction analyzer fetches r and s from the input scriptSigs via blockchain.info and detects shared r across inputs.
• The analyzer does not reconstruct the real per-input Bitcoin SIGHASH_ALL preimage. Recovering a private key from the pure transaction-id endpoint therefore intentionally stops after detection — the required ECDSA z values aren't available.
• Use the POST /api/analyze/ecdsa, POST /api/recover/low-s-with-nonce, POST /api/calculate/nonce or the offline calculator at /standalone-calculator when you have real z values to feed in.

This tool is for defensive security research / education. It is not a "key recovery" magic wand — the math only works when the underlying mathematical preconditions are actually satisfied by the data you supply.

Routes

Path	Purpose
/	Landing page with quick links and live-scan buttons
/transaction	Analyze a single transaction by id
/address	Analyze every transaction for a given address
/ecdsa-analysis	Manual ECDSA parameter playground
/standalone-calculator	Render the offline ECDSA calculator
/download-calculator	Download the offline calculator HTML
/api/analyze/transaction	POST {tx_id}
/api/analyze/address	POST {address}
/api/analyze/ecdsa	POST {tx_id} or POST {r1, s1, m1, r2, s2, m2}
/api/recover/low-s-with-nonce	POST {r, s, z, k}
/api/recover/malleability-signatures	POST {r, s_values, z}
/api/calculate/nonce	POST {r, s1, s2, z1, z2}
/api/calculate/nonce-from-private-key	POST {r, s, z, x}
/api/auto-scan	Scan the latest block for vulnerable signatures
/api/monitor-mempool	Scan the mempool for vulnerable signatures

Local setup

# Option A: pip
python -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

# Option B: uv (uses pyproject.toml)
uv sync

# Run the dev server
FLASK_DEBUG=1 python main.py
# or
gunicorn -w 2 -b 0.0.0.0:5000 main:app

The server listens on port 5000 by default. FLASK_DEBUG and PORT env vars are honored by main.py.

Project layout

app.py                       Flask routes
btc_analyzer.py              ECDSA analysis / recovery code
attached_assets/             utils, validators, address list
static/                      JS, CSS, downloadable offline calculator
*.html                       Jinja templates (template_folder='.')
block_scanner.py             Standalone block scanner
continuous_scanner.py        Long-running mempool / block hunter
enhanced_hunter.py           Async variant of the hunter
run_hunter.py                CLI entry point for the hunters

Security & ethics

This is a defensive analysis tool. Do not use it to attempt access to Bitcoin funds you do not control. The recovery code only succeeds against mathematical preconditions that arise from genuinely broken signing implementations; keys returned for transactions whose preconditions are not met are not valid keys.