RFC 6979 Collision Check

RFC 6979 makes the ECDSA nonce deterministic: k = HMAC(d, H(m)), so two different messages must produce two different nonces. A broken implementation can emit the same nonce k (same R) for different messages under one key — and that leaks the key. Paste a Bitcoin address (or a transaction ID); this tool groups each key's signatures, flags any R repeated across different Z, and recovers the private key with k = (z1−z2)/(s1−s2), d = (s1·k−z1)/r, verified against the on-chain public key. Everything runs in your browser.

bitcoin
Enter a Bitcoin address or a 64-character transaction ID (TXID). Balance and stats load for every chain; the transaction graph loads where a keyless explorer is available.
newest for the address (exactly this many are scanned; a single TXID fetches just that one transaction)
A collision = one key signs two different messages with the same R (reused nonce). Every recovered key is verified against the on-chain public key, so there are no false positives.
Balance 0 BTC
Received 0 BTC
TX 0 
Instructions:
1. Enter a Bitcoin address (recommended) or a 64-character TXID.
2. Signatures are grouped by public key; any R that repeats across two DIFFERENT message hashes (Z) means the same nonce k was reused — a broken RFC 6979 deterministic nonce.
3. The private key is recovered with k = (z1−z2)/(s1−s2) then d = (s1·k−z1)/r, and is shown only when d·G reproduces the on-chain public key (no false positives). Recovery needs at least two signatures from the same key.
4. An internet connection is required to fetch transaction data from public block explorers.
Educational / read-only tool. Transaction data is fetched live from public block-explorer APIs (blockstream.info, with blockchain.info as a fallback). Key recovery only succeeds on wallets whose RFC 6979 implementation was broken and reused a deterministic nonce across different messages — it demonstrates why a correct, unique-per-message nonce is essential. Every result is verified against the on-chain public key; nothing is guessed. Never enter keys for wallets you use.