If you're not familiar with multisig Bitcoin security, think of it like a bank vault that needs multiple keys to open - except you control all the keys and there's no bank!

Here's what you need to know:

• Multisig is like having a lockbox that needs 2 out of 3 keys to open - even if one key is lost or compromised, your Bitcoin stays safe
• Sigbash provides one of those keys - but with a special twist: it only works when conditions YOU set are met
• You maintain complete control - Sigbash can't access your funds on its own, it's just one piece of your security puzzle

For the more technically inclined:

• Extended Public Keys (xpubs) allow Bitcoin wallets to generate a sequence of public keys without revealing the private keys, enhancing security and privacy.
• Multi-signature (multisig) setup requires multiple keys to authorize a Bitcoin transaction, distributing risk across multiple devices or parties.
• Partially Signed Bitcoin Transactions (PSBTs) are a standard format for transactions that need signatures from multiple parties.

Sigbash turns your Bitcoin security from static to dynamic with powerful conditional locks:

Real-World Use Cases:

• Inheritance Planning: Create a Bitcoin inheritance solution that unlocks after a certain date without trusting lawyers or third parties
• Price-Based Trading: Set up automatic access to funds when Bitcoin hits your target price
• Emergency Fund: Create a backup key that only activates when specific market conditions are met
• Business Controls: Add spending conditions based on transaction size or recipient address for corporate treasuries

Our keys can enforce conditions like:

• Time restrictions: Only sign after specific dates or Bitcoin block heights, or with passkey authorization
• Market conditions: Only sign if Bitcoin (or 170+ other assets) is above/below your target price
• Network conditions: Only sign if mining hashrate or specific address balances meet your criteria
• Transaction parameters: Only sign if the transaction inputs, outputs, or fees are within your defined limits

All while maintaining your privacy through our unique blinding technology.

Sigbash is designed to minimize trust requirements, but like any service, isn't completely trustless. This is why we recommend using Sigbash as just one key in a multisig setup (like 2-of-3) rather than for single-key wallets.

Here's our trust model and safeguards:

Trust Minimization:

• Sigbash can't move your funds on its own - it's just one key in your multisig setup
• We don't know what funds you're protecting until you request a signature
• Every xpub comes with a cryptographically signed receipt proving its conditions
• Our receipts are timestamped on the Bitcoin blockchain via OpenTimestamps

If Sigbash doesn't sign when it should: Contact support at sigbashsupport@proton.me with your signed receipt. We recommend having backup plans like timelocked recovery paths in your wallet setup.

If Sigbash signs when it shouldn't: This would require a significant breach of our security model. Our reputation as a service depends on never violating signing conditions, which is why we provide GPG-signed receipts attesting to them.

You can verify our GPG key (601993EC97CE3A71) here and read more about GPG contracts here.

Sigbash is built from the ground up with privacy in mind:

• No personal information required - no accounts, email, ID, or contact details needed
• Tor access available at 5dsaboekmamlwfhbrqd5d6jk6vbx7hun6ftyie2cskcl63zbnkqmdpyd.onion to hide your IP address
• Blinded xpub technology means we don't know what key we've given you until you ask us to sign

How xpub blinding works: When you request an extended public key from Sigbash, your browser creates random numbers to generate a unique derivation path that only you know. We only see a hash of your xpub, not the xpub itself, until you need a signature.

This means until signing time, Sigbash has zero knowledge about:

• What Bitcoin addresses you're using
• Your transaction history and balance
• Your multisig setup details

Even if Sigbash were legally compelled to share information, we simply don't have it to share until you request a signature.

Privacy levels with Sigbash:

Basic Privacy (Good): Purchase an xpub from your normal connection and use it in a multisig setup. Sigbash won't know what you're protecting until signature time, but will see your IP and transaction details when you request signing.

Enhanced Privacy (Better): Purchase an xpub over Tor, a VPN, or public WiFi. Sigbash won't be able to connect your xpub to your identity, but will still see transaction details at signing time.

Maximum Privacy (Best): Purchase an xpub over Tor and use it in a multisig with other blinded xpubs. Use coin mixing before and after transactions. When a signing condition is met, show your GPG-signed receipt to your other multisig partners and have them sign instead of revealing the transaction to Sigbash.

This last scenario highlights a key benefit: Just having a Sigbash key in your multisig with verified conditions can encourage other signing parties to honor those conditions without ever revealing details to Sigbash.

Getting started with Sigbash is straightforward:

1. Purchase a Sigbash xpub using the form on our "Buy an Xpub" tab. Set your desired conditions.
2. Save your blinded xpub receipt that will be provided for download.
3. Add your Sigbash xpub to your multisig wallet setup using compatible software like Sparrow or Specter.
4. Create your multisig wallet with your personal keys plus the Sigbash key.
5. Fund your wallet and use it normally.
6. When you need to spend, create a PSBT with your wallet software, sign with your keys, and submit to Sigbash for the final signature (if conditions are met).

For detailed step-by-step guides with specific wallet software, check our tutorials page or contact our support team.

Current limitations to be aware of:

• Beta status: Sigbash is currently beta software. We're constantly improving, but you may encounter occasional issues.
• Single use: Each Sigbash xpub can only be signed for once. After signing a PSBT, that specific xpub will be marked as redeemed.
• Hardware compatibility: Some hardware wallets have limited support for blinded derivation paths (see our compatibility table).
• No warranty: Sigbash services are provided "as-is" without warranties. Users are responsible for understanding the risks of multisig setups.

For enterprise users needing multi-use xpubs or custom solutions, please contact us at sigbashsupport@proton.me to discuss your requirements.

If you're experiencing issues with Sigbash, here's how to troubleshoot:

1. Verify your xpub: Use our "Verify Xpub" tab to confirm your Sigbash xpub is valid and check its conditions.
2. Check PSBT format: Ensure your PSBT is correctly formatted using tools like bip174.org.
3. Review compatibility: Make sure your wallet software supports blinded xpubs (see our compatibility table).
4. Check our documentation: Visit our tutorials page for step-by-step guides with common wallet software.

If you're still having issues after these steps, contact us at sigbashsupport@proton.me with:

• Your signed receipt (to verify ownership)
• The error message you're receiving
• The wallet software you're using

We typically respond within 24 hours to all support requests.