TANOS is a library implementing atomic swaps between Bitcoin and Nostr, using Taproot and Schnorr adaptor signatures, developed for the MIT Bitcoin Hackathon.
TANOS allows atomic swaps between:
- Bitcoin transactions using Taproot P2TR addresses
- Nostr events with Schnorr signatures
The protocol uses adaptor signatures to ensure atomicity: the buyer only gets the signed Nostr event if they pay with Bitcoin, and the seller only gets the Bitcoin if they reveal the secret from the Nostr signature.
This project is inspired by NIP 455: Atomic Signature Swaps, which proposes a standard for performing atomic swaps of cryptographic signatures over Nostr.
- BIP340-compliant Schnorr adaptor signatures
- Taproot address creation and transaction handling
- Nostr event creation and signing
- Complete atomic swap protocol implementation
- Pure Go implementation
The project is organized into the following packages:
pkg/adaptor- Adaptor signature implementation using Schnorrpkg/bitcoin- Bitcoin-related functionality (Taproot, transactions)pkg/crypto- Common cryptographic utilitiespkg/nostr- Nostr-related functionalitypkg/tanos- High-level swap protocol implementationexamples/swap- Example implementation of a complete swap
- Go 1.24.1 or later
- Bitcoin and Nostr dependencies
git clone https://github.com/GustavoStingelin/tanos.git
cd tanos
go mod downloadgo run examples/swap/main.go-
Setup:
- Seller has a Nostr private key
- Buyer has Bitcoin
-
Commitment:
- Seller creates and signs a Nostr event
- Seller extracts the nonce (R) from the signature
- Seller computes the commitment T = R + e*P
-
Locking:
- Buyer creates a Bitcoin transaction locking funds to a P2TR address
- Buyer creates an adaptor signature using the commitment T
- Buyer sends the adaptor signature to the seller
-
Revealing:
- Seller completes the adaptor signature using the secret from the Nostr signature
- Seller broadcasts the Bitcoin transaction with the completed signature
-
Verification:
- Buyer extracts the secret from the completed signature
- Buyer verifies that the secret matches the one in the Nostr signature
TANOS carefully implements BIP340 parity rules for Schnorr signatures. According to the specification:
- Schnorr signatures in BIP340 require the Y-coordinate of the nonce point (R) to be even
- When the Y-coordinate is odd, the signature value 's' must be negated
- This affects how secrets are extracted from completed signatures
This implementation automatically handles these parity adjustments, ensuring that:
- Generated Bitcoin signatures are valid according to BIP340
- Secrets extracted from signatures are correctly recovered, even after parity adjustments
For enhanced security, the library uses BIP340-style tagged hashes for all signature challenges, ensuring signatures from different contexts cannot be reused.
This project is licensed under the MIT License - see the LICENSE file for details.
- BIP340 (Schnorr Signatures)
- BIP341 (Taproot)
- Nostr Protocol
- MIT Bitcoin Hackathon
- NIP 455: Atomic Signature Swaps