TANOS: Taproot Adaptor for Nostr-Orchestrated Swaps

Atomic Bitcoin–Nostr swaps powered by Taproot and adaptor signatures.

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✨ Inspiration

TANOS was inspired by a friend who is building a marketplace on the Nostr ecosystem. He previously implemented a similar concept for Cashu–Nostr swaps (sig4sats-script) and even proposed a NIP for atomic signature swaps.

This showed me that these types of cryptographic primitives can have real, practical value in the Bitcoin ecosystem — and this hackathon was the perfect opportunity to contribute with something meaningful.

⚡ What it does

TANOS enables trustless and atomic swaps between a signed Nostr event and a Bitcoin Taproot UTXO, using adaptor signatures. It ensures that either the event is revealed and Bitcoin is paid — or nothing happens.

🛠️ How I built it

I built a custom library in Go to handle the cryptographic operations required for the swap. It uses:

The core logic handles adaptor signature creation, nonce tweaking, Taproot output construction, and final signature recovery.

🧱 Challenges I ran into

  • Correctly computing adaptor signatures according to BIP340
  • Handling point negation and parity bits to ensure valid Schnorr signatures
  • Validating Taproot tweak logic
  • Managing the interaction between Bitcoin and Nostr in a stateless way

🏆 Accomplishments I'm proud of

  • Successfully recovering a valid Nostr signature via adaptor signature
  • Fully trustless and atomic behavior with no escrow or third party
  • A working cryptographic core written from scratch in Go

📚 What I learned

  • That I don’t know nearly enough cryptography 😅
  • Seriously, I gained deep insight into the intricacies of Schnorr signatures, Taproot script construction, and Bitcoin’s sigops limitations
  • I also gained experience integrating off-chain protocols (Nostr) with on-chain enforcement (Bitcoin)

🚀 What's next for TANOS

  • Implement a proper timelock refund path to prevent stuck funds or malicious behavior
  • Test extensively on testnet and signet
  • Add unit tests, documentation, and example flows
  • Release a beta version for feedback
  • Collaborate with other Nostr and Bitcoin projects to support adoption and integration

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