Add Support for Taproot & Schnorr Signatures Across All Bitcore Libraries

[JavadTorabiKh]

Description

With Taproot (BIP 340-342) now activated on Bitcoin mainnet, Bitcore should provide comprehensive support for this major upgrade across all relevant libraries. This implementation will position Bitcore as a cutting-edge toolkit for modern Bitcoin application development.

Problem Statement

Current Bitcore libraries lack native support for:

• Schnorr signatures (BIP 340)
• Taproot outputs (BIP 341)
• Tapscript (BIP 342)
• Key aggregation and MuSig protocols

This limits developers from building next-generation Bitcoin applications with improved privacy, efficiency, and flexibility.

Proposed Implementation

Phase 1: Core Schnorr & Taproot Support

1. bitcore-lib enhancements:

• Add Schnorr signature class with sign/verify methods

• Implement Taproot address support (P2TR)

• Add Taproot script parsing and creation

• Support for key-path spending and script-path spending

2. bitcore-p2p updates:

• Support for parsing Taproot transactions in message protocols

• Updated transaction validation rules

Phase 2: Advanced Features

3. MuSig implementation:

• Multi-party Schnorr signatures (MuSig1/MuSig2)
• Key aggregation protocols
• Nonce management and session handling

4. Wallet integration:

• Taproot key derivation paths (BIP86)
• PSBT support for Taproot transactions
• Hardware wallet compatibility

Technical Specifications

// Proposed API examples:

// Schnorr signatures
const privateKey = new bitcore.PrivateKey();
const message = bitcore.crypto.Hash.sha256(Buffer.from('message'));
const signature = bitcore.crypto.Schnorr.sign(message, privateKey);

// Taproot addresses
const taprootAddress = new bitcore.Address.Taproot({
  publicKey: internalPubkey,
  script: tapscript // optional
});

// MuSig sessions
const musigSession = new bitcore.MuSigSession([pubkey1, pubkey2, pubkey3]);
const aggregatedKey = musigSession.aggregate();

Benefits to Ecosystem

1. Privacy: Taproot makes complex contracts indistinguishable from regular transactions
2. Efficiency: Schnorr signatures enable smaller multi-signature transactions
3. Flexibility: Advanced smart contract capabilities
4. Future-proofing: Aligns with Bitcoin's roadmap and developer needs

Acceptance Criteria

• Full test coverage including edge cases
• Compatibility with existing Bitcoin Core implementation
• Documentation with practical examples
• Performance benchmarks comparing to ECDSA
• Integration tests with popular hardware wallets

Why Bitcore Should Lead This

As a comprehensive Bitcoin development stack, Bitcore is uniquely positioned to provide consistent, well-tested Taproot support across its entire ecosystem rather than forcing developers to patch together multiple libraries.