Wanted to create an issue to track the various changes needed for taproot support

Tagged hashes

• Merge Tagged hashes for taproot #259 for tagged hashes

Signatures & PSBTs

• Unified SighashCache implemented in Adds Taproot BIP341 signature message and create a unified sighash cache for legacy, segwit and taproot inputs #628
• Signature data serialziation according to BIP-341 in witness and BIP-371 in PSBTs: PSBT taproot spending signature type #671
• PSBT taproot-specific fields: Add support for taproot psbt fields BIP 371 #681, PSBT taproot spending signature type #671

Script

• new_p2tr() Taproot P2TR address #563, P2TR address from untweaked key #691 [requires Add bip340 schnorr rust-secp256k1#237]
• to/is_p2tr() Taproot tweaks generalization & KeyPair support #696 (previous work: P2TR improvements #646)
• Construction of taproot script branches and script conversion to P2TR Add taproot data structures #677 (previous attempt: Taproot-related data types #666)
• Test coverage BIP341 test vectors #695
• Converting LeafVersion into an enum Converting LeafVersion into an enum #718

Opcode

• OP_CHECKSIGADD Add OP_CHECKSIGADD and OP_SUCCESSxxx #644

Address

• Witness version type introduction: WitnessVersion type #617
• AddressType::P2t Taproot P2TR address #563 [requires Support bech32m rust-bech32#48]
• p2t(pubkey: secp256k1::bip340::PublicKey, network: Network) Taproot P2TR address #563 [requires Add bip340 schnorr rust-secp256k1#237]
• address_type match segwit version 1 to AddressType::P2t Taproot P2TR address #563
• Address-related type refactoring for better witness v1 support: Address type system #668

Key

• Key refactoring strategy: Taproot keys implementation strategy #588 and its step-by-step implementation:
  • Non-API breaking changes for 0.26.1 Non-API breaking introduction of Schnorr keys #589
  • Refactor key export names Minimally-invasive separation of bitcoin keys from ECDSA signature types #757
  • API-breaking changes to Extended keys internal key representation: Taproot: BIP32 extended keys using Scep256k1 keys instead of bitcoin ECDSA #590
  • API-breaking changes to PSBT internal BIP32 key representation: PSBT BIP32 keys using to Secp256k1 keys instead of bitcoin ECDSA #591
• Support for proper key tweaks: Add taproot data structures #677 & Taproot tweaks generalization & KeyPair support #696 (previous work: API for taproot tweaked keys #585, Taproot-related data types #666; parallel/alternative Implement taproot specific script helpers #604)
• Rejected first implementation attempt, but a lot of important discussions on implementation details Taproot PublicKey refactoring #561
• Other Important discussions addressing Taproot as a part of overall crate refactoring: Proposal: split bitcoin into multi-crate workspace #550