Taproot Assets on Mainnet: Announcing tapd v0.3.0-alpha

The sender provides a link to the work on their website: https://petertodd.org/2017/scalable-single-use-seal-asset-transfer. They also mention that the key concepts in universes are very similar and provide an email address for further contact: 'peter'[:-1]@petertodd.org.

The sender announces the release of tapd v0.3.0-alpha, which is the first software release that supports the Taproot Asset Protocol on mainnet. They provide a link to the deterministic and reproducible release on GitHub: https://github.com/lightninglabs/taproot-assets/releases/tag/v0.3.0. Additionally, they share a blog post about the launch, which can be found here: https://lightning.engineering/posts/2023-10-18-taproot-assets-v0.3/.

For those interested in tracking the usage/activity of the protocol, the sender mentions that there are two Universes servers available. The mainnet server can be accessed at https://universe.lightning.finance/v1/taproot-assets/universe/roots, while the testnet server can be accessed at https://testnet.universe.lightning.finance/v1/taproot-assets/universe/roots. The REST API documentation for the Universe servers is provided at https://lightning.engineering/api-docs/api/taproot-assets/rest-endpoints. Users can also interact directly via gRPC.

The sender informs that users have the option to run their own Universe server and federate with other universe servers using the relevant "as of" command (tapcli universe federation). They also mention that a technical specification for the Universe/Multiverse protocol can be found in the BIP at https://github.com/Roasbeef/bips/blob/bip-tap-pr/bip-tap-universe.mediawiki.

Explaining the functionality of a Universe server, the sender states that it is used by clients to verify new asset issuance, archive off-chain transaction data, and transmit proof information for transfers. They describe the Universe data structure as an authenticated merkle-sum sparse merkle tree that maps an (outpoint, scriptKey) tuple to proof data. The scriptKey is the protocol's version of the pkScript/scriptPubkey. In the initial version of the protocol, the scriptKey is a taproot output public key. The sender mentions that Bitcoin transactions are signed+verified under the hood, mapping a logical state transition to a 1-in-1-out Bitcoin transaction. The mapping from an asset state transition to a virtual transaction can be found at https://github.com/Roasbeef/bips/blob/bip-tap-pr/bip-tap-vm.mediawiki.

The email also highlights the use of vPSBTs (partially signed Bitcoin transactions) and SIGHASH_NONE on the TAP layer to construct a protocol for non-interactive, non-custodial swaps. An example of this implementation can be found at https://github.com/lightninglabs/taproot-assets/issues/577.

In conclusion, the sender expresses excitement about the mainnet alpha release of the Taproot Asset Protocol and invites experimentation and feedback to further enhance the protocol. They extend their thanks to those who have provided critical feedback in earlier versions, as it has contributed to the success of this release.