XRGB L2 Chain

XRGB chain implemented XRGB protocol and introduced the enhanced transactional privacy of RGB protocol. It aspires to be the quintessential Bitcoin Interoperability layer, prioritizing scalability and privacy while fostering a vibrant asset liquidity for all the BTC Layer2s and other BTC extensive solution. The architecture diagram is as follows:

There are four main components in XRGB chain: Oracles, Relayers, Vaults and Validators.

On Bitcoin chain, Vaults were deployed to manage the bridging liquidity. Any user who stake enough XRGB token can be qualified to register as a Vault. The address of the Vault was decided by the requester's Bitcoin address as well as the validator set. On EVM chains, XRGB endpoint contracts were deployed to manage the issue and burn of the ERC404 assets.

Oracles are ChainLink nodes which periodically submit Bitcoin and EVM blockchain headers to XRGB chain. Relayer will monitor all the transactions on Vaults Muitisig 2 and the XRGB contracts endpoints, submitting them to the XRGB chain.

When user want to bridge their Bitcoin assets, they need to lock their assets to one of the Vaults, the lock transaction will be collected by Relayers network and submitted to XRGB chain. Once the transaction is verified by validators via the Bitcoin block headers, the Relayers will sign the threshold signature, and the Muitisig will be then relayed to the related EVM chain, the XRGB endpoint contract will verify the signature and issue ERC404 assets

When users want to bridge back their ERC404 assets from EVM chains to Bitcoin, first they need to burn their ERC404 token via the XRGB endpoint contracts deployed on each EVM blockchain. The burn transaction will be collected and submitted to XRGB chain via the relayers network. Once a consensus was made against the burn transaction proof verification, each relayer will sign the issuing transaction and the threshold signatures will be submitted to the Vault Multisig 2, then the Vault will send Bitcoin taproot transaction to unlock the assets for users.