Flyover Protocol Design
The Flyover system allows a user to transfer BTC from Bitcoin to RSK and vice versa in a fast way, where a third party takes the risk to advance the payment for the user. Flyover also provides the new feature to transfer BTC from Bitcoin directly to a smart contract in RSK.
The outstanding feature of the Flyover system is that it accomplishes the above without giving any third party custody of the transferred funds. This is an outstanding security guarantee to the user. The system comprises one or more liquidity providers (LPs) that store their BTC in RSK and Bitcoin. The first version of the Flyover protocol supports only the peg-in process (BTC to RBTC). Later versions will also support the peg-out process (RBTC to BTC).
Workflow
The following diagram shows the interaction of the different components during the peg-in process. Note that the call to isOperational could be performed at a different time:
The following diagrams show the interactions between Liquidity Provider, Liquidity Bridge Contract and RSK Bridge Contract in three different scenarios:
- Basic fast bridge workflow (happy path)
- Unsuccessful call on behalf of a user
- Liquidity Provider fails to deliver funds to LBC
Figure 1 - Basic fast bridge workflow. Note that step (3) registerPegin can be called by the LP or any other entity.
Figure 2 - Fast bridge interactions when the call on behalf of the user is unsuccessful. The LP keeps the call fee and the rest is refunded to the refund RSK address.
Figure 3 - Fast bridge interactions when the LP fails to call the LBC on behalf of the user. The LBC slashes the LP's collateral and refunds the user on the refund RSK address.