The Flyover system allows a user to transfer BTC to RSK and vice versa in a fast way, where a third party takes the risk to advance the payment for the user. It also provides the new feature to transfer BTC from Bitcoin directly to a smart contract in RSK.
A pivotal 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 BTC. The first version of the Flyover converts only the peg-in process (BTC to RBTC). Later versions will also enable streamlining the peg-out process (RBTC to BTC).
One of the unexplored possibilities of Flyover is to assign BTC addresses to RSK contracts. Currently the Bridge prevents address reuse, but we could in the future lift this restriction for some kind of Flyover peg-ins that do not trigger smart-contract execution. For this to work, a directory contract would be needed to map BTC addresses to contracts, so that Powpeg nodes can identify those peg-ins and process them as normal.