Off-chain payment channels have tremendous utility. Thousands of transactions can be aggregated every minute without consuming block space; and seamless point-of-sale transactions would make Monero purchases feel no different to using a credit card or Venmo.

Unfortunately, payment channels require a persistent state mechanism to keep track of the payment channel balance; something that is highly unlikely to be introduced to Monero (for good reason). Therefore it may appear that payment channels are impossible in Monero.

Enter Grease: a minimal, bidirectional proof-of-concept payment channel implementation for Monero. It makes use of verifiable, consecutive, one-way functions (VCOF) and consecutive linkable ring adapter signatures (CLRAS) in concert with a smart-contract enabled blockchain (SCEB)
to provide payment channels with the promise of unlocking these and other use cases.

We discuss our implementation, potential refinements and improvements and the impact of FCMP of future development.