A Bitcoin developer by the name of Burak recently unveiled Ark, a Layer 2 protocol designed to enable fast and secure transactions. According a message on the bitcoin dev mailing list, Ark offers an alternative scaling approach that allows users to send and receive funds without liquidity constraints, making it easier for recipients to get paid without onboarding setup. Unlike other Layer 2 solutions like Lightning, Ark does not require channels to be opened and closed, significantly reducing the on-chain footprint.
The protocol works using virtual UTXOs (vTXOs), which are short-lived notes that expire after four weeks. When a payment is made, existing vTXOs are exchanged and new ones are created. Coin ownership anonymity is improved by limiting vTXO values to a range of sats values. Users can acquire vTXOs from other users or use a process called lifting, which allows them to remove their on-chain UTXOs from the chain for virtual UTXOs.
The protocol introduces an intermediary called Ark Service Provider (ASP), which serves as a liquidity provider, CoinJoin coordinator, and Lightning service provider. ASPs create fast, blind CoinJoin sessions every five seconds, called pools, which ensure payment schedules are atomic. Recipients can claim their funds through a txlock condition that requires the connector’s exit point to remain unchanged.
Ark’s integration with the Lightning Network allows users to attach HTLCs (or PTLCs) to a pool transaction, enabling interoperability between the two protocols. Multiple ASPs can be used to pay Lightning bills from different vTXO sources using multi-part payments. Payouts on Ark are credited every five seconds, allowing users to immediately spend their conf-free vTXOs without waiting for on-chain confirmations.
The developer behind Ark highlighted the protocol’s potential for future expansions and improvements. A hypothetical data manipulation opcode could deter double spend, and users could forge an ASP’s signature to recover their vTXOs in the event of a double spend. Overall, Ark offers a promising solution for efficient and secure off-chain transactions on the Bitcoin network.
For more information about Ark and its technical details, curious users are encouraged to visit https://arkpill.me/deep-dive.