ARK: (Smart)Bridging blockchains - Smith + Crown
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ARK: (Smart)Bridging blockchains

ARK aims to support cross-chain transactions using a feature called SmartBridge. How does SmartBridge work?

ARK is a Lisk-forked cryptocurrency currently holding a crowdsale. It boasts the ability to communicate (and transact) across blockchains, a smart card for consumer use, and IPFS integration. The core development team is comprised of key players of the Lisk network, including a primary Lisk developer, Francois-Xavier Thoorens, a number of prominent validators from the Lisk network, and co-founders from Crypti.

Cross-blockchain communication is rapidly becoming a core issue in the cryptocurrency community. Almost 200 coins have launched in 2016. Consensus 2016 identified interoperability as one of the biggest challenges facing the industry. Komodo and SuperNET have proposed a way to support cross-chain communication for Bitcoin-based cryptocurrencies. The Polkadot protocol, developed by Gavin Wood, also has a proposed approach.

ARK’s solution is called SmartBridge. One of Lisk’s goals with sidechains was to allow other distributed applications to have their own chains but stay connected to the Lisk ecosystem. Instead of using sidechains, ARK has SmartBridge, which enables other blockchains to send special messages to and through ARK. Someone could issue an ARK transaction using Ethereum or trigger an Ethereum smart contract from Bitcoin through ARK–once Bitcoin and Ethereum become SmartBridge compatible.

ARK accomplishes this by supporting encoded listeners: special nodes that listen to other chains specifically for transactions that bear ARK-compatible messages. These nodes can take the contents of those messages and execute them–including transactions on other chains. Presumably, the messages themselves are executable transactions that nodes can easily parse and relay.


This could have a number of applications in the emerging cryptocurrency industry.

  • Allowing users to use other blockchains without necessarily managing the native tokens. Some projects being launched have their own currencies or tokens which let holders use their platform. Instead of acquiring a new token directly, a user could issue a transaction to pay five ETH worth of the new token. The encoded listener–which could be Shapeshift–would be able to claim the five ETH and pay the other chain on bob’s behalf.
  • Transact across blockchains using just ARK. Many cryptocurrency holders have a myriad of coins, spread across different wallets and exchanges. ARK could let them manage their holdings from ARK itself. This could include cross-chain swaps if there was support for decentralized exchange activity.

One catch is that ARK won’t be able to speak with every chain immediately. Instead, it will support others in developing these encoded listeners specific to other sets of chains. Other services would develop encoded listeners for their customers or create cross-blockchain payment schemes that others could use for a fee. SmartBridge is the underlying technology that protects information and allows it to migrate from one chain to another–it’s the job of another application to make use of that information.

Other chains can be made compatible with SmartBridge through a couple lines of code the ARK team has developed. These can be easily put into a new blockchain or implemented on an existing chain through a fork.

There are a number of open questions, including how trusted encoded listeners need to be, the escrow feature for currency swaps, the integration with IPFS, and the price feeds for cross-chain transfers. At time of writing, a number of technical details were still being reviewed by the community. The ARK team made their initial code available on November 12th.