Cross-chain ETH-WAN Bridge LIVE on the Rinkbey Testnet

Noah Maizels
4 min readSep 4, 2020

We first announced Wanchain 5.0 with its Wanchain to Ethereum cross-chain bridge less than two months ago in our mid year update article. Since then, Wanchain’s R&D team including several of PhDs in cryptography & other related disciplines, and our over thirty skilled software engineers have been working non-stop to bring Wanchain 5.0 to fruition. The fruits of their labor are now here and open to the world with the launch of the Wanchain 5.0 cross-chain bridge on Ethereum’s Rinkbey Testnet.

On August 26, 2020, the Wanchain R&D team successfully deployed the Wanchain 5.0 cross-chain bridge prototype on the Ethereum Rinkeby testnet. The bridge now enables the cross-chain transfer of testnet WAN between Wanchain’s public testnet and the Ethereum Rinkbey testnet.

This technology is now live on the testnets of Wanchain and Ethereum. This means that WAN from the Wanchain testnet can now be securely sent to the Ethereum testnet, and back. The ERC20 version of WAN generated on the Ethereum testnet is referred to as WAN@Ethereum. The update also allows ETH and other ERC20 tokens to be sent to the Wanchain testnet as placeholder WRC20 tokens. The WRC20 version of ETH on Wanchain is refferred to as wanETH

You can check out the ERC20 WAN token on the official Rinkbey Tesntet Explorer site.

What is a Two Way Cross-chain Bridge?

A cross-chain bridge is a mechanism which allows for assets to flow back and forth between two different blockchains. Wanchain’s first version of a cross-chain bridge first launched about two years prior allowed for a one directional flow of assets from other chains on to Wanchain. With the launch of Wanchain 5.0, these bridges will be upgraded from one way to two way. While previously the WAN-ETH bridge only allowed for ETH and ERC20 tokens to be transferred from Ethereum to Wanchain, the new two way bridge also allows for WAN and WRC20 tokens to flow the other way on to Ethereum.

Cross-chain Powered by Wanchain’s MPC & TSS Enabled Storeman Nodes

Wanchain’s two-way bridges are powered by a group of nodes referred to as Storeman Nodes. When working as a group, those nodes are referred to as a Storeman Group.

As we discussed in our earlier article digging into renBTC’s current implementation of their ETH-BTC cross-chain bridge, MPC & TSS (multiparty-computation and threshold secret schemes) play a major role in guaranteeing the security of cross-chain bridges. In short, this technology allows for a large group of nodes to securely and collectively manage the process of moving value back and forth between different chains. In this prototype testnet bridge we have set the group number to 21 nodes, and have set the threshold number at 16 (for more information about “threshold” numbers, MPC & TSS, check out the articles linked to at the start of this paragraph).

Rapid Cross-Chain

For the upcoming Wanchain 5.0, we are introducing a new rapid cross-chain cross-chain method. This method has already been completed successfully on the testnet. In prior versions of Wanchain’s cross-chain bridge, the cross-chain process required multiple steps starting with the Storeman cross-chain node group initiating the cross-chain request on the source chain. After initiating the request on the source chain, the user must then also perform a redeem transaction on the target chain.

With the new rapid cross-chain mechanism, that redeem step is no longer required. Rather, an initiator on the source chain can directly send tokens to an address on the target chain without any redeem transaction required to confirm receipt.

Compared with the previous cross-chain method based on hash time locks (HTLC), the rapid cross-chain method greatly shortens the cross-chain transaction time (no need to wait for the user to redeem), and greatly reduces the cross-chain cost (reduced by two on-chain interactions) At the same time, it also greatly reduces the difficulty of the cross-chain operation and improves the cross-chain transaction experience.

One downside to the rapid cross-chain method is that it is a little less secure than the old method, and so may not be suitable for large transactions. For transactions which require higher security, the old HTLC version is still available, and we encourage users to use it for high value transactions.

Examples of HTLC cross-chain transactions on Rinkeby:
https://rinkeby.etherscan.io/tx/0x9267c7f276f5f0318715611491e3e4feba4405227079da2aa5c2cf74bf09e3d6#statechange

Examples of rapid cross-chain transactions on Rinkeby:
https://rinkeby.etherscan.io/tx/0xf126a3117cd08fc188ddd09b381a34cc4c1d74bd8712cd47cc412c2a7bc805e1#statechange

Of course, our cross-chain research does not stop at two-way bridges. In addition to the two-way bridge and fast cross-chain features, we’re very excited about the development of what we have been referring to as “direct” bridges. In a follow-up article, we will introduce “direct” bridges in detail, and explain how they differ from previously discussed bridges.

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