POA Forum

ETH-to-xDai Arbitrary Message Bridge launched

Although the TokenBridge AMB functionality has been available since the 3.0.0 release , we were waiting for a finalized security audit before implementing this new piece of code. Now that the security audit provided by Quantstamp is complete, we have deployed a trial version of the Arbitrary Message Bridge (AMB) between the Ethereum Mainnet and the xDai chain.

Contracts that serve the new bridge:

Since the AMB allows us to relay contract method calls from one chain to another, it can be used for a broad set of use cases. For DApp developers it means they don’t need to set up their own bridge infrastructure. Instead, DApps can use the existing AMB instance with the associated set of validators to make transfer calls.

To demonstrate the bridge’s ability to transfer data, we deployed an erc20-to-erc20 extension on top of AMB so anyone can transfer Synth sUSD from the Ethereum Mainnet to the xDai chain and back.

This is only one example of how the Arbitrary Message Bridge can be used - look for more examples soon!

More information about how to write your own mediators to provide a service through AMB can be found in the TokenBridge documentation.


Anyone who is interested in experiments with the new bridge could use the instructions describing how to transfer sUSD tokens through the bridge extension.

This is great news! Are there still plans to implement it from POA to Mainnet Ethereum? Will this bridge stay online? How are Eth Mainnet gas fees being handled?

We plan to deploy in for POA this week.

Do you have the extension (plugin) for the AMB bridge for your token/contract?
If not, could you please share more information what you plan to be transferred and we can help you with the extension.

Very cool AMB between the Ethereum Mainnet and the xDai chain.

I was able to transfer some sUSD

I also set up a quick little sUSD Token Balance On xDai Chain tool


Here is information about the ETH-POA Arbitrary Message Bridge: https://docs.tokenbridge.net/eth-poa-amb-bridge/about-the-eth-poa-amb. So far it is working in the subsidised mode so no need to cover gas fees by the bridge contracts callers.

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