This proposal aims to upgrade the Snowbridge Gateway contract on Ethereum, which is remotely governed by OpenGov utilizing Snowbridge itself as a cross-chain governance bridge.

The related bridge hub changes are included in the 1.71 upgrade. https://polkadot.subsquare.io/referenda/1756

New Features

The upgraded gateway supports new user-facing features:

Tighter XCM integration allowing users to send a user contructed XCM message from Ethereum to Polkadot.
Arbitrary message passing between Ethereum and Polkadot via XCM Transact.
Un-ordered message delivery.
Lower fees: all fee related calculation is moved offchain and is now dynamically calculated based on live gas prices.

Technical Details

This proposal will update the Gateway proxy at 0x27ca963c279c93801941e1eb8799c23f407d68e7 with a new implementation contract at 0x8a887783e945233d51881e06835ec78a8b575ece

This contract was built and deployed using:

Repository: https://github.com/Snowfork/snowbridge
Commit: 8662d76740960aee660487221712f1537274ddb5
Command: cd contracts; scripts/deploy.sh contracts/scripts/upgrade/DeployGateway202509.sol

The proposal will also update a storage key that sets the default base price for the bridge at 0.1 DOT.

Storage Key: 0xd0ed50b03e9a49e836dd934b425ba4c3

Key Source

Verification Script: https://gist.github.com/alistair-singh/7d4e5986fa6fcb73df71079771a2aa54

The key, value and the preimage for this ref was built with the Snowbridge control tool.

Testing

The upgrade proposal was extensively tested using simulations on forked instances of both Polkadot and Ethereum mainnet. This was done using Chopsticks and Foundry for Polkadot and Ethereum respectively.

Since the Ethereum side of snowbridge has no fallback governance or centralized escape hatches, it is critical to ensure that the upgrade does not affect the ongoing viability the gateway. In this regard, the fork tests in ForkUpgrade202509.t.sol verify that cross-chain signalling is preserved.

Audits

The Ethereum contracts were audited at revision 9bcac977155belbe0fc55e2d16ac3244667a50f4, which includes the features described above.
Oak Security Audit Report