The xDai bridge is an instance of TokenBridge between Ethereum and xDai Chain. Using the bridge, token holders of Dai can move their Dai from Ethereum to a pegged native token on xDai Chain. In reverse order, token holders of xDai can move their xDai to Dai using the same bridge.
The bridge consists of multiple independent parts:
- TokenBridge smart contracts on xDai Network;
- TokenBridge smart contracts on Ethereum Network;
- Multisigs on both networks to manage essential parameters of smart contracts such as daily limits, quotas per transaction, set of validators, upgradability;
- Nodes of oracles between two networks. Oracles listen for token transfer events and relay them between networks.
After the ceremony on the network initiation, which finished in December 2018, the bridge has following decentralization and security assumptions:
- Four validators can relay events;
- Three of the four validators are required to relay an event;
- Four validators can modify bridge parameters
- Three of four signatures are required to modify bridge parameters such as daily limits, quotas per transaction, set of validators, upgradability
You can always double check provided information yourself:
- List of validators of the bridge and the required number of signatures https://dai-bridge.poa.network/status
- Management multisig on Mainnet https://blockscout.com/poa/dai/address/0x0d3726e5a9f37234d6b55216fc971d30f150a60f/contracts
- Management multisig on xDai https://blockscout.com/eth/mainnet/address/0xff1a8eda5eacdb6aaf729905492bdc6376dbe2dd/contracts