To provide stable rewards, Dai is locked in the bridge contract. xDai is minted on the xDai chain, and the locked Dai in the bridge is converted to Chai. Chai earns interest during this time. When a user requests to move xDai back to Dai, xDai is burned, Chai is converted back to locked Dai, and Dai is unlocked and returned to the user on the Ethereum Mainnet. The accumulated interest is distributed to stakers in xDai during the staking epoch.