This page allows you to revoke or manage token contract approvals. What on earth does that mean?
What's an approval? — The first time you bridge an ERC-20 token like USDC from Ethereum, you'll notice that the first step is an "approval" transaction, which gives the Rainbow Bridge the permission to transfer that particular token. So that you only have to do this once, the amount approved is "unlimited".
What's the risk? — Unlimited approval is nearly universal practice in DeFi, but it does present a security risk you should be aware of. If the Rainbow Bridge suffered a particular kind of security exploit, the attacker could transfer your entire balance of that particular coin on Ethereum. The risk is low, but not zero.
What can I do about it? — The purpose of this page is two-fold:
1. Should the Rainbow Bridge ever suffer such an exploit, we would announce (as soon as we know about it) that all users return to this page, and revoke all approvals.
2. You can, at any time, revoke an approval, or manually set approval limits.
How do approval limits work?
Say your MetaMask wallet has 50,000 USDC, and you typically bridge 1,000 USDC from Ethereum to Aurora. You could set an approval limit here of 10,000 USDC, which would then be the maximum amount you could lose in an exploit. This would allow you 10 transfers of 1,000 USDC before the Rainbow Bridge would again ask you for an (unlimited) approval, after which you'd return here to again manually set a limit of 10,000 USDC.