ZkLogin is a way to use Sui with your online accounts, such as Google or Facebook. It lets you prove that you own a Sui address without revealing your password or other personal information. This is how it works:

• The wallet makes a temporary key pair, which has a public key and a private key.
• The wallet asks you to log in with your online account and uses the public key as a random code.
• The wallet gets a special token from the online service, which has your account ID and other data. The wallet also gets proof from another service, which shows that the wallet knows the private key and the token, and that the token is valid.
• The wallet gets random salt from another service, which makes your Sui address more secure and unique.
• The wallet calculates the ZkLogin Sui address by mixing the account ID and the salt together.
• The wallet signs the transaction with the private key and adds the proof and the salt to it.

The transaction is sent to the Sui network, where it is checked by Sui nodes using the proof, the salt, and the public key.