Which two statements about IPsec authentication on FortiGate are correct? (Choose two.)

Which two statements about IPsec authentication on FortiGate are correct? (Choose two.)

A. A certificate is not required on the remote peer when you set the signature as the authentication method. B. Enabling XAuth results in a faster authentication because fewer packets are exchanged. C. FortiGate supports pre-shared key and signature as authentication methods. D. For a stronger authentication, you can also enable extended authentication (XAuth) to request the remote peer to provide a username and password.