Switch to https

Episerver stores passwords hashed so np there. If you want encrypted network traffic use https. If you want to store username encrypted too, override standard membership provider methods and add encryption to username there. Dont normally do that though. Https and hashed passwords out of the box is usually good enough.

Daniel are correct, the way for you to encrypt the communication is to use https.

If you want to implement the encryption and hash'ing by yourself there are a good article about it here:

https://crackstation.net/hashing-security.htm