how does the login block works?

I am wondering how the login block works in terms of sending the password in plaintext through http.

Once I had everything configured I checked the chrome network tab to check the network traffic and I saw the first post to node with the user login got back with a redirect to 302, but, isn't the plain text password sent anyway the first time to the server through http before the redirection get there, or the post is captured by the module before sending it and the request is made all through ssl?

I just would like to understand properly how this works, thanks.