Obviously, they have to know your User ID and password.
Team Viewer is an effective tool that allows a zero configuration desktop session using a 3rd party server. When you install and run it, you are assigned an ID which is the username, and a password generated by team viewer broker servers. Whoever wishes to connect to a remote desktop must acquire the pin codes from the client. You cannot access a remote computer without both the username and the password of the client.
answer; i believe the answer is tls,transport layer security;