Safe communication with Tox

µTox

After starting µTox, the most common Tox client, a pretty clear communication center opens (see the "Installing µTox" box for more details). Your first step is to set the program preferences by way of the gear icon at the lower window edge (Figure 1).

Figure 1: You find your Tox ID in the µTox user settings. It's best to share this ID in an analog manner to allow encrypted chatting.

These are your personal settings, beginning with a username of your choice. You also set status information at this point, such as I'm available or Only in urgent cases .

The Preview function allows you to test phone calls and to find out if an attached webcam is working. You also choose which sound input and output devices to use. In further settings, you should also specify whether the program should save chat histories. It's disabled by default.

Under the settings, you'll find your personal Tox ID, which you'll need to securely share with your friends and acquaintances. Save the ID in the buffer by clicking Copy . Your friends will use this passphrase to add you to their contacts. The plus sign at the bottom of the window is used for this purpose. Clicking it drags a new communication partner into the Tox ID field; you accept a friend using Add . The ID owner then gets a request confirmation message, which he then acknowledges. Nothing now stands in the way of your communication.

You can tell if one of your contacts is online and has Tox loaded when the circle icon next to the contact name is green.

Secure Communication

Messages written with Tox pass encrypted over the Internet. The method used for it is based on the NaCl [5] open software library, named after the chemical symbol for salt. NaCl wants to be the salt in the soup for program developers who need as simple but reliable encryption integrated in their applications as possible. Threema also uses the library for security.

Sending messages works like other instant messaging systems. You select from a contact list, write the message in the text window at the bottom edge of the window, and then send it off (see Figure 2).

Figure 2: The chat function works like other messaging systems, but your data is encrypted and goes via P2P over the Internet without a central server.

µTox also supports group chats, which you can start by clicking the group chat icon next to the plus icon. You then add contacts to the group chat by dragging their usernames while holding the left mouse button.

Tox supports sending files of any type, which you can do by clicking the paperclip icon at the upper right and opening a file selection dialog. Your recipient has to acknowledge the file before it's actually sent.

For video calling, you'll find the camera icon at the upper right. Select a contact and click the icon. As soon as the other party accepts the call, Tox builds the video connection and the image appears in its own window. The connection often took a while in tests. Whereas the image already appeared for the called party, the caller had to wait. The transmission quality was also mixed: Sometimes, the user was left with a still image, which only a new call would remedy.