You can generate an encrpting key by performing an interactive key agreement protocol with your friend. To start, you click on the Connect button in the Friend Node Settings dialog. This will display a new KeyAgreement Dialog window. The interactive key agreement protocol takes place inside this window. The new key is created incrementally, through an interactive questions and answers session. You and your friend will in turn ask questions for which you both know the answer (Example - "What is the name of our high school math teacher?"). You can select sample questions from the Possible questions dropbox. If the answers you provide match, they are computed into the shared key. The strength of the key depends on the number of questions/answers you submit. If you don't know an answer to a question, push the Don't Know button; your friend has the choice to send you another question, or abort the agreement. In order to have a secure key, it is important that answers depend on shared knowledge between you and your friend (it should be hard for a stranger to guess these answers!).
Once a friend node has been added, and a shared key has been agreed upon, the Turtle software will automatically connect to the friend node, and establish a secure encrypted channel to it.