The common implementation of tor does use 3, but as you can see on page 5 the basic concept functions with 2: https://svn.torproject.org/svn/projects/design-pa

The common implementation of tor does use 3, but as you can see on page 5 the basic concept functions with 2: https://svn.torproject.org/svn/projects/design-paper/tor-design.pdf https://svn.torproject.org/svn/projects/design-paper/tor-des... It helps to simplify when explaining to others.