Overlay networks etc - http://eprint.iacr.org/2009/294.pdf
There is an updated version of this paper available at http://www.sciencedirect.com/science/article/pii/S0020025512003374 that describes the mechanisms in more detail. From this paper, path_cost.erl and path_cost_salt.erl implements 4.3.4 Hash tree and psp.erl and psp_salt.erl implements 4.4 Pseudo path.
To use the salt version of these modules, you'll need https://github.com/freza/salt