@misc{cryptoeprint:2015:287,
author = {John Schanck and William Whyte and Zhenfei Zhang},
title = {A quantum-safe circuit-extension handshake for Tor},
howpublished = {Cryptology ePrint Archive, Report 2015/287},
year = {2015},
note = {\url{http://eprint.iacr.org/}},
}
You will need the url.sty package (comes with most LaTeX installations) for the last line. Otherwise, remove the \url command.