@misc{cryptoeprint:2014:953,
author = {Pooya Farshim and Gordon Procter},
title = {The Related-Key Security of Iterated Even-Mansour Ciphers},
howpublished = {Cryptology ePrint Archive, Report 2014/953},
year = {2014},
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.