@misc{cryptoeprint:2015:134,
author = {Pierre Karpman},
title = {From Related-Key Distinguishers to Related-Key-Recovery on Even-Mansour Constructions},
howpublished = {Cryptology ePrint Archive, Report 2015/134},
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.