@misc{cryptoeprint:2013:556,
author = {Oleksandr Kazymyrov and Valentyna Kazymyrova},
title = {Algebraic Aspects of the Russian Hash Standard GOST R 34.11-2012},
howpublished = {Cryptology ePrint Archive, Report 2013/556},
year = {2013},
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.