@misc{cryptoeprint:2012:283,
author = {Deep Singh and Maheshanand Bhaintwal},
title = {Some properties of q-ary functions based on spectral analysis},
howpublished = {Cryptology ePrint Archive, Report 2012/283},
year = {2012},
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.