@misc{cryptoeprint:2006:075,
author = {TOMOHIRO HARAYAMA},
title = {ON THE WEIL SUM EVALUATION OF CENTRAL POLYNOMIAL IN MULTIVARIATE QUADRATIC CRYPTOSYSTEM},
howpublished = {Cryptology ePrint Archive, Report 2006/075},
year = {2006},
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.