@misc{cryptoeprint:2009:546,
author = {Masao Kasahara},
title = {Construction of A New Class of Linear Multivariate Public Key Cryptosystem, K(I)SE(1)PKC},
howpublished = {Cryptology ePrint Archive, Report 2009/546},
year = {2009},
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.