@misc{cryptoeprint:2009:587,
author = {Rajesh P. Singh, A. Saikia and B.K. Sarma},
title = {Poly-Dragon: An efficient Multivariate Public Key Cryptosystem},
howpublished = {Cryptology ePrint Archive, Report 2009/587},
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.