@misc{cryptoeprint:2005:432,
author = {Dieter Schmidt},
title = {On the Security of Kaweichel},
howpublished = {Cryptology ePrint Archive, Report 2005/432},
year = {2005},
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.