@misc{cryptoeprint:2009:402,
author = {Michael Vielhaber},
title = {AIDA Breaks BIVIUM (A&B) in 1 Minute Dual Core CPU Time},
howpublished = {Cryptology ePrint Archive, Report 2009/402},
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.