Cryptology ePrint Archive: BibTeX Citation of Report 2004/291

@misc{cryptoeprint:2004:291,
    author = {Martin Boesgaard and Thomas Pedersen and Mette Vesterager and Erik Zenner},
    title = {The Rabbit Stream Cipher - Design and Security Analysis},
    howpublished = {Cryptology ePrint Archive, Report 2004/291},
    year = {2004},
    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.