Cryptology ePrint Archive: BibTeX Citation of Report 2009/389

@misc{cryptoeprint:2009:389,
    author = {Joppe W. Bos and Marcelo E. Kaihara and Thorsten Kleinjung and Arjen K. Lenstra and Peter L. Montgomery},
    title = {On the Security of 1024-bit RSA and 160-bit Elliptic Curve Cryptography},
    howpublished = {Cryptology ePrint Archive, Report 2009/389},
    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.