Cryptology ePrint Archive: BibTeX Citation of Report 2006/360

@misc{cryptoeprint:2006:360,
    author = {Marc Stevens and Arjen Lenstra and Benne de Weger},
    title = {Target Collisions for MD5 and Colliding X.509 Certificates for Different Identities},
    howpublished = {Cryptology ePrint Archive, Report 2006/360},
    year = {2006},
    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.