Cryptology ePrint Archive: BibTeX Citation of Report 2011/210

@misc{cryptoeprint:2011:210,
    author = {Jooyoung Lee and Martijn Stam and John Steinberger},
    title = {The preimage security of double-block-length compression functions},
    howpublished = {Cryptology ePrint Archive, Report 2011/210},
    year = {2011},
    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.