Cryptology ePrint Archive: BibTeX Citation of Report 2001/091

@misc{cryptoeprint:2001:091,
    author = {Ivan Damgård and Jesper B. Nielsen},
    title = {Perfect Hiding and Perfect Binding Universally Composable Commitment Schemes with Constant Expansion Factor},
    howpublished = {Cryptology ePrint Archive, Report 2001/091},
    year = {2001},
    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.