Cryptology ePrint Archive: BibTeX Citation of Report 2013/230

@misc{cryptoeprint:2013:230,
    author = {Yang Wang and Mark Manulis and Man Ho Au and Willy Susilo},
    title = {Relations among Privacy Notions for Signcryption and Key Invisible "Sign-then-Encrypt''},
    howpublished = {Cryptology ePrint Archive, Report 2013/230},
    year = {2013},
    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.