Cryptology ePrint Archive: BibTeX Citation of Report 2011/687

@misc{cryptoeprint:2011:687,
    author = {Mohammad Ali Orumiehchiha and Josef Pieprzyk and Ron Steinfeld},
    title = {Cryptanalysis of WG-7  (A Lightweight Stream Cipher for RFID Encryption)},
    howpublished = {Cryptology ePrint Archive, Report 2011/687},
    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.