Cryptology ePrint Archive: BibTeX Citation of Report 2012/656

@misc{cryptoeprint:2012:656,
    author = {Mohammad Ali Orumiehchiha and Josef Pieprzyk and Elham Shakour and Ron Steinfeld},
    title = {Security Evaluation of Rakaposhi Stream Cipher},
    howpublished = {Cryptology ePrint Archive, Report 2012/656},
    year = {2012},
    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.