Cryptology ePrint Archive: BibTeX Citation of Report 2013/572

@misc{cryptoeprint:2013:572,
    author = {Goutam Paul and Subhamoy Maitra and Anupam Chattopadhyay},
    title = {Quad-RC4: Merging Four RC4 States towards a 32-bit Stream Cipher},
    howpublished = {Cryptology ePrint Archive, Report 2013/572},
    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.