Cryptology ePrint Archive: BibTeX Citation of Report 2011/475

@misc{cryptoeprint:2011:475,
    author = {Nicolas T. Courtois, Daniel Hulme and Theodosis Mourouzis},
    title = {Solving Circuit Optimisation Problems in Cryptography and Cryptanalysis},
    howpublished = {Cryptology ePrint Archive, Report 2011/475},
    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.