Cryptology ePrint Archive: BibTeX Citation of Report 2007/152

@misc{cryptoeprint:2007:152,
    author = {Nicolas T. Courtois},
    title = {CTC2 and Fast Algebraic Attacks on Block Ciphers Revisited},
    howpublished = {Cryptology ePrint Archive, Report 2007/152},
    year = {2007},
    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.