Cryptology ePrint Archive: BibTeX Citation of Report 2003/040

@misc{cryptoeprint:2003:040,
    author = {Kishan Chand Gupta and Palash Sarkar},
    title = {Computing Partial Walsh Transform from the Algebraic Normal Form of a Boolean Function
},
    howpublished = {Cryptology ePrint Archive, Report 2003/040},
    year = {2003},
    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.