Cryptology ePrint Archive: BibTeX Citation of Report 2011/642

@misc{cryptoeprint:2011:642,
    author = {Yongqiang Li and Mingsheng Wang},
    title = {Constructing differentially 4-uniform permutations over $\mbf_{2^{2m}}$ from quadratic APN permutations over $\mbf_{2^{2m+1}}$},
    howpublished = {Cryptology ePrint Archive, Report 2011/642},
    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.