@misc{cryptoeprint:2010:655,
author = {İsa Sertkaya and Ali Doğanaksoy},
title = {On the Affine Equivalence and Nonlinearity Preserving Bijective Mappings},
howpublished = {Cryptology ePrint Archive, Report 2010/655},
year = {2010},
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.