@misc{cryptoeprint:2009:011,
author = {D. Canright and Lejla Batina},
title = {A Very Compact "Perfectly Masked" S-Box for AES (corrected)},
howpublished = {Cryptology ePrint Archive, Report 2009/011},
year = {2009},
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.