@misc{cryptoeprint:2013:524,
author = {Teng Guo, Feng Liu, ChuanKun Wu, ChingNung Yang, Wen Wang and YaWei Ren},
title = {Threshold Secret Image Sharing},
howpublished = {Cryptology ePrint Archive, Report 2013/524},
year = {2013},
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.