@misc{cryptoeprint:2013:443,
author = {Jiangxiao Zhang. Hua Guo. Zhoujun Li. Chang Xu},
title = {Optimally Anonymous and Transferable Conditional E-cash},
howpublished = {Cryptology ePrint Archive, Report 2013/443},
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.