@misc{cryptoeprint:2000:056,
author = {Amit Sahai and Salil Vadhan},
title = {A Complete Problem for Statistical Zero Knowledge},
howpublished = {Cryptology ePrint Archive, Report 2000/056},
year = {2000},
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.