@misc{cryptoeprint:2011:655,
author = {T-H. Hubert Chan, Elaine Shi and Dawn Song},
title = {Privacy-Preserving Stream Aggregation with Fault Tolerance},
howpublished = {Cryptology ePrint Archive, Report 2011/655},
year = {2011},
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.