@misc{cryptoeprint:2000:023,
author = {Igor Shparlinski},
title = {Security of Polynomial Transformations of the Diffie--Hellman Key},
howpublished = {Cryptology ePrint Archive, Report 2000/023},
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.