@misc{cryptoeprint:2014:426,
author = {Ivan Damg{\aa}rd and Sunoo Park},
title = {Towards Optimally Efficient Secret-Key Authentication from PRG},
howpublished = {Cryptology ePrint Archive, Report 2014/426},
year = {2014},
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.