@misc{cryptoeprint:2009:052,
author = {S.Sree Vivek and S.Sharmila Deva Selvi and C.Pandu Rangan},
title = {ON THE SECURITY OF TWO RING SIGNCRYPTION SCHEMES},
howpublished = {Cryptology ePrint Archive, Report 2009/052},
year = {2009},
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.