Where do u get an authenticator for rift?

Answer 1

if you have an android phone you can get it here

http://forums.riftgame.com/showthread.php?144530-RIFT-Android-Authenticator-Now-Available

Answer 2

Currently, only iOS and Android have the authenticator. You can find them on their respective app stores.

They will eventually release a physical Authenticator device for those without one of these mobile platforms, but it is not available at the moment.