In the past I've created minor terminologies when divulging divinations that the party would need to decipher, but that takes a lot of planning.
For an easier solution when playing the role of the deity or otherworldy force giving them hints, simply refer to characters or locations using defining features instead of directly stating names. For example, if there's a Paladin of Pelor who is going to kill some Necromancer and inevitably mess something up, say something like "the jade servant of the sun will strike down the messenger of death and free that which should not." Then you just need to tack on some jade items to the pally, and voila easy encrypted message with no forethought.
Last edited by roguemetal : 10-30-2012 at 05:30 PM.