Outside of himself, nobody in Darsh could read it but the woman who had sent it; if, as he thought highly probable, the Statisticalists had spies among the hotel staff, it might serve to reduce some cryptanalyst to gibbering insanity.
"Last Enemy"
Henry Beam Piper
We turned the letters themselves over to Doc Petrie, the Ulleran philology sharp, who is a pretty fair cryptanalyst.
"Uller Uprising"
Henry Beam Piper, John D. Clark and John F. Carr