The Imperial Japanese Navy IKA Cipher Machine

Abstract

The Imperial Japanese Navy IKA cipher machine was a predecessor to the more familiar Japanese cipher machines of the 1931 and 1937 series. Nothing is known about the machine itself, but the cryptography of the machine is known. What follows describes the cryptography of the IKA machine and discusses that machine in the context of the 1931 and 1937 series of Japanese cipher machines that followed it.