USA HISTORY

Detailed explanation-1: -’AF’ Identified as Code for Midway Back in March, a Japanese plane reporting weather conditions near the islands had also mentioned “AF, ” suggesting strongly that the designator referred to Midway. But not everyone was convinced the codebreakers were right.

Detailed explanation-2: -Using complex mathematical analysis, IBM punch-card tabulating machines, and a cipher machine, Friedman had developed the ECM Mark III, the unit was able to crack most of the code by January 1942.

Detailed explanation-3: -JN-25 is the name given by codebreakers to the main, and most secure, command and control communications scheme used by the IJN during World War II. Named as the 25th Japanese Navy system identified, it was initially given the designation AN-1 as a “research project” rather than a “current decryption” job.

Detailed explanation-4: -The radio message was duly intercepted by Japan and reported by a message encoded in JN25 stating that AF’s desalinization plant was out of order. That message was intercepted by Station HYPO. AF was thus confirmed as Midway. There remained the question of the timing of the attack.