Japanes Naval Codes_IST323

Japanese naval codes

During World War 2, Allies and Axis were not only satisfied to protect information in simple method of substitution cipher. People began to pursue the more complicated way to protect the information. However, both Allies and Axis wanted to decode the code from the other side which made the World War not only a cruel war for humans, but also a rivalry of high technology. One of the most famous rivalry should be Japanese naval codes.

Japan had one of the most powerful naval power in the world in Asia-Pacific area during World War 2, so American Naval might not defeat Japanese naval easily without the help from decoding department. Backing in 1836, American artist Samuel F. B. Morse, American physicist Joseph Henry, and Alfred Vail developed an electrical telegraph system. The system use signal “on” and “off” to represent the information. There are correspondent letters and Morse code for English. However, since Japan had Japanese letter, Japan Naval has their own Morse code system. Moreover, Japanese Naval developed a more sophisticated system to replace the words they would use during War which was the Japanese Naval codes.

Japanese Naval codes were unlike German codes in World War 2. Japanese naval had book for their codes, while German codes used mechanical enci

Professors monitoring telegram

pherment, like Enigma. The principle of book cipher was that the sender composes the message and then checking in the code book to make the message in groups. Usually, common words and phrases (en example in World War two was Midway), and the remaining text is encoded individually. The receiver then looks up the group in code book and reassembles the message. There is also an advanced version of code book which enciphering the group themselves which is called super ciphering.

The most famous Japanese Naval code system was JN25. JN25 has more than 90,000 words and phrases. There were also a lot of super ciphering methods. In generally, even American Naval can decipher the major of the meaning of the codes, the most important information like position or force name were also hard to decipher because these information was only appearing in the code book in the rules defined by Japanese so that American could not decipher by machines. However, American used strategy to know what the specific information was. In the case of Midway, Japanese used AF to present Midway Island. At that time, American only learned that Japanese Naval would attack a position called AF after they decipher Japanese cipher. They did not know where AF was. Then, American sent a message in plain text said that there was a short of fresh water on Midway. After that American monitored Japanese telegram and found one piece of information said that AF was lack of fresh water. In this way, American learned that AF was referred to Midway.

Code book was strong. However, it was finally be deciphered. In World War 2, the information Security was not only a competition between technology, but also the battle between humanity and strategy.