The name Purple was given to the machine by American cryptanalysists. The U.S. called it Purple because the first Japanese code, called Orange had increased in difficulty and went on to the color Red until the most difficult, the Purple, was reached. This was the code constructed on a machine, unlike previous codes, which were constructed with pen and paper. In Japan Purple was simply referred to as "the machine" or "J".

Purple was a poly-alphabetic substitution system, which is a form of simple substitution cipher - every position on the disk in the machine gives a different cipher alphabet. In other words, instead of having only one cipher alphabet, this system had many. The Purple Cipher Machine had three different forms, which were classified as Type A, Type B, and Type C. Type A systems were not very complex. They used text, which was mostly in the English language. This type

The intelligence produced by the solution of foreign codes and ciphers, including Purple, was given the cover name MAGIC. MAGIC received its name from William F. Friedman because he referred to his staff of cryptanalysists working on the ciphers as magicians. The Japanese would issue replacements once a version of Purple was cracked. This presented challenges to the Americans because they would have to wait until the fragments of the messages built up before they could solve the key again. The messages sent by Purple sometimes took several weeks or months to be completely deciphered.

Although MAGIC could not provide any information that the Japanese did not first send, it had a way of making the Allies think that they knew every step that the Japanese were going to take. This was probably because Purple contained reports of conversations with Nazi

able to encipher numbers or punctuation, the code clerk first had to transform all numbers and punctuation into three letter code words. These code words were given to the clerks in a code list. Once the code words were assigned they were encrypted. When the receiving clerk got the message, he had to restore the punctuation and paragraphing before he could read the decoded cipher.

officials and Japanese diplomats on their views of the conditions of the war efforts in Germany. The messages sent from Japan usually contained very detailed military data. When the Allies cracked Purple it became a great contribution to the war effort because it allowed the Allies to read the messages from Japan's ambassador and military attache in Germany on Hitler's capabilities and plans. The ciphers of the Purple Machine gave much insight to Hitler's plans on the Eastern and Western fronts of Europe. The intelligence also informed the Allies that Hitler's main objective was in Europe. This information came from messages from the Japanese ambassador in Berlin to his leaders in Tokyo about his conversations with Hitler.

Purple revealed much more than Hitler's plans in Europe. MAGIC reported conversations between Japan and Germany dealing with declaring war on the United States. Although Purple provided this information, the United States did not recognize its seriousness. This information was foreshadowing the attack on Pearl Harbor. The United States government was not sure how the attack on Pearl Harbor had come about. American cryptanalysists had cracked the Japanese Purple diplomatic cipher before the attack on Pearl Harbor. However, they did not want to let the word out that Purple had been cracked. The Americans knew that it would cause the Japanese to change their code system. The message that contained the information that Japan and Germany were going to declare war on the U.S. was available in Washington the day before the attack on Pearl Harbor. The Americans missed the significance because they were busy reading ciphers and working on solving other systems at the same time that t!

Kahn, David. Kahn on Codes. Secrets of the New Cryptology. New York: Macmillan Publishing, 1983.

The Purple Cipher Machine played such an important role in the war time efforts of the Allies that if it hadn't been cracked the outcome of the war could have been drastically changed. Although the information sent through the Purple Cipher Machine did not prevent the attack

Some common words found in the essay are:
Type Japanese, Alphabetical Typewriter, William Friedman, YuGo YuGo, Cipher Machine, Americans Japanese, Purple Japanese, Pearl Harbor, Japan Germany, Japan Purple, purple cipher, purple cipher machine, cipher machine, cipher text, pearl harbor, coding wheels, attack pearl harbor, attack pearl, messages sent, text machine, type systems, alphabetical typewriter, cipher text machine, code purple cipher, world war ii,
Approximate Word count = 2237
Approximate Pages = 9 (250 words per page double spaced)