Purple.

This is coolbert:

“Seek and ye’ shall find!!” - - Matthew 7:7.

While looking over the wiki entry for the Japanese Purple cryptographic machine, came across something that partially answers a question I had posed in a previous blog entry:

The Japanese Army cipher machine, analogous to the Enigma, but more secure [??] was not decrypted by Allied intelligence until 1943!! Now it can be understood WHY! Japanese army cryptologic theoreticians had looked at the Purple machine and found it to be wanting??!!

"Just before the end of the war, the Army warned the Navy of a weak point of PURPLE, but the Navy failed to act on this advice."

"The Army developed their own cipher machines on the same principle as Enigma, 92-shiki injiki, 97-shiki injiki and 1-shiki 1-go injiki from 1932 to 1941. The Army judged that these machines had lower security than the Navy did its PURPLE design, so they were less used."

[it is not entirely clear from the wiki article if the Army machines were more secure than Enigma? Confidence in these crypto machines was lacking and they just tended to be used less?]

Rather than use Purple, the Japananese Army devised and used THEIR own cryptographic machines, NOT HAVING the same weakness as Purple!! Machines that were used with less frequency.

There is also confusion here. It seems that the cryptographic success achieved in 1943 was against an enciphered code system used by the Japanese Army, and NOT against a machine cipher??

"It is the first square recovered by Central Bureau and Arlington Hall in April 1943, for the 2468 Japanese army water transport system, the first Japanese army system to be read."

This was an enciphered code system as opposed to a machine cipher.

The Japanese Army had crypto machines, but just used them less and not with confidence?

However, the various Japanese military attaches’ stationed in Europe continued to use Purple for their correspondence [they had diplomatic status!!]. That Purple traffic “read” by the allies [primarily the U.S.] was the proverbial “goldmine”.

NOW we know the rest of the story!?

It seems I am going in a circle with this.

coolbert.