[Jalapeno]

I missed Codebreakers, heard it was ok. I have not heard of "The Man Who Broke Purple"...see it was in 1977, but have not found a good reference.

[jamaksin]

This may be helpful:

"The Codebreakers - The Story of Secret Writing"
David Kahn, The MacMillan Company, New York, 1967.
pages 863-73, 953.
[This is the first edition, there is also a paperback, and a later hardcover.]

"The Man Who Broke Purple: The Life of Colonel William F. Friedman, Who Deciphered the Japanese Codes in World War II"
Ronald Clark, Little Brown, Boston, 1977.
[The Japanese Code here is the diplomatic variant - NOT TO THE VARIOUS MILITARY. That is a different story.]