In the article they link a page with more details on the code and the "iron fish" : http://www.history.navy.mil/faqs/faq61-2.htm http://www.history.navy.mil/faq

In the article they link a page with more details on the code and the "iron fish" : http://www.history.navy.mil/faqs/faq61-2.htm http://www.history.navy.mil/faqs/faq61-2.htm A bit strange that it's the most critical words which had the less variation in the end.