May I recommend a book to those who love ciphers/codes/good story ? "From SIlk To Cyanide" by Marks. Published within the last year in US. As noted I am hopeless with codes but this is also a whacking good tale, and true. The writer is the son of the owner-founder of Marks & Co of London, a bookstore that is featured in the delightful tale "34 Charing Cross Road." The story is set in England in WWII years where he was in the business of helping spies. Anyone who has done some reading on WWII will recognize the names of many spies who became famous after the war when their work and sacrifice were finally recognized. Happy reading, wow