During the war, British cryptologists decrypted a vast number of messages enciphered on Enigma. Allied codebreakers read much enciphered German message traffic, especially that encrypted with the Enigma machine. Messages were sent to and fro across the Atlantic by enciphered teleprinter links. Messages were sent to and from across the Atlantic by enciphered teleprinter links. The former had one in plaintext saying "You Are Already Dead"; the rest were enciphered. The resultant 6-letter indicator, was then transmitted before the enciphered text of the message. The rest of the text letters are then enciphered with subsequent alphabets. The second letter of the message was enciphered using the second shifted alphabet, etc. The rightmost rotor moved as each character was enciphered. I, Riverbank was the only facility in the U.S. capable of solving enciphered messages. Numbers are enciphered one digit at a time. When Bob receives the newly enciphered message, he believes it came from Alice. To indicate spaces between words in the message, the letter "Z" is enciphered. Then, the result is enciphered with one of the following two equivalent methods. Frequency analysis is also impossible because the same letter is always enciphered differently.