Shannon published an earlier version of this research in the classified report `` A Mathematical Theory of Cryptography , '' Memorandum MM 45-110-02 , Sept. 1 , 1945 , Bell Laboratories .
Shannon published an earlier version of this research in the classified report A Mathematical Theory of Cryptography , Memorandum MM 45-110-02 , Sept. 1 , 1945 , Bell Laboratories .