William F. Friedman eBooks

This book provides an excellent foundation for solving cipher systems. The text describes the fundamental principles of cipher solution plus use of the unilateral frequency distribution in the solution process is covered in some detail. Various unilateral and multilateral systems are carefully discussed. In addition, the text introduces the student to the solution of digraphic substitution ciphers, including the solution of the Playfair Cipher. Numerous problems are provided for solution by the student....