Part I. Cryptography: Introductory Synopsis.- Aims and Methods of Cryptography.- Encryption Steps: Simple Substitution.- Encryption Steps: Polygraphic Substitution and Coding.- Encryption Steps: Linear Substitution.- Encryption Steps: Transposition.- Polyalphabetic Encryption: Families of Alphabets.- Polyalphabetic Encryption: Keys.- Composition of Classes of Methods.- Open Encryption Key Systems.- Encryption Security.- Part II. Cryptanalysis: Exhausting Combinatorial Complexity.- Anatomy of Language: Patterns.- Polyalphabetic Case: Probable Words.- Anatomy of Language: Frequencies.- Kappa and Chi.- Periodicity Examination.- Alignment of Accompanying Alphabets.- Compromises.- Linear Basis Analysis.- Anagramming.- Concluding Remarks.- Appendix: Axiomatic Information Theory.- Bibliography.- Index.- Photo Credits.