Thorough, systematic introduction to serious cryptography, especially strong in modern forms of cipher solution used by experts. Nihilist, grille, U. S. Army, key-phrase, multiple-alphabet, Gronsfeld, Porta, Beaufort, periodic ciphers, and more. Simple and advanced methods. 166 specimens to solve with solutions.

Preface
General Information
Concealment Devices
Transposition Types
Geometrical Types--The Nihilist Transposition
Geometrical Types--The Turning Grille
Irregular Types--Columnar Transposition
"General Methods--Multiple Anagramming, Etc."
Substitution Types
Simple Substitution--Fundamentals
The Consonant-Line Short Cut
  A Method for Attacking Difficult Cases (by George C. Lamb)
Simple Substitution with Complexities
Multiple-Alphabet Ciphers--The Vigenere
"The Gronsfeld, Porta, and Beaufort Ciphers"
The Kasiski Method for Periodic Ciphers
Miscellaneous Phases of Vigenere Decryptment
Auto-Encipherment
Some Periodic Number-Ciphers
Periodic Ciphers with Mixed Alphabets
Polyalphabetical Encipherment Applied by Groups
Vigenere with Key-Progression
Polygram Substitution--The Playfair Cipher
Highlights of Fractional Substitution
Investigating the Unknown Cipher
Appendix
  English Frequency and Sequence Data
  Comparative Table of Single-Letter Frequencies
  Chart Showing Normal Contact Percentages (by F.R. Carter)
  Chart Showing Frequencies of English Digrams (by O. Phelps Meaker)
  Some Foreign Language Data
  Bibliography (by W.D. Witt)
  The Commonest English Words (by Frank R. Fraprie)
  English Trigrams (by Frank R. Fraprie)
  English Digrams (by Frank R. Fraprie)
Solutions
Index