Helen F. Gaines 
Cryptanalysis 
A Study of Ciphers and Their Solution

Gaines’s
Cryptanalysis (formerly published as
Elementary Cryptanalysis) is a standard elementary and intermediate text for persons seriously interested in modern science methods for enciphering and deciphering cryptograms. It does not simply repeat older material, but contains much about modern cryptanalysis that is not generally known except to experts. It is especially strong in modern forms of cipher solution.

This clear and thorough text also provides the reader with 166 specimen codes to solve. This edition for the first time also includes solutions. A special appendix includes final letters, sequence charts, digram, trigram tables, most common words in English and frequencies in English, German, French, Italian, Spanish, and Portuguese.

Table of Content

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