Ebook: Elementary cryptanalysis

Pt. 1. Monoalphabetic ciphers using additive alphabets. The Caesar cipher -- Modular arithmetic -- Additive alphabets -- Solution of additive alphabets -- Frequency considerations -- Multiplications -- Solution of multiplicative alphabets -- Affine ciphers -- Pt. 2. General monoalphabetic substitution . Mixed alphabets -- Solution of mixed alphabet ciphers -- Solution of five-letter groupings -- Monoalphabets with symbols -- Pt. 3. Polyalphabetic substitution. Polyalphabetic ciphers -- Recognition of polyalphabetic ciphers -- Determination of number of alphabets -- Solutions of additive subalphabets -- Mixed plain sequences -- Matching alphabets -- Reduction to a monoalphabet -- Mixed cipher sequences -- General comments;Pt. 4. Polygraphic systems. Linear transformations -- Multiplication of matrices -- inverses -- Involutory transformations -- Recognition of digraphic ciphers -- Solution of a linear transformation -- How to make the Hill system more secure -- Pt. 5. Transposition. Columnar transposition -- Completely filled rectangles -- Incompletely filled rectangles -- Probable word method -- General case -- Identical length messages -- Pt. 6. RSA encryption. Public-key encryption -- The RSA method -- Creating the RSA keys -- Why RSA works -- Fermat's Little Theorem -- Computational considerations -- Maple and Mathematica for RSA -- Breaking RSA and signatures -- Pt. 7. Perfect security. One-time pads -- Pseudo-random number generators;In this introduction, Professor Sinkov explains some of the fundamental techniques at the basis of cryptanalytic endeavour from which much more sophisticated techniques have evolved, especially since the advent of computers.