This document provides an overview of the topics to be covered in the course CS8792 - Cryptography and Network Security. It discusses foundations of modern cryptography including perfect security, information theory, and product cryptosystems. Product cryptosystems combine two or more transformations, like substitution, permutation, and modular arithmetic, to encrypt messages. An example of a product cipher discussed is the ADFGVX cipher used by the German Army in World War I, which combined a simple substitution with a transposition step.

1. CS8792 –
CRYPTOGRAPHY AND
NETWORK SECURITY
~ S. Janani, AP/CSE
KCET
Foundations of Modern Cryptography – Product

2. Unit I - Introduction
Topic Teaching Aid Activity
Security trends -
Legal, Ethical and Professional Aspects of Security
PPT -
Need for Security at Multiple levels, Security Policies PPT -
Model of network security,
Security attacks, services and mechanism,
OSI security architecture
PPT Quiz
Classical Encryption techniques (Symmetric cipher model, substitution
techniques, transposition techniques, steganography)
WB Worksheet
Foundations of modern cryptography: perfect security, information
theory, product cryptosystem, cryptanalysis
PPT Worksheet

3. Product Cryptosystems
 Shannon
 Combines two or more transformations in a manner intending that
the resulting cipher is more secure
 The product cipher combines a sequence of simple
transformations such as substitution (S-box), permutation (P-box),
and modular arithmetic.

4. ADFGVX Cipher
 German Army during World war I
 PT: COMPUTER KEY: LEMON
A D F G V X
A
D
F
G
V
X

5.  Intermediate Cipher Text
 DD AG AF FG GF GD AD AX
 Transposition by Row – Columnar Matrix
 KEY : BREAD

6. B R E A D A B
D E R
 X
 GGDDFGXAFFAGADAD
F