Lecture: Introduction to Cryptography and Cryptanalysis

Background Material

• String manipulation
• Probability distribution

Reading

• None.

Topics

• Terminology: cypher, plaintext, cyphertext, encryption, decryption, key, alphabet, message space, cypher space, key space, cryptanalysis.
• Ceasar cypher
• Monoalphabetic substitution cyphers
• Transposition cyphers
• Frequency analysis
• Introduction to Maple, string processing, and substitution cypers. See sub.mw.

Resources

• www.maplesoft.com (Maplesoft Web site)
• sub.mw - Maple worksheet introducing string functions and simple substitution cyphers.
• Sample cypher using the following code.
• freq.xls - frequency distribution for .
• Scott Bryce's Cryptogram page - useful information for frequency analysis and an applet for generating and solving cryptograms.
• Letter Frequencies
• Introduction to frequency analysis

Assignments

• Write a program to determine the frequencies of letters occurring in the book War and Peace
• Attempt to solve several cryptograms from Scott Bryce's Cryptogram page.
• Download and install Maple 12 from the IRT software site and review the worksheet from the lecture - sub.mw.
• Work on lab1.mw