Web Tools for Classical Cryptology Tristan Beeble Overview

Web Tools for Classical Cryptology Tristan Beeble

Overview l l l Background Types of problems Tools

Cryptology l Cryptography – l Encoding a message Cryptoanalysis – Decoding a message

Background l l l Client: Professor Lesh Gen-ed Math course Help solve homework problems

Goals l l Decoding Additional study Aid, not solve Easy to use

Terms l l l Plaintext: Message you want to send Ciphertext: Actual text sent Key: What’s needed to decode Algorithm: How to decode Cipher: allowed plaintexts, keyspace, encryption and decryption algorithm

Types of Ciphers l l l Caesar Cipher Monoalphabetic Ciphers Polyalphabetic Ciphers – Vigenère Cipher

Caesar Cipher Plaintext: tristan Key: 7 Ciphertext: aypzahu

Monoalphabetic Cipher Caesar Plaintext: A B C D E Ciphertext: B C D E F Monoalphabetic Plaintext: A B C D E Ciphertext: E C A B D

Monoalphabetic cipher

Polyalphabetic Cipher l Vigenère cipher Plaintext: i n i t i a t e Key: u n i o n u n i

Vigenère cipher

Vigenère Cipher Plaintext: i n i t i a t e Key: u n i o n u n i Ciphertext: c a q h v u g m

Caesar Cipher Decryption l l Same idea as Encryption Backwards Ciphertext: aypzahu Key: 7(-7) Plaintext: tristan

Caesar Cipher Tool

Caesar Cipher Tool

Monoalphabetic Cipher Decryption l First Step: Guess work – – l Word length Partial solutions Second Step: Frequency Analysis

Frequency analysis

Frequency Analysis Tool

Monoalphabetic Cipher Tool lmstn qtomq ***e* te**t t e

Vigenère Cipher Decryption l l Repeated Segments Factors – – – Plaintext: the bird ate the cat Key: uni onun ion uni onu Cipher: num pvlq ihr num qnn 10 l Multiple Frequency Analysis

Vigenère Cipher Tools fgsjetladkjdjkeifldlkowf gewsloiodkjplkjhgfetllk DJK 21

Repeated Substrings T H B Z T H B T T 1 0 0 0 1 Repeated substring started H 0 2 0 0 B 0 0 3 0 Z 0 0 0 4 0 0 T 1 0 0 0 5 0 0 1 H 0 2 0 0 0 6 0 0 B 0 0 3 0 0 0 7 0 T 1 0 0 0 1 0 0 8 Repeated substring ended

Vigenère Cipher Tools

Future work l l Encryption More types of Ciphers

Accomplishments l l Save the student time Allow them to do more Easier for the professor More complex examples

Questions?