1. Web Tools for Classical Cryptology Tristan Beeble

2. Overview Background Types of problems Tools

3. Cryptology Cryptography – Encoding a message Cryptoanalysis – Decoding a message

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

5. Goals Decoding Additional study Aid, not solve Easy to use

6. Terms 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

7. Types of Ciphers Caesar Cipher Monoalphabetic Ciphers Polyalphabetic Ciphers – Vigenère Cipher

8. Caesar Cipher Plaintext: tristan Key: 7 Ciphertext: aypzahu

9. 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

10. Monoalphabetic cipher

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

12. Vigenère cipher

13. 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

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

15. Caesar Cipher Tool

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

18. Frequency analysis

19. Frequency Analysis Tool

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

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

22. Vigenère Cipher Tools fgsjetladkjdjkeifldlkowf gewsloiodkjplkjhgfetllk DJK 21

23. Repeated Substrings T H B Z T H B T T 1 0 0 0 1 0 0 1 H 0 2 0 0 0 2 0 0 B 0 0 3 0 0 0 3 0 Z 0 0 0 4 0 0 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 started Repeated substring ended

24. Vigenère Cipher Tools

25. Future work Encryption More types of Ciphers

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

27. Questions?