web tools for classical cryptology tristan beeble
TRANSCRIPT
Web Tools for Classical Cryptology
Tristan Beeble
Overview
Background Types of problems Tools
Cryptology
Cryptography– Encoding a message
Cryptoanalysis– Decoding a message
Background
Client: Professor Lesh Gen-ed Math course Help solve homework problems
Goals
Decoding Additional study Aid, not solve Easy to use
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
Types of Ciphers
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
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
Same idea as Encryption Backwards
Ciphertext: aypzahu
Key: 7(-7)
Plaintext: tristan
Caesar Cipher Tool
Caesar Cipher Tool
Monoalphabetic Cipher Decryption
First Step:Guess work– Word length– Partial solutions
Second Step:Frequency Analysis
Frequency analysis
Frequency Analysis Tool
Monoalphabetic Cipher Tool
e
lmstn qtomq ***e* te**t
t
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
Vigenère Cipher Tools
fgsjetladkjdjkeifldlkowfgewsloiodkjplkjhgfetllk
DJK 21
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
Vigenère Cipher Tools
Future work
Encryption More types of Ciphers
Accomplishments
Save the student time Allow them to do more Easier for the professor More complex examples
Questions?