Ciphers-Python

Atbash Cipher

• A cipher that encodes a message using the reverse of the alphabet

• Atbash decode function isn't necessary, you can simply run the encoded message back through the encoder

Caesar Cipher

• A cipher that encodes a message by replacing each letter with a shifted letter X units away

Affine Cipher

• A substitution cipher where each letter is mapped to its numeric equivalent, encrypted using a mathematical function and then turned back into a letter

• E(x) = (ax + b) mod m

• m = 26, the length of the alphabet

• Verify that the value chosen for a is coprime to m

• D(x) = a^-1 (x - b) mod m

• a^ -1 = modular multiplicative inverse

Viginere Cipher

• A cipher that encodes text using a Caesar cipher based on a key
• E(x) = (x + k) mod 26
• D(x) = (x - k) mod 26

Testing

• pip install pytest
• run in terminal with:

pytest test_ciphers.py

FUTURE ADDITIONS

• (GUI) graphical user interface