Introduction

This is a Python module that provides tools to encode, decode, and analyze ciphers.

Installation

This package is not yet on pip, and so must be installed manually.

1. git clone git@github.com:EasyElectrons/cipher-tools.git
2. Either symlink, copy, or move the package into your Python dist-packages directory.

Usage

This package uses a standard notation to represent ciphertext (CT) and plaintext (PT).

• PT should always be entered/represented as lowercase.
• CT should always be entered/represented as UPPERCASE.

Take for example the caesar cipher. Let’s encipher the string 'hello world' using the standard +3 shift.

>>> from cipher_tools import encode
>>> 
>>> encode.caesar('hello world')
'KHOOR ZRUOG'

Now lets see what happens when we try to encode 'HELLO WORLD'.

>>> encode.caesar('HELLO WORLD')
'HELLO WORLD'

This is because the encoder engine is already interpreting the string 'HELLO WORLD' as CT, and thus doesn’t need to be enciphered further. This allows for partial enciphering/deciphering of a string and skipping over text for complicated “shift register” style cipher schemes.

If multi-layered enciphering is desired, simply convert the section in question back to the appropriate case.

>>> from cipher_tools import encode, decode
>>> stage1 = encode.caesar('hello world')
>>> print(stage1)
KHOOR ZRUOG
>>> stage2 = encode.vigenere(stage1.tolower(), 'lemon')
>>> print(stage2)
VLACE KVGCT
>>> reverse1 = decode.vigenere(stage2, 'lemon')
>>> print(reverse1)
khoor zruog
>>> reverse2 = decode.caesar(reverse1.upper())
>>> print(reverse2)
hello world