CTx

Caesar Cipher with a Twist.

• Florian, 2021

tl;dr

Based on the existing Caesar Cipher, we have a set code where we skip steps in the alphabet to encrypt a message or text. In Example 1 we only have the code initial code 538(x). In Example 3 we use 2 code rotation(s), which uses the initial cipher (538(x)), which gets rotated every time based on the x value of the initial code.

For this simple (initial) example of encryption we are gonna use a simple calculation (unlike the Enigma machine) where we just divide the input by 2, to create a new value for the rotation (rotor) (* This will be improved in the future).

Testing

Just run the following for testing the code.

  $ python cipher.py

Encryption

Simple initial encyption example explained

    ## One rotation (x==1)
    # initial rotor code: 538(1)
    # calculation: ($input/2)
    538
      > (5/2 = 2.5 == 3)
      > (3/2 = 1.5 == 2)
      > (8/2 = 4.0 == 4)
    ==> 324

    # New rotor code:
    > 324

    # * (float value gets rounded up)

Encryption Examples

No rotation

code	input	output
5380	ik kan niet slapen	NNSFQUNHBYOIUQ

One Rotation

code	input	output
5381	ik kan niet slapen	NNSFQUNHBYOIUQ
324	NNSFQUNHBYOIUQ	QPWISYQJFBQMXS

Two Rotations

code	input	output
5382	ik kan niet slapen	NNSFQUNHBYOIUQ
324	NNSFQUNHBYOIUQ	QPWISYQJFBQMXS
212	QPWISYQJFBQMXS	SQYKTASKHDROZT

  # initial
  538(2)
  >= 538

  # rotation (x-1)
  > (5/2 = 2.5 == 3)
  > (3/2 = 1.5 == 2)
  > (8/2 = 4.0 == 4)
  >= 324

  # rotation (x-1)
  > (3/2 = 1.5 == 2)
  > (2/2 = 1.0 == 1)
  > (4/2 = 2.0 == 2)
  >= 212

Decryption

This is easy peazy, when you have the initial key. Same with the rotation steps, you can re-create the codes with the init.

zodus