An implementation of the Enigma machine in Python. Simulates a common 3-rotor machine with the common 8 rotors and 3 reflectors. Wikipedia has a good overview. Project inspired by this video.
The transformation of each letter is implemented as a product of permutations (Rejewski, 1980), in this case 26x26 matrices. The transform, E, in this formulation, can therefore be expressed as:
where P is the plugboard, L, M and R are the left, middle and right rotors respectively, U is the reflector and p is the cyclic permutation of the mapping of A to B, B to C, etc. a, b and c are the rotations of each rotor as caused when a key was pressed.
Can be used to encrypt/decrypt messages ('X' was used to replace spaces) as such:
from enigma_simulator.enigma import Enigma
# Encrypting
enigma1 = Enigma(["I", "II", "III"], [1, 1, 1], "B", "AD", [0, 0, 0])
enigma1.encrypt("HELLOXWORLD") # Returns "LOFUHZZLZOB"
# Decrypting
enigma2 = Enigma(["I", "II", "III"], [1, 1, 1], "B", "AD", [0, 0, 0])
enigma2.encrypt("LOFUHZZLZOB") # Returns "HELLOXWORLD" back