def test_Rotor_encode_letters_forward_return_letter():
A = Rotor('I', 'a')
ret = A.encode_letter('a', return_letter=True)
index = ALPHABET.index('a'.upper())
output_letter = A.wiring['forward'][(index + A.offset) % 26]
output_index = (ALPHABET.index(output_letter) - A.offset) % 26
assert ret == ALPHABET[output_index]
assert A.encode_letter('a', printit=True)
def test_Rotor_encode_letters_forward_nothing():
A = Rotor('I', 'a')
ret = A.encode_letter('a')
index = ALPHABET.index('a'.upper())
output_letter = A.wiring['forward'][(index + A.offset) % 26]
output_index = (ALPHABET.index(output_letter) - A.offset) % 26
assert ret == output_index
def test_Rotor_encode_letters_forward_next():
C = Rotor('III', 'a')
B = Rotor('II', 'a')
A = Rotor('I', 'a')
index = ALPHABET.index('a'.upper())
A.next_rotor = B
B.prev_rotor = A
B.next_rotor = C
ret = B.encode_letter('a', forward=True)
output_letter = B.wiring['forward'][(index + B.offset) % 26]
output_index = (ALPHABET.index(output_letter) - B.offset) % 26
assert ret == B.next_rotor.encode_letter(output_index, True)
def encode_decode_letter(self, letter):
""" Takes a letter as input, steps rotors accordingly, and returns letter output.
Because Enigma is symmetrical, this works the same whether you encode or decode.
"""
# Make sure the letter is in a-zA-Z.
if bool(re.compile(r'[^a-zA-Z ]').search(letter)):
return 'Please provide a letter in a-zA-Z.'
# First, go through plugboard.
if letter in self.plugboard.swaps:
letter = self.plugboard.swaps[letter.upper()]
# Next, step the rotors.
self.r_rotor.step()
# Send the letter through the rotors to the reflector.
# Get the index of the letter that emerges from the rotor.
left_pass = self.r_rotor.encode_letter(ALPHABET.index(letter.upper()))
# Must match letter INDEX, not letter name to reflector as before.
refl_output = self.reflector.wiring[ALPHABET[(left_pass)%26]]
# Send the reflected letter back through the rotors.
final_letter = ALPHABET[self.l_rotor.encode_letter(
ALPHABET.index(refl_output), forward=False)]
if final_letter in self.plugboard.swaps:
return self.plugboard.swaps[final_letter]
else:
return final_letter