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Python/ciphers/enigma_machine2.py
Maxim Smolskiy f45e392cf6
Fix sphinx/build_docs warnings for ciphers (#12485) 
* Fix sphinx/build_docs warnings for ciphers

* Fix
2024-12-30 12:56:24 +03:00

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"""
| Wikipedia: https://en.wikipedia.org/wiki/Enigma_machine
| Video explanation: https://youtu.be/QwQVMqfoB2E
| Also check out Numberphile's and Computerphile's videos on this topic
This module contains function ``enigma`` which emulates
the famous Enigma machine from WWII.
Module includes:
- ``enigma`` function
- showcase of function usage
- ``9`` randomly generated rotors
- reflector (aka static rotor)
- original alphabet
Created by TrapinchO
"""
from __future__ import annotations
RotorPositionT = tuple[int, int, int]
RotorSelectionT = tuple[str, str, str]
# used alphabet --------------------------
# from string.ascii_uppercase
abc = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
# -------------------------- default selection --------------------------
# rotors --------------------------
rotor1 = "EGZWVONAHDCLFQMSIPJBYUKXTR"
rotor2 = "FOBHMDKEXQNRAULPGSJVTYICZW"
rotor3 = "ZJXESIUQLHAVRMDOYGTNFWPBKC"
# reflector --------------------------
reflector = {
"A": "N",
"N": "A",
"B": "O",
"O": "B",
"C": "P",
"P": "C",
"D": "Q",
"Q": "D",
"E": "R",
"R": "E",
"F": "S",
"S": "F",
"G": "T",
"T": "G",
"H": "U",
"U": "H",
"I": "V",
"V": "I",
"J": "W",
"W": "J",
"K": "X",
"X": "K",
"L": "Y",
"Y": "L",
"M": "Z",
"Z": "M",
}
# -------------------------- extra rotors --------------------------
rotor4 = "RMDJXFUWGISLHVTCQNKYPBEZOA"
rotor5 = "SGLCPQWZHKXAREONTFBVIYJUDM"
rotor6 = "HVSICLTYKQUBXDWAJZOMFGPREN"
rotor7 = "RZWQHFMVDBKICJLNTUXAGYPSOE"
rotor8 = "LFKIJODBEGAMQPXVUHYSTCZRWN"
rotor9 = "KOAEGVDHXPQZMLFTYWJNBRCIUS"
def _validator(
rotpos: RotorPositionT, rotsel: RotorSelectionT, pb: str
) -> tuple[RotorPositionT, RotorSelectionT, dict[str, str]]:
"""
Checks if the values can be used for the ``enigma`` function
>>> _validator((1,1,1), (rotor1, rotor2, rotor3), 'POLAND')
((1, 1, 1), ('EGZWVONAHDCLFQMSIPJBYUKXTR', 'FOBHMDKEXQNRAULPGSJVTYICZW', \
'ZJXESIUQLHAVRMDOYGTNFWPBKC'), \
{'P': 'O', 'O': 'P', 'L': 'A', 'A': 'L', 'N': 'D', 'D': 'N'})
:param rotpos: rotor_positon
:param rotsel: rotor_selection
:param pb: plugb -> validated and transformed
:return: (`rotpos`, `rotsel`, `pb`)
"""
# Checks if there are 3 unique rotors
if (unique_rotsel := len(set(rotsel))) < 3:
msg = f"Please use 3 unique rotors (not {unique_rotsel})"
raise Exception(msg)
# Checks if rotor positions are valid
rotorpos1, rotorpos2, rotorpos3 = rotpos
if not 0 < rotorpos1 <= len(abc):
msg = f"First rotor position is not within range of 1..26 ({rotorpos1}"
raise ValueError(msg)
if not 0 < rotorpos2 <= len(abc):
msg = f"Second rotor position is not within range of 1..26 ({rotorpos2})"
raise ValueError(msg)
if not 0 < rotorpos3 <= len(abc):
msg = f"Third rotor position is not within range of 1..26 ({rotorpos3})"
raise ValueError(msg)
# Validates string and returns dict
pbdict = _plugboard(pb)
return rotpos, rotsel, pbdict
def _plugboard(pbstring: str) -> dict[str, str]:
"""
https://en.wikipedia.org/wiki/Enigma_machine#Plugboard
>>> _plugboard('PICTURES')
{'P': 'I', 'I': 'P', 'C': 'T', 'T': 'C', 'U': 'R', 'R': 'U', 'E': 'S', 'S': 'E'}
>>> _plugboard('POLAND')
{'P': 'O', 'O': 'P', 'L': 'A', 'A': 'L', 'N': 'D', 'D': 'N'}
In the code, ``pb`` stands for ``plugboard``
Pairs can be separated by spaces
:param pbstring: string containing plugboard setting for the Enigma machine
:return: dictionary containing converted pairs
"""
# tests the input string if it
# a) is type string
# b) has even length (so pairs can be made)
if not isinstance(pbstring, str):
msg = f"Plugboard setting isn't type string ({type(pbstring)})"
raise TypeError(msg)
elif len(pbstring) % 2 != 0:
msg = f"Odd number of symbols ({len(pbstring)})"
raise Exception(msg)
elif pbstring == "":
return {}
pbstring.replace(" ", "")
# Checks if all characters are unique
tmppbl = set()
for i in pbstring:
if i not in abc:
msg = f"'{i}' not in list of symbols"
raise Exception(msg)
elif i in tmppbl:
msg = f"Duplicate symbol ({i})"
raise Exception(msg)
else:
tmppbl.add(i)
del tmppbl
# Created the dictionary
pb = {}
for j in range(0, len(pbstring) - 1, 2):
pb[pbstring[j]] = pbstring[j + 1]
pb[pbstring[j + 1]] = pbstring[j]
return pb
def enigma(
text: str,
rotor_position: RotorPositionT,
rotor_selection: RotorSelectionT = (rotor1, rotor2, rotor3),
plugb: str = "",
) -> str:
"""
The only difference with real-world enigma is that ``I`` allowed string input.
All characters are converted to uppercase. (non-letter symbol are ignored)
| How it works:
| (for every letter in the message)
- Input letter goes into the plugboard.
If it is connected to another one, switch it.
- Letter goes through ``3`` rotors.
Each rotor can be represented as ``2`` sets of symbol, where one is shuffled.
Each symbol from the first set has corresponding symbol in
the second set and vice versa.
example::
| ABCDEFGHIJKLMNOPQRSTUVWXYZ | e.g. F=D and D=F
| VKLEPDBGRNWTFCJOHQAMUZYIXS |
- Symbol then goes through reflector (static rotor).
There it is switched with paired symbol.
The reflector can be represented as ``2`` sets, each with half of the alphanet.
There are usually ``10`` pairs of letters.
Example::
| ABCDEFGHIJKLM | e.g. E is paired to X
| ZYXWVUTSRQPON | so when E goes in X goes out and vice versa
- Letter then goes through the rotors again
- If the letter is connected to plugboard, it is switched.
- Return the letter
>>> enigma('Hello World!', (1, 2, 1), plugb='pictures')
'KORYH JUHHI!'
>>> enigma('KORYH, juhhi!', (1, 2, 1), plugb='pictures')
'HELLO, WORLD!'
>>> enigma('hello world!', (1, 1, 1), plugb='pictures')
'FPNCZ QWOBU!'
>>> enigma('FPNCZ QWOBU', (1, 1, 1), plugb='pictures')
'HELLO WORLD'
:param text: input message
:param rotor_position: tuple with ``3`` values in range ``1``.. ``26``
:param rotor_selection: tuple with ``3`` rotors
:param plugb: string containing plugboard configuration (default ``''``)
:return: en/decrypted string
"""
text = text.upper()
rotor_position, rotor_selection, plugboard = _validator(
rotor_position, rotor_selection, plugb.upper()
)
rotorpos1, rotorpos2, rotorpos3 = rotor_position
rotor1, rotor2, rotor3 = rotor_selection
rotorpos1 -= 1
rotorpos2 -= 1
rotorpos3 -= 1
result = []
# encryption/decryption process --------------------------
for symbol in text:
if symbol in abc:
# 1st plugboard --------------------------
if symbol in plugboard:
symbol = plugboard[symbol]
# rotor ra --------------------------
index = abc.index(symbol) + rotorpos1
symbol = rotor1[index % len(abc)]
# rotor rb --------------------------
index = abc.index(symbol) + rotorpos2
symbol = rotor2[index % len(abc)]
# rotor rc --------------------------
index = abc.index(symbol) + rotorpos3
symbol = rotor3[index % len(abc)]
# reflector --------------------------
# this is the reason you don't need another machine to decipher
symbol = reflector[symbol]
# 2nd rotors
symbol = abc[rotor3.index(symbol) - rotorpos3]
symbol = abc[rotor2.index(symbol) - rotorpos2]
symbol = abc[rotor1.index(symbol) - rotorpos1]
# 2nd plugboard
if symbol in plugboard:
symbol = plugboard[symbol]
# moves/resets rotor positions
rotorpos1 += 1
if rotorpos1 >= len(abc):
rotorpos1 = 0
rotorpos2 += 1
if rotorpos2 >= len(abc):
rotorpos2 = 0
rotorpos3 += 1
if rotorpos3 >= len(abc):
rotorpos3 = 0
# else:
# pass
# Error could be also raised
# raise ValueError(
# 'Invalid symbol('+repr(symbol)+')')
result.append(symbol)
return "".join(result)
if __name__ == "__main__":
message = "This is my Python script that emulates the Enigma machine from WWII."
rotor_pos = (1, 1, 1)
pb = "pictures"
rotor_sel = (rotor2, rotor4, rotor8)
en = enigma(message, rotor_pos, rotor_sel, pb)
print("Encrypted message:", en)
print("Decrypted message:", enigma(en, rotor_pos, rotor_sel, pb))
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