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* from __future__ import annotations
* updating DIRECTORY.md
* from __future__ import annotations
* from __future__ import annotations
* Update xor_cipher.py
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
295 lines
8.6 KiB
Python
295 lines
8.6 KiB
Python
"""
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Wikipedia: https://en.wikipedia.org/wiki/Enigma_machine
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Video explanation: https://youtu.be/QwQVMqfoB2E
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Also check out Numberphile's and Computerphile's videos on this topic
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This module contains function 'enigma' which emulates
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the famous Enigma machine from WWII.
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Module includes:
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- enigma function
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- showcase of function usage
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- 9 randnomly generated rotors
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- reflector (aka static rotor)
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- original alphabet
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Created by TrapinchO
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"""
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from __future__ import annotations
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RotorPositionT = tuple[int, int, int]
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RotorSelectionT = tuple[str, str, str]
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# used alphabet --------------------------
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# from string.ascii_uppercase
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abc = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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# -------------------------- default selection --------------------------
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# rotors --------------------------
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rotor1 = "EGZWVONAHDCLFQMSIPJBYUKXTR"
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rotor2 = "FOBHMDKEXQNRAULPGSJVTYICZW"
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rotor3 = "ZJXESIUQLHAVRMDOYGTNFWPBKC"
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# reflector --------------------------
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reflector = {
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"A": "N",
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"N": "A",
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"B": "O",
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"O": "B",
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"C": "P",
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"P": "C",
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"D": "Q",
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"Q": "D",
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"E": "R",
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"R": "E",
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"F": "S",
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"S": "F",
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"G": "T",
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"T": "G",
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"H": "U",
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"U": "H",
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"I": "V",
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"V": "I",
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"J": "W",
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"W": "J",
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"K": "X",
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"X": "K",
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"L": "Y",
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"Y": "L",
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"M": "Z",
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"Z": "M",
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}
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# -------------------------- extra rotors --------------------------
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rotor4 = "RMDJXFUWGISLHVTCQNKYPBEZOA"
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rotor5 = "SGLCPQWZHKXAREONTFBVIYJUDM"
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rotor6 = "HVSICLTYKQUBXDWAJZOMFGPREN"
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rotor7 = "RZWQHFMVDBKICJLNTUXAGYPSOE"
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rotor8 = "LFKIJODBEGAMQPXVUHYSTCZRWN"
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rotor9 = "KOAEGVDHXPQZMLFTYWJNBRCIUS"
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def _validator(
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rotpos: RotorPositionT, rotsel: RotorSelectionT, pb: str
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) -> tuple[RotorPositionT, RotorSelectionT, dict[str, str]]:
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"""
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Checks if the values can be used for the 'enigma' function
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>>> _validator((1,1,1), (rotor1, rotor2, rotor3), 'POLAND')
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((1, 1, 1), ('EGZWVONAHDCLFQMSIPJBYUKXTR', 'FOBHMDKEXQNRAULPGSJVTYICZW', \
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'ZJXESIUQLHAVRMDOYGTNFWPBKC'), \
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{'P': 'O', 'O': 'P', 'L': 'A', 'A': 'L', 'N': 'D', 'D': 'N'})
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:param rotpos: rotor_positon
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:param rotsel: rotor_selection
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:param pb: plugb -> validated and transformed
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:return: (rotpos, rotsel, pb)
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"""
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# Checks if there are 3 unique rotors
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unique_rotsel = len(set(rotsel))
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if unique_rotsel < 3:
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raise Exception(f"Please use 3 unique rotors (not {unique_rotsel})")
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# Checks if rotor positions are valid
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rotorpos1, rotorpos2, rotorpos3 = rotpos
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if not 0 < rotorpos1 <= len(abc):
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raise ValueError(
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f"First rotor position is not within range of 1..26 (" f"{rotorpos1}"
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)
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if not 0 < rotorpos2 <= len(abc):
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raise ValueError(
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f"Second rotor position is not within range of 1..26 (" f"{rotorpos2})"
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)
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if not 0 < rotorpos3 <= len(abc):
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raise ValueError(
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f"Third rotor position is not within range of 1..26 (" f"{rotorpos3})"
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)
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# Validates string and returns dict
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pbdict = _plugboard(pb)
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return rotpos, rotsel, pbdict
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def _plugboard(pbstring: str) -> dict[str, str]:
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"""
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https://en.wikipedia.org/wiki/Enigma_machine#Plugboard
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>>> _plugboard('PICTURES')
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{'P': 'I', 'I': 'P', 'C': 'T', 'T': 'C', 'U': 'R', 'R': 'U', 'E': 'S', 'S': 'E'}
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>>> _plugboard('POLAND')
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{'P': 'O', 'O': 'P', 'L': 'A', 'A': 'L', 'N': 'D', 'D': 'N'}
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In the code, 'pb' stands for 'plugboard'
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Pairs can be separated by spaces
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:param pbstring: string containing plugboard setting for the Enigma machine
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:return: dictionary containing converted pairs
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"""
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# tests the input string if it
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# a) is type string
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# b) has even length (so pairs can be made)
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if not isinstance(pbstring, str):
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raise TypeError(f"Plugboard setting isn't type string ({type(pbstring)})")
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elif len(pbstring) % 2 != 0:
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raise Exception(f"Odd number of symbols ({len(pbstring)})")
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elif pbstring == "":
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return {}
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pbstring.replace(" ", "")
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# Checks if all characters are unique
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tmppbl = set()
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for i in pbstring:
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if i not in abc:
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raise Exception(f"'{i}' not in list of symbols")
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elif i in tmppbl:
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raise Exception(f"Duplicate symbol ({i})")
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else:
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tmppbl.add(i)
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del tmppbl
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# Created the dictionary
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pb = {}
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for j in range(0, len(pbstring) - 1, 2):
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pb[pbstring[j]] = pbstring[j + 1]
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pb[pbstring[j + 1]] = pbstring[j]
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return pb
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def enigma(
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text: str,
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rotor_position: RotorPositionT,
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rotor_selection: RotorSelectionT = (rotor1, rotor2, rotor3),
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plugb: str = "",
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) -> str:
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"""
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The only difference with real-world enigma is that I allowed string input.
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All characters are converted to uppercase. (non-letter symbol are ignored)
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How it works:
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(for every letter in the message)
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- Input letter goes into the plugboard.
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If it is connected to another one, switch it.
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- Letter goes through 3 rotors.
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Each rotor can be represented as 2 sets of symbol, where one is shuffled.
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Each symbol from the first set has corresponding symbol in
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the second set and vice versa.
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example:
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| ABCDEFGHIJKLMNOPQRSTUVWXYZ | e.g. F=D and D=F
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| VKLEPDBGRNWTFCJOHQAMUZYIXS |
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- Symbol then goes through reflector (static rotor).
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There it is switched with paired symbol
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The reflector can be represented as2 sets, each with half of the alphanet.
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There are usually 10 pairs of letters.
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Example:
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| ABCDEFGHIJKLM | e.g. E is paired to X
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| ZYXWVUTSRQPON | so when E goes in X goes out and vice versa
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- Letter then goes through the rotors again
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- If the letter is connected to plugboard, it is switched.
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- Return the letter
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>>> enigma('Hello World!', (1, 2, 1), plugb='pictures')
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'KORYH JUHHI!'
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>>> enigma('KORYH, juhhi!', (1, 2, 1), plugb='pictures')
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'HELLO, WORLD!'
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>>> enigma('hello world!', (1, 1, 1), plugb='pictures')
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'FPNCZ QWOBU!'
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>>> enigma('FPNCZ QWOBU', (1, 1, 1), plugb='pictures')
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'HELLO WORLD'
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:param text: input message
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:param rotor_position: tuple with 3 values in range 1..26
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:param rotor_selection: tuple with 3 rotors ()
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:param plugb: string containing plugboard configuration (default '')
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:return: en/decrypted string
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"""
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text = text.upper()
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rotor_position, rotor_selection, plugboard = _validator(
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rotor_position, rotor_selection, plugb.upper()
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)
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rotorpos1, rotorpos2, rotorpos3 = rotor_position
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rotor1, rotor2, rotor3 = rotor_selection
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rotorpos1 -= 1
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rotorpos2 -= 1
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rotorpos3 -= 1
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result = []
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# encryption/decryption process --------------------------
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for symbol in text:
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if symbol in abc:
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# 1st plugboard --------------------------
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if symbol in plugboard:
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symbol = plugboard[symbol]
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# rotor ra --------------------------
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index = abc.index(symbol) + rotorpos1
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symbol = rotor1[index % len(abc)]
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# rotor rb --------------------------
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index = abc.index(symbol) + rotorpos2
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symbol = rotor2[index % len(abc)]
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# rotor rc --------------------------
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index = abc.index(symbol) + rotorpos3
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symbol = rotor3[index % len(abc)]
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# reflector --------------------------
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# this is the reason you don't need another machine to decipher
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symbol = reflector[symbol]
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# 2nd rotors
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symbol = abc[rotor3.index(symbol) - rotorpos3]
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symbol = abc[rotor2.index(symbol) - rotorpos2]
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symbol = abc[rotor1.index(symbol) - rotorpos1]
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# 2nd plugboard
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if symbol in plugboard:
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symbol = plugboard[symbol]
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# moves/resets rotor positions
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rotorpos1 += 1
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if rotorpos1 >= len(abc):
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rotorpos1 = 0
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rotorpos2 += 1
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if rotorpos2 >= len(abc):
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rotorpos2 = 0
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rotorpos3 += 1
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if rotorpos3 >= len(abc):
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rotorpos3 = 0
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# else:
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# pass
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# Error could be also raised
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# raise ValueError(
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# 'Invalid symbol('+repr(symbol)+')')
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result.append(symbol)
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return "".join(result)
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if __name__ == "__main__":
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message = "This is my Python script that emulates the Enigma machine from WWII."
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rotor_pos = (1, 1, 1)
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pb = "pictures"
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rotor_sel = (rotor2, rotor4, rotor8)
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en = enigma(message, rotor_pos, rotor_sel, pb)
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print("Encrypted message:", en)
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print("Decrypted message:", enigma(en, rotor_pos, rotor_sel, pb))
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