Porta Cipher

alphabet = {
    "A": ("ABCDEFGHIJKLM", "NOPQRSTUVWXYZ"),
    "B": ("ABCDEFGHIJKLM", "NOPQRSTUVWXYZ"),
    "C": ("ABCDEFGHIJKLM", "ZNOPQRSTUVWXY"),
    "D": ("ABCDEFGHIJKLM", "ZNOPQRSTUVWXY"),
    "E": ("ABCDEFGHIJKLM", "YZNOPQRSTUVWX"),
    "F": ("ABCDEFGHIJKLM", "YZNOPQRSTUVWX"),
    "G": ("ABCDEFGHIJKLM", "XYZNOPQRSTUVW"),
    "H": ("ABCDEFGHIJKLM", "XYZNOPQRSTUVW"),
    "I": ("ABCDEFGHIJKLM", "WXYZNOPQRSTUV"),
    "J": ("ABCDEFGHIJKLM", "WXYZNOPQRSTUV"),
    "K": ("ABCDEFGHIJKLM", "VWXYZNOPQRSTU"),
    "L": ("ABCDEFGHIJKLM", "VWXYZNOPQRSTU"),
    "M": ("ABCDEFGHIJKLM", "UVWXYZNOPQRST"),
    "N": ("ABCDEFGHIJKLM", "UVWXYZNOPQRST"),
    "O": ("ABCDEFGHIJKLM", "TUVWXYZNOPQRS"),
    "P": ("ABCDEFGHIJKLM", "TUVWXYZNOPQRS"),
    "Q": ("ABCDEFGHIJKLM", "STUVWXYZNOPQR"),
    "R": ("ABCDEFGHIJKLM", "STUVWXYZNOPQR"),
    "S": ("ABCDEFGHIJKLM", "RSTUVWXYZNOPQ"),
    "T": ("ABCDEFGHIJKLM", "RSTUVWXYZNOPQ"),
    "U": ("ABCDEFGHIJKLM", "QRSTUVWXYZNOP"),
    "V": ("ABCDEFGHIJKLM", "QRSTUVWXYZNOP"),
    "W": ("ABCDEFGHIJKLM", "PQRSTUVWXYZNO"),
    "X": ("ABCDEFGHIJKLM", "PQRSTUVWXYZNO"),
    "Y": ("ABCDEFGHIJKLM", "OPQRSTUVWXYZN"),
    "Z": ("ABCDEFGHIJKLM", "OPQRSTUVWXYZN"),
}


def generate_table(key: str) -> list[tuple[str, str]]:
    """
    >>> generate_table('marvin')  # doctest: +NORMALIZE_WHITESPACE
    [('ABCDEFGHIJKLM', 'UVWXYZNOPQRST'), ('ABCDEFGHIJKLM', 'NOPQRSTUVWXYZ'),
     ('ABCDEFGHIJKLM', 'STUVWXYZNOPQR'), ('ABCDEFGHIJKLM', 'QRSTUVWXYZNOP'),
     ('ABCDEFGHIJKLM', 'WXYZNOPQRSTUV'), ('ABCDEFGHIJKLM', 'UVWXYZNOPQRST')]
    """
    return [alphabet[char] for char in key.upper()]


def encrypt(key: str, words: str) -> str:
    """
    >>> encrypt('marvin', 'jessica')
    'QRACRWU'
    """
    cipher = ""
    count = 0
    table = generate_table(key)
    for char in words.upper():
        cipher += get_opponent(table[count], char)
        count = (count + 1) % len(table)
    return cipher


def decrypt(key: str, words: str) -> str:
    """
    >>> decrypt('marvin', 'QRACRWU')
    'JESSICA'
    """
    return encrypt(key, words)


def get_position(table: tuple[str, str], char: str) -> tuple[int, int]:
    """
    >>> get_position(generate_table('marvin')[0], 'M')
    (0, 12)
    """
    # `char` is either in the 0th row or the 1st row
    row = 0 if char in table[0] else 1
    col = table[row].index(char)
    return row, col


def get_opponent(table: tuple[str, str], char: str) -> str:
    """
    >>> get_opponent(generate_table('marvin')[0], 'M')
    'T'
    """
    row, col = get_position(table, char.upper())
    if row == 1:
        return table[0][col]
    else:
        return table[1][col] if row == 0 else char


if __name__ == "__main__":
    import doctest

    doctest.testmod()  # Fist ensure that all our tests are passing...
    """
    Demo:

    Enter key: marvin
    Enter text to encrypt: jessica
    Encrypted: QRACRWU
    Decrypted with key: JESSICA
    """
    key = input("Enter key: ").strip()
    text = input("Enter text to encrypt: ").strip()
    cipher_text = encrypt(key, text)

    print(f"Encrypted: {cipher_text}")
    print(f"Decrypted with key: {decrypt(key, cipher_text)}")
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We are a group of programmers helping each other build new things, whether it be writing complex encryption programs, or simple ciphers. Our goal is to work together to document and model beautiful, helpful and interesting algorithms using code. We are an open-source community - anyone can contribute. We check each other's work, communicate and collaborate to solve problems. We strive to be welcoming, respectful, yet make sure that our code follows the latest programming guidelines.