Function decrypt_message

ciphers/trifid_cipher.py:169–205

decrypt_message =============== Decrypts a trifid_cipher encrypted message. PARAMETERS ---------- * `message`: The message you want to decrypt. * `alphabet` (optional): The characters used for the cipher. * `period` (optional): The number of chara

(
    message: str, alphabet: str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ.", period: int = 5
)

def decrypt_message(
    message: str, alphabet: str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ.", period: int = 5
) -> str:
    """
    decrypt_message
    ===============

    Decrypts a trifid_cipher encrypted message.

    PARAMETERS
    ----------

    *   `message`: The message you want to decrypt.
    *   `alphabet` (optional): The characters used for the cipher.
    *   `period` (optional): The number of characters used in grouping when it
        was encrypted.

    >>> decrypt_message('BCDGBQY')
    'IAMABOY'

    Decrypting with your own alphabet and period

    >>> decrypt_message('FMJFVOISSUFTFPUFEQQC','FELIXMARDSTBCGHJKNOPQUVWYZ+',5)
    'AIDETOILECIELTAIDERA'
    """
    message, alphabet, character_to_number, number_to_character = __prepare(
        message, alphabet
    )

    decrypted_numeric = []
    for i in range(0, len(message), period):
        a, b, c = __decrypt_part(message[i : i + period], character_to_number)

        for j in range(len(a)):
            decrypted_numeric.append(a[j] + b[j] + c[j])

    return "".join(number_to_character[each] for each in decrypted_numeric)


if __name__ == "__main__":