permutation_cipher.py

import textwrap


class PermutationCipher:
    def __init__(self, permutation):
        self.permutation = permutation
        self.permutation_transpose = [0] * len(self.permutation)
        for index, value in enumerate(self.permutation):
            self.permutation_transpose[value] = index

    def encrypt(self, plain_text):
        return self._permutation(plain_text, self.permutation)

    def decrypt(self, cipher_text):
        return self._permutation(cipher_text, self.permutation_transpose)

    @staticmethod
    def _permutation(text, permutation):
        text = text.upper()
        return "".join(
            "".join(text_bucket[value] for value in permutation)
            for text_bucket in textwrap.wrap(text, width=len(permutation))
        )