Krypto_Grundlagen/chapter_one/Permutations-Chiffre.py

import random

from utils import AlphabetUtils as au
from utils import CipherUtils as cu


def encrypt_text(cleartext: str, key: [int]) -> str:
	"""
	Encrypts the given text with the given key
	:param cleartext: The text to encrypt
	:param key: The key to use. Has to be a list of indices of the alphabet, so [0...25] shuffled
	:return: The encrypted text
	"""

	cleartext = cu.transform_invalid_chars(cleartext)

	resulting = ''

	for char in cleartext:
		char_index = au.get_index_of_letter(char)
		cipher_index = key.index(char_index)
		cipher_char = au.get_letter_at_index(cipher_index)
		resulting += cipher_char

	return resulting


def decrypt_text(ciphertext: str, key: [int]) -> str:
	"""
	Decrypts the given ciphertext with the given key
	:param ciphertext: The text to decrypt
	:param key: The key to use. Has to be a list of indices of the alphabet, so [0...25] shuffled
	:return: The decrypted text
	"""
	resulting = ''

	for char in ciphertext:
		char_index = au.get_index_of_letter(char)
		clear_index = key[char_index]
		clear_char = au.get_letter_at_index(clear_index)
		resulting += clear_char

	return resulting


def generate_key() -> [int]:
	"""
	Generates a key that can be used for this cipher.
	:return: The key as a list of indices
	"""
	indices = [i for i in range(26)]

	random.shuffle(indices)

	return indices


def generate_key_with_keyword(keyword: str) -> [int]:
	"""
	Generates a key that can be used for this cipher by using the given keyword as a starting point
	:param keyword: The keyword to use to generate the key
	:return: The key as a list of indices
	"""
	result = []

	for char in keyword:
		char_index = au.get_index_of_letter(char)
		if char_index not in result:
			result.append(char_index)

	remaining_indices = [i for i in range(26 - len(result))]

	result.extend(remaining_indices)

	return result


if __name__ == '__main__':
	key = generate_key_with_keyword('patrick')
	print(key)
	encrypted = encrypt_text('BonkRocks', key)
	print(encrypted)
	print(decrypt_text(encrypted, key))