Krypto_Grundlagen/chapter_one/Permutations-Chiffre.py

import random

from utils import AlphabetUtils as au


def encrypt_text(cleartext: str, key: [int]):
	"""
	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
	"""
	resulting = ''

	for char in cleartext:
		charIndex = au.get_index_of_letter(char)
		cipherIndex = key.index(charIndex)
		cipherChar = au.get_letter_at_index(cipherIndex)
		resulting += cipherChar

	return resulting


def decrypt_text(ciphertext: str, key: [int]):
	"""
	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:
		charIndex = au.get_index_of_letter(char)
		clearIndex = key[charIndex]
		clearChar = au.get_letter_at_index(clearIndex)
		resulting += clearChar

	return resulting


def generate_key():
	"""
	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):
	result = []

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

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

	result.extend(remainingIndices)

	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))