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https://github.com/szymon-jozef/ZUT-notatki.git
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83 lines
1.9 KiB
Python
83 lines
1.9 KiB
Python
import numpy as np
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def letter_to_num(letter):
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return ord(letter.upper()) - ord('A')
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def num_to_letter(num):
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return chr(num + ord('A'))
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def matrix_mod_inv(key):
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det = int(round(np.linalg.det(key)))
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det_mod = det % 26
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det_inv = pow(det_mod, -1, 26)
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adj = np.array([[key[1, 1], -key[0, 1]],
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[-key[1, 0], key[0, 0]]])
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return (det_inv * adj) % 26
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def cipher(text: str, key: int):
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text_upper = text.upper().replace(' ', '')
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if not validate_key(key):
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print("Macierz klucz nie jest odwracalna, wybierz inną")
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exit(1)
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if len(text_upper) % 2 != 0:
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text_upper += "X"
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nums = [letter_to_num(letter) for letter in text_upper]
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mat = np.array(nums).reshape(-1, 2).T
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c = (key @ mat) % 26
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return "".join(num_to_letter(n) for n in c.T.flatten())
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def decipher(text: str, key: int):
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text_upper = text.upper().replace(' ', '')
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if not validate_key(key):
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print("Macierz klucz nie jest odwracalna, wybierz inną")
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exit(1)
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key_inv = matrix_mod_inv(key)
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if len(text_upper) % 2 != 0:
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text_upper += "X"
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nums = [letter_to_num(letter) for letter in text_upper]
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mat = np.array(nums).reshape(-1, 2).T
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p = (key_inv @ mat) % 26
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return "".join(num_to_letter(n) for n in p.T.flatten())
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def validate_key(key) -> bool:
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key = np.asarray(key)
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if key.shape != (2, 2):
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return False
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if not np.all((0 <= key) & (key < 26)):
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return False
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det = int(round(np.linalg.det(key)))
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det_mod = det % 26
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return np.gcd(det_mod, 26) == 1
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if __name__ == "__main__":
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key = np.array([[3, 3],
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[2, 5]])
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test_text = "TEST"
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ciphered_text = cipher(test_text, key)
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deciphered_text = decipher(ciphered_text, key)
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print("Text:", test_text)
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print("Cipher:", ciphered_text)
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print("Decipher:", deciphered_text)
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