55 lines
1.3 KiB
Python
55 lines
1.3 KiB
Python
import random
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import binascii
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from Crypto.Cipher import AES
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from Crypto.Hash import CMAC, HMAC, SHA256
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KEY = b'1337133713371337'
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def pkcs7(message: bytes, block_size: int = 16) -> bytes:
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gap_size = block_size - (len(message) % block_size)
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return message + bytes([gap_size] * gap_size)
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def calc_cbc_mac(message: bytes, iv: bytes, key: bytes) -> bytes:
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cipher = AES.new(key, AES.MODE_CBC, iv)
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message = pkcs7(message)
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last_block = cipher.encrypt(message)[-16:]
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return last_block
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def calc_hmac(message: bytes, key: bytes) -> bytes:
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# Create HMAC object with the key and message using SHA-256
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hmac = HMAC.new(KEY, msg=message, digestmod=SHA256)
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# Calculate the HMAC
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mac = hmac.hexdigest()
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return mac
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def calc_cmac(message: bytes, key: bytes) -> bytes:
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c = CMAC.new(key, ciphermod=AES)
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c.update(message)
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return c.digest()
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def check_challenge(challenge: bytes):
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return (
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calc_cbc_mac(challenge, b'\x00' * 16, KEY),
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calc_cmac(challenge, KEY),
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calc_hmac(challenge, KEY)
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)
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def decode_message(msg):
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return binascii.unhexlify(msg)
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def main():
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challenge = "f681e8625406c40419ae7771eac8f8a2eb6a6fcb1fc0396ab8fdca793a27c93a6dafbb"
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challenge = decode_message(challenge)
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print(check_challenge(challenge))
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if __name__ == "__main__":
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main() |