from libdes import DES_Encrypt, DES_Decrypt
def validate_des_key(key: bytes) -> bool:
for keyByte in key:
binStr: str = "{0:0>8b}".format(keyByte)
if sum([1 if b == '1' else 0 for b in binStr]) % 2 == 0:
return False
return True
if __name__ == '__main__':
plaintextHex: str = input('plaintext:')
key1Hex: str = input('key1:')
if not validate_des_key(bytes.fromhex(key1Hex)):
raise Exception('Parity check failed on the key.')
key2Hex: str = input('key2:')
if not validate_des_key(bytes.fromhex(key2Hex)):
raise Exception('Parity check failed on the key.')
key3Hex: str = input('key3:')
if not validate_des_key(bytes.fromhex(key3Hex)):
raise Exception('Parity check failed on the key.')
ciphertext1: bytes = DES_Encrypt(
bytes.fromhex(plaintextHex),
bytes.fromhex(key1Hex),
)
ciphertext2: bytes = DES_Decrypt(
ciphertext1,
bytes.fromhex(key2Hex),
)
ciphertext3: bytes = DES_Encrypt(
ciphertext2,
bytes.fromhex(key3Hex),
)
print('ciphertext:', ciphertext3.hex())
plaintext3: bytes = DES_Decrypt(
ciphertext3,
bytes.fromhex(key3Hex),
)
plaintext2: bytes = DES_Encrypt(
plaintext3,
bytes.fromhex(key2Hex),
)
plaintext1: bytes = DES_Decrypt(
plaintext2,
bytes.fromhex(key1Hex),
)
print('plaintext:', plaintext1.hex())
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