def set_param(self, index: int, value: bytes) -> None:
if not isinstance(value, bytes):
raise HTypeError("value", value, bytes)
if index == 0:
if len(value) != len(self._key):
raise CipherParameterError("IV of XorCipher must be a bytes object "
"which is the same size as the key.")
else:
self._iv = value
else:
raise CipherParameterError("Index exceeds (XorCipher use only one parameter).")
def decrypt(self, ciphertext: bytes, finalize=True) -> bytes:
if not isinstance(ciphertext, bytes):
raise HTypeError("ciphertext", ciphertext, bytes)
if not self._key:
raise KeyError("Please provide key before calling decrypt()")
if self._in_process is CipherProcess.NONE:
self._in_process = CipherProcess.DECRYPT
self._data = b""
if self._in_process is not CipherProcess.DECRYPT:
raise ResetError("You are in {} process, please call reset() "
"before calling decrypt().".format(self._in_process.name))
if self._iv is None:
raise CipherParameterError("IV has not yet been set.")
self._data += ciphertext
plaintext = b""
while len(self._data) > len(self._key):
data_to_enc, self._data = self._data[:len(self._key)], self._data[len(self._key):]
block = bxor(data_to_enc, self._key)
plaintext += bxor(block, self._iv)
if finalize:
plaintext += self.finalize()
return plaintext
def decrypt(self, ciphertext: bytes, finalize=True) -> bytes:
if not isinstance(ciphertext, bytes):
raise HTypeError("ciphertext", ciphertext, bytes)
if not self._key:
raise KeyError("Please provide key before calling decrypt()")
if self._aes is None:
raise CipherParameterError("Please set iv value "
"before calling decrypt().")
if self._in_process is CipherProcess.NONE:
self._in_process = CipherProcess.DECRYPT
self._decryptor = self._aes.decryptor()
self._unpadder = self._pkcs7.unpadder()
if self._in_process is not CipherProcess.DECRYPT:
raise ResetError("You are in {} process, please call reset() "
"before calling decrypt().".format(self._in_process.name))
padded_text = self._decryptor.update(ciphertext)
plaintext = self._unpadder.update(padded_text)
if finalize:
plaintext += self.finalize()
return plaintext
def encrypt(self, plaintext: bytes, finalize=True) -> bytes:
if not isinstance(plaintext, bytes):
raise HTypeError("plaintext", plaintext, bytes)
if not self._key:
raise KeyError("Please provide key before calling encrypt()")
if self._aes is None:
raise CipherParameterError("Please set nonce "
"value before calling encrypt().")
if self._in_process is CipherProcess.NONE:
self._in_process = CipherProcess.ENCRYPT
self._encryptor = self._aes.encryptor()
if self._in_process is not CipherProcess.ENCRYPT:
raise ResetError("You are in {} process, please call reset() "
"before calling encrypt().".format(self._in_process.name))
ciphertext = self._encryptor.update(plaintext)
if finalize:
ciphertext += self.finalize()
return ciphertext
def set_param(self, index: int, param: bytes) -> None:
if not isinstance(param, bytes):
raise CipherParameterError("Parameters of AES must "
"be a bytes object.")
if index == 0:
if len(param) * 8 != algorithms.AES.block_size:
raise CipherParameterError("Invalid length of nonce "
"value ({} bits), expected less than {} bits.".format(
len(param) * 8,
algorithms.AES.block_size
))
self._nonce = param
self._aes = Cipher(
algorithms.AES(self._key),
modes.CTR(self._nonce),
default_backend()
)
else:
raise CipherParameterError("AES only use the nonce "
"value as its parameter.")
def __init__(self, key: bytes):
if not isinstance(key, bytes):
raise HTypeError("key", key, bytes)
if len(key) * 8 not in algorithms.AES.key_sizes:
raise CipherParameterError("Key size of AES must be in {} (bits), "
"not {} (bytes).".format(
set(algorithms.AES.key_sizes),
len(key)
))
super().__init__(key, number_of_params=1)
self._aes: Cipher = None
self._encryptor: CipherContext = None
self._decryptor: CipherContext = None
self._in_process: CipherProcess = CipherProcess.NONE
self._nonce = None
def __init__(self, key: bytes):
if not isinstance(key, bytes):
raise HTypeError("key", key, bytes)
if len(key) * 8 not in algorithms.AES.key_sizes:
raise CipherParameterError("Key size of AES must be "
"in {} (bits), not {} (bytes).".format(
set(algorithms.AES.key_sizes),
len(key)
))
super().__init__(key, number_of_params=1)
self._aes = None
self._encryptor = None
self._decryptor = None
self._in_process = CipherProcess.NONE
self._pkcs7 = padding.PKCS7(128)
self._padder = None
self._unpadder = None
self._iv = None
def finalize(self) -> bytes:
if self._aes is None:
raise CipherParameterError("Please set nonce value "
"before calling finalize().")
if self._in_process is CipherProcess.ENCRYPT:
finaltext = self._encryptor.finalize()
self._encryptor = None
elif self._in_process is CipherProcess.DECRYPT:
finaltext = self._decryptor.finalize()
self._decryptor = None
elif self._in_process is CipherProcess.FINALIZED:
raise ResetError("Unknown process in your object "
"({}).".format(self._in_process.name))
else:
raise SymmetricError("Unknown process ({}).".format(self._in_process.name))
self._in_process = CipherProcess.FINALIZED
return finaltext
def get_param(self, index) -> bytes:
if index == 0:
return self._iv
else:
raise CipherParameterError("AES CBC only use the "
"IV value as its parameter.")
def get_param(self, index):
raise CipherParameterError("Index exceeds (NoCipher doesn't use any parameters).")
def get_param(self, index) -> bytes:
if index == 0:
return self._nonce
else:
raise CipherParameterError("AES only use the nonce "
"value as its parameter.")
def get_param(self, index: int) -> bytes:
if index == 0:
return self._iv
raise CipherParameterError("XorCipher use only one parameter.")