def test_decryptor_update(patch_default_backend, patch_cipher):
tester = Decryptor(algorithm=MagicMock(),
key=sentinel.key,
associated_data=sentinel.aad,
iv=sentinel.iv,
tag=sentinel.tag)
test = tester.update(sentinel.ciphertext)
tester._decryptor.update.assert_called_once_with(sentinel.ciphertext)
assert test is tester._decryptor.update.return_value
class StreamDecryptor(_EncryptionStream): # pylint: disable=too-many-instance-attributes
"""Provides a streaming encryptor for encrypting a stream source.
Behaves as a standard file-like object.
.. note::
Take care when decrypting framed messages with large frame length and large non-framed
messages. See :class:`aws_encryption_sdk.stream` for more details.
.. note::
If config is provided, all other parameters are ignored.
:param config: Client configuration object (config or individual parameters required)
:type config: aws_encryption_sdk.streaming_client.DecryptorConfig
:param source: Source data to encrypt or decrypt
:type source: str, bytes, io.IOBase, or file
:param materials_manager: `CryptoMaterialsManager` from which to obtain cryptographic materials
(either `materials_manager` or `key_provider` required)
:type materials_manager: aws_encryption_sdk.materials_managers.base.CryptoMaterialsManager
:param key_provider: `MasterKeyProvider` from which to obtain data keys for decryption
(either `materials_manager` or `key_provider` required)
:type key_provider: aws_encryption_sdk.key_providers.base.MasterKeyProvider
:param int source_length: Length of source data (optional)
.. note::
If source_length is not provided and read() is called, will attempt to seek()
to the end of the stream and tell() to find the length of source data.
:param int max_body_length: Maximum frame size (or content length for non-framed messages)
in bytes to read from ciphertext message.
"""
_config_class = DecryptorConfig
def __init__(self, **kwargs): # pylint: disable=unused-argument,super-init-not-called
"""Prepares necessary initial values."""
self.last_sequence_number = 0
def _prep_message(self):
"""Performs initial message setup."""
self._header, self.header_auth = self._read_header()
if self._header.content_type == ContentType.NO_FRAMING:
self._prep_non_framed()
self._message_prepped = True
def _read_header(self):
"""Reads the message header from the input stream.
:returns: tuple containing deserialized header and header_auth objects
:rtype: tuple of aws_encryption_sdk.structures.MessageHeader
and aws_encryption_sdk.internal.structures.MessageHeaderAuthentication
:raises CustomMaximumValueExceeded: if frame length is greater than the custom max value
"""
header_start = self.source_stream.tell()
header = aws_encryption_sdk.internal.formatting.deserialize.deserialize_header(
self.source_stream)
if (self.config.max_body_length is not None
and header.content_type == ContentType.FRAMED_DATA
and header.frame_length > self.config.max_body_length):
raise CustomMaximumValueExceeded(
'Frame Size in header found larger than custom value: {found} > {custom}'
.format(found=header.frame_length,
custom=self.config.max_body_length))
header_end = self.source_stream.tell()
decrypt_materials_request = DecryptionMaterialsRequest(
encrypted_data_keys=header.encrypted_data_keys,
algorithm=header.algorithm,
encryption_context=header.encryption_context)
decryption_materials = self.config.materials_manager.decrypt_materials(
request=decrypt_materials_request)
if decryption_materials.verification_key is None:
self.verifier = None
else:
self.verifier = Verifier.from_key_bytes(
algorithm=header.algorithm,
key_bytes=decryption_materials.verification_key)
if self.verifier is not None:
self.source_stream.seek(header_start)
self.verifier.update(
self.source_stream.read(header_end - header_start))
header_auth = aws_encryption_sdk.internal.formatting.deserialize.deserialize_header_auth(
stream=self.source_stream,
algorithm=header.algorithm,
verifier=self.verifier)
self._derived_data_key = derive_data_encryption_key(
source_key=decryption_materials.data_key.data_key,
algorithm=header.algorithm,
message_id=header.message_id)
aws_encryption_sdk.internal.formatting.deserialize.validate_header(
header=header,
header_auth=header_auth,
stream=self.source_stream,
header_start=header_start,
header_end=header_end,
data_key=self._derived_data_key)
return header, header_auth
def _prep_non_framed(self):
"""Prepare the opening data for a non-framed message."""
iv, tag, self.body_length = aws_encryption_sdk.internal.formatting.deserialize.deserialize_non_framed_values(
stream=self.source_stream,
header=self._header,
verifier=self.verifier)
if self.config.max_body_length is not None and self.body_length > self.config.max_body_length:
raise CustomMaximumValueExceeded(
'Non-framed message content length found larger than custom value: {found} > {custom}'
.format(found=self.body_length,
custom=self.config.max_body_length))
aad_content_string = aws_encryption_sdk.internal.utils.get_aad_content_string(
content_type=self._header.content_type, is_final_frame=True)
associated_data = aws_encryption_sdk.internal.formatting.encryption_context.assemble_content_aad(
message_id=self._header.message_id,
aad_content_string=aad_content_string,
seq_num=1,
length=self.body_length)
self.decryptor = Decryptor(algorithm=self._header.algorithm,
key=self._derived_data_key,
associated_data=associated_data,
iv=iv,
tag=tag)
self.body_start = self.source_stream.tell()
self.body_end = self.body_start + self.body_length
def _read_bytes_from_non_framed_body(self, b):
"""Reads the requested number of bytes from a streaming non-framed message body.
:param int b: Number of bytes to read
:returns: Decrypted bytes from source stream
:rtype: bytes
"""
_LOGGER.debug('starting non-framed body read')
# Always read the entire message for non-framed message bodies.
bytes_to_read = self.body_end - self.source_stream.tell()
_LOGGER.debug('%s bytes requested; reading %s bytes', b, bytes_to_read)
ciphertext = self.source_stream.read(bytes_to_read)
if len(self.output_buffer) + len(ciphertext) < self.body_length:
raise SerializationError(
'Total message body contents less than specified in body description'
)
if self.verifier is not None:
self.verifier.update(ciphertext)
plaintext = self.decryptor.update(ciphertext)
plaintext += self.decryptor.finalize()
aws_encryption_sdk.internal.formatting.deserialize.update_verifier_with_tag(
stream=self.source_stream,
header=self._header,
verifier=self.verifier)
self.footer = aws_encryption_sdk.internal.formatting.deserialize.deserialize_footer(
stream=self.source_stream, verifier=self.verifier)
self.source_stream.close()
return plaintext
def _read_bytes_from_framed_body(self, b):
"""Reads the requested number of bytes from a streaming framed message body.
:param int b: Number of bytes to read
:returns: Bytes read from source stream and decrypted
:rtype: bytes
"""
plaintext = b''
final_frame = False
_LOGGER.debug('collecting %s bytes', b)
while len(plaintext) < b and not final_frame:
_LOGGER.debug('Reading frame')
frame_data, final_frame = aws_encryption_sdk.internal.formatting.deserialize.deserialize_frame(
stream=self.source_stream,
header=self._header,
verifier=self.verifier)
_LOGGER.debug('Read complete for frame %s',
frame_data.sequence_number)
if frame_data.sequence_number != self.last_sequence_number + 1:
raise SerializationError(
'Malformed message: frames out of order')
self.last_sequence_number += 1
aad_content_string = aws_encryption_sdk.internal.utils.get_aad_content_string(
content_type=self._header.content_type,
is_final_frame=frame_data.final_frame)
associated_data = aws_encryption_sdk.internal.formatting.encryption_context.assemble_content_aad(
message_id=self._header.message_id,
aad_content_string=aad_content_string,
seq_num=frame_data.sequence_number,
length=len(frame_data.ciphertext))
plaintext += decrypt(algorithm=self._header.algorithm,
key=self._derived_data_key,
encrypted_data=frame_data,
associated_data=associated_data)
_LOGGER.debug('bytes collected: %s', len(plaintext))
if final_frame:
_LOGGER.debug('Reading footer')
self.footer = aws_encryption_sdk.internal.formatting.deserialize.deserialize_footer(
stream=self.source_stream, verifier=self.verifier)
self.source_stream.close()
return plaintext
def _read_bytes(self, b):
"""Reads the requested number of bytes from a streaming message body.
:param int b: Number of bytes to read
:raises NotSupportedError: if content type is not supported
"""
if self.source_stream.closed:
_LOGGER.debug('Source stream closed')
return
if b <= len(self.output_buffer):
_LOGGER.debug(
'%s bytes requested less than or equal to current output buffer size %s',
b, len(self.output_buffer))
return
if self._header.content_type == ContentType.FRAMED_DATA:
self.output_buffer += self._read_bytes_from_framed_body(b)
elif self._header.content_type == ContentType.NO_FRAMING:
self.output_buffer += self._read_bytes_from_non_framed_body(b)
else:
raise NotSupportedError('Unsupported content type')
def close(self):
"""Closes out the stream."""
_LOGGER.debug('Closing stream')
if not hasattr(self, 'footer'):
raise SerializationError('Footer not read')
super(StreamDecryptor, self).close()
class StreamDecryptor(_EncryptionStream): # pylint: disable=too-many-instance-attributes
"""Provides a streaming encryptor for encrypting a stream source.
Behaves as a standard file-like object.
.. note::
Take care when decrypting framed messages with large frame length and large non-framed
messages. See :class:`aws_encryption_sdk.stream` for more details.
.. note::
If config is provided, all other parameters are ignored.
.. versionadded:: 1.5.0
The *keyring* parameter.
:param config: Client configuration object (config or individual parameters required)
:type config: aws_encryption_sdk.streaming_client.DecryptorConfig
:param source: Source data to encrypt or decrypt
:type source: str, bytes, io.IOBase, or file
:param CryptoMaterialsManager materials_manager:
Cryptographic materials manager to use for encryption
(either ``materials_manager``, ``keyring``, ``key_provider`` required)
:param Keyring keyring: Keyring to use for encryption
(either ``materials_manager``, ``keyring``, ``key_provider`` required)
:param MasterKeyProvider key_provider:
Master key provider to use for encryption
(either ``materials_manager``, ``keyring``, ``key_provider`` required)
:param int source_length: Length of source data (optional)
.. note::
If source_length is not provided and read() is called, will attempt to seek()
to the end of the stream and tell() to find the length of source data.
:param int max_body_length: Maximum frame size (or content length for non-framed messages)
in bytes to read from ciphertext message.
"""
_config_class = DecryptorConfig
def __init__(self, **kwargs): # pylint: disable=unused-argument,super-init-not-called
"""Prepares necessary initial values."""
self.last_sequence_number = 0
self.__unframed_bytes_read = 0
def _prep_message(self):
"""Performs initial message setup."""
self._header, self.header_auth = self._read_header()
if self._header.content_type == ContentType.NO_FRAMING:
self._prep_non_framed()
self._message_prepped = True
def _read_header(self):
"""Reads the message header from the input stream.
:returns: tuple containing deserialized header and header_auth objects
:rtype: tuple of aws_encryption_sdk.structures.MessageHeader
and aws_encryption_sdk.internal.structures.MessageHeaderAuthentication
:raises CustomMaximumValueExceeded: if frame length is greater than the custom max value
"""
header, raw_header = deserialize_header(self.source_stream)
self.__unframed_bytes_read += len(raw_header)
if (
self.config.max_body_length is not None
and header.content_type == ContentType.FRAMED_DATA
and header.frame_length > self.config.max_body_length
):
raise CustomMaximumValueExceeded(
"Frame Size in header found larger than custom value: {found:d} > {custom:d}".format(
found=header.frame_length, custom=self.config.max_body_length
)
)
decrypt_materials_request = DecryptionMaterialsRequest(
encrypted_data_keys=header.encrypted_data_keys,
algorithm=header.algorithm,
encryption_context=header.encryption_context,
)
decryption_materials = self.config.materials_manager.decrypt_materials(request=decrypt_materials_request)
self.keyring_trace = decryption_materials.keyring_trace
if decryption_materials.verification_key is None:
self.verifier = None
else:
self.verifier = Verifier.from_key_bytes(
algorithm=header.algorithm, key_bytes=decryption_materials.verification_key
)
if self.verifier is not None:
self.verifier.update(raw_header)
header_auth = deserialize_header_auth(
stream=self.source_stream, algorithm=header.algorithm, verifier=self.verifier
)
self._derived_data_key = derive_data_encryption_key(
source_key=decryption_materials.data_key.data_key, algorithm=header.algorithm, message_id=header.message_id
)
validate_header(header=header, header_auth=header_auth, raw_header=raw_header, data_key=self._derived_data_key)
return header, header_auth
def _prep_non_framed(self):
"""Prepare the opening data for a non-framed message."""
self._unframed_body_iv, self.body_length = deserialize_non_framed_values(
stream=self.source_stream, header=self._header, verifier=self.verifier
)
if self.config.max_body_length is not None and self.body_length > self.config.max_body_length:
raise CustomMaximumValueExceeded(
"Non-framed message content length found larger than custom value: {found:d} > {custom:d}".format(
found=self.body_length, custom=self.config.max_body_length
)
)
self.__unframed_bytes_read += self._header.algorithm.iv_len
self.__unframed_bytes_read += 8 # encrypted content length field
self._body_start = self.__unframed_bytes_read
self._body_end = self._body_start + self.body_length
def _read_bytes_from_non_framed_body(self, b):
"""Reads the requested number of bytes from a streaming non-framed message body.
:param int b: Number of bytes to read
:returns: Decrypted bytes from source stream
:rtype: bytes
"""
_LOGGER.debug("starting non-framed body read")
# Always read the entire message for non-framed message bodies.
bytes_to_read = self.body_length
_LOGGER.debug("%d bytes requested; reading %d bytes", b, bytes_to_read)
ciphertext = self.source_stream.read(bytes_to_read)
if len(self.output_buffer) + len(ciphertext) < self.body_length:
raise SerializationError("Total message body contents less than specified in body description")
if self.verifier is not None:
self.verifier.update(ciphertext)
tag = deserialize_tag(stream=self.source_stream, header=self._header, verifier=self.verifier)
aad_content_string = aws_encryption_sdk.internal.utils.get_aad_content_string(
content_type=self._header.content_type, is_final_frame=True
)
associated_data = assemble_content_aad(
message_id=self._header.message_id,
aad_content_string=aad_content_string,
seq_num=1,
length=self.body_length,
)
self.decryptor = Decryptor(
algorithm=self._header.algorithm,
key=self._derived_data_key,
associated_data=associated_data,
iv=self._unframed_body_iv,
tag=tag,
)
plaintext = self.decryptor.update(ciphertext)
plaintext += self.decryptor.finalize()
self.footer = deserialize_footer(stream=self.source_stream, verifier=self.verifier)
return plaintext
def _read_bytes_from_framed_body(self, b):
"""Reads the requested number of bytes from a streaming framed message body.
:param int b: Number of bytes to read
:returns: Bytes read from source stream and decrypted
:rtype: bytes
"""
plaintext = b""
final_frame = False
_LOGGER.debug("collecting %d bytes", b)
while len(plaintext) < b and not final_frame:
_LOGGER.debug("Reading frame")
frame_data, final_frame = deserialize_frame(
stream=self.source_stream, header=self._header, verifier=self.verifier
)
_LOGGER.debug("Read complete for frame %d", frame_data.sequence_number)
if frame_data.sequence_number != self.last_sequence_number + 1:
raise SerializationError("Malformed message: frames out of order")
self.last_sequence_number += 1
aad_content_string = aws_encryption_sdk.internal.utils.get_aad_content_string(
content_type=self._header.content_type, is_final_frame=frame_data.final_frame
)
associated_data = assemble_content_aad(
message_id=self._header.message_id,
aad_content_string=aad_content_string,
seq_num=frame_data.sequence_number,
length=len(frame_data.ciphertext),
)
plaintext += decrypt(
algorithm=self._header.algorithm,
key=self._derived_data_key,
encrypted_data=frame_data,
associated_data=associated_data,
)
plaintext_length = len(plaintext)
_LOGGER.debug("bytes collected: %d", plaintext_length)
if final_frame:
_LOGGER.debug("Reading footer")
self.footer = deserialize_footer(stream=self.source_stream, verifier=self.verifier)
return plaintext
def _read_bytes(self, b):
"""Reads the requested number of bytes from a streaming message body.
:param int b: Number of bytes to read
:raises NotSupportedError: if content type is not supported
"""
if hasattr(self, "footer"):
_LOGGER.debug("Source stream processing complete")
return
buffer_length = len(self.output_buffer)
if 0 <= b <= buffer_length:
_LOGGER.debug("%d bytes requested less than or equal to current output buffer size %d", b, buffer_length)
return
if self._header.content_type == ContentType.FRAMED_DATA:
self.output_buffer += self._read_bytes_from_framed_body(b)
elif self._header.content_type == ContentType.NO_FRAMING:
self.output_buffer += self._read_bytes_from_non_framed_body(b)
else:
raise NotSupportedError("Unsupported content type")
def close(self):
"""Closes out the stream."""
_LOGGER.debug("Closing stream")
if not hasattr(self, "footer"):
raise SerializationError("Footer not read")
super(StreamDecryptor, self).close()