def test_validate_encryption(self):
# Arrange
self.bbs.require_encryption = True
kek = KeyWrapper('key1')
self.bbs.key_encryption_key = kek
blob_name = self._create_small_blob('block_blob')
# Act
self.bbs.require_encryption = False
self.bbs.key_encryption_key = None
blob = self.bbs.get_blob_to_bytes(self.container_name, blob_name)
encryption_data = _dict_to_encryption_data(
loads(blob.metadata['encryptiondata']))
iv = encryption_data.content_encryption_IV
content_encryption_key = _validate_and_unwrap_cek(
encryption_data, kek, None)
cipher = _generate_AES_CBC_cipher(content_encryption_key, iv)
decryptor = cipher.decryptor()
unpadder = PKCS7(128).unpadder()
content = decryptor.update(blob.content) + decryptor.finalize()
content = unpadder.update(content) + unpadder.finalize()
self.assertEqual(self.bytes, content)
def _get_blob_encryptor_and_padder(cek, iv, should_pad):
encryptor = None
padder = None
if cek is not None and iv is not None:
cipher = _generate_AES_CBC_cipher(cek, iv)
encryptor = cipher.encryptor()
padder = PKCS7(128).padder() if should_pad else None
return encryptor, padder
def _get_blob_encryptor_and_padder(cek, iv, should_pad):
encryptor = None
padder = None
if cek is not None and iv is not None:
cipher = _generate_AES_CBC_cipher(cek, iv)
encryptor = cipher.encryptor()
padder = PKCS7(128).padder() if should_pad else None
return encryptor, padder
def _decrypt_entity(entity, encrypted_properties_list, content_encryption_key,
entityIV, isJavaV1):
'''
Decrypts the specified entity using AES256 in CBC mode with 128 bit padding. Unwraps the CEK
using either the specified KEK or the key returned by the key_resolver. Properties
specified in the encrypted_properties_list, will be decrypted and decoded to utf-8 strings.
:param entity:
The entity being retrieved and decrypted. Could be a dict or an entity object.
:param list encrypted_properties_list:
The encrypted list of all the properties that are encrypted.
:param bytes[] content_encryption_key:
The key used internally to encrypt the entity. Extrated from the entity metadata.
:param bytes[] entityIV:
The intialization vector used to seed the encryption algorithm. Extracted from the
entity metadata.
:return: The decrypted entity
:rtype: Entity
'''
_validate_not_none('entity', entity)
decrypted_entity = deepcopy(entity)
try:
for property in entity.keys():
if property in encrypted_properties_list:
value = entity[property]
propertyIV = _generate_property_iv(entityIV,
entity['PartitionKey'],
entity['RowKey'], property,
isJavaV1)
cipher = _generate_AES_CBC_cipher(content_encryption_key,
propertyIV)
# Decrypt the property.
decryptor = cipher.decryptor()
decrypted_data = (decryptor.update(value.value) +
decryptor.finalize())
# Unpad the data.
unpadder = PKCS7(128).unpadder()
decrypted_data = (unpadder.update(decrypted_data) +
unpadder.finalize())
decrypted_data = decrypted_data.decode('utf-8')
decrypted_entity[property] = decrypted_data
decrypted_entity.pop('_ClientEncryptionMetadata1')
decrypted_entity.pop('_ClientEncryptionMetadata2')
return decrypted_entity
except:
raise AzureException(_ERROR_DECRYPTION_FAILURE)
def _encrypt_queue_message(message, key_encryption_key):
'''
Encrypts the given plain text message using AES256 in CBC mode with 128 bit padding.
Wraps the generated content-encryption-key using the user-provided key-encryption-key (kek).
Returns a json-formatted string containing the encrypted message and the encryption metadata.
:param object message:
The plain text messge to be encrypted.
:param object key_encryption_key:
The user-provided key-encryption-key. Must implement the following methods:
wrap_key(key)--wraps the specified key using an algorithm of the user's choice.
get_key_wrap_algorithm()--returns the algorithm used to wrap the specified symmetric key.
get_kid()--returns a string key id for this key-encryption-key.
:return: A json-formatted string containing the encrypted message and the encryption metadata.
:rtype: str
'''
_validate_not_none('message', message)
_validate_not_none('key_encryption_key', key_encryption_key)
_validate_key_encryption_key_wrap(key_encryption_key)
# AES256 uses 256 bit (32 byte) keys and always with 16 byte blocks
content_encryption_key = os.urandom(32)
initialization_vector = os.urandom(16)
# Queue encoding functions all return unicode strings, and encryption should
# operate on binary strings.
message = message.encode('utf-8')
cipher = _generate_AES_CBC_cipher(content_encryption_key,
initialization_vector)
# PKCS7 with 16 byte blocks ensures compatibility with AES.
padder = PKCS7(128).padder()
padded_data = padder.update(message) + padder.finalize()
# Encrypt the data.
encryptor = cipher.encryptor()
encrypted_data = encryptor.update(padded_data) + encryptor.finalize()
# Build the dictionary structure.
queue_message = {
'EncryptedMessageContents':
_encode_base64(encrypted_data),
'EncryptionData':
_generate_encryption_data_dict(key_encryption_key,
content_encryption_key,
initialization_vector)
}
return dumps(queue_message)
def _decrypt_entity(entity, encrypted_properties_list, content_encryption_key, entityIV, isJavaV1):
'''
Decrypts the specified entity using AES256 in CBC mode with 128 bit padding. Unwraps the CEK
using either the specified KEK or the key returned by the key_resolver. Properties
specified in the encrypted_properties_list, will be decrypted and decoded to utf-8 strings.
:param entity:
The entity being retrieved and decrypted. Could be a dict or an entity object.
:param list encrypted_properties_list:
The encrypted list of all the properties that are encrypted.
:param bytes[] content_encryption_key:
The key used internally to encrypt the entity. Extrated from the entity metadata.
:param bytes[] entityIV:
The intialization vector used to seed the encryption algorithm. Extracted from the
entity metadata.
:return: The decrypted entity
:rtype: Entity
'''
_validate_not_none('entity', entity)
decrypted_entity = deepcopy(entity)
try:
for property in entity.keys():
if property in encrypted_properties_list:
value = entity[property]
propertyIV = _generate_property_iv(entityIV,
entity['PartitionKey'], entity['RowKey'],
property, isJavaV1)
cipher = _generate_AES_CBC_cipher(content_encryption_key,
propertyIV)
# Decrypt the property.
decryptor = cipher.decryptor()
decrypted_data = (decryptor.update(value.value) + decryptor.finalize())
# Unpad the data.
unpadder = PKCS7(128).unpadder()
decrypted_data = (unpadder.update(decrypted_data) + unpadder.finalize())
decrypted_data = decrypted_data.decode('utf-8')
decrypted_entity[property] = decrypted_data
decrypted_entity.pop('_ClientEncryptionMetadata1')
decrypted_entity.pop('_ClientEncryptionMetadata2')
return decrypted_entity
except:
raise AzureException(_ERROR_DECRYPTION_FAILURE)
def _encrypt_blob(blob, key_encryption_key):
'''
Encrypts the given blob using AES256 in CBC mode with 128 bit padding.
Wraps the generated content-encryption-key using the user-provided key-encryption-key (kek).
Returns a json-formatted string containing the encryption metadata. This method should
only be used when a blob is small enough for single shot upload. Encrypting larger blobs
is done as a part of the _upload_blob_chunks method.
:param bytes blob:
The blob to be encrypted.
:param object key_encryption_key:
The user-provided key-encryption-key. Must implement the following methods:
wrap_key(key)--wraps the specified key using an algorithm of the user's choice.
get_key_wrap_algorithm()--returns the algorithm used to wrap the specified symmetric key.
get_kid()--returns a string key id for this key-encryption-key.
:return: A tuple of json-formatted string containing the encryption metadata and the encrypted blob data.
:rtype: (str, bytes)
'''
_validate_not_none('blob', blob)
_validate_not_none('key_encryption_key', key_encryption_key)
_validate_key_encryption_key_wrap(key_encryption_key)
# AES256 uses 256 bit (32 byte) keys and always with 16 byte blocks
content_encryption_key = urandom(32)
initialization_vector = urandom(16)
cipher = _generate_AES_CBC_cipher(content_encryption_key,
initialization_vector)
# PKCS7 with 16 byte blocks ensures compatibility with AES.
padder = PKCS7(128).padder()
padded_data = padder.update(blob) + padder.finalize()
# Encrypt the data.
encryptor = cipher.encryptor()
encrypted_data = encryptor.update(padded_data) + encryptor.finalize()
encryption_data = _generate_encryption_data_dict(key_encryption_key,
content_encryption_key,
initialization_vector)
encryption_data['EncryptionMode'] = 'FullBlob'
return dumps(encryption_data), encrypted_data
def _encrypt_blob(blob, key_encryption_key):
'''
Encrypts the given blob using AES256 in CBC mode with 128 bit padding.
Wraps the generated content-encryption-key using the user-provided key-encryption-key (kek).
Returns a json-formatted string containing the encryption metadata. This method should
only be used when a blob is small enough for single shot upload. Encrypting larger blobs
is done as a part of the _upload_blob_chunks method.
:param bytes blob:
The blob to be encrypted.
:param object key_encryption_key:
The user-provided key-encryption-key. Must implement the following methods:
wrap_key(key)--wraps the specified key using an algorithm of the user's choice.
get_key_wrap_algorithm()--returns the algorithm used to wrap the specified symmetric key.
get_kid()--returns a string key id for this key-encryption-key.
:return: A tuple of json-formatted string containing the encryption metadata and the encrypted blob data.
:rtype: (str, bytes)
'''
_validate_not_none('blob', blob)
_validate_not_none('key_encryption_key', key_encryption_key)
_validate_key_encryption_key_wrap(key_encryption_key)
# AES256 uses 256 bit (32 byte) keys and always with 16 byte blocks
content_encryption_key = urandom(32)
initialization_vector = urandom(16)
cipher = _generate_AES_CBC_cipher(content_encryption_key, initialization_vector)
# PKCS7 with 16 byte blocks ensures compatibility with AES.
padder = PKCS7(128).padder()
padded_data = padder.update(blob) + padder.finalize()
# Encrypt the data.
encryptor = cipher.encryptor()
encrypted_data = encryptor.update(padded_data) + encryptor.finalize()
encryption_data = _generate_encryption_data_dict(key_encryption_key, content_encryption_key,
initialization_vector)
encryption_data['EncryptionMode'] = 'FullBlob'
return dumps(encryption_data), encrypted_data
def _decrypt(message, encryption_data, key_encryption_key=None, resolver=None):
'''
Decrypts the given ciphertext using AES256 in CBC mode with 128 bit padding.
Unwraps the content-encryption-key using the user-provided or resolved key-encryption-key (kek). Returns the original plaintex.
:param str message:
The ciphertext to be decrypted.
:param _EncryptionData encryption_data:
The metadata associated with this ciphertext.
:param object key_encryption_key:
The user-provided key-encryption-key. Must implement the following methods:
unwrap_key(key, algorithm)--returns the unwrapped form of the specified symmetric key using the string-specified algorithm.
get_kid()--returns a string key id for this key-encryption-key.
:param function resolver(kid):
The user-provided key resolver. Uses the kid string to return a key-encryption-key implementing the interface defined above.
:return: The decrypted plaintext.
:rtype: str
'''
_validate_not_none('message', message)
content_encryption_key = _validate_and_unwrap_cek(encryption_data,
key_encryption_key,
resolver)
if not (_EncryptionAlgorithm.AES_CBC_256
== encryption_data.encryption_agent.encryption_algorithm):
raise ValueError(_ERROR_UNSUPPORTED_ENCRYPTION_ALGORITHM)
cipher = _generate_AES_CBC_cipher(content_encryption_key,
encryption_data.content_encryption_IV)
# decrypt data
decrypted_data = message
decryptor = cipher.decryptor()
decrypted_data = (decryptor.update(decrypted_data) + decryptor.finalize())
# unpad data
unpadder = PKCS7(128).unpadder()
decrypted_data = (unpadder.update(decrypted_data) + unpadder.finalize())
return decrypted_data
def test_validate_encryption(self):
# Arrange
self.bbs.require_encryption = True
kek = KeyWrapper('key1')
self.bbs.key_encryption_key = kek
blob_name = self._create_small_blob('block_blob')
# Act
self.bbs.require_encryption = False
self.bbs.key_encryption_key = None
blob = self.bbs.get_blob_to_bytes(self.container_name, blob_name)
encryption_data = _dict_to_encryption_data(loads(blob.metadata['encryptiondata']))
iv = encryption_data.content_encryption_IV
content_encryption_key = _validate_and_unwrap_cek(encryption_data, kek, None)
cipher = _generate_AES_CBC_cipher(content_encryption_key, iv)
decryptor = cipher.decryptor()
unpadder = PKCS7(128).unpadder()
content = decryptor.update(blob.content) + decryptor.finalize()
content = unpadder.update(content) + unpadder.finalize()
self.assertEqual(self.bytes, content)
def _decrypt_blob(require_encryption, key_encryption_key, key_resolver,
response, start_offset, end_offset):
'''
Decrypts the given blob contents and returns only the requested range.
:param bool require_encryption:
Whether or not the calling blob service requires objects to be decrypted.
:param object key_encryption_key:
The user-provided key-encryption-key. Must implement the following methods:
wrap_key(key)--wraps the specified key using an algorithm of the user's choice.
get_key_wrap_algorithm()--returns the algorithm used to wrap the specified symmetric key.
get_kid()--returns a string key id for this key-encryption-key.
:param key_resolver(kid):
The user-provided key resolver. Uses the kid string to return a key-encryption-key
implementing the interface defined above.
:return: The decrypted blob content.
:rtype: bytes
'''
_validate_not_none('response', response)
content = response.body
_validate_not_none('content', content)
try:
encryption_data = _dict_to_encryption_data(loads(response.headers['x-ms-meta-encryptiondata']))
except:
if require_encryption:
raise ValueError(_ERROR_DATA_NOT_ENCRYPTED)
else:
return content
if not (encryption_data.encryption_agent.encryption_algorithm == _EncryptionAlgorithm.AES_CBC_256):
raise ValueError(_ERROR_UNSUPPORTED_ENCRYPTION_ALGORITHM)
blob_type = response.headers['x-ms-blob-type']
iv = None
unpad = False
start_range, end_range = 0, len(content)
if 'content-range' in response.headers:
content_range = response.headers['content-range']
# Format: 'bytes x-y/size'
# Ignore the word 'bytes'
content_range = content_range.split(' ')
content_range = content_range[1].split('-')
start_range = int(content_range[0])
content_range = content_range[1].split('/')
end_range = int(content_range[0])
blob_size = int(content_range[1])
if start_offset >= 16:
iv = content[:16]
content = content[16:]
start_offset -= 16
else:
iv = encryption_data.content_encryption_IV
if end_range == blob_size - 1:
unpad = True
else:
unpad = True
iv = encryption_data.content_encryption_IV
if blob_type == 'PageBlob':
unpad = False
content_encryption_key = _validate_and_unwrap_cek(encryption_data, key_encryption_key, key_resolver)
cipher = _generate_AES_CBC_cipher(content_encryption_key, iv)
decryptor = cipher.decryptor()
content = decryptor.update(content) + decryptor.finalize()
if unpad:
unpadder = PKCS7(128).unpadder()
content = unpadder.update(content) + unpadder.finalize()
return content[start_offset: len(content) - end_offset]
def test_validate_encryption(self):
# Arrange
entity = self._create_default_entity_for_encryption()
key_encryption_key = KeyWrapper('key1')
self.ts.key_encryption_key = key_encryption_key
self.ts.insert_entity(self.table_name, entity)
# Act
self.ts.key_encryption_key = None
entity = self.ts.get_entity(self.table_name, entity['PartitionKey'], entity['RowKey'])
# Note the minor discrepancy from the normal decryption process: because the entity was retrieved
# without being decrypted, the encrypted_properties list is now stored in an EntityProperty object
# and is already raw bytes.
encrypted_properties_list = entity['_ClientEncryptionMetadata2'].value
encryption_data = entity['_ClientEncryptionMetadata1']
encryption_data = _dict_to_encryption_data(loads(encryption_data))
content_encryption_key = key_encryption_key.unwrap_key(encryption_data.wrapped_content_key.encrypted_key,
encryption_data.wrapped_content_key.algorithm)
digest = Hash(SHA256(), default_backend())
digest.update(encryption_data.content_encryption_IV +
(entity['RowKey'] + entity['PartitionKey'] + '_ClientEncryptionMetadata2').encode('utf-8'))
metadataIV = digest.finalize()
metadataIV = metadataIV[:16]
cipher = _generate_AES_CBC_cipher(content_encryption_key, metadataIV)
# Decrypt the data.
decryptor = cipher.decryptor()
encrypted_properties_list = decryptor.update(encrypted_properties_list) + decryptor.finalize()
# Unpad the data.
unpadder = PKCS7(128).unpadder()
encrypted_properties_list = unpadder.update(encrypted_properties_list) + unpadder.finalize()
encrypted_properties_list = encrypted_properties_list.decode('utf-8')
# Strip the square braces from the ends and split string into list.
encrypted_properties_list = loads(encrypted_properties_list)
entity_iv, encrypted_properties, content_encryption_key = \
(encryption_data.content_encryption_IV, encrypted_properties_list, content_encryption_key)
decrypted_entity = deepcopy(entity)
for property in encrypted_properties_list:
value = entity[property]
digest = Hash(SHA256(), default_backend())
digest.update(entity_iv +
(entity['RowKey'] + entity['PartitionKey'] + property).encode('utf-8'))
propertyIV = digest.finalize()
propertyIV = propertyIV[:16]
cipher = _generate_AES_CBC_cipher(content_encryption_key,
propertyIV)
# Decrypt the property.
decryptor = cipher.decryptor()
decrypted_data = (decryptor.update(value.value) + decryptor.finalize())
# Unpad the data.
unpadder = PKCS7(128).unpadder()
decrypted_data = (unpadder.update(decrypted_data) + unpadder.finalize())
decrypted_data = decrypted_data.decode('utf-8')
decrypted_entity[property] = decrypted_data
decrypted_entity.pop('_ClientEncryptionMetadata1')
decrypted_entity.pop('_ClientEncryptionMetadata2')
# Assert
self.assertEqual(decrypted_entity['sex'], 'male')
def _encrypt_entity(entity, key_encryption_key, encryption_resolver):
'''
Encrypts the given entity using AES256 in CBC mode with 128 bit padding.
Will generate a content-encryption-key (cek) to encrypt the properties either
stored in an EntityProperty with the 'encrypt' flag set or those
specified by the encryption resolver. This cek is then wrapped using the
provided key_encryption_key (kek). Only strings may be encrypted and the
result is stored as binary on the service.
:param entity:
The entity to insert. Could be a dict or an entity object.
:param object key_encryption_key:
The user-provided key-encryption-key. Must implement the following methods:
wrap_key(key)--wraps the specified key using an algorithm of the user's choice.
get_key_wrap_algorithm()--returns the algorithm used to wrap the specified symmetric key.
get_kid()--returns a string key id for this key-encryption-key.
:param function(partition_key, row_key, property_name) encryption_resolver:
A function that takes in an entities partition key, row key, and property name and returns
a boolean that indicates whether that property should be encrypted.
:return: An entity with both the appropriate properties encrypted and the
encryption data.
:rtype: object
'''
_validate_not_none('entity', entity)
_validate_not_none('key_encryption_key', key_encryption_key)
_validate_key_encryption_key_wrap(key_encryption_key)
# AES256 uses 256 bit (32 byte) keys and always with 16 byte blocks
content_encryption_key = os.urandom(32)
entity_initialization_vector = os.urandom(16)
encrypted_properties = []
encrypted_entity = Entity()
for key, value in entity.items():
# If the property resolver says it should be encrypted
# or it is an EntityProperty with the 'encrypt' property set.
if (isinstance(value, EntityProperty) and value.encrypt) or \
(encryption_resolver is not None \
and encryption_resolver(entity['PartitionKey'], entity['RowKey'], key)):
# Only strings can be encrypted and None is not an instance of str.
if isinstance(value, EntityProperty):
if value.type == EdmType.STRING:
value = value.value
else:
raise ValueError(_ERROR_UNSUPPORTED_TYPE_FOR_ENCRYPTION)
if not isinstance(value, str):
raise ValueError(_ERROR_UNSUPPORTED_TYPE_FOR_ENCRYPTION)
# Value is now confirmed to hold a valid string value to be encrypted
# and should be added to the list of encrypted properties.
encrypted_properties.append(key)
propertyIV = _generate_property_iv(entity_initialization_vector,
entity['PartitionKey'], entity['RowKey'],
key, False)
# Encode the strings for encryption.
value = value.encode('utf-8')
cipher = _generate_AES_CBC_cipher(content_encryption_key, propertyIV)
# PKCS7 with 16 byte blocks ensures compatibility with AES.
padder = PKCS7(128).padder()
padded_data = padder.update(value) + padder.finalize()
# Encrypt the data.
encryptor = cipher.encryptor()
encrypted_data = encryptor.update(padded_data) + encryptor.finalize()
# Set the new value of this key to be a binary EntityProperty for proper serialization.
value = EntityProperty(EdmType.BINARY, encrypted_data)
encrypted_entity[key] = value
encrypted_properties = dumps(encrypted_properties)
# Generate the metadata iv.
metadataIV = _generate_property_iv(entity_initialization_vector,
entity['PartitionKey'], entity['RowKey'],
'_ClientEncryptionMetadata2', False)
encrypted_properties = encrypted_properties.encode('utf-8')
cipher = _generate_AES_CBC_cipher(content_encryption_key, metadataIV)
padder = PKCS7(128).padder()
padded_data = padder.update(encrypted_properties) + padder.finalize()
encryptor = cipher.encryptor()
encrypted_data = encryptor.update(padded_data) + encryptor.finalize()
encrypted_entity['_ClientEncryptionMetadata2'] = EntityProperty(EdmType.BINARY, encrypted_data)
encryption_data = _generate_encryption_data_dict(key_encryption_key, content_encryption_key,
entity_initialization_vector)
encrypted_entity['_ClientEncryptionMetadata1'] = dumps(encryption_data)
return encrypted_entity
def _extract_encryption_metadata(entity, require_encryption, key_encryption_key, key_resolver):
'''
Extracts the encryption metadata from the given entity, setting them to be utf-8 strings.
If no encryption metadata is present, will return None for all return values unless
require_encryption is true, in which case the method will throw.
:param entity:
The entity being retrieved and decrypted. Could be a dict or an entity object.
:param bool require_encryption:
If set, will enforce that the retrieved entity is encrypted and decrypt it.
:param object key_encryption_key:
The user-provided key-encryption-key. Must implement the following methods:
unwrap_key(key, algorithm)--returns the unwrapped form of the specified symmetric key using the
string-specified algorithm.
get_kid()--returns a string key id for this key-encryption-key.
:param function key_resolver(kid):
The user-provided key resolver. Uses the kid string to return a key-encryption-key implementing
the interface defined above.
:returns: a tuple containing the entity iv, the list of encrypted properties, the entity cek,
and whether the entity was encrypted using JavaV1.
:rtype: tuple (bytes[], list, bytes[], bool)
'''
_validate_not_none('entity', entity)
try:
encrypted_properties_list = _decode_base64_to_bytes(entity['_ClientEncryptionMetadata2'])
encryption_data = entity['_ClientEncryptionMetadata1']
encryption_data = _dict_to_encryption_data(loads(encryption_data))
except Exception:
# Message did not have properly formatted encryption metadata.
if require_encryption:
raise ValueError(_ERROR_ENTITY_NOT_ENCRYPTED)
else:
return None, None, None, None
if not (encryption_data.encryption_agent.encryption_algorithm == _EncryptionAlgorithm.AES_CBC_256):
raise ValueError(_ERROR_UNSUPPORTED_ENCRYPTION_ALGORITHM)
content_encryption_key = _validate_and_unwrap_cek(encryption_data, key_encryption_key, key_resolver)
# Special check for compatibility with Java V1 encryption protocol.
isJavaV1 = (encryption_data.key_wrapping_metadata is None) or \
((encryption_data.encryption_agent.protocol == _ENCRYPTION_PROTOCOL_V1) and
'EncryptionLibrary' in encryption_data.key_wrapping_metadata and
'Java' in encryption_data.key_wrapping_metadata['EncryptionLibrary'])
metadataIV = _generate_property_iv(encryption_data.content_encryption_IV,
entity['PartitionKey'], entity['RowKey'],
'_ClientEncryptionMetadata2', isJavaV1)
cipher = _generate_AES_CBC_cipher(content_encryption_key, metadataIV)
# Decrypt the data.
decryptor = cipher.decryptor()
encrypted_properties_list = decryptor.update(encrypted_properties_list) + decryptor.finalize()
# Unpad the data.
unpadder = PKCS7(128).unpadder()
encrypted_properties_list = unpadder.update(encrypted_properties_list) + unpadder.finalize()
encrypted_properties_list = encrypted_properties_list.decode('utf-8')
if isJavaV1:
# Strip the square braces from the ends and split string into list.
encrypted_properties_list = encrypted_properties_list[1:-1]
encrypted_properties_list = encrypted_properties_list.split(', ')
else:
encrypted_properties_list = loads(encrypted_properties_list)
return encryption_data.content_encryption_IV, encrypted_properties_list, content_encryption_key, isJavaV1
def _decrypt_blob(require_encryption, key_encryption_key, key_resolver,
response, start_offset, end_offset):
'''
Decrypts the given blob contents and returns only the requested range.
:param bool require_encryption:
Whether or not the calling blob service requires objects to be decrypted.
:param object key_encryption_key:
The user-provided key-encryption-key. Must implement the following methods:
wrap_key(key)--wraps the specified key using an algorithm of the user's choice.
get_key_wrap_algorithm()--returns the algorithm used to wrap the specified symmetric key.
get_kid()--returns a string key id for this key-encryption-key.
:param key_resolver(kid):
The user-provided key resolver. Uses the kid string to return a key-encryption-key
implementing the interface defined above.
:return: The decrypted blob content.
:rtype: bytes
'''
_validate_not_none('response', response)
content = response.body
_validate_not_none('content', content)
try:
encryption_data = _dict_to_encryption_data(
loads(response.headers['x-ms-meta-encryptiondata']))
except:
if require_encryption:
raise ValueError(_ERROR_DATA_NOT_ENCRYPTED)
else:
return content
if not (encryption_data.encryption_agent.encryption_algorithm
== _EncryptionAlgorithm.AES_CBC_256):
raise ValueError(_ERROR_UNSUPPORTED_ENCRYPTION_ALGORITHM)
blob_type = response.headers['x-ms-blob-type']
iv = None
unpad = False
start_range, end_range = 0, len(content)
if 'content-range' in response.headers:
content_range = response.headers['content-range']
# Format: 'bytes x-y/size'
# Ignore the word 'bytes'
content_range = content_range.split(' ')
content_range = content_range[1].split('-')
start_range = int(content_range[0])
content_range = content_range[1].split('/')
end_range = int(content_range[0])
blob_size = int(content_range[1])
if start_offset >= 16:
iv = content[:16]
content = content[16:]
start_offset -= 16
else:
iv = encryption_data.content_encryption_IV
if end_range == blob_size - 1:
unpad = True
else:
unpad = True
iv = encryption_data.content_encryption_IV
if blob_type == 'PageBlob':
unpad = False
content_encryption_key = _validate_and_unwrap_cek(encryption_data,
key_encryption_key,
key_resolver)
cipher = _generate_AES_CBC_cipher(content_encryption_key, iv)
decryptor = cipher.decryptor()
content = decryptor.update(content) + decryptor.finalize()
if unpad:
unpadder = PKCS7(128).unpadder()
content = unpadder.update(content) + unpadder.finalize()
return content[start_offset:len(content) - end_offset]
