def test_unsigned_item(static_cmp_crypto_config):
item = {"test": "no signature"}
with pytest.raises(DecryptionError) as exc_info:
decrypt_python_item(item, static_cmp_crypto_config)
exc_info.match(r"No signature attribute found in item")
def test_no_decryption_key_but_decryption_requested(actions,
parametrized_item):
encryption_key = JceNameLocalDelegatedKey.generate("AES", 256)
signing_key = JceNameLocalDelegatedKey.generate("HmacSHA256", 256)
encrypting_cmp = StaticCryptographicMaterialsProvider(
encryption_materials=RawEncryptionMaterials(
encryption_key=encryption_key, signing_key=signing_key))
decrypting_cmp = StaticCryptographicMaterialsProvider(
decryption_materials=RawDecryptionMaterials(
verification_key=signing_key))
encrypted_item = encrypt_python_item(
parametrized_item,
CryptoConfig(materials_provider=encrypting_cmp,
encryption_context=EncryptionContext(),
attribute_actions=actions),
)
with pytest.raises(DecryptionError) as excinfo:
decrypt_python_item(
encrypted_item,
CryptoConfig(materials_provider=decrypting_cmp,
encryption_context=EncryptionContext(),
attribute_actions=actions),
)
excinfo.match(
"Attribute actions ask for some attributes to be decrypted but no decryption key is available"
)
def get_main_key(self, key_id: str) -> MainKey:
index_key = {"key_id": key_id}
encryption_context = EncryptionContext(
table_name=self._table_name,
partition_key_name="key_id",
attributes=dict_to_ddb(index_key),
)
crypto_config = CryptoConfig(
materials_provider=self._materials_provider,
encryption_context=encryption_context,
attribute_actions=self._actions,
)
encrypted_item = self._get_item(key_id=key_id)
if encrypted_item["restricted"]:
raise Exception("Access restricted.")
decrypted_item = decrypt_python_item(encrypted_item, crypto_config)
return MainKey(
key_id=key_id,
key_bytes=decrypted_item["key"].value,
)
def test_only_sign_item(parametrized_item):
signing_key = JceNameLocalDelegatedKey.generate("HmacSHA256", 256)
cmp = StaticCryptographicMaterialsProvider(
encryption_materials=RawEncryptionMaterials(signing_key=signing_key),
decryption_materials=RawDecryptionMaterials(verification_key=signing_key),
)
actions = AttributeActions(default_action=CryptoAction.SIGN_ONLY)
crypto_config = CryptoConfig(
materials_provider=cmp, encryption_context=EncryptionContext(), attribute_actions=actions
)
signed_item = encrypt_python_item(parametrized_item, crypto_config)
material_description = signed_item[ReservedAttributes.MATERIAL_DESCRIPTION.value].value
assert MaterialDescriptionKeys.ATTRIBUTE_ENCRYPTION_MODE.value.encode("utf-8") not in material_description
decrypt_python_item(signed_item, crypto_config)
def cycle_item_check(plaintext_item, crypto_config):
"""Check that cycling (plaintext->encrypted->decrypted) an item has the expected results."""
ciphertext_item = encrypt_python_item(plaintext_item, crypto_config)
check_encrypted_item(plaintext_item, ciphertext_item, crypto_config.attribute_actions)
cycled_item = decrypt_python_item(ciphertext_item, crypto_config)
assert cycled_item == plaintext_item
del ciphertext_item
del cycled_item
def encrypt_item(table_name, aws_cmk_id):
"""Demonstrate use of EncryptedTable to transparently encrypt an item."""
index_key = {
'partition_attribute': 'is this',
'sort_attribute': 55
}
plaintext_item = {
'example': 'data',
'some numbers': 99,
'and some binary': Binary(b'\x00\x01\x02'),
'leave me': 'alone' # We want to ignore this attribute
}
# Collect all of the attributes that will be encrypted (used later).
encrypted_attributes = set(plaintext_item.keys())
encrypted_attributes.remove('leave me')
# Collect all of the attributes that will not be encrypted (used later).
unencrypted_attributes = set(index_key.keys())
unencrypted_attributes.add('leave me')
# Add the index pairs to the item.
plaintext_item.update(index_key)
# Create a normal table resource.
table = boto3.resource('dynamodb').Table(table_name)
# Use the TableInfo helper to collect information about the indexes.
table_info = TableInfo(name=table_name)
table_info.refresh_indexed_attributes(table.meta.client)
# Create a crypto materials provider using the specified AWS KMS key.
aws_kms_cmp = AwsKmsCryptographicMaterialsProvider(key_id=aws_cmk_id)
encryption_context = EncryptionContext(
table_name=table_name,
partition_key_name=table_info.primary_index.partition,
sort_key_name=table_info.primary_index.sort,
# The only attributes that are used by the AWS KMS cryptographic materials providers
# are the primary index attributes.
# These attributes need to be in the form of a DynamoDB JSON structure, so first
# convert the standard dictionary.
attributes=dict_to_ddb(index_key)
)
# Create attribute actions that tells the encrypted table to encrypt all attributes,
# only sign the primary index attributes, and ignore the one identified attribute to
# ignore.
actions = AttributeActions(
default_action=CryptoAction.ENCRYPT_AND_SIGN,
attribute_actions={'leave me': CryptoAction.DO_NOTHING}
)
actions.set_index_keys(*table_info.protected_index_keys())
# Build the crypto config to use for this item.
# When using the higher-level helpers, this is handled for you.
crypto_config = CryptoConfig(
materials_provider=aws_kms_cmp,
encryption_context=encryption_context,
attribute_actions=actions
)
# Encrypt the plaintext item directly
encrypted_item = encrypt_python_item(plaintext_item, crypto_config)
# You could now put the encrypted item to DynamoDB just as you would any other item.
# table.put_item(Item=encrypted_item)
# We will skip this for the purposes of this example.
# Decrypt the encrypted item directly
decrypted_item = decrypt_python_item(encrypted_item, crypto_config)
# Verify that all of the attributes are different in the encrypted item
for name in encrypted_attributes:
assert encrypted_item[name] != plaintext_item[name]
assert decrypted_item[name] == plaintext_item[name]
# Verify that all of the attributes that should not be encrypted were not.
for name in unencrypted_attributes:
assert decrypted_item[name] == encrypted_item[name] == plaintext_item[name]