DynamoDB Client Side encryption using the DDB Encryption SDK

sample_ddb.py

# Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file is
# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
# ANY KIND, either express or implied. See the License for the specific
# language governing permissions and limitations under the License.

from dynamodb_encryption_sdk.encrypted import CryptoConfig
from dynamodb_encryption_sdk.encrypted.client import EncryptedClient
from dynamodb_encryption_sdk.identifiers import CryptoAction
from dynamodb_encryption_sdk.encrypted import CryptoConfig
from dynamodb_encryption_sdk.material_providers.aws_kms import AwsKmsCryptographicMaterialsProvider
from dynamodb_encryption_sdk.structures import AttributeActions

import boto3
from boto3.dynamodb.types import Binary
import uuid
from datetime import datetime


def encrypt_item(table_name, aws_cmk_id, index_key, plaintext_item, ignored_attributes):
    """Demonstrate use of EncryptedClient to transparently encrypt an item."""

    # Collect all of the attributes that will be encrypted (used later).
    encrypted_attributes = set(plaintext_item.keys())
    # Collect all of the attributes that will not be encrypted (used later).
    # Here, we leave out the index keys as we can't use them if they are encrypted client side!
    unencrypted_attributes = set(index_key.keys())
    for attrib in ignored_attributes:
        encrypted_attributes.remove(attrib)
        unencrypted_attributes.add(attrib)

    # Add the index pairs back to the item.
    plaintext_item.update(index_key)

    # Create a normal client.
    client = boto3.client("dynamodb")
    # Create a crypto materials provider using the specified AWS KMS key.
    aws_kms_cmp = AwsKmsCryptographicMaterialsProvider(key_id=aws_cmk_id)
    # Create attribute actions that tells the encrypted client to encrypt all attributes except one.
    actions = AttributeActions(
        default_action=CryptoAction.ENCRYPT_AND_SIGN, attribute_actions={x: CryptoAction.DO_NOTHING for x in unencrypted_attributes}
    )
    # Use these objects to create an encrypted client.
    encrypted_client = EncryptedClient(client=client, materials_provider=aws_kms_cmp, attribute_actions=actions)

    # Put the item to the table, using the encrypted client to transparently encrypt it.
    encrypted_client.put_item(TableName=table_name, Item=plaintext_item)

    # Get the encrypted item using the standard client.
    encrypted_item = client.get_item(TableName=table_name, Key=index_key)["Item"]

    return encrypted_item

def decrypt_item(table_name, aws_cmk_id, index_key, ignored_attributes):
    """Demonstrate use of EncryptedClient to transparently decrypt an item."""
    unencrypted_attributes = set(index_key.keys())
    for attrib in ignored_attributes:
        unencrypted_attributes.add(attrib)
    actions = AttributeActions (
        default_action = CryptoAction.ENCRYPT_AND_SIGN, attribute_actions={x: CryptoAction.DO_NOTHING for x in unencrypted_attributes}
    )
    aws_kms_cmp = AwsKmsCryptographicMaterialsProvider(key_id=aws_cmk_id)
    client = boto3.client("dynamodb")
    encrypted_client = EncryptedClient(client=client, materials_provider=aws_kms_cmp, attribute_actions = actions)
    decrypted_item = encrypted_client.get_item(TableName=table_name, Key=index_key)["Item"]
    return decrypted_item
    
if __name__ == '__main__':
    index_key = {"CustomerID": {"S": uuid.uuid4().hex }}
    plaintext_item = {
        "DateOfLastContact": {"S": datetime.now().isoformat()},
        "ChatToken": {"S": "datadatadatadata"},
        "OtherMetadata": {"N": "99"},
        "BinaryField": {"B": b"\x00\x01\x02"},
        "leave me": {"S": "alone"},  # We want to ignore this attribute
    }
    # We will not encrypt or sign these attributes, everythign else gets encrypted and signed
    ignored_attributes = ["leave me", "OtherMetadata"]
    #Outputs from stack
    table_name = "YOUR_TEST_DYNAMODB_TABLE_NAME"
    aws_cmk_id = "AWS CMK ID FOR TESTING"
    encrypted_item = encrypt_item(table_name, aws_cmk_id, index_key, plaintext_item, ignored_attributes)
    print("encrypted item is {}".format(encrypted_item))
    decrypted_item = decrypt_item(table_name, aws_cmk_id, index_key, ignored_attributes)
    print ("decrypted: is {}".format(decrypted_item))