chore: Added KMS keyring example (#659)

Author: RitvikKapila

examples/src/keyrings/aws_kms_keyring_example.py

@@ -0,0 +1,119 @@
+# Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+"""
+This example sets up the KMS Keyring
+
+The AWS KMS keyring uses symmetric encryption KMS keys to generate, encrypt and
+decrypt data keys. This example creates a KMS Keyring and then encrypts a custom input EXAMPLE_DATA
+with an encryption context. This example also includes some sanity checks for demonstration:
+1. Ciphertext and plaintext data are not the same
+2. Encryption context is correct in the decrypted message header
+3. Decrypted plaintext value matches EXAMPLE_DATA
+These sanity checks are for demonstration in the example only. You do not need these in your code.
+
+AWS KMS keyrings can be used independently or in a multi-keyring with other keyrings
+of the same or a different type.
+
+For more information on how to use KMS keyrings, see
+https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/use-kms-keyring.html
+"""
+import sys
+
+import boto3
+from aws_cryptographic_materialproviders.mpl import AwsCryptographicMaterialProviders
+from aws_cryptographic_materialproviders.mpl.config import MaterialProvidersConfig
+from aws_cryptographic_materialproviders.mpl.models import CreateAwsKmsKeyringInput
+from aws_cryptographic_materialproviders.mpl.references import IKeyring
+from typing import Dict
+
+import aws_encryption_sdk
+from aws_encryption_sdk import CommitmentPolicy
+
+# TODO-MPL: Remove this as part of removing PYTHONPATH hacks.
+MODULE_ROOT_DIR = '/'.join(__file__.split("/")[:-1])
+
+sys.path.append(MODULE_ROOT_DIR)
+
+EXAMPLE_DATA: bytes = b"Hello World"
+
+
+def encrypt_and_decrypt_with_keyring(
+    kms_key_id: str
+):
+    """Demonstrate an encrypt/decrypt cycle using an AWS KMS keyring.
+
+    Usage: encrypt_and_decrypt_with_keyring(kms_key_id)
+    :param kms_key_id: KMS Key identifier for the KMS key you want to use for encryption and
+    decryption of your data keys.
+    :type kms_key_id: string
+
+    For more information on KMS Key identifiers, see
+    https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#key-id
+    """
+    # 1. Instantiate the encryption SDK client.
+    # This builds the client with the REQUIRE_ENCRYPT_REQUIRE_DECRYPT commitment policy,
+    # which enforces that this client only encrypts using committing algorithm suites and enforces
+    # that this client will only decrypt encrypted messages that were created with a committing
+    # algorithm suite.
+    # This is the default commitment policy if you were to build the client as
+    # `client = aws_encryption_sdk.EncryptionSDKClient()`.
+    client = aws_encryption_sdk.EncryptionSDKClient(
+        commitment_policy=CommitmentPolicy.REQUIRE_ENCRYPT_REQUIRE_DECRYPT
+    )
+
+    # 2. Create a boto3 client for KMS.
+    kms_client = boto3.client('kms', region_name="us-west-2")
+
+    # 3. Create encryption context.
+    # Remember that your encryption context is NOT SECRET.
+    # For more information, see
+    # https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#encryption-context
+    encryption_context: Dict[str, str] = {
+        "encryption": "context",
+        "is not": "secret",
+        "but adds": "useful metadata",
+        "that can help you": "be confident that",
+        "the data you are handling": "is what you think it is",
+    }
+
+    # 4. Create a KMS keyring
+    mat_prov: AwsCryptographicMaterialProviders = AwsCryptographicMaterialProviders(
+        config=MaterialProvidersConfig()
+    )
+
+    keyring_input: CreateAwsKmsKeyringInput = CreateAwsKmsKeyringInput(
+        kms_key_id=kms_key_id,
+        kms_client=kms_client
+    )
+
+    kms_keyring: IKeyring = mat_prov.create_aws_kms_keyring(
+        input=keyring_input
+    )
+
+    # 5. Encrypt the data with the encryptionContext.
+    ciphertext, _ = client.encrypt(
+        source=EXAMPLE_DATA,
+        keyring=kms_keyring,
+        encryption_context=encryption_context
+    )
+
+    # 6. Demonstrate that the ciphertext and plaintext are different.
+    # (This is an example for demonstration; you do not need to do this in your own code.)
+    assert ciphertext != EXAMPLE_DATA, \
+        "Ciphertext and plaintext data are the same. Invalid encryption"
+
+    # 7. Decrypt your encrypted data using the same keyring you used on encrypt.
+    plaintext_bytes, dec_header = client.decrypt(
+        source=ciphertext,
+        keyring=kms_keyring
+    )
+
+    # 8. Demonstrate that the encryption context is correct in the decrypted message header
+    # (This is an example for demonstration; you do not need to do this in your own code.)
+    for k, v in encryption_context.items():
+        assert v == dec_header.encryption_context[k], \
+            "Encryption context does not match expected values"
+
+    # 9. Demonstrate that the decrypted plaintext is identical to the original plaintext.
+    # (This is an example for demonstration; you do not need to do this in your own code.)
+    assert plaintext_bytes == EXAMPLE_DATA

examples/test/keyrings/test_i_aws_kms_keyring_example.py

@@ -0,0 +1,14 @@
+# Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+"""Test suite for the AWS KMS keyring example."""
+import pytest
+
+from ...src.keyrings.aws_kms_keyring_example import encrypt_and_decrypt_with_keyring
+
+pytestmark = [pytest.mark.examples]
+
+
+def test_encrypt_and_decrypt_with_keyring():
+    """Test function for encrypt and decrypt using the AWS KMS Keyring example."""
+    kms_key_id = "arn:aws:kms:us-west-2:658956600833:key/b3537ef1-d8dc-4780-9f5a-55776cbb2f7f"
+    encrypt_and_decrypt_with_keyring(kms_key_id)

examples/test/keyrings/test_i_hierarchical_keyring.py

@@ -9,6 +9,7 @@
 
 
 def test_encrypt_and_decrypt_with_keyring():
+    """Test function for encrypt and decrypt using the AWS KMS Hierarchical Keyring example."""
     key_store_table_name = "KeyStoreDdbTable"
-    key_arn = "arn:aws:kms:us-west-2:370957321024:key/9d989aa2-2f9c-438c-a745-cc57d3ad0126"
-    encrypt_and_decrypt_with_keyring(key_store_table_name, key_store_table_name, key_arn)
+    kms_key_id = "arn:aws:kms:us-west-2:370957321024:key/9d989aa2-2f9c-438c-a745-cc57d3ad0126"
+    encrypt_and_decrypt_with_keyring(key_store_table_name, key_store_table_name, kms_key_id)