Example for using multiple keys in multiple regions

examples/src/multiple_kms_cmk_regions.py

@@ -0,0 +1,77 @@
+# Copyright 2019 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.
+"""
+Example showing basic encryption and decryption of a value already in memory
+using multiple KMS CMKs in multiple regions.
+"""
+import aws_encryption_sdk
+
+
+def encrypt(kms_key_provider, source_plaintext):
+    """Encrypts source_plaintext with the key(s) in kms_key_provider"""
+    return aws_encryption_sdk.encrypt(source=source_plaintext, key_provider=kms_key_provider)
+
+
+def decrypt(kms_key_provider, ciphertext):
+    """Decrypts ciphertext with the key(s) in kms_key_provider"""
+    return aws_encryption_sdk.decrypt(source=ciphertext, key_provider=kms_key_provider)
+
+
+def multiple_kms_cmk_regions(key_arn1, key_arn2, source_plaintext, botocore_session=None):
+    """Encrypts and then decrypts a string under multiple KMS customer master keys (CMKs) in multiple regions.
+
+    :param str key_arn1: Amazon Resource Name (ARN) of the KMS CMK
+    :param str key_arn2: Amazon Resource Name (ARN) of another KMS CMK
+    :param bytes source_plaintext: Data to encrypt
+    :param botocore_session: existing botocore session instance
+    :type botocore_session: botocore.session.Session
+    """
+    # Check that these keys are in different regions
+    assert not key_arn1[12:21] == key_arn2[12:21]
+
+    kwargs = dict(key_ids=[key_arn1, key_arn2])
+
+    if botocore_session is not None:
+        kwargs["botocore_session"] = botocore_session
+
+    # Create master key provider using the ARNs of the keys and the session (botocore_session)
+    kms_key_provider = aws_encryption_sdk.KMSMasterKeyProvider(**kwargs)
+
+    # Encrypt the plaintext using the AWS Encryption SDK. It returns the encrypted message and the header
+    ciphertext, encrypted_message_header = encrypt(kms_key_provider, source_plaintext)
+
+    # Check that both key ARNs are in the message headers
+    assert len(encrypted_message_header.encrypted_data_keys) == 2
+
+    # Decrypt the encrypted message using the AWS Encryption SDK. It returns the decrypted message and the header
+    # Either of our keys can be used to decrypt the message
+    plaintext1, decrypted_message_header1 = decrypt(
+        aws_encryption_sdk.KMSMasterKeyProvider(**dict(key_ids=[key_arn1])), ciphertext
+    )
+    plaintext2, decrypted_message_header2 = decrypt(
+        aws_encryption_sdk.KMSMasterKeyProvider(**dict(key_ids=[key_arn2])), ciphertext
+    )
+
+    # Check that the original message and the decrypted message are the same
+    assert source_plaintext == plaintext1
+    assert source_plaintext == plaintext2
+
+    # Check that the headers of the encrypted message and decrypted message match
+    assert all(
+        pair in encrypted_message_header.encryption_context.items()
+        for pair in decrypted_message_header1.encryption_context.items()
+    )
+    assert all(
+        pair in encrypted_message_header.encryption_context.items()
+        for pair in decrypted_message_header2.encryption_context.items()
+    )

examples/test/test_i_multiple_kms_cmk_regions.py

@@ -0,0 +1,33 @@
+# Copyright 2019 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.
+"""Unit test suite for the encryption and decryption using multiple KMS CMKs in multiple regions example."""
+
+import botocore.session
+import pytest
+
+from ..src.multiple_kms_cmk_regions import multiple_kms_cmk_regions
+
+# from .examples_test_utils import get_cmk_arn
+from .examples_test_utils import static_plaintext
+
+
+pytestmark = [pytest.mark.examples]
+
+
+def test_multiple_kms_cmk_regions():
+    plaintext = static_plaintext
+    cmk_arn1 = "arn:aws:kms:us-west-2:658956600833:alias/EncryptDecrypt"
+    cmk_arn2 = "arn:aws:kms:eu-central-1:658956600833:alias/EncryptDecrypt"
+    multiple_kms_cmk_regions(
+        cmk_arn1, cmk_arn2, source_plaintext=plaintext, botocore_session=botocore.session.Session()
+    )