docs: add master key provider examples

examples/README.md

@@ -33,26 +33,32 @@ We start with AWS KMS examples, then show how to use other wrapping keys.
 * Using AWS Key Management Service (AWS KMS)
     * How to use one AWS KMS CMK
         * [with keyrings](./src/keyring/aws_kms/single_cmk.py)
+        * [with master key providers](./src/master_key_provider/aws_kms/single_cmk.py)
     * How to use multiple AWS KMS CMKs in different regions
         * [with keyrings](./src/keyring/aws_kms/multiple_regions.py)
+        * [with master key providers](./src/master_key_provider/aws_kms/multiple_regions.py)
     * How to decrypt when you don't know the CMK
         * [with keyrings](./src/keyring/aws_kms/discovery_decrypt.py)
+        * [with master key providers](./src/master_key_provider/aws_kms/discovery_decrypt.py)
     * How to decrypt within a region
         * [with keyrings](./src/keyring/aws_kms/discovery_decrypt_in_region_only.py)
     * How to decrypt with a preferred region but failover to others
         * [with keyrings](./src/keyring/aws_kms/discovery_decrypt_with_preferred_regions.py)
 * Using raw wrapping keys
     * How to use a raw AES wrapping key
         * [with keyrings](./src/keyring/raw_aes/raw_aes.py)
+        * [with master key providers](./src/master_key_provider/raw_aes/raw_aes.py)
     * How to use a raw RSA wrapping key
         * [with keyrings](./src/keyring/raw_rsa/private_key_only.py)
     * How to use a raw RSA wrapping key when the key is PEM or DER encoded
         * [with keyrings](./src/keyring/raw_rsa/private_key_only_from_pem.py)
+        * [with master key providers](./src/master_key_provider/raw_rsa/private_key_only_from_pem.py)
     * How to encrypt with a raw RSA public key wrapping key without access to the private key
         * [with keyrings](./src/keyring/raw_rsa/public_private_key_separate.py)
 * Combining wrapping keys
     * How to combine AWS KMS with an offline escrow key
         * [with keyrings](./src/keyring/multi/aws_kms_with_escrow.py)
+        * [with master key providers](./src/master_key_provider/multi/aws_kms_with_escrow.py)
 
 ### Keyrings
 

examples/src/keyring/raw_aes/raw_aes.py

@@ -42,7 +42,7 @@ def run(source_plaintext):
     # Create the keyring that determines how your data keys are protected.
     keyring = RawAESKeyring(
         # The key namespace and key name are defined by you
-        # and are used by the raw RSA keyring
+        # and are used by the raw AES keyring
         # to determine whether it should attempt to decrypt
         # an encrypted data key.
         #

examples/src/master_key_provider/__init__.py

@@ -0,0 +1,7 @@
+# Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+"""
+Master key provider examples.
+
+These examples show how to use master key providers.
+"""

examples/src/master_key_provider/aws_kms/__init__.py

@@ -0,0 +1,7 @@
+# Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+"""
+AWS KMS master key provider examples.
+
+These examples show how to use the KMS master key provider.
+"""

examples/src/master_key_provider/aws_kms/discovery_decrypt.py

@@ -0,0 +1,71 @@
+# Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+"""
+This example is intended to serve as reference material for users migrating away from master key providers.
+We recommend using keyrings rather than master key providers.
+For examples using keyrings, see the ``examples/src/keyrings`` directory.
+
+The KMS master key provider uses any key IDs that you specify on encrypt,
+but attempts to decrypt *any* data keys that were encrypted under a KMS CMK.
+This means that you do not need to know which CMKs were used to encrypt a message.
+
+This example shows how to configure and use a KMS master key provider to decrypt without provider key IDs.
+
+https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#master-key-provider
+
+For an example of how to use the KMS master key with a single CMK,
+see the ``master_key_provider/aws_kms/single_cmk`` example.
+
+For an example of how to use the KMS master key provider with CMKs in multiple regions,
+see the ``master_key_provider/aws_kms/multiple_regions`` example.
+"""
+import aws_encryption_sdk
+from aws_encryption_sdk.key_providers.kms import KMSMasterKey, KMSMasterKeyProvider
+
+
+def run(aws_kms_cmk, source_plaintext):
+    # type: (str, bytes) -> None
+    """Demonstrate configuring a KMS master key provider for decryption.
+
+    :param str aws_kms_cmk: The ARN of an AWS KMS CMK that protects data keys
+    :param bytes source_plaintext: Plaintext to encrypt
+    """
+    # Prepare your encryption context.
+    # https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#encryption-context
+    encryption_context = {
+        "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",
+    }
+
+    # Create the master key that determines how your data keys are protected.
+    encrypt_master_key = KMSMasterKey(key_id=aws_kms_cmk)
+
+    # Create a KMS master key provider to use on decrypt.
+    decrypt_master_key_provider = KMSMasterKeyProvider()
+
+    # Encrypt your plaintext data.
+    ciphertext, _encrypt_header = aws_encryption_sdk.encrypt(
+        source=source_plaintext, encryption_context=encryption_context, key_provider=encrypt_master_key
+    )
+
+    # Demonstrate that the ciphertext and plaintext are different.
+    assert ciphertext != source_plaintext
+
+    # Decrypt your encrypted data using the KMS master key provider.
+    #
+    # You do not need to specify the encryption context on decrypt
+    # because the header of the encrypted message includes the encryption context.
+    decrypted, decrypt_header = aws_encryption_sdk.decrypt(source=ciphertext, key_provider=decrypt_master_key_provider)
+
+    # Demonstrate that the decrypted plaintext is identical to the original plaintext.
+    assert decrypted == source_plaintext
+
+    # Verify that the encryption context used in the decrypt operation includes
+    # the encryption context that you specified when encrypting.
+    # The AWS Encryption SDK can add pairs, so don't require an exact match.
+    #
+    # In production, always use a meaningful encryption context.
+    assert set(encryption_context.items()) <= set(decrypt_header.encryption_context.items())

examples/src/master_key_provider/aws_kms/multiple_regions.py

@@ -0,0 +1,91 @@
+# Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+"""
+This example is intended to serve as reference material for users migrating away from master key providers.
+We recommend using keyrings rather than master key providers.
+For examples using keyrings, see the ``examples/src/keyrings`` directory.
+
+This example shows how to configure and use a KMS master key provider with with CMKs in multiple regions.
+
+https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#master-key-provider
+
+For an example of how to use the KMS master key with a single CMK,
+see the ``master_key_provider/aws_kms/single_cmk`` example.
+
+For an example of how to use the KMS master key provider in discovery mode on decrypt,
+see the ``master_key_provider/aws_kms/discovery_decrypt`` example.
+"""
+import aws_encryption_sdk
+from aws_encryption_sdk.key_providers.kms import KMSMasterKey, KMSMasterKeyProvider
+
+try:  # Python 3.5.0 and 3.5.1 have incompatible typing modules
+    from typing import Sequence  # noqa pylint: disable=unused-import
+except ImportError:  # pragma: no cover
+    # We only actually need these imports when running the mypy checks
+    pass
+
+
+def run(aws_kms_generator_cmk, aws_kms_additional_cmks, source_plaintext):
+    # type: (str, Sequence[str], bytes) -> None
+    """Demonstrate an encrypt/decrypt cycle using a KMS master key provider with CMKs in multiple regions.
+
+    :param str aws_kms_generator_cmk: The ARN of the primary AWS KMS CMK
+    :param List[str] aws_kms_additional_cmks: Additional ARNs of secondary KMS CMKs
+    :param bytes source_plaintext: Plaintext to encrypt
+    """
+    # Prepare your encryption context.
+    # https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#encryption-context
+    encryption_context = {
+        "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",
+    }
+
+    # Create the master key provider that will encrypt your data keys under all requested CMKs.
+    #
+    # The KMS master key provider generates the data key using the first key ID in the list.
+    key_ids = [aws_kms_generator_cmk]
+    key_ids.extend(aws_kms_additional_cmks)
+    master_key_provider = KMSMasterKeyProvider(key_ids=key_ids)
+
+    # Create master keys that each only use one of the CMKs.
+    # We will use these later to demonstrate that any of the CMKs can be used to decrypt the message.
+    single_cmk_master_key_that_generated = KMSMasterKey(key_id=aws_kms_generator_cmk)
+    single_cmk_master_key_that_encrypted = KMSMasterKey(key_id=aws_kms_additional_cmks[0])
+
+    # Encrypt your plaintext data using the master key provider that uses all requests CMKs.
+    ciphertext, encrypt_header = aws_encryption_sdk.encrypt(
+        source=source_plaintext, encryption_context=encryption_context, key_provider=master_key_provider
+    )
+
+    # Verify that the header contains the expected number of encrypted data keys (EDKs).
+    # It should contain one EDK for each CMK.
+    assert len(encrypt_header.encrypted_data_keys) == len(aws_kms_additional_cmks) + 1
+
+    # Demonstrate that the ciphertext and plaintext are different.
+    assert ciphertext != source_plaintext
+
+    # Decrypt your encrypted data separately using the single-CMK master keys.
+    #
+    # You do not need to specify the encryption context on decrypt
+    # because the header of the encrypted message includes the encryption context.
+    decrypted_1, decrypt_header_1 = aws_encryption_sdk.decrypt(
+        source=ciphertext, key_provider=single_cmk_master_key_that_generated
+    )
+    decrypted_2, decrypt_header_2 = aws_encryption_sdk.decrypt(
+        source=ciphertext, key_provider=single_cmk_master_key_that_encrypted
+    )
+
+    # Demonstrate that the decrypted plaintext is identical to the original plaintext.
+    assert decrypted_1 == source_plaintext
+    assert decrypted_2 == source_plaintext
+
+    # Verify that the encryption context used in the decrypt operation includes
+    # the encryption context that you specified when encrypting.
+    # The AWS Encryption SDK can add pairs, so don't require an exact match.
+    #
+    # In production, always use a meaningful encryption context.
+    assert set(encryption_context.items()) <= set(decrypt_header_1.encryption_context.items())
+    assert set(encryption_context.items()) <= set(decrypt_header_2.encryption_context.items())

examples/src/master_key_provider/aws_kms/single_cmk.py

@@ -0,0 +1,64 @@
+# Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+"""
+This example is intended to serve as reference material for users migrating away from master key providers.
+We recommend using keyrings rather than master key providers.
+For examples using keyrings, see the ``examples/src/keyrings`` directory.
+
+This example shows how to configure and use a KMS master key with a single KMS CMK.
+
+https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#master-key-provider
+
+For an example of how to use the KMS master key provider with CMKs in multiple regions,
+see the ``master_key_provider/aws_kms/multiple_regions`` example.
+
+For an example of how to use the KMS master key provider in discovery mode on decrypt,
+see the ``master_key_provider/aws_kms/discovery_decrypt`` example.
+"""
+import aws_encryption_sdk
+from aws_encryption_sdk.key_providers.kms import KMSMasterKey
+
+
+def run(aws_kms_cmk, source_plaintext):
+    # type: (str, bytes) -> None
+    """Demonstrate an encrypt/decrypt cycle using a KMS master key with a single CMK.
+
+    :param str aws_kms_cmk: The ARN of an AWS KMS CMK that protects data keys
+    :param bytes source_plaintext: Plaintext to encrypt
+    """
+    # Prepare your encryption context.
+    # https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#encryption-context
+    encryption_context = {
+        "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",
+    }
+
+    # Create the master key that determines how your data keys are protected.
+    master_key = KMSMasterKey(key_id=aws_kms_cmk)
+
+    # Encrypt your plaintext data.
+    ciphertext, _encrypt_header = aws_encryption_sdk.encrypt(
+        source=source_plaintext, encryption_context=encryption_context, key_provider=master_key
+    )
+
+    # Demonstrate that the ciphertext and plaintext are different.
+    assert ciphertext != source_plaintext
+
+    # Decrypt your encrypted data using the same master key you used on encrypt.
+    #
+    # You do not need to specify the encryption context on decrypt
+    # because the header of the encrypted message includes the encryption context.
+    decrypted, decrypt_header = aws_encryption_sdk.decrypt(source=ciphertext, key_provider=master_key)
+
+    # Demonstrate that the decrypted plaintext is identical to the original plaintext.
+    assert decrypted == source_plaintext
+
+    # Verify that the encryption context used in the decrypt operation includes
+    # the encryption context that you specified when encrypting.
+    # The AWS Encryption SDK can add pairs, so don't require an exact match.
+    #
+    # In production, always use a meaningful encryption context.
+    assert set(encryption_context.items()) <= set(decrypt_header.encryption_context.items())

examples/src/master_key_provider/multi/__init__.py

@@ -0,0 +1,7 @@
+# Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+"""
+Multi-master key provider examples.
+
+These examples show how to combine master key providers.
+"""