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AWS Encryption SDK for Python のコードの例
以下の例では、AWS Encryption SDK for Python を使用してデータの暗号化と復号を行う方法を示します。
このセクションの例では、AWS Encryption SDK for Python のバージョン 2.0.x 以降の使用方法について説明します。前バージョンを使用する例については、GitHub の aws-encryption-sdk-python
文字列の暗号化と復号
次の例は、AWS Encryption SDK を使用して文字列の暗号化と復号を行う方法を示しています。この例では、マスターキーとして AWS Key Management Service (AWS KMS)
StrictAwsKmsMasterKeyProvider コンストラクタは、暗号化時に、キー ID、キー ARN、エイリアス名、またはエイリアス ARN を受け取ります。復号化時にはキー ARN が必要です。この場合、keyArn パラメータを暗号化と復号化に使用するため、その値はキー ARN である必要があります。AWS KMS キーの ID については、「AWS Key Management Service デベロッパーガイド」の「キー識別子」を参照してください。
# Copyright 2017 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.""" import aws_encryption_sdk from aws_encryption_sdk import CommitmentPolicy def cycle_string(key_arn, source_plaintext, botocore_session=None): """Encrypts and then decrypts a string under an &KMS; key. :param str key_arn: Amazon Resource Name (ARN) of the &KMS; key :param bytes source_plaintext: Data to encrypt :param botocore_session: existing botocore session instance :type botocore_session: botocore.session.Session """ # Set up an encryption client with an explicit commitment policy. If you do not explicitly choose a # commitment policy, REQUIRE_ENCRYPT_REQUIRE_DECRYPT is used by default. client = aws_encryption_sdk.EncryptionSDKClient(commitment_policy=CommitmentPolicy.REQUIRE_ENCRYPT_REQUIRE_DECRYPT) # Create an AWS KMS master key provider kms_kwargs = dict(key_ids=[key_arn]) if botocore_session is not None: kms_kwargs["botocore_session"] = botocore_session master_key_provider = aws_encryption_sdk.StrictAwsKmsMasterKeyProvider(**kms_kwargs) # Encrypt the plaintext source data ciphertext, encryptor_header = client.encrypt(source=source_plaintext, key_provider=master_key_provider) # Decrypt the ciphertext cycled_plaintext, decrypted_header = client.decrypt(source=ciphertext, key_provider=master_key_provider) # Verify that the "cycled" (encrypted, then decrypted) plaintext is identical to the source plaintext assert cycled_plaintext == source_plaintext # Verify that the encryption context used in the decrypt operation includes all key pairs from # the encrypt operation. (The SDK can add pairs, so don't require an exact match.) # # In production, always use a meaningful encryption context. In this sample, we omit the # encryption context (no key pairs). assert all( pair in decrypted_header.encryption_context.items() for pair in encryptor_header.encryption_context.items() )
バイトストリームの暗号化と復号
次の例は、AWS Encryption SDK を使用してバイトストリームの暗号化と復号を行う方法を示しています。この例では、AWS を使用しません。静的な一時マスターキープロバイダーを使用します。
この例では、暗号化するときに、デジタル署名のない代替アルゴリズムスイート (AES_256_GCM_HKDF_SHA512_COMMIT_KEY) を指定します。このアルゴリズムスイートは、データの暗号化と復号を行うユーザーが同等に信頼されている場合に適しています。次に、この例では復号化時に decrypt-unsigned ストリーミングモードを使用します。これは署名付き暗号化テキストが検出されると失敗します。decrypt-unsigned ストリーミングモードは、AWS Encryption SDK バージョン 1.9.x および 2.2.x で導入されています。
# Copyright 2017 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 creation and use of a RawMasterKeyProvider.""" import filecmp import os import aws_encryption_sdk from aws_encryption_sdk.identifiers import Algorithm, CommitmentPolicy, EncryptionKeyType, WrappingAlgorithm from aws_encryption_sdk.internal.crypto.wrapping_keys import WrappingKey from aws_encryption_sdk.key_providers.raw import RawMasterKeyProvider class StaticRandomMasterKeyProvider(RawMasterKeyProvider): """Randomly generates 256-bit keys for each unique key ID.""" provider_id = "static-random" def __init__(self, **kwargs): # pylint: disable=unused-argument """Initialize empty map of keys.""" self._static_keys = {} def _get_raw_key(self, key_id): """Returns a static, randomly-generated symmetric key for the specified key ID. :param str key_id: Key ID :returns: Wrapping key that contains the specified static key :rtype: :class:`aws_encryption_sdk.internal.crypto.WrappingKey` """ try: static_key = self._static_keys[key_id] except KeyError: static_key = os.urandom(32) self._static_keys[key_id] = static_key return WrappingKey( wrapping_algorithm=WrappingAlgorithm.AES_256_GCM_IV12_TAG16_NO_PADDING, wrapping_key=static_key, wrapping_key_type=EncryptionKeyType.SYMMETRIC, ) def cycle_file(source_plaintext_filename): """Encrypts and then decrypts a file under a custom static master key provider. :param str source_plaintext_filename: Filename of file to encrypt """ # Set up an encryption client with an explicit commitment policy. Note that if you do not explicitly choose a # commitment policy, REQUIRE_ENCRYPT_REQUIRE_DECRYPT is used by default. client = aws_encryption_sdk.EncryptionSDKClient(commitment_policy=CommitmentPolicy.REQUIRE_ENCRYPT_REQUIRE_DECRYPT) # Create a static random master key provider key_id = os.urandom(8) master_key_provider = StaticRandomMasterKeyProvider() master_key_provider.add_master_key(key_id) ciphertext_filename = source_plaintext_filename + ".encrypted" cycled_plaintext_filename = source_plaintext_filename + ".decrypted" # Encrypt the plaintext source data # We can use an unsigning algorithm suite here under the assumption that the contexts that encrypt # and decrypt are equally trusted. with open(source_plaintext_filename, "rb") as plaintext, open(ciphertext_filename, "wb") as ciphertext: with client.stream( algorithm=Algorithm.AES_256_GCM_HKDF_SHA512_COMMIT_KEY, mode="e", source=plaintext, key_provider=master_key_provider, ) as encryptor: for chunk in encryptor: ciphertext.write(chunk) # Decrypt the ciphertext # We can use the recommended "decrypt-unsigned" streaming mode since we encrypted with an unsigned algorithm suite. with open(ciphertext_filename, "rb") as ciphertext, open(cycled_plaintext_filename, "wb") as plaintext: with client.stream(mode="decrypt-unsigned", source=ciphertext, key_provider=master_key_provider) as decryptor: for chunk in decryptor: plaintext.write(chunk) # Verify that the "cycled" (encrypted, then decrypted) plaintext is identical to the source # plaintext assert filecmp.cmp(source_plaintext_filename, cycled_plaintext_filename) # Verify that the encryption context used in the decrypt operation includes all key pairs from # the encrypt operation # # In production, always use a meaningful encryption context. In this sample, we omit the # encryption context (no key pairs). assert all( pair in decryptor.header.encryption_context.items() for pair in encryptor.header.encryption_context.items() ) return ciphertext_filename, cycled_plaintext_filename
複数のマスターキープロバイダーでのバイトストリームの暗号化と復号
次の例では、複数のマスターキープロバイダでの AWS Encryption SDK の使用方法について説明します。複数のマスターキープロバイダーを使用する場合、1 つのマスターキープロバイダーが復号に利用できないと冗長化されます。この例では、AWS KMS key および RSA キーペアをマスターキーとして使用します。
この例では、デジタル署名を含むデフォルトのアルゴリズムスイートで暗号化します。ストリーミングの際、AWS Encryption SDK は、整合性チェックの後、デジタル署名を検証する前にプレーンテキストをリリースします。署名が検証されるまでプレーンテキストを使用しないようにするため、この例ではプレーンテキストをバッファリングし、復号化および検証が完了したときにのみディスクに書き込みます。
# Copyright 2017 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 creation of a RawMasterKeyProvider, how to use multiple master key providers to encrypt, and demonstrating that each master key provider can then be used independently to decrypt the same encrypted message. """ import filecmp import os from cryptography.hazmat.backends import default_backend from cryptography.hazmat.primitives import serialization from cryptography.hazmat.primitives.asymmetric import rsa import aws_encryption_sdk from aws_encryption_sdk.identifiers import CommitmentPolicy, EncryptionKeyType, WrappingAlgorithm from aws_encryption_sdk.internal.crypto.wrapping_keys import WrappingKey from aws_encryption_sdk.key_providers.raw import RawMasterKeyProvider class StaticRandomMasterKeyProvider(RawMasterKeyProvider): """Randomly generates and provides 4096-bit RSA keys consistently per unique key id.""" provider_id = "static-random" def __init__(self, **kwargs): # pylint: disable=unused-argument """Initialize empty map of keys.""" self._static_keys = {} def _get_raw_key(self, key_id): """Retrieves a static, randomly generated, RSA key for the specified key id. :param str key_id: User-defined ID for the static key :returns: Wrapping key that contains the specified static key :rtype: :class:`aws_encryption_sdk.internal.crypto.WrappingKey` """ try: static_key = self._static_keys[key_id] except KeyError: private_key = rsa.generate_private_key(public_exponent=65537, key_size=4096, backend=default_backend()) static_key = private_key.private_bytes( encoding=serialization.Encoding.PEM, format=serialization.PrivateFormat.PKCS8, encryption_algorithm=serialization.NoEncryption(), ) self._static_keys[key_id] = static_key return WrappingKey( wrapping_algorithm=WrappingAlgorithm.RSA_OAEP_SHA1_MGF1, wrapping_key=static_key, wrapping_key_type=EncryptionKeyType.PRIVATE, ) def cycle_file(key_arn, source_plaintext_filename, botocore_session=None): """Encrypts and then decrypts a file using an AWS KMS master key provider and a custom static master key provider. Both master key providers are used to encrypt the plaintext file, so either one alone can decrypt it. :param str key_arn: Amazon Resource Name (ARN) of the &KMS; key (http://docs.aws.amazon.com/kms/latest/developerguide/viewing-keys.html) :param str source_plaintext_filename: Filename of file to encrypt :param botocore_session: existing botocore session instance :type botocore_session: botocore.session.Session """ # "Cycled" means encrypted and then decrypted ciphertext_filename = source_plaintext_filename + ".encrypted" cycled_kms_plaintext_filename = source_plaintext_filename + ".kms.decrypted" cycled_static_plaintext_filename = source_plaintext_filename + ".static.decrypted" # Set up an encryption client with an explicit commitment policy. Note that if you do not explicitly choose a # commitment policy, REQUIRE_ENCRYPT_REQUIRE_DECRYPT is used by default. client = aws_encryption_sdk.EncryptionSDKClient(commitment_policy=CommitmentPolicy.REQUIRE_ENCRYPT_REQUIRE_DECRYPT) # Create an AWS KMS master key provider kms_kwargs = dict(key_ids=[key_arn]) if botocore_session is not None: kms_kwargs["botocore_session"] = botocore_session kms_master_key_provider = aws_encryption_sdk.StrictAwsKmsMasterKeyProvider(**kms_kwargs) # Create a static master key provider and add a master key to it static_key_id = os.urandom(8) static_master_key_provider = StaticRandomMasterKeyProvider() static_master_key_provider.add_master_key(static_key_id) # Add the static master key provider to the AWS KMS master key provider # The resulting master key provider uses AWS KMS master keys to generate (and encrypt) # data keys and static master keys to create an additional encrypted copy of each data key. kms_master_key_provider.add_master_key_provider(static_master_key_provider) # Encrypt plaintext with both AWS KMS and static master keys with open(source_plaintext_filename, "rb") as plaintext, open(ciphertext_filename, "wb") as ciphertext: with client.stream(source=plaintext, mode="e", key_provider=kms_master_key_provider) as encryptor: for chunk in encryptor: ciphertext.write(chunk) # Decrypt the ciphertext with only the AWS KMS master key # Buffer the data in memory before writing to disk. This ensures verfication of the digital signature before returning plaintext. with open(ciphertext_filename, "rb") as ciphertext, open(cycled_kms_plaintext_filename, "wb") as plaintext: with client.stream( source=ciphertext, mode="d", key_provider=aws_encryption_sdk.StrictAwsKmsMasterKeyProvider(**kms_kwargs) ) as kms_decryptor: plaintext.write(kms_decryptor.read()) # Decrypt the ciphertext with only the static master key # Buffer the data in memory before writing to disk to ensure verfication of the signature before returning plaintext. with open(ciphertext_filename, "rb") as ciphertext, open(cycled_static_plaintext_filename, "wb") as plaintext: with client.stream(source=ciphertext, mode="d", key_provider=static_master_key_provider) as static_decryptor: plaintext.write(static_decryptor.read()) # Verify that the "cycled" (encrypted, then decrypted) plaintext is identical to the source plaintext assert filecmp.cmp(source_plaintext_filename, cycled_kms_plaintext_filename) assert filecmp.cmp(source_plaintext_filename, cycled_static_plaintext_filename) # Verify that the encryption context in the decrypt operation includes all key pairs from the # encrypt operation. # # In production, always use a meaningful encryption context. In this sample, we omit the # encryption context (no key pairs). assert all( pair in kms_decryptor.header.encryption_context.items() for pair in encryptor.header.encryption_context.items() ) assert all( pair in static_decryptor.header.encryption_context.items() for pair in encryptor.header.encryption_context.items() ) return (ciphertext_filename, cycled_kms_plaintext_filename, cycled_static_plaintext_filename)
データキーキャッシュを使用したメッセージの暗号化
以下の例は、AWS Encryption SDK for Python でのデータキーキャッシュの使用方法を示します。キャッシュ暗号化マテリアルマネージャー (キャッシュ CMM) の必要な容量値とインスタンスにより、キャッシュセキュリティのしきい値を使用して、ローカルキャッシュのインスタンス (LocalCryptoMaterialsCache) を設定する方法を示しています。
この非常に基本的な例では、固定文字列を暗号化する関数を作成します。この関数では、AWS KMS key、必要なキャッシュのサイズ (容量)、最大保持期間の値を指定することができます。データキーキャッシュのより複雑で現実的な例については、「データキーキャッシュのコード例」を参照してください。
この例はオプションですが、この例でも、暗号化コンテキストを追加認証データとして使用します。暗号化コンテキストで暗号化されたデータを復号するときは、その暗号化コンテキストが適切な内容であるとアプリケーションで検証済みであることを確認してから、プレーンテキストデータを発信者に返してください。暗号化コンテキストは、あらゆる暗号化オペレーションまたは復号オペレーションのベストプラクティス要素ですが、データキーキャッシュでは特別なロールを担います。詳細については、「暗号化コンテキスト: キャッシュエントリを選択する方法」を参照してください。
# Copyright 2017 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 of encryption with data key caching.""" import aws_encryption_sdk from aws_encryption_sdk import CommitmentPolicy def encrypt_with_caching(kms_key_arn, max_age_in_cache, cache_capacity): """Encrypts a string using an &KMS; key and data key caching. :param str kms_key_arn: Amazon Resource Name (ARN) of the &KMS; key :param float max_age_in_cache: Maximum time in seconds that a cached entry can be used :param int cache_capacity: Maximum number of entries to retain in cache at once """ # Data to be encrypted my_data = "My plaintext data" # Security thresholds # Max messages (or max bytes per) data key are optional MAX_ENTRY_MESSAGES = 100 # Create an encryption context encryption_context = {"purpose": "test"} # Set up an encryption client with an explicit commitment policy. Note that if you do not explicitly choose a # commitment policy, REQUIRE_ENCRYPT_REQUIRE_DECRYPT is used by default. client = aws_encryption_sdk.EncryptionSDKClient(commitment_policy=CommitmentPolicy.REQUIRE_ENCRYPT_REQUIRE_DECRYPT) # Create a master key provider for the &KMS; key key_provider = aws_encryption_sdk.StrictAwsKmsMasterKeyProvider(key_ids=[kms_key_arn]) # Create a local cache cache = aws_encryption_sdk.LocalCryptoMaterialsCache(cache_capacity) # Create a caching CMM caching_cmm = aws_encryption_sdk.CachingCryptoMaterialsManager( master_key_provider=key_provider, cache=cache, max_age=max_age_in_cache, max_messages_encrypted=MAX_ENTRY_MESSAGES, ) # When the call to encrypt data specifies a caching CMM, # the encryption operation uses the data key cache specified # in the caching CMM encrypted_message, _header = client.encrypt( source=my_data, materials_manager=caching_cmm, encryption_context=encryption_context ) return encrypted_message
