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Amazon S3 client-side encryption with AWS KMS managed keys

The following examples use the AmazonS3EncryptionClientV2Builder class to create an Amazon S3 client with client-side encryption enabled. Once configured, any objects you upload to Amazon S3 using this client will be encrypted. Any objects you get from Amazon S3 using this client are automatically decrypted.

You can choose from two encryption modes when enabling client-side Amazon S3 encryption: strict authenticated or authenticated. The following sections show how to enable each type. To learn which algorithms each mode uses, see the CryptoMode definition.

Required imports

Import the following classes for these examples.

Imports

import com.amazonaws.ClientConfiguration;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.kms.AWSKMS;
import com.amazonaws.services.kms.AWSKMSClientBuilder;
import com.amazonaws.services.kms.model.GenerateDataKeyRequest;
import com.amazonaws.services.kms.model.GenerateDataKeyResult;
import com.amazonaws.services.s3.AmazonS3EncryptionClientV2Builder;
import com.amazonaws.services.s3.AmazonS3EncryptionV2;
import com.amazonaws.services.s3.model.CryptoConfigurationV2;
import com.amazonaws.services.s3.model.CryptoMode;
import com.amazonaws.services.s3.model.EncryptionMaterials;
import com.amazonaws.services.s3.model.KMSEncryptionMaterialsProvider;

Strict authenticated encryption

Strict authenticated encryption is the default mode if no CryptoMode is specified.

To explicitly enable this mode, specify the StrictAuthenticatedEncryption value in the withCryptoConfiguration method.

Code

AmazonS3EncryptionV2 s3Encryption = AmazonS3EncryptionClientV2Builder.standard()
         .withRegion(Regions.US_WEST_2)
         .withCryptoConfiguration(new CryptoConfigurationV2().withCryptoMode((CryptoMode.StrictAuthenticatedEncryption)))
         .withEncryptionMaterialsProvider(new KMSEncryptionMaterialsProvider(keyId))
         .build();

s3Encryption.putObject(bucket_name, ENCRYPTED_KEY3, "This is the 3rd content to encrypt with a key created in the {console}");
System.out.println(s3Encryption.getObjectAsString(bucket_name, ENCRYPTED_KEY3));

Call the putObject method on the Amazon S3 encryption client to upload objects.

Code

s3Encryption.putObject(bucket_name, ENCRYPTED_KEY3, "This is the 3rd content to encrypt with a key created in the {console}");

You can retrieve the object using the same client. This example calls the getObjectAsString method to retrieve the string that was stored.

Code

System.out.println(s3Encryption.getObjectAsString(bucket_name, ENCRYPTED_KEY3));

Authenticated encryption mode

When you use AuthenticatedEncryption mode, an improved key wrapping algorithm is applied during encryption. When decrypting in this mode, the algorithm can verify the integrity of the decrypted object and throw an exception if the check fails. For more details about how authenticated encryption works, see the Amazon S3 Client-Side Authenticated Encryption blog post.

To enable this mode, specify the AuthenticatedEncryption value in the withCryptoConfiguration method.

Code

AmazonS3EncryptionV2 s3Encryption = AmazonS3EncryptionClientV2Builder.standard()
         .withRegion(Regions.US_WEST_2)
         .withCryptoConfiguration(new CryptoConfigurationV2().withCryptoMode((CryptoMode.AuthenticatedEncryption)))
         .withEncryptionMaterialsProvider(new KMSEncryptionMaterialsProvider(keyId))
         .build();

Configuring the AWS KMS client

The Amazon S3 encryption client creates a AWS KMS client by default, unless one is explicitly specified.

To set the region for this automatically-created AWS KMS client, set the awsKmsRegion.

Code

Region kmsRegion = Region.getRegion(Regions.AP_NORTHEAST_1);

AmazonS3EncryptionV2 s3Encryption = AmazonS3EncryptionClientV2Builder.standard()
        .withRegion(Regions.US_WEST_2)
        .withCryptoConfiguration(new CryptoConfigurationV2().withAwsKmsRegion(kmsRegion))
        .withEncryptionMaterialsProvider(new KMSEncryptionMaterialsProvider(keyId))
        .build();

Alternatively, you can use your own AWS KMS client to initialize the encryption client.

Code

AWSKMS kmsClient = AWSKMSClientBuilder.standard()
        .withRegion(Regions.US_WEST_2);
        .build();

AmazonS3EncryptionV2 s3Encryption = AmazonS3EncryptionClientV2Builder.standard()
        .withRegion(Regions.US_WEST_2)
        .withKmsClient(kmsClient)
        .withCryptoConfiguration(new CryptoConfigurationV2().withCryptoMode((CryptoMode.AuthenticatedEncryption)))
        .withEncryptionMaterialsProvider(new KMSEncryptionMaterialsProvider(keyId))
        .build();