AWS Encryption SDK for Java

This topic explains how to install and use the AWS Encryption SDK for Java. For details about programming with the AWS Encryption SDK for Java, see the aws-encryption-sdk-java repository on GitHub. For API documentation, see the Javadoc for the AWS Encryption SDK for Java.

Prerequisites

Before you install the AWS Encryption SDK for Java, be sure you have the following prerequisites.

Installation

Install the latest version of the AWS Encryption SDK for Java.

You can install the AWS Encryption SDK for Java in the following ways.

After you install the SDK, get started by looking at the example Java code in this guide and the Javadoc on GitHub.

AWS KMS keyrings in the AWS Encryption SDK for Java

Version 3.x of the AWS Encryption SDK for Java uses keyrings to perform envelope encryption. The basic AWS KMS keyrings in the AWS Encryption SDK for Java take only one KMS key. They also require an AWS KMS client, which gives you an opportunity to configure the client for the AWS Region of the KMS key.

To create a AWS KMS keyring with one or more wrapping keys, use a multi-keyring. The AWS Encryption SDK for Java has a special multi-keyring that takes one or more AWS KMS keys, and a standard multi-keyring that takes one or more keyrings of any supported type. Some programmers prefer to use a multi-keyring method to create all of their keyrings, and the AWS Encryption SDK for Java supports that strategy.

The AWS Encryption SDK for Java provides basic single-key keyrings and multi-keyrings for all typical use-cases, including AWS KMS multi-Region keys.

For example, to create a AWS KMS keyring with one AWS KMS key, you can use the CreateAwsKmsKeyring()] method.

// Instantiate the AWS Encryption SDK and material providers
final AwsCrypto crypto = AwsCrypto.builder().build();
final MaterialProviders materialProviders = MaterialProviders.builder()
        .MaterialProvidersConfig(MaterialProvidersConfig.builder().build())
        .build();

// Create the keyring
CreateAwsKmsKeyringInput kmsKeyringInput = CreateAwsKmsKeyringInput.builder()
        .kmsKeyId(keyArn)
        .kmsClient(KmsClient.create())
        .build();
IKeyring kmsKeyring = materialProviders.CreateAwsKmsKeyring(kmsKeyringInput);

To create a keyring with one or more AWS KMS keys, use the CreateAwsKmsMultiKeyring() method. This example uses two KMS keys. To specify one KMS key, use only the generator parameter. The msKeyIds parameter that specifies additional KMS keys is optional.

The input for this keyring doesn't take an AWS KMS client. Instead, the AWS Encryption SDK uses the default AWS KMS client for each Region represented by a KMS key in the keyring. For example, if the KMS key identified by the value of the Generator parameter is in the US West (Oregon) Region (us-west-2), the AWS Encryption SDK creates a default AWS KMS client for the us-west-2 Region. If you need to customize the AWS KMS client, use the CreateAwsKmsKeyring() method.

// Instantiate the AWS Encryption SDK and material providers
final AwsCrypto crypto = AwsCrypto.builder().build();
final MaterialProviders materialProviders = MaterialProviders.builder()
            .MaterialProvidersConfig(MaterialProvidersConfig.builder().build())
            .build();

String generatorKey = "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab";
List<String> additionalKey = Collections.singletonList("arn:aws:kms:us-west-2:111122223333:key/0987dcba-09fe-87dc-65ba-ab0987654321");
// Create the keyring
final CreateAwsKmsMultiKeyringInput keyringInput = CreateAwsKmsMultiKeyringInput.builder()
        .generator(generatorKey)
        .kmsKeyIds(additionalKey)
        .build();
final IKeyring kmsKeyring = materialProviders.CreateAwsKmsMultiKeyring(keyringInput);

AWS Encryption SDK for Java supports AWS KMS keyrings that use symmetric encryption (SYMMETRIC_DEFAULT) or asymmetric RSA KMS keys. AWS KMS keyrings created with asymmetric RSA KMS keys can only contain one key pair.

To encrypt with an asymmetric RSA AWS KMS keyring, you do not need kms:GenerateDataKey or kms:Encrypt because you must specify the public key material that you want to use for encryption when you create the keyring. No AWS KMS calls are made when encrypting with this keyring. To decrypt with an asymmetric RSA AWS KMS keyring, you need kms:Decrypt permission.

To create an asymmetric RSA AWS KMS keyring, you must provide the public key and private key ARN from your asymmetric RSA KMS key. The public key must be PEM encoded. The following example creates an AWS KMS keyring with an asymmetric RSA key pair.

// Instantiate the AWS Encryption SDK and material providers
final AwsCrypto crypto = AwsCrypto.builder()
        // Specify algorithmSuite without asymmetric signing here
        //
        // ALG_AES_128_GCM_IV12_TAG16_NO_KDF("0x0014"),
        // ALG_AES_192_GCM_IV12_TAG16_NO_KDF("0x0046"),
        // ALG_AES_256_GCM_IV12_TAG16_NO_KDF("0x0078"),
        // ALG_AES_128_GCM_IV12_TAG16_HKDF_SHA256("0x0114"),
        // ALG_AES_192_GCM_IV12_TAG16_HKDF_SHA256("0x0146"),
        // ALG_AES_256_GCM_IV12_TAG16_HKDF_SHA256("0x0178")
        .withEncryptionAlgorithm(CryptoAlgorithm.ALG_AES_256_GCM_IV12_TAG16_HKDF_SHA256)
        .build();
                
final MaterialProviders matProv = MaterialProviders.builder()
        .MaterialProvidersConfig(MaterialProvidersConfig.builder().build())
        .build();

// Create a KMS RSA keyring.
//    This keyring takes in:
//     - kmsClient
//     - kmsKeyId: Must be an ARN representing an asymmetric RSA KMS key
//     - publicKey: A ByteBuffer of a UTF-8 encoded PEM file representing the public
//                  key for the key passed into kmsKeyId
//     - encryptionAlgorithm: Must be either RSAES_OAEP_SHA_256 or RSAES_OAEP_SHA_1
final CreateAwsKmsRsaKeyringInput createAwsKmsRsaKeyringInput =
        CreateAwsKmsRsaKeyringInput.builder()
                .kmsClient(KmsClient.create())
                .kmsKeyId(rsaKeyArn)
                .publicKey(publicKey)
                .encryptionAlgorithm(EncryptionAlgorithmSpec.RSAES_OAEP_SHA_256)
                .build();
IKeyring awsKmsRsaKeyring = matProv.CreateAwsKmsRsaKeyring(createAwsKmsRsaKeyringInput);

Required encryption contexts in version 3.x

With version 3.x of the AWS Encryption SDK for Java, you can use the required encryption context CMM to require encryption contexts in your cryptographic operations. An encryption context is a set of non-secret key–value pairs. The encryption context is cryptographically bound to the encrypted data so that the same encryption context is required to decrypt the field. When you use the required encryption context CMM, you can specify one or more required encryption context keys (required keys) that must be included in all encrypt and decrypt calls.

On encrypt, the AWS Encryption SDK verifies that all required encryption context keys are included in the encryption context that you specified. The AWS Encryption SDK signs the encryption contexts that you specified. Only the key-value pairs that are not required keys are serialized and stored in plaintext in the header of the encrypted message that the encrypt operation returns.

On decrypt, you must provide an encryption context that contains all of the key-value pairs that represent the required keys. The AWS Encryption SDK uses this encryption context and the key-value pairs stored in the encrypted message’s header to reconstruct the original encryption context that you specified in the encrypt operation. If the AWS Encryption SDK cannot reconstruct the original encryption context, then the decrypt operation fails. If you provide a key-value pair that contains the required key with an incorrect value, the encrypted message cannot be decrypted. You must provide the same key-value pair that was specified on encrypt.

The following example initializes an AWS KMS keyring with the required encryption context CMM.

// Instantiate the AWS Encryption SDK
final AwsCrypto crypto = AwsCrypto.builder()
        .withCommitmentPolicy(CommitmentPolicy.RequireEncryptRequireDecrypt)
        .build();
    
// Create your encryption context
final Map<String, String> encryptionContext = new HashMap<>();
encryptionContext.put("encryption", "context");
encryptionContext.put("is not", "secret");
encryptionContext.put("but adds", "useful metadata");
encryptionContext.put("that can help you", "be confident that");
encryptionContext.put("the data you are handling", "is what you think it is");    

// Create a list of required encryption contexts
final List<String> requiredEncryptionContextKeys = Arrays.asList("encryption", "context");
    
// Create the keyring
final MaterialProviders materialProviders = MaterialProviders.builder()
        .MaterialProvidersConfig(MaterialProvidersConfig.builder().build())
        .build();
final CreateAwsKmsKeyringInput keyringInput = CreateAwsKmsKeyringInput.builder()
        .kmsKeyId(keyArn)
        .kmsClient(KmsClient.create())
        .build();
IKeyring kmsKeyring = materialProviders.CreateAwsKmsKeyring(keyringInput);
    
// Create the required encryption context CMM
ICryptographicMaterialsManager cmm = 
    materialProviders.CreateDefaultCryptographicMaterialsManager(
        CreateDefaultCryptographicMaterialsManagerInput.builder()
            .keyring(kmsKeyring)
            .build()
    );
ICryptographicMaterialsManager requiredCMM = 
    materialProviders.CreateRequiredEncryptionContextCMM(
        CreateRequiredEncryptionContextCMMInput.builder()
            .requiredEncryptionContextKeys(requiredEncryptionContextKeys)
            .underlyingCMM(cmm)
            .build()
        );