# Amazon DynamoDB Encryption Client for Java
**Note**
Our client-side encryption library was [renamed to AWS Database Encryption SDK](DDBEC-rename.md). The following topic provides information on versions 1.*x*—2.*x* of the DynamoDB Encryption Client for Java and versions 1.*x*—3.*x* of the DynamoDB Encryption Client for Python. For more information, see [AWS Database Encryption SDK for DynamoDB version support](legacy-dynamodb-encryption-client.md#legacy-support).
This topic explains how to install and use the Amazon DynamoDB Encryption Client for Java. For details about programming with the DynamoDB Encryption Client, see the [Java examples](java-examples.md), the [examples](https://github.com/aws/aws-dynamodb-encryption-java/tree/master/examples) in the aws-dynamodb-encryption-java repository on GitHub, and the [Javadoc](https://aws.github.io/aws-dynamodb-encryption-java/) for the DynamoDB Encryption Client.
**Note**
Versions 1.*x*.*x* of the DynamoDB Encryption Client for Java are in [end-of-support phase](what-is-database-encryption-sdk.md#support) effective July 2022. Upgrade to a newer version as soon as possible.
**Topics**
+ [Prerequisites](#java-prerequisites)
+ [Installation](#java-installation)
+ [Using the DynamoDB Encryption Client for Java](java-using.md)
+ [Java examples](java-examples.md)
## Prerequisites
Before you install the Amazon DynamoDB Encryption Client for Java, be sure you have the following prerequisites.
**A Java development environment**
You will need Java 8 or later. On the Oracle website, go to [Java SE Downloads](https://www.oracle.com/java/technologies/downloads/), and then download and install the Java SE Development Kit (JDK).
If you use the Oracle JDK, you must also download and install the [Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files](http://www.oracle.com/java/technologies/javase-jce8-downloads.html).
**AWS SDK for Java**
The DynamoDB Encryption Client requires the DynamoDB module of the AWS SDK for Java even if your application doesn't interact with DynamoDB. You can install the entire SDK or just this module. If you are using Maven, add `aws-java-sdk-dynamodb` to your `pom.xml` file.
For more information about installing and configuring the AWS SDK for Java, see [AWS SDK for Java](https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/getting-started.html).
## Installation
You can install the Amazon DynamoDB Encryption Client for Java in the following ways.
**Manually**
To install the Amazon DynamoDB Encryption Client for Java, clone or download the [aws-dynamodb-encryption-java](https://github.com/aws/aws-dynamodb-encryption-java/) GitHub repository.
**Using Apache Maven**
The Amazon DynamoDB Encryption Client for Java is available through [Apache Maven](https://maven.apache.org/) with the following dependency definition.
```
com.amazonaws
aws-dynamodb-encryption-java
version-number
```
After you install the SDK, get started by looking at the example code in this guide and the [DynamoDB Encryption Client Javadoc](https://aws.github.io/aws-dynamodb-encryption-java/) on GitHub.
# Using the DynamoDB Encryption Client for Java
**Note**
Our client-side encryption library was [renamed to AWS Database Encryption SDK](DDBEC-rename.md). The following topic provides information on versions 1.*x*—2.*x* of the DynamoDB Encryption Client for Java and versions 1.*x*—3.*x* of the DynamoDB Encryption Client for Python. For more information, see [AWS Database Encryption SDK for DynamoDB version support](legacy-dynamodb-encryption-client.md#legacy-support).
This topic explains some of the features of the DynamoDB Encryption Client in Java that might not be found in other programming language implementations.
For details about programming with the DynamoDB Encryption Client, see the [Java examples](java-examples.md), the [examples](https://github.com/aws/aws-dynamodb-encryption-java/tree/master/examples) in the `aws-dynamodb-encryption-java repository` on GitHub, and the [Javadoc](https://aws.github.io/aws-dynamodb-encryption-java/) for the DynamoDB Encryption Client.
**Topics**
+ [Item encryptors](#attribute-encryptor)
+ [Configuring save behavior](#save-behavior)
+ [Attribute actions in Java](#attribute-actions-java)
+ [Overriding table names](#override-table-name)
## Item encryptors: AttributeEncryptor and DynamoDBEncryptor
The DynamoDB Encryption Client in Java has two [item encryptors](DDBEC-legacy-concepts.md#item-encryptor): the lower-level [DynamoDBEncryptor](https://aws.github.io/aws-dynamodb-encryption-java/com/amazonaws/services/dynamodbv2/datamodeling/encryption/DynamoDBEncryptor.html) and the [AttributeEncryptor](#attribute-encryptor).
The `AttributeEncryptor` is a helper class that helps you use the [DynamoDBMapper](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBMapper.Methods.html) in the AWS SDK for Java with the `DynamoDB Encryptor` in the DynamoDB Encryption Client. When you use the `AttributeEncryptor` with the `DynamoDBMapper`, it transparently encrypts and signs your items when you save them. It also transparently verifies and decrypts your items when you load them.
## Configuring save behavior
You can use the `AttributeEncryptor` and `DynamoDBMapper` to add or replace table items with attributes that are signed only or encrypted and signed. For these tasks, we recommend that you configure it to use the `PUT` save behavior, as shown in the following example. Otherwise, you might not be able to decrypt your data.
```
DynamoDBMapperConfig mapperConfig = DynamoDBMapperConfig.builder().withSaveBehavior(SaveBehavior.PUT).build();
DynamoDBMapper mapper = new DynamoDBMapper(ddb, mapperConfig, new AttributeEncryptor(encryptor));
```
If you use the default save behavior, which updates only the attributes that are modeled in the table item, attributes that are not modeled are not included in the signature, and are not changed by table writes. As a result, on later reads of all attributes, the signature will not validate, because it doesn't include un-modeled attributes.
You can also use the `CLOBBER` save behavior. This behavior is identical to the `PUT` save behavior except that it disables optimistic locking and overwrites the item in the table.
To prevent signature errors, the DynamoDB Encryption Client throws a runtime exception if an `AttributeEncryptor` is used with a `DynamoDBMapper` that is not configured with a save behavior of `CLOBBER` or `PUT`.
To see this code used in an example, see [Using the DynamoDBMapper](java-examples.md#java-example-dynamodb-mapper) and the [AwsKmsEncryptedObject.java](https://github.com/aws/aws-dynamodb-encryption-java/blob/master/examples/src/main/java/com/amazonaws/examples/AwsKmsEncryptedObject.java) example in the `aws-dynamodb-encryption-java` repository in GitHub.
## Attribute actions in Java
[Attribute actions](DDBEC-legacy-concepts.md#legacy-attribute-actions) determine which attribute values are encrypted and signed, which are only signed, and which are ignored. The method you use to specify attribute actions depends on whether you use the `DynamoDBMapper` and `AttributeEncryptor`, or the lower-level [DynamoDBEncryptor](https://aws.github.io/aws-dynamodb-encryption-java/com/amazonaws/services/dynamodbv2/datamodeling/encryption/DynamoDBEncryptor.html).
**Important**
After you use your attribute actions to encrypt your table items, adding or removing attributes from your data model might cause a signature validation error that prevents you from decrypting your data. For a detailed explanation, see [Changing your data model](data-model.md).
### Attribute actions for the DynamoDBMapper
When you use the `DynamoDBMapper` and `AttributeEncryptor`, you use annotations to specify the attribute actions. The DynamoDB Encryption Client uses the [standard DynamoDB attribute annotations](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBMapper.Annotations.html) that define the attribute type to determine how to protect an attribute. By default, all attributes are encrypted and signed except for primary keys, which are signed but not encrypted.
**Note**
Do not encrypt the value of attributes with the [@DynamoDBVersionAttribute annotation](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBMapper.OptimisticLocking.html), although you can (and should) sign them. Otherwise, conditions that use its value will have unintended effects.
```
// Attributes are encrypted and signed
@DynamoDBAttribute(attributeName="Description")
// Partition keys are signed but not encrypted
@DynamoDBHashKey(attributeName="Title")
// Sort keys are signed but not encrypted
@DynamoDBRangeKey(attributeName="Author")
```
To specify exceptions, use the encryption annotations defined in the DynamoDB Encryption Client for Java. If you specify them at the class level, they become the default value for the class.
```
// Sign only
@DoNotEncrypt
// Do nothing; not encrypted or signed
@DoNotTouch
```
For example, these annotations sign but do not encrypt the `PublicationYear` attribute, and do not encrypt or sign the `ISBN` attribute value.
```
// Sign only (override the default)
@DoNotEncrypt
@DynamoDBAttribute(attributeName="PublicationYear")
// Do nothing (override the default)
@DoNotTouch
@DynamoDBAttribute(attributeName="ISBN")
```
### Attribute actions for the DynamoDBEncryptor
To specify attribute actions when you use the [DynamoDBEncryptor](https://aws.github.io/aws-dynamodb-encryption-java/com/amazonaws/services/dynamodbv2/datamodeling/encryption/DynamoDBEncryptor.html) directly, create a `HashMap` object in which the name-value pairs represent attribute names and the specified actions.
The valid values are for the attribute actions are defined in the `EncryptionFlags` enumerated type. You can use `ENCRYPT` and `SIGN` together, use `SIGN` alone, or omit both. However, if you use `ENCRYPT` alone, the DynamoDB Encryption Client throws an error. You cannot encrypt an attribute that you don't sign.
```
ENCRYPT
SIGN
```
**Warning**
Do not encrypt the primary key attributes. They must remain in plaintext so DynamoDB can find the item without running a full table scan.
If you specify a primary key in the encryption context and then specify `ENCRYPT` in the attribute action for either primary key attribute, the DynamoDB Encryption Client throws an exception.
For example, the following Java code creates an `actions` HashMap that encrypts and signs all attributes in the `record` item. The exceptions are the partition key and sort key attributes, which are signed but not encrypted, and the `test` attribute, which is not signed or encrypted.
```
final EnumSet signOnly = EnumSet.of(EncryptionFlags.SIGN);
final EnumSet encryptAndSign = EnumSet.of(EncryptionFlags.ENCRYPT, EncryptionFlags.SIGN);
final Map> actions = new HashMap<>();
for (final String attributeName : record.keySet()) {
switch (attributeName) {
case partitionKeyName: // no break; falls through to next case
case sortKeyName:
// Partition and sort keys must not be encrypted, but should be signed
actions.put(attributeName, signOnly);
break;
case "test":
// Don't encrypt or sign
break;
default:
// Encrypt and sign everything else
actions.put(attributeName, encryptAndSign);
break;
}
}
```
Then, when you call the [encryptRecord](https://aws.github.io/aws-dynamodb-encryption-java/com/amazonaws/services/dynamodbv2/datamodeling/encryption/DynamoDBEncryptor.html#encryptRecord-java.util.Map-java.util.Map-com.amazonaws.services.dynamodbv2.datamodeling.encryption.EncryptionContext-) method of the `DynamoDBEncryptor`, specify the map as the value of the `attributeFlags` parameter. For example, this call to `encryptRecord` uses the `actions` map.
```
// Encrypt the plaintext record
final Map encrypted_record = encryptor.encryptRecord(record, actions, encryptionContext);
```
## Overriding table names
In the DynamoDB Encryption Client, the name of the DynamoDB table is an element of the [DynamoDB encryption context](concepts.md#encryption-context) that is passed to the encryption and decryption methods. When you encrypt or sign table items, the DynamoDB encryption context, including the table name, is cryptographically bound to the ciphertext. If the DynamoDB encryption context that is passed to the decrypt method doesn't match the DynamoDB encryption context that was passed to the encrypt method, the decrypt operation fails.
Occasionally, the name of a table changes, such as when you back up a table or perform a [point-in-time recovery](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/PointInTimeRecovery.html). When you decrypt or verify the signature of these items, you must pass in the same DynamoDB encryption context that was used to encrypt and sign the items, including the original table name. The current table name is not needed.
When you use the `DynamoDBEncryptor`, you assemble the DynamoDB encryption context manually. However, if you are using the `DynamoDBMapper`, the `AttributeEncryptor` creates the DynamoDB encryption context for you, including the current table name. To tell the `AttributeEncryptor` to create an encryption context with a different table name, use the `EncryptionContextOverrideOperator`.
For example, the following code creates instances of the cryptographic materials provider (CMP) and the `DynamoDBEncryptor`. Then it calls the `setEncryptionContextOverrideOperator` method of the `DynamoDBEncryptor`. It uses the `overrideEncryptionContextTableName` operator, which overrides one table name. When it is configured this way, the `AttributeEncryptor` creates a DynamoDB encryption context that includes `newTableName` in place of `oldTableName`. For a complete example, see [EncryptionContextOverridesWithDynamoDBMapper.java](https://github.com/aws/aws-dynamodb-encryption-java/blob/master/examples/src/main/java/com/amazonaws/examples/EncryptionContextOverridesWithDynamoDBMapper.java).
```
final DirectKmsMaterialProvider cmp = new DirectKmsMaterialProvider(kms, keyArn);
final DynamoDBEncryptor encryptor = DynamoDBEncryptor.getInstance(cmp);
encryptor.setEncryptionContextOverrideOperator(EncryptionContextOperators.overrideEncryptionContextTableName(
oldTableName, newTableName));
```
When you call the load method of the `DynamoDBMapper`, which decrypts and verifies the item, you specify the original table name.
```
mapper.load(itemClass, DynamoDBMapperConfig.builder()
.withTableNameOverride(DynamoDBMapperConfig.TableNameOverride.withTableNameReplacement(oldTableName))
.build());
```
You can also use the `overrideEncryptionContextTableNameUsingMap` operator, which overrides multiple table names.
The table name override operators are typically used when decrypting data and verifying signatures. However, you can use them to set the table name in the DynamoDB encryption context to a different value when encrypting and signing.
Do not use the table name override operators if you are using the `DynamoDBEncryptor`. Instead, create an encryption context with the original table name and submit it to the decryption method.
# Example code for the DynamoDB Encryption Client for Java
**Note**
Our client-side encryption library was [renamed to AWS Database Encryption SDK](DDBEC-rename.md). The following topic provides information on versions 1.*x*—2.*x* of the DynamoDB Encryption Client for Java and versions 1.*x*—3.*x* of the DynamoDB Encryption Client for Python. For more information, see [AWS Database Encryption SDK for DynamoDB version support](legacy-dynamodb-encryption-client.md#legacy-support).
The following examples show you how to use the DynamoDB Encryption Client for Java to protect DynamoDB table items in your application. You can find more examples (and contribute your own) in the [examples](https://github.com/aws/aws-dynamodb-encryption-java/tree/master/examples) directory of the [aws-dynamodb-encryption-java](https://github.com/aws/aws-dynamodb-encryption-java/) repository on GitHub.
**Topics**
+ [Using the DynamoDBEncryptor](#java-example-ddb-encryptor)
+ [Using the DynamoDBMapper](#java-example-dynamodb-mapper)
## Using the DynamoDBEncryptor
This example shows how to use the lower-level [DynamoDBEncryptor](https://aws.github.io/aws-dynamodb-encryption-java/com/amazonaws/services/dynamodbv2/datamodeling/encryption/DynamoDBEncryptor.html) with the [Direct KMS Provider](direct-kms-provider.md). The Direct KMS Provider generates and protects its cryptographic materials under an [AWS KMS key](https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#master_keys) in AWS Key Management Service (AWS KMS) that you specify.
You can use any compatible [cryptographic materials provider](DDBEC-legacy-concepts.md#concept-material-provider) (CMP) with the `DynamoDBEncryptor`, and you can use the Direct KMS Provider with the `DynamoDBMapper` and [AttributeEncryptor](java-using.md#attribute-encryptor).
**See the complete code sample**: [AwsKmsEncryptedItem.java](https://github.com/aws/aws-dynamodb-encryption-java/blob/master/examples/src/main/java/com/amazonaws/examples/AwsKmsEncryptedItem.java)
Step 1: Create the Direct KMS Provider
Create an instance of the AWS KMS client with the specified region. Then, use the client instance to create an instance of the Direct KMS Provider with your preferred AWS KMS key.
This example uses the Amazon Resource Name (ARN) to identify the AWS KMS key, but you can use [any valid key identifier](https://docs.aws.amazon.com/kms/latest/developerguide/viewing-keys.html#find-cmk-id-arn).
```
final String keyArn = "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab";
final String region = "us-west-2";
final AWSKMS kms = AWSKMSClientBuilder.standard().withRegion(region).build();
final DirectKmsMaterialProvider cmp = new DirectKmsMaterialProvider(kms, keyArn);
```
Step 2: Create an item
This example defines a `record` HashMap that represents a sample table item.
```
final String partitionKeyName = "partition_attribute";
final String sortKeyName = "sort_attribute";
final Map record = new HashMap<>();
record.put(partitionKeyName, new AttributeValue().withS("value1"));
record.put(sortKeyName, new AttributeValue().withN("55"));
record.put("example", new AttributeValue().withS("data"));
record.put("numbers", new AttributeValue().withN("99"));
record.put("binary", new AttributeValue().withB(ByteBuffer.wrap(new byte[]{0x00, 0x01, 0x02})));
record.put("test", new AttributeValue().withS("test-value"));
```
Step 3: Create a DynamoDBEncryptor
Create an instance of the `DynamoDBEncryptor` with the Direct KMS Provider.
```
final DynamoDBEncryptor encryptor = DynamoDBEncryptor.getInstance(cmp);
```
Step 4: Create a DynamoDB encryption context
The [DynamoDB encryption context](concepts.md#encryption-context) contains information about the table structure and how it is encrypted and signed. If you use the `DynamoDBMapper`, the `AttributeEncryptor` creates the encryption context for you.
```
final String tableName = "testTable";
final EncryptionContext encryptionContext = new EncryptionContext.Builder()
.withTableName(tableName)
.withHashKeyName(partitionKeyName)
.withRangeKeyName(sortKeyName)
.build();
```
Step 5: Create the attribute actions object
[Attribute actions](DDBEC-legacy-concepts.md#legacy-attribute-actions) determine which attributes of the item are encrypted and signed, which are only signed, and which are not encrypted or signed.
In Java, to specify attribute actions, you create a HashMap of attribute name and `EncryptionFlags` value pairs.
For example, the following Java code creates an `actions` HashMap that encrypts and signs all attributes in the `record` item, except for the partition key and sort key attributes, which are signed, but not encrypted, and the `test` attribute, which is not signed or encrypted.
```
final EnumSet signOnly = EnumSet.of(EncryptionFlags.SIGN);
final EnumSet encryptAndSign = EnumSet.of(EncryptionFlags.ENCRYPT, EncryptionFlags.SIGN);
final Map> actions = new HashMap<>();
for (final String attributeName : record.keySet()) {
switch (attributeName) {
case partitionKeyName: // fall through to the next case
case sortKeyName:
// Partition and sort keys must not be encrypted, but should be signed
actions.put(attributeName, signOnly);
break;
case "test":
// Neither encrypted nor signed
break;
default:
// Encrypt and sign all other attributes
actions.put(attributeName, encryptAndSign);
break;
}
}
```
Step 6: Encrypt and sign the item
To encrypt and sign the table item, call the `encryptRecord` method on the instance of the `DynamoDBEncryptor`. Specify the table item (`record`), the attribute actions (`actions`), and the encryption context (`encryptionContext`).
```
final Map encrypted_record = encryptor.encryptRecord(record, actions, encryptionContext);
```
Step 7: Put the item in the DynamoDB table
Finally, put the encrypted and signed item in the DynamoDB table.
```
final AmazonDynamoDB ddb = AmazonDynamoDBClientBuilder.defaultClient();
ddb.putItem(tableName, encrypted_record);
```
## Using the DynamoDBMapper
The following example shows you how to use the DynamoDB mapper helper class with the [Direct KMS Provider](direct-kms-provider.md). The Direct KMS Provider generates and protects its cryptographic materials under an [AWS KMS key](https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#master_keys) in AWS Key Management Service (AWS KMS) that you specify.
You can use any compatible [cryptographic materials provider](DDBEC-legacy-concepts.md#concept-material-provider) (CMP) with the `DynamoDBMapper`, and you can use the Direct KMS Provider with the lower-level `DynamoDBEncryptor`.
**See the complete code sample**: [AwsKmsEncryptedObject.java](https://github.com/aws/aws-dynamodb-encryption-java/blob/master/examples/src/main/java/com/amazonaws/examples/AwsKmsEncryptedObject.java)
Step 1: Create the Direct KMS Provider
Create an instance of the AWS KMS client with the specified region. Then, use the client instance to create an instance of the Direct KMS Provider with your preferred AWS KMS key.
This example uses the Amazon Resource Name (ARN) to identify the AWS KMS key, but you can use [any valid key identifier](https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#key-id).
```
final String keyArn = "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab";
final String region = "us-west-2";
final AWSKMS kms = AWSKMSClientBuilder.standard().withRegion(region).build();
final DirectKmsMaterialProvider cmp = new DirectKmsMaterialProvider(kms, keyArn);
```
Step 2: Create the DynamoDB Encryptor and DynamoDBMapper
Use the Direct KMS Provider that you created in the previous step to create an instance of the [DynamoDB Encryptor](java-using.md#attribute-encryptor). You need to instantiate the lower-level DynamoDB Encryptor to use the DynamoDB Mapper.
Next, create an instance of your DynamoDB database and a mapper configuration, and use them to create an instance of the DynamoDB Mapper.
When using the `DynamoDBMapper` to add or edit signed (or encrypted and signed) items, configure it to [use a save behavior](java-using.md#save-behavior), such as `PUT`, that includes all attributes, as shown in the following example. Otherwise, you might not be able to decrypt your data.
```
final DynamoDBEncryptor encryptor = DynamoDBEncryptor.getInstance(cmp)
final AmazonDynamoDB ddb = AmazonDynamoDBClientBuilder.standard().withRegion(region).build();
DynamoDBMapperConfig mapperConfig = DynamoDBMapperConfig.builder().withSaveBehavior(SaveBehavior.PUT).build();
DynamoDBMapper mapper = new DynamoDBMapper(ddb, mapperConfig, new AttributeEncryptor(encryptor));
```
Step 3: Define your DynamoDB table
Next, define your DynamoDB table. Use annotations to specify the [attribute actions](java-using.md#attribute-actions-java). This example creates a DynamoDB table, `ExampleTable`, and a `DataPoJo` class that represents table items.
In this sample table, the primary key attributes will be signed but not encrypted. This applies to the `partition_attribute`, which is annotated with `@DynamoDBHashKey`, and the `sort_attribute`, which is annotated with `@DynamoDBRangeKey`.
Attributes that are annotated with `@DynamoDBAttribute`, such as `some numbers`, will be encrypted and signed. The exceptions are attributes that use the `@DoNotEncrypt` (sign only) or `@DoNotTouch` (do not encrypt or sign) encryption annotations defined by the DynamoDB Encryption Client. For example, because the `leave me` attribute has a `@DoNotTouch` annotation, it will not be encrypted or signed.
```
@DynamoDBTable(tableName = "ExampleTable")
public static final class DataPoJo {
private String partitionAttribute;
private int sortAttribute;
private String example;
private long someNumbers;
private byte[] someBinary;
private String leaveMe;
@DynamoDBHashKey(attributeName = "partition_attribute")
public String getPartitionAttribute() {
return partitionAttribute;
}
public void setPartitionAttribute(String partitionAttribute) {
this.partitionAttribute = partitionAttribute;
}
@DynamoDBRangeKey(attributeName = "sort_attribute")
public int getSortAttribute() {
return sortAttribute;
}
public void setSortAttribute(int sortAttribute) {
this.sortAttribute = sortAttribute;
}
@DynamoDBAttribute(attributeName = "example")
public String getExample() {
return example;
}
public void setExample(String example) {
this.example = example;
}
@DynamoDBAttribute(attributeName = "some numbers")
public long getSomeNumbers() {
return someNumbers;
}
public void setSomeNumbers(long someNumbers) {
this.someNumbers = someNumbers;
}
@DynamoDBAttribute(attributeName = "and some binary")
public byte[] getSomeBinary() {
return someBinary;
}
public void setSomeBinary(byte[] someBinary) {
this.someBinary = someBinary;
}
@DynamoDBAttribute(attributeName = "leave me")
@DoNotTouch
public String getLeaveMe() {
return leaveMe;
}
public void setLeaveMe(String leaveMe) {
this.leaveMe = leaveMe;
}
@Override
public String toString() {
return "DataPoJo [partitionAttribute=" + partitionAttribute + ", sortAttribute="
+ sortAttribute + ", example=" + example + ", someNumbers=" + someNumbers
+ ", someBinary=" + Arrays.toString(someBinary) + ", leaveMe=" + leaveMe + "]";
}
}
```
Step 4: Encrypt and save a table item
Now, when you create a table item and use the DynamoDB Mapper to save it, the item is automatically encrypted and signed before it is added to the table.
This example defines a table item called `record`. Before it is saved in the table, its attributes are encrypted and signed based on the annotations in the `DataPoJo` class. In this case, all attributes except for `PartitionAttribute`, `SortAttribute`, and `LeaveMe` are encrypted and signed. `PartitionAttribute` and `SortAttributes` are only signed. The `LeaveMe` attribute is not encrypted or signed.
To encrypt and sign the `record` item, and then add it to the `ExampleTable`, call the `save` method of the `DynamoDBMapper` class. Because your DynamoDB Mapper is configured to use the `PUT` save behavior, the item replaces any item with the same primary keys, instead of updating it. This ensures that the signatures match and you can decrypt the item when you get it from the table.
```
DataPoJo record = new DataPoJo();
record.setPartitionAttribute("is this");
record.setSortAttribute(55);
record.setExample("data");
record.setSomeNumbers(99);
record.setSomeBinary(new byte[]{0x00, 0x01, 0x02});
record.setLeaveMe("alone");
mapper.save(record);
```