Replicating encrypted objects

By default, Amazon S3 doesn't replicate objects that are stored at rest using server-side encryption with KMS keys. To replicate encrypted objects, you modify the bucket replication configuration to tell Amazon S3 to replicate these objects. This example explains how to use the Amazon S3 console and the AWS Command Line Interface (AWS CLI) to change the bucket replication configuration to enable replicating encrypted objects. For more information, see Replicating objects created with server-side encryption (SSE-C, SSE-S3, SSE-KMS).

Note

You can use multi-Region AWS KMS keys in Amazon S3. However, Amazon S3 currently treats multi-Region keys as though they were single-Region keys, and does not use the multi-Region features of the key. For more information, see Using multi-Region keys in AWS Key Management Service Developer Guide.

For step-by-step instructions, see Configuring replication for source and destination buckets owned by the same account. This topic provides instructions for setting replication configuration when buckets are owned by same and different AWS accounts.

To replicate encrypted objects with the AWS CLI, you create buckets, enable versioning on the buckets, create an IAM role that gives Amazon S3 permission to replicate objects, and add the replication configuration to the source bucket. The replication configuration provides information related to replicating objects encrypted using KMS keys. The IAM role permissions include necessary permissions to replicate the encrypted objects. You also test the setup.

To replicate server-side encrypted objects (AWS CLI)

In this example, we create both the source and destination buckets in the same AWS account. Set a credentials profile for the AWS CLI. In this example, we use the profile name acctA. For more information about setting credential profiles, see Named Profiles in the AWS Command Line Interface User Guide.

Create the source bucket and enable versioning on it. In this example, we create the source bucket in the US East (N. Virginia) (us-east-1) Region.


aws s3api create-bucket \
--bucket source \
--region us-east-1 \
--profile acctA


aws s3api put-bucket-versioning \
--bucket source \
--versioning-configuration Status=Enabled \
--profile acctA

Create the destination bucket and enable versioning on it. In this example, we create the destination bucket in the US West (Oregon) (us-west-2) Region.

Note
To set up replication configuration when both source and destination buckets are in the same AWS account, you use the same profile. In this example, we use acctA. To test replication configuration when the buckets are owned by different AWS accounts, you specify different profiles for each.
```
aws s3api create-bucket \
--bucket destination \
--region us-west-2 \
--create-bucket-configuration LocationConstraint=us-west-2 \
--profile acctA
```
```
aws s3api put-bucket-versioning \
--bucket destination \
--versioning-configuration Status=Enabled \
--profile acctA
```

Create an IAM role. You specify this role in the replication configuration that you add to the source bucket later. Amazon S3 assumes this role to replicate objects on your behalf. You create an IAM role in two steps:

Create a role
Attach a permissions policy to the role

Create an IAM role.
1. Copy the following trust policy and save it to a file called s3-role-trust-policy-kmsobj.json in the current directory on your local computer. This policy grants Amazon S3 service principal permissions to assume the role so Amazon S3 can perform tasks on your behalf.
```
{
   "Version":"2012-10-17",
   "Statement":[
      {
         "Effect":"Allow",
         "Principal":{
            "Service":"s3.amazonaws.com"
         },
         "Action":"sts:AssumeRole"
      }
   ]
}
```
2. Create a role.
```
$ aws iam create-role \
--role-name replicationRolekmsobj \
--assume-role-policy-document file://s3-role-trust-policy-kmsobj.json  \
--profile acctA
```

Attach a permissions policy to the role. This policy grants permissions for various Amazon S3 bucket and object actions.

Copy the following permissions policy and save it to a file named s3-role-permissions-policykmsobj.json in the current directory on your local computer. You create an IAM role and attach the policy to it later.

Important

In the permissions policy, you specify the AWS KMS key IDs that will be used for encryption of source and destination buckets. You must create two separate KMS keys for the source and destination buckets. AWS KMS keys are never shared outside the AWS Region in which they were created.


{
   "Version":"2012-10-17",
   "Statement":[
      {
         "Action":[
            "s3:ListBucket",
            "s3:GetReplicationConfiguration",
            "s3:GetObjectVersionForReplication",
            "s3:GetObjectVersionAcl",
            "s3:GetObjectVersionTagging"
         ],
         "Effect":"Allow",
         "Resource":[
            "arn:aws:s3:::source",
            "arn:aws:s3:::source/*"
         ]
      },
      {
         "Action":[
            "s3:ReplicateObject",
            "s3:ReplicateDelete",
            "s3:ReplicateTags"
         ],
         "Effect":"Allow",
         "Condition":{
            "StringLikeIfExists":{
               "s3:x-amz-server-side-encryption":[
                  "aws:kms",
                  "AES256"
               ],
               "s3:x-amz-server-side-encryption-aws-kms-key-id":[
                  "AWS KMS key IDs(in ARN format) to use for encrypting object replicas"  
               ]
            }
         },
         "Resource":"arn:aws:s3:::destination/*"
      },
      {
         "Action":[
            "kms:Decrypt"
         ],
         "Effect":"Allow",
         "Condition":{
            "StringLike":{
               "kms:ViaService":"s3.us-east-1.amazonaws.com",
               "kms:EncryptionContext:aws:s3:arn":[
                  "arn:aws:s3:::source/*"
               ]
            }
         },
         "Resource":[
            "AWS KMS key IDs(in ARN format) used to encrypt source objects." 
         ]
      },
      {
         "Action":[
            "kms:Encrypt"
         ],
         "Effect":"Allow",
         "Condition":{
            "StringLike":{
               "kms:ViaService":"s3.us-west-2.amazonaws.com",
               "kms:EncryptionContext:aws:s3:arn":[
                  "arn:aws:s3:::destination/*"
               ]
            }
         },
         "Resource":[
            "AWS KMS key IDs(in ARN format) to use for encrypting object replicas" 
         ]
      }
   ]
}

Create a policy and attach it to the role.


$ aws iam put-role-policy \
--role-name replicationRolekmsobj \
--policy-document file://s3-role-permissions-policykmsobj.json \
--policy-name replicationRolechangeownerPolicy \
--profile acctA

Add the following replication configuration to the source bucket. It tells Amazon S3 to replicate objects with the Tax/ prefix to the destination bucket.

Important

In the replication configuration you specify the IAM role that Amazon S3 can assume. You can do this only if you have the iam:PassRole permission. The profile you specify in the CLI command must have the permission. For more information, see Granting a User Permissions to Pass a Role to an AWS Service in the IAM User Guide.


 <ReplicationConfiguration>
  <Role>IAM-Role-ARN</Role>
  <Rule>
    <Priority>1</Priority>
    <DeleteMarkerReplication>
       <Status>Disabled</Status>
    </DeleteMarkerReplication>
    <Filter>
       <Prefix>Tax</Prefix>
    </Filter>
    <Status>Enabled</Status>
    <SourceSelectionCriteria>
      <SseKmsEncryptedObjects>
        <Status>Enabled</Status>
      </SseKmsEncryptedObjects>
    </SourceSelectionCriteria>
    <Destination>
      <Bucket>arn:aws:s3:::dest-bucket-name</Bucket>
      <EncryptionConfiguration>
        <ReplicaKmsKeyID>AWS KMS key IDs to use for encrypting object replicas</ReplicaKmsKeyID>
      </EncryptionConfiguration>
    </Destination>
  </Rule>
</ReplicationConfiguration>

To add replication configuration to the source bucket, do the following:

The AWS CLI requires you to specify the replication configuration as JSON. Save the following JSON in a file (replication.json) in the current directory on your local computer.


{
   "Role":"IAM-Role-ARN",
   "Rules":[
      {
         "Status":"Enabled",
         "Priority":1,
         "DeleteMarkerReplication":{
            "Status":"Disabled"
         },
         "Filter":{
            "Prefix":"Tax"
         },
         "Destination":{
            "Bucket":"arn:aws:s3:::destination",
            "EncryptionConfiguration":{
               "ReplicaKmsKeyID":"AWS KMS key IDs(in ARN format)  to use for encrypting object replicas"
            }
         },
         "SourceSelectionCriteria":{
            "SseKmsEncryptedObjects":{
               "Status":"Enabled"
            }
         }
      }
   ]
}

Edit the JSON to provide values for the destination bucket, KMS ID ARN and IAM-role-ARN. Save the changes.

Add the replication configuration to your source bucket. Be sure to provide the source bucket name.


$ aws s3api put-bucket-replication \
--replication-configuration file://replication.json \
--bucket source \
--profile acctA

Test the setup to verify that encrypted objects are replicated. In the Amazon S3 console:
1. Sign in to the AWS Management Console and open the Amazon S3 console at https://console.aws.amazon.com/s3/.
2. In the source bucket, create a folder named Tax.
3. Add sample objects to the folder. Be sure to choose the encryption option and specify your KMS key to encrypt the objects.
4. Verify that the destination bucket contains the object replicas and that they are encrypted using the KMS key that you specified in the configuration.

For a code example to add replication configuration, see Using the AWS SDKs. You need to modify the replication configuration appropriately.

For conceptual information, see Replicating objects created with server-side encryption (SSE-C, SSE-S3, SSE-KMS).

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Document Conventions

Changing replica owner

Using S3 Replication Time Control