Using customer-managed encryption keys

Go to concepts

This page describes how to use a Cloud Key Management Service encryption key with Cloud Storage, including setting default keys on buckets and adding keys to individual objects. The Cloud KMS encryption key is a customer-managed encryption key, which is created by Cloud KMS and managed by you.

For more general information about Cloud KMS, see Cloud KMS.

Prerequisites

Before using this feature in Cloud Storage, you should:

Enable the Cloud KMS API for the project that will store your encryption keys.

Enable the API
Have sufficient permission on the project that will store your encryption keys:
- If you own the project that will store your keys, you most likely have the necessary permission.
- If you plan to create new encryption key rings and keys, you should have cloudkms.keyRings.create and cloudkms.cryptoKey.create permission.
- Whether you plan to use new or existing key rings and keys, you should have cloudkms.cryptoKey.setIamPolicy permission for the keys that you will use for encryption.
  
  This permission allows you to give Cloud Storage service agents access to Cloud KMS keys.
- The above permissions are contained in the Cloud KMS Admin role.
  
  See Using IAM with Cloud KMS for instructions on how to get this or other Cloud KMS roles.
Have sufficient permission to work with objects in your Cloud Storage bucket:
- If you own the project that contains the bucket, you most likely have the necessary permission.
- If you use IAM, you should have storage.objects.create permission to write objects to the bucket and storage.objects.get permission to read objects from the bucket. See Using IAM Permissions for instructions on how to get a role, such as Storage Object Admin that has these permissions.
- If you use ACLs, you should have bucket-scoped WRITER permission to write objects to the bucket and object-scoped READER permission to read objects from the bucket. See Setting ACLs for instructions on how to do this.
Have a Cloud KMS key ring, and have at least one key within the key ring.

Note: You must create the Cloud KMS key in the same location as the data you intend to encrypt. For available Cloud KMS locations, see Cloud KMS locations.
Note: The following step is not necessary if you are using the gsutil tool.

Get the email address of the service agent associated with the project that contains your Cloud Storage bucket.

Assigning a Cloud KMS key to a service agent

In order to use customer-managed encryption keys, give your Cloud Storage service agent permission to use your Cloud KMS key:

Console

Open the Cloud Key Management Service Keys browser in the Google Cloud Console.
Open the Cloud KMS Keys browser
Click on the name of the key ring that contains the desired key.
Select the checkbox for the desired key.

The Permissions tab in the right window pane becomes available.
In the Add members dialog, specify the email address of the Cloud Storage service agent you are granting access.
In the Select a role drop down, select Cloud KMS CryptoKey Encrypter/Decrypter.
Click Add.

To learn how to get detailed error information about failed operations in the Cloud Storage browser, see Troubleshooting.

gsutil

Use the gsutil kms authorize command to give the service agent associated with your bucket permission to encrypt and decrypt objects using your Cloud KMS key:

gsutil kms authorize -p PROJECT_STORING_OBJECTS -k KEY_RESOURCE

Where:

PROJECT_STORING_OBJECTS is the ID for the project containing the objects you want to encrypt or decrypt. For example, my-pet-project.
KEY_RESOURCE is your Cloud KMS key resource. For example, projects/my-pet-project/locations/us-east1/keyRings/my-key-ring/cryptoKeys/my-key.

If you want to remove the granted permission, you need to use either the gcloud command-line tool or the Google Cloud Console.

Code samples

C#

For more information, see the Cloud Storage C# API reference documentation.

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using Google.Cloud.Iam.V1;
using Google.Cloud.Kms.V1;

public class IamAddMemberSample
{
    public Policy IamAddMember(
      string projectId = "my-project", string locationId = "us-east1", string keyRingId = "my-key-ring", string keyId = "my-key",
      string member = "user:foo@example.com")
    {
        // Create the client.
        KeyManagementServiceClient client = KeyManagementServiceClient.Create();

        // Build the resource name.
        CryptoKeyName resourceName = new CryptoKeyName(projectId, locationId, keyRingId, keyId);

        // The resource name could also be a key ring.
        // var resourceName = new KeyRingName(projectId, locationId, keyRingId);

        // Get the current IAM policy.
        Policy policy = client.GetIamPolicy(resourceName);

        // Add the member to the policy.
        policy.AddRoleMember("roles/cloudkms.cryptoKeyEncrypterDecrypter", member);

        // Save the updated IAM policy.
        Policy result = client.SetIamPolicy(resourceName, policy);

        // Return the resulting policy.
        return result;
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

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import (
	"context"
	"fmt"
	"io"

	kms "cloud.google.com/go/kms/apiv1"
)

// iamAddMember adds a new IAM member to the Cloud KMS key
func iamAddMember(w io.Writer, name, member string) error {
	// NOTE: The resource name can be either a key or a key ring. If IAM
	// permissions are granted on the key ring, the permissions apply to all keys
	// in the key ring.
	//
	// name := "projects/my-project/locations/us-east1/keyRings/my-key-ring/cryptoKeys/my-key"
	// member := "user:foo@example.com"

	// Create the client.
	ctx := context.Background()
	client, err := kms.NewKeyManagementClient(ctx)
	if err != nil {
		return fmt.Errorf("failed to create kms client: %v", err)
	}

	// Get the current IAM policy.
	handle := client.ResourceIAM(name)
	policy, err := handle.Policy(ctx)
	if err != nil {
		return fmt.Errorf("failed to get IAM policy: %v", err)
	}

	// Grant the member permissions. This example grants permission to use the key
	// to encrypt data.
	policy.Add(member, "roles/cloudkms.cryptoKeyEncrypterDecrypter")
	if err := handle.SetPolicy(ctx, policy); err != nil {
		return fmt.Errorf("failed to save policy: %v", err)
	}

	fmt.Fprintf(w, "Updated IAM policy for %s\n", name)
	return nil
}

Java

For more information, see the Cloud Storage Java API reference documentation.

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import com.google.cloud.kms.v1.CryptoKeyName;
import com.google.cloud.kms.v1.KeyManagementServiceClient;
import com.google.iam.v1.Binding;
import com.google.iam.v1.Policy;
import java.io.IOException;

public class IamAddMember {

  public void iamAddMember() throws IOException {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    String locationId = "us-east1";
    String keyRingId = "my-key-ring";
    String keyId = "my-key";
    String member = "user:foo@example.com";
    iamAddMember(projectId, locationId, keyRingId, keyId, member);
  }

  // Add the given IAM member to the key.
  public void iamAddMember(
      String projectId, String locationId, String keyRingId, String keyId, String member)
      throws IOException {
    // Initialize client that will be used to send requests. This client only
    // needs to be created once, and can be reused for multiple requests. After
    // completing all of your requests, call the "close" method on the client to
    // safely clean up any remaining background resources.
    try (KeyManagementServiceClient client = KeyManagementServiceClient.create()) {
      // Build the key version name from the project, location, key ring, key,
      // and key version.
      CryptoKeyName resourceName = CryptoKeyName.of(projectId, locationId, keyRingId, keyId);

      // The resource name could also be a key ring.
      // KeyRingName resourceName = KeyRingName.of(projectId, locationId, keyRingId);

      // Get the current policy.
      Policy policy = client.getIamPolicy(resourceName);

      // Create a new IAM binding for the member and role.
      Binding binding =
          Binding.newBuilder()
              .setRole("roles/cloudkms.cryptoKeyEncrypterDecrypter")
              .addMembers(member)
              .build();

      // Add the binding to the policy.
      Policy newPolicy = policy.toBuilder().addBindings(binding).build();

      client.setIamPolicy(resourceName, newPolicy);
      System.out.printf("Updated IAM policy for %s%n", resourceName.toString());
    }
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

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//
// TODO(developer): Uncomment these variables before running the sample.
//
// const projectId = 'my-project';
// const locationId = 'us-east1';
// const keyRingId = 'my-key-ring';
// const keyId = 'my-key';
// const member = 'user:foo@example.com';

// Imports the Cloud KMS library
const {KeyManagementServiceClient} = require('@google-cloud/kms');

// Instantiates a client
const client = new KeyManagementServiceClient();

// Build the resource name
const resourceName = client.cryptoKeyPath(
  projectId,
  locationId,
  keyRingId,
  keyId
);

// The resource name could also be a key ring.
// const resourceName = client.keyRingPath(projectId, locationId, keyRingId);

async function iamAddMember() {
  // Get the current IAM policy.
  const [policy] = await client.getIamPolicy({
    resource: resourceName,
  });

  // Add the member to the policy.
  policy.bindings.push({
    role: 'roles/cloudkms.cryptoKeyEncrypterDecrypter',
    members: [member],
  });

  // Save the updated policy.
  const [updatedPolicy] = await client.setIamPolicy({
    resource: resourceName,
    policy: policy,
  });

  console.log('Updated policy');
  return updatedPolicy;
}

return iamAddMember();

PHP

For more information, see the Cloud Storage PHP API reference documentation.

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use Google\Cloud\Iam\V1\Binding;
use Google\Cloud\Kms\V1\KeyManagementServiceClient;

function iam_add_member_sample(
    string $projectId = 'my-project',
    string $locationId = 'us-east1',
    string $keyRingId = 'my-key-ring',
    string $keyId = 'my-key',
    string $member = 'user:foo@example.com'
) {
    // Create the Cloud KMS client.
    $client = new KeyManagementServiceClient();

    // Build the resource name.
    $resourceName = $client->cryptoKeyName($projectId, $locationId, $keyRingId, $keyId);

    // The resource name could also be a key ring.
    // $resourceName = $client->keyRingName($projectId, $locationId, $keyRingId);

    // Get the current IAM policy.
    $policy = $client->getIamPolicy($resourceName);

    // Add the member to the policy.
    $bindings = $policy->getBindings();
    $bindings[] = (new Binding())
        ->setRole('roles/cloudkms.cryptoKeyEncrypterDecrypter')
        ->setMembers([$member]);
    $policy->setBindings($bindings);

    // Save the updated IAM policy.
    $updatedPolicy = $client->setIamPolicy($resourceName, $policy);
    printf('Added %s' . PHP_EOL, $member);
    return $updatedPolicy;
}

Python

For more information, see the Cloud Storage Python API reference documentation.

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def iam_add_member(project_id, location_id, key_ring_id, key_id, member):
    """
    Add an IAM member to a resource.

    Args:
        project_id (string): Google Cloud project ID (e.g. 'my-project').
        location_id (string): Cloud KMS location (e.g. 'us-east1').
        key_ring_id (string): ID of the Cloud KMS key ring (e.g. 'my-key-ring').
        key_id (string): ID of the key to use (e.g. 'my-key').
        member (string): Member to add (e.g. 'user:foo@example.com')

    Returns:
        Policy: Updated Cloud IAM policy.

    """

    # Import the client library.
    from google.cloud import kms

    # Create the client.
    client = kms.KeyManagementServiceClient()

    # Build the resource name.
    resource_name = client.crypto_key_path(project_id, location_id, key_ring_id, key_id)

    # The resource name could also be a key ring.
    # resource_name = client.key_ring_path(project_id, location_id, key_ring_id);

    # Get the current policy.
    policy = client.get_iam_policy(request={'resource': resource_name})

    # Add the member to the policy.
    policy.bindings.add(
        role='roles/cloudkms.cryptoKeyEncrypterDecrypter',
        members=[member])

    # Save the updated IAM policy.
    request = {
        'resource': resource_name,
        'policy': policy
    }

    updated_policy = client.set_iam_policy(request=request)
    print('Added {} to {}'.format(member, resource_name))
    return updated_policy

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

View on GitHub Feedback

# TODO(developer): uncomment these values before running the sample.
# project_id  = "my-project"
# location_id = "us-east1"
# key_ring_id = "my-key-ring"
# key_id      = "my-key"
# member      = "user:foo@example.com"

# Require the library.
require "google/cloud/kms"

# Create the client.
client = Google::Cloud::Kms.key_management_service

# Build the resource name.
resource_name = client.crypto_key_path project:    project_id,
                                       location:   location_id,
                                       key_ring:   key_ring_id,
                                       crypto_key: key_id

# The resource name could also be a key ring.
# resource_name = client.key_ring_path project: project_id, location: location_id, key_ring: key_ring_id

# Create the IAM client.
iam_client = Google::Cloud::Kms::V1::IAMPolicy::Client.new

# Get the current IAM policy.
policy = iam_client.get_iam_policy resource: resource_name

# Add the member to the policy.
policy.bindings << Google::Iam::V1::Binding.new(
  members: [member],
  role:    "roles/cloudkms.cryptoKeyEncrypterDecrypter"
)

# Save the updated policy.
updated_policy = iam_client.set_iam_policy resource: resource_name, policy: policy
puts "Added #{member}"

REST APIs

JSON API

Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.
Create a .json file that contains the following information:
```
{
  "policy": {
    "bindings": {
      "role": "roles/cloudkms.cryptoKeyEncrypterDecrypter",
      "members": "SERVICE_AGENT_EMAIL_ADDRESS"
    },
  }
}
```
Where SERVICE_AGENT_EMAIL_ADDRESS is the email address associated with your service agent. For example, service-7550275089395@gs-project-accounts.iam.gserviceaccount.com.
Use cURL to call the Cloud KMS API with a POST setIamPolicy request:
```
curl -X POST --data-binary @JSON_FILE_NAME.json \
-H "Authorization: Bearer OAUTH2_TOKEN" \
-H "Content-Type: application/json" \
"https://cloudkms.googleapis.com/v1/KEY_RESOURCE:setIamPolicy"
```
Where:
- JSON_FILE_NAME is the name of the file you created in Step 2.
- OAUTH2_TOKEN is the access token you generated in Step 1.
- KEY_RESOURCE is your Cloud KMS key resource. For example, projects/my-pet-project/locations/us-east1/keyRings/my-key-ring/cryptoKeys/my-key.

XML API

The XML API cannot be used to assign a Cloud KMS to a service agent. Use one of the other Cloud Storage tools, such as gsutil, instead.

Using default encryption keys

Adding or changing the default key for a bucket

To add or change the Cloud KMS key that is used by default when objects are written to a bucket:

Console

In the Google Cloud Console, go to the Cloud Storage Browser page.

Go to Browser
In the list of buckets, click on the desired bucket.
In the bucket details page, click on the Configuration tab.
Click on the Pencil icon associated with the Encryption type entry.
If the bucket isn't currently using a Cloud KMS key, select the Customer-managed key radio button.
In the drop-down menu associated with customer-managed keys, select one of the available keys.
Click Save.

To learn how to get detailed error information about failed operations in the Cloud Storage browser, see Troubleshooting.

gsutil

Use the gsutil kms encryption command:

gsutil kms encryption -k KEY_RESOURCE gs://BUCKET_NAME

Where:

KEY_RESOURCE is your Cloud KMS key resource. For example, projects/my-pet-project/locations/us-east1/keyRings/my-key-ring/cryptoKeys/my-key.
BUCKET_NAME is the name of the relevant bucket. For example, my-bucket.

If successful, the response looks like:

Setting default KMS key for bucket gs://my-bucket...

Code samples

C++

For more information, see the Cloud Storage C++ API reference documentation.

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namespace gcs = google::cloud::storage;
using ::google::cloud::StatusOr;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& key_name) {
  StatusOr<gcs::BucketMetadata> updated = client.PatchBucket(
      bucket_name, gcs::BucketMetadataPatchBuilder().SetEncryption(
                       gcs::BucketEncryption{key_name}));
  if (!updated) throw std::runtime_error(updated.status().message());

  if (!updated->has_encryption()) {
    std::cerr << "The change to set the encryption attribute on bucket "
              << updated->name()
              << " was sucessful, but the encryption is not set."
              << "This is unexpected, maybe a concurrent change?\n";
    return;
  }

  std::cout << "Successfully set default KMS key on bucket "
            << updated->name() << " to "
            << updated->encryption().default_kms_key_name << "."
            << "\nFull metadata: " << *updated << "\n";
}

C#

For more information, see the Cloud Storage C# API reference documentation.

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using Google.Apis.Storage.v1.Data;
using Google.Cloud.Storage.V1;
using System;

public class EnableDefaultKMSKeySample
{
    public Bucket EnableDefaultKMSKey(
        string projectId = "your-project-id",
        string bucketName = "your-unique-bucket-name",
        string keyLocation = "us-west1",
        string kmsKeyRing = "kms-key-ring",
        string kmsKeyName = "key-name")
    {
        // KMS Key identifier of an already created KMS key.
        // If you use the Google.Cloud.Kms.V1 library, you can construct these names using helper class CryptoKeyName.
        // var fullKeyName = new CryptoKeyName(projectId, keyLocation, kmsKeyRing, kmsKeyName).ToString();
        string keyPrefix = $"projects/{projectId}/locations/{keyLocation}";
        string fullKeyringName = $"{keyPrefix}/keyRings/{kmsKeyRing}";
        string fullKeyName = $"{fullKeyringName}/cryptoKeys/{kmsKeyName}";
        var storage = StorageClient.Create();
        var bucket = storage.GetBucket(bucketName, new GetBucketOptions { Projection = Projection.Full });
        bucket.Encryption = new Bucket.EncryptionData { DefaultKmsKeyName = fullKeyName };
        var updatedBucket = storage.UpdateBucket(bucket);
        Console.WriteLine($"Default KMS key for {bucketName} was set to {kmsKeyName}.");
        return updatedBucket;
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

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import (
	"context"
	"fmt"
	"io"
	"time"

	"cloud.google.com/go/storage"
)

// setBucketDefaultKMSKey sets the Cloud KMS encryption key for the bucket.
func setBucketDefaultKMSKey(w io.Writer, bucketName, keyName string) error {
	// bucketName := "bucket-name"
	// keyName := "key"
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %v", err)
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
	defer cancel()

	bucket := client.Bucket(bucketName)
	bucketAttrsToUpdate := storage.BucketAttrsToUpdate{
		Encryption: &storage.BucketEncryption{DefaultKMSKeyName: keyName},
	}
	if _, err := bucket.Update(ctx, bucketAttrsToUpdate); err != nil {
		return fmt.Errorf("Bucket(%q).Update: %v", bucketName, err)
	}
	fmt.Fprintf(w, "Default KMS Key Name: %v", bucketAttrsToUpdate.Encryption.DefaultKMSKeyName)
	return nil
}

Java

For more information, see the Cloud Storage Java API reference documentation.

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// Instantiate a Google Cloud Storage client
Storage storage = StorageOptions.getDefaultInstance().getService();

// The name of the existing bucket to set a default KMS key for, e.g. "my-bucket"
// String bucketName = "my-bucket"

// The name of the KMS-key to use as a default
// Key names are provided in the following format:
// 'projects/<PROJECT>/locations/<LOCATION>/keyRings/<RING_NAME>/cryptoKeys/<KEY_NAME>'
// String kmsKeyName = ""

BucketInfo bucketInfo =
    BucketInfo.newBuilder(bucketName).setDefaultKmsKeyName(kmsKeyName).build();

Bucket bucket = storage.update(bucketInfo);

System.out.println("Default KMS Key Name: " + bucket.getDefaultKmsKeyName());

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

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/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The name of the KMS-key to use as a default
// const defaultKmsKeyName = 'my-key';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function enableDefaultKMSKey() {
  await storage.bucket(bucketName).setMetadata({
    encryption: {
      defaultKmsKeyName,
    },
  });

  console.log(
    `Default KMS key for ${bucketName} was set to ${defaultKmsKeyName}.`
  );
}

enableDefaultKMSKey().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

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use Google\Cloud\Storage\StorageClient;

/**
 * Enable a bucket's requesterpays metadata.
 *
 * @param string $projectId Your Google Cloud project ID.
 * @param string $bucketName Name of your Google Cloud Storage bucket.
 * @param string $kmsKeyName KMS key ID to use as the default KMS key.
 *
 * @return void
 */
function enable_default_kms_key($projectId, $bucketName, $kmsKeyName)
{
    $storage = new StorageClient([
        'projectId' => $projectId
    ]);
    $bucket = $storage->bucket($bucketName);
    $bucket->update([
        'encryption' => [
            'defaultKmsKeyName' => $kmsKeyName
        ]
    ]);
    printf('Default KMS key for %s was set to %s' . PHP_EOL,
        $bucketName,
        $bucket->info()['encryption']['defaultKmsKeyName']);
}

Python

For more information, see the Cloud Storage Python API reference documentation.

View on GitHub Feedback

from google.cloud import storage


def enable_default_kms_key(bucket_name, kms_key_name):
    """Sets a bucket's default KMS key."""
    # bucket_name = "your-bucket-name"
    # kms_key_name = "projects/PROJ/locations/LOC/keyRings/RING/cryptoKey/KEY"

    storage_client = storage.Client()
    bucket = storage_client.get_bucket(bucket_name)
    bucket.default_kms_key_name = kms_key_name
    bucket.patch()

    print(
        "Set default KMS key for bucket {} to {}.".format(
            bucket.name, bucket.default_kms_key_name
        )
    )

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

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def set_bucket_default_kms_key bucket_name:, default_kms_key:
  # The ID of your GCS bucket
  # bucket_name = "your-unique-bucket-name"

  # The name of the KMS key to manage this object with
  # default_kms_key = "projects/your-project-id/locations/global/keyRings/your-key-ring/cryptoKeys/your-key"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new
  bucket  = storage.bucket bucket_name

  bucket.default_kms_key = default_kms_key

  puts "Default KMS key for #{bucket.name} was set to #{bucket.default_kms_key}"
end

REST APIs

JSON API

Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.
Create a .json file that contains the following information:
```
{
  "encryption": {
    "defaultKmsKeyName": "KEY_RESOURCE"
  }
}
```
Where KEY_RESOURCE is your Cloud KMS key resource. For example, projects/my-pet-project/locations/us-east1/keyRings/my-key-ring/cryptoKeys/my-key.
Use cURL to call the JSON API with a PATCH Bucket request:
```
curl -X PATCH --data-binary @JSON_FILE_NAME.json \
-H "Authorization: Bearer OAUTH2_TOKEN" \
-H "Content-Type: application/json" \
"https://storage.googleapis.com/storage/v1/b/BUCKET_NAME?fields=encryption"
```
Where:
- JSON_FILE_NAME is the file you created in Step 2.
- OAUTH2_TOKEN is the access token you generated in Step 1.
- BUCKET_NAME is the name of the relevant bucket. For example, my-bucket.

XML API

Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.
Create a .xml file that contains the following information:
```
<EncryptionConfiguration>
  <DefaultKmsKeyName>KEY_RESOURCE</DefaultKmsKeyName>
</EncryptionConfiguration>
```
Where KEY_RESOURCE is your Cloud KMS key resource. For example, projects/my-pet-project/locations/us-east1/keyRings/my-key-ring/cryptoKeys/my-key.
Use cURL to call the XML API with a PUT Bucket request and encryption query string paratmeter:
```
curl -X PUT --data-binary @XML_FILE_NAME.xml \
-H "Authorization: Bearer OAUTH2_TOKEN" \
"https://storage.googleapis.com/BUCKET_NAME?encryptionConfig"
```
Where:
- XML_FILE_NAME is the file you created in Step 2.
- OAUTH2_TOKEN is the access token you generated in Step 1.
- BUCKET_NAME is the name of the relevant bucket. For example, my-bucket.

Viewing the default key for a bucket

To view the Cloud KMS key that is currently set as default for your bucket:

Console

In the Google Cloud Console, go to the Cloud Storage Browser page.

Go to Browser
In the list of buckets, click on the desired bucket.
In the bucket details page, click on the Configuration tab.
The current default key for your bucket appears in the Encryption key field.

To learn how to get detailed error information about failed operations in the Cloud Storage browser, see Troubleshooting.

gsutil

Use the gsutil kms encryption command:

gsutil kms encryption gs://BUCKET_NAME

Where BUCKET_NAME is the name of the bucket whose key you want to view. For example, my-bucket.

If successful, the response looks like:

Default encryption key for gs://my-bucket:
KEY_RESOURCE

Code samples

C++

For more information, see the Cloud Storage C++ API reference documentation.

View on GitHub Feedback

namespace gcs = google::cloud::storage;
using ::google::cloud::StatusOr;
[](gcs::Client client, std::string const& bucket_name) {
  StatusOr<gcs::BucketMetadata> metadata =
      client.GetBucketMetadata(bucket_name);
  if (!metadata) throw std::runtime_error(metadata.status().message());

  if (!metadata->has_encryption()) {
    std::cout << "The bucket " << metadata->name()
              << " does not have a default KMS key set.\n";
    return;
  }

  std::cout << "The default KMS key for bucket " << metadata->name()
            << " is: " << metadata->encryption().default_kms_key_name << "\n";
}