Cloud HSM

using Google.Cloud.Kms.V1;
using Google.Protobuf.WellKnownTypes;

public class CreateKeyHsmSample
{
    public CryptoKey CreateKeyHsm(
      string projectId = "my-project", string locationId = "us-east1", string keyRingId = "my-key-ring",
      string id = "my-hsm-encryption-key")
    {
        // Create the client.
        KeyManagementServiceClient client = KeyManagementServiceClient.Create();

        // Build the parent key ring name.
        KeyRingName keyRingName = new KeyRingName(projectId, locationId, keyRingId);

        // Build the key.
        CryptoKey key = new CryptoKey
        {
            Purpose = CryptoKey.Types.CryptoKeyPurpose.EncryptDecrypt,
            VersionTemplate = new CryptoKeyVersionTemplate
            {
                ProtectionLevel = ProtectionLevel.Hsm,
                Algorithm = CryptoKeyVersion.Types.CryptoKeyVersionAlgorithm.GoogleSymmetricEncryption,
            },

            // Optional: customize how long key versions should be kept before destroying.
            DestroyScheduledDuration = new Duration
            {
                Seconds = 24 * 60 * 60,
            }
        };

        // Call the API.
        CryptoKey result = client.CreateCryptoKey(keyRingName, id, key);

        // Return the result.
        return result;
    }
}

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

	kms "cloud.google.com/go/kms/apiv1"
	"cloud.google.com/go/kms/apiv1/kmspb"
	"google.golang.org/protobuf/types/known/durationpb"
)

// createKeyHSM creates a new symmetric encrypt/decrypt key on Cloud KMS.
func createKeyHSM(w io.Writer, parent, id string) error {
	// parent := "projects/my-project/locations/us-east1/keyRings/my-key-ring"
	// id := "my-hsm-encryption-key"

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

	// Build the request.
	req := &kmspb.CreateCryptoKeyRequest{
		Parent:      parent,
		CryptoKeyId: id,
		CryptoKey: &kmspb.CryptoKey{
			Purpose: kmspb.CryptoKey_ENCRYPT_DECRYPT,
			VersionTemplate: &kmspb.CryptoKeyVersionTemplate{
				ProtectionLevel: kmspb.ProtectionLevel_HSM,
				Algorithm:       kmspb.CryptoKeyVersion_GOOGLE_SYMMETRIC_ENCRYPTION,
			},

			// Optional: customize how long key versions should be kept before destroying.
			DestroyScheduledDuration: durationpb.New(24 * time.Hour),
		},
	}

	// Call the API.
	result, err := client.CreateCryptoKey(ctx, req)
	if err != nil {
		return fmt.Errorf("failed to create key: %w", err)
	}
	fmt.Fprintf(w, "Created key: %s\n", result.Name)
	return nil
}

import com.google.cloud.kms.v1.CryptoKey;
import com.google.cloud.kms.v1.CryptoKey.CryptoKeyPurpose;
import com.google.cloud.kms.v1.CryptoKeyVersion.CryptoKeyVersionAlgorithm;
import com.google.cloud.kms.v1.CryptoKeyVersionTemplate;
import com.google.cloud.kms.v1.KeyManagementServiceClient;
import com.google.cloud.kms.v1.KeyRingName;
import com.google.cloud.kms.v1.ProtectionLevel;
import com.google.protobuf.Duration;
import java.io.IOException;

public class CreateKeyHsm {

  public void createKeyHsm() 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 id = "my-hsm-key";
    createKeyHsm(projectId, locationId, keyRingId, id);
  }

  // Create a new key that is stored in an HSM.
  public void createKeyHsm(String projectId, String locationId, String keyRingId, String id)
      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 parent name from the project, location, and key ring.
      KeyRingName keyRingName = KeyRingName.of(projectId, locationId, keyRingId);

      // Build the hsm key to create.
      CryptoKey key =
          CryptoKey.newBuilder()
              .setPurpose(CryptoKeyPurpose.ENCRYPT_DECRYPT)
              .setVersionTemplate(
                  CryptoKeyVersionTemplate.newBuilder()
                      .setProtectionLevel(ProtectionLevel.HSM)
                      .setAlgorithm(CryptoKeyVersionAlgorithm.GOOGLE_SYMMETRIC_ENCRYPTION))

              // Optional: customize how long key versions should be kept before destroying.
              .setDestroyScheduledDuration(Duration.newBuilder().setSeconds(24 * 60 * 60))
              .build();

      // Create the key.
      CryptoKey createdKey = client.createCryptoKey(keyRingName, id, key);
      System.out.printf("Created hsm key %s%n", createdKey.getName());
    }
  }
}

//
// TODO(developer): Uncomment these variables before running the sample.
//
// const projectId = 'my-project';
// const locationId = 'us-east1';
// const keyRingId = 'my-key-ring';
// const id = 'my-hsm-encryption-key';

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

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

// Build the parent key ring name
const keyRingName = client.keyRingPath(projectId, locationId, keyRingId);

async function createKeyHsm() {
  const [key] = await client.createCryptoKey({
    parent: keyRingName,
    cryptoKeyId: id,
    cryptoKey: {
      purpose: 'ENCRYPT_DECRYPT',
      versionTemplate: {
        algorithm: 'GOOGLE_SYMMETRIC_ENCRYPTION',
        protectionLevel: 'HSM',
      },

      // Optional: customize how long key versions should be kept before
      // destroying.
      destroyScheduledDuration: {seconds: 60 * 60 * 24},
    },
  });

  console.log(`Created hsm key: ${key.name}`);
  return key;
}

return createKeyHsm();

use Google\Cloud\Kms\V1\Client\KeyManagementServiceClient;
use Google\Cloud\Kms\V1\CreateCryptoKeyRequest;
use Google\Cloud\Kms\V1\CryptoKey;
use Google\Cloud\Kms\V1\CryptoKey\CryptoKeyPurpose;
use Google\Cloud\Kms\V1\CryptoKeyVersion\CryptoKeyVersionAlgorithm;
use Google\Cloud\Kms\V1\CryptoKeyVersionTemplate;
use Google\Cloud\Kms\V1\ProtectionLevel;
use Google\Protobuf\Duration;

function create_key_hsm(
    string $projectId = 'my-project',
    string $locationId = 'us-east1',
    string $keyRingId = 'my-key-ring',
    string $id = 'my-hsm-key'
): CryptoKey {
    // Create the Cloud KMS client.
    $client = new KeyManagementServiceClient();

    // Build the parent key ring name.
    $keyRingName = $client->keyRingName($projectId, $locationId, $keyRingId);

    // Build the key.
    $key = (new CryptoKey())
        ->setPurpose(CryptoKeyPurpose::ENCRYPT_DECRYPT)
        ->setVersionTemplate((new CryptoKeyVersionTemplate())
            ->setAlgorithm(CryptoKeyVersionAlgorithm::GOOGLE_SYMMETRIC_ENCRYPTION)
            ->setProtectionLevel(ProtectionLevel::HSM)
        )

        // Optional: customize how long key versions should be kept before destroying.
        ->setDestroyScheduledDuration((new Duration())
            ->setSeconds(24 * 60 * 60)
        );

    // Call the API.
    $createCryptoKeyRequest = (new CreateCryptoKeyRequest())
        ->setParent($keyRingName)
        ->setCryptoKeyId($id)
        ->setCryptoKey($key);
    $createdKey = $client->createCryptoKey($createCryptoKeyRequest);
    printf('Created hsm key: %s' . PHP_EOL, $createdKey->getName());

    return $createdKey;
}

import datetime

from google.cloud import kms
from google.protobuf import duration_pb2  # type: ignore


def create_key_hsm(
    project_id: str, location_id: str, key_ring_id: str, key_id: str
) -> kms.CryptoKey:
    """
    Creates a new key in Cloud KMS backed by Cloud HSM.

    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 create (e.g. 'my-hsm-key').

    Returns:
        CryptoKey: Cloud KMS key.

    """

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

    # Build the parent key ring name.
    key_ring_name = client.key_ring_path(project_id, location_id, key_ring_id)

    # Build the key.
    purpose = kms.CryptoKey.CryptoKeyPurpose.ENCRYPT_DECRYPT
    algorithm = (
        kms.CryptoKeyVersion.CryptoKeyVersionAlgorithm.GOOGLE_SYMMETRIC_ENCRYPTION
    )
    protection_level = kms.ProtectionLevel.HSM
    key = {
        "purpose": purpose,
        "version_template": {
            "algorithm": algorithm,
            "protection_level": protection_level,
        },
        # Optional: customize how long key versions should be kept before
        # destroying.
        "destroy_scheduled_duration": duration_pb2.Duration().FromTimedelta(
            datetime.timedelta(days=1)
        ),
    }

    # Call the API.
    created_key = client.create_crypto_key(
        request={"parent": key_ring_name, "crypto_key_id": key_id, "crypto_key": key}
    )
    print(f"Created hsm key: {created_key.name}")
    return created_key

# TODO(developer): uncomment these values before running the sample.
# project_id  = "my-project"
# location_id = "us-east1"
# key_ring_id = "my-key-ring"
# id          = "my-hsm-key"

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

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

# Build the parent key ring name.
key_ring_name = client.key_ring_path project: project_id, location: location_id, key_ring: key_ring_id

# Build the key.
key = {
  purpose:          :ENCRYPT_DECRYPT,
  version_template: {
    algorithm:        :GOOGLE_SYMMETRIC_ENCRYPTION,
    protection_level: :HSM
  },

  # Optional: customize how long key versions should be kept before destroying.
  destroy_scheduled_duration: {
    seconds: 24 * 60 * 60
  }
}

# Call the API.
created_key = client.create_crypto_key parent: key_ring_name, crypto_key_id: id, crypto_key: key
puts "Created hsm key: #{created_key.name}"

using Google.Cloud.Kms.V1;
using Google.Protobuf;
using System.Text;

public class EncryptSymmetricSample
{
    public byte[] EncryptSymmetric(
      string projectId = "my-project", string locationId = "us-east1", string keyRingId = "my-key-ring", string keyId = "my-key",
      string message = "Sample message")
    {
        // Create the client.
        KeyManagementServiceClient client = KeyManagementServiceClient.Create();

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

        // Convert the message into bytes. Cryptographic plaintexts and
        // ciphertexts are always byte arrays.
        byte[] plaintext = Encoding.UTF8.GetBytes(message);

        // Call the API.
        EncryptResponse result = client.Encrypt(keyName, ByteString.CopyFrom(plaintext));

        // Return the ciphertext.
        return result.Ciphertext.ToByteArray();
    }
}

import (
	"context"
	"fmt"
	"hash/crc32"
	"io"

	kms "cloud.google.com/go/kms/apiv1"
	"cloud.google.com/go/kms/apiv1/kmspb"
	"google.golang.org/protobuf/types/known/wrapperspb"
)

// encryptSymmetric encrypts the input plaintext with the specified symmetric
// Cloud KMS key.
func encryptSymmetric(w io.Writer, name string, message string) error {
	// name := "projects/my-project/locations/us-east1/keyRings/my-key-ring/cryptoKeys/my-key"
	// message := "Sample message"

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

	// Convert the message into bytes. Cryptographic plaintexts and
	// ciphertexts are always byte arrays.
	plaintext := []byte(message)

	// Optional but recommended: Compute plaintext's CRC32C.
	crc32c := func(data []byte) uint32 {
		t := crc32.MakeTable(crc32.Castagnoli)
		return crc32.Checksum(data, t)
	}
	plaintextCRC32C := crc32c(plaintext)

	// Build the request.
	req := &kmspb.EncryptRequest{
		Name:            name,
		Plaintext:       plaintext,
		PlaintextCrc32C: wrapperspb.Int64(int64(plaintextCRC32C)),
	}

	// Call the API.
	result, err := client.Encrypt(ctx, req)
	if err != nil {
		return fmt.Errorf("failed to encrypt: %w", err)
	}

	// Optional, but recommended: perform integrity verification on result.
	// For more details on ensuring E2E in-transit integrity to and from Cloud KMS visit:
	// https://cloud.google.com/kms/docs/data-integrity-guidelines
	if result.VerifiedPlaintextCrc32C == false {
		return fmt.Errorf("Encrypt: request corrupted in-transit")
	}
	if int64(crc32c(result.Ciphertext)) != result.CiphertextCrc32C.Value {
		return fmt.Errorf("Encrypt: response corrupted in-transit")
	}

	fmt.Fprintf(w, "Encrypted ciphertext: %s", result.Ciphertext)
	return nil
}

import com.google.cloud.kms.v1.CryptoKeyName;
import com.google.cloud.kms.v1.EncryptResponse;
import com.google.cloud.kms.v1.KeyManagementServiceClient;
import com.google.protobuf.ByteString;
import java.io.IOException;

public class EncryptSymmetric {

  public void encryptSymmetric() 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 plaintext = "Plaintext to encrypt";
    encryptSymmetric(projectId, locationId, keyRingId, keyId, plaintext);
  }

  // Encrypt data with a given key.
  public void encryptSymmetric(
      String projectId, String locationId, String keyRingId, String keyId, String plaintext)
      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 keyVersionName = CryptoKeyName.of(projectId, locationId, keyRingId, keyId);

      // Encrypt the plaintext.
      EncryptResponse response = client.encrypt(keyVersionName, ByteString.copyFromUtf8(plaintext));
      System.out.printf("Ciphertext: %s%n", response.getCiphertext().toStringUtf8());
    }
  }
}

//
// 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 plaintextBuffer = Buffer.from('...');

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

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

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

// Optional, but recommended: compute plaintext's CRC32C.
const crc32c = require('fast-crc32c');
const plaintextCrc32c = crc32c.calculate(plaintextBuffer);

async function encryptSymmetric() {
  const [encryptResponse] = await client.encrypt({
    name: keyName,
    plaintext: plaintextBuffer,
    plaintextCrc32c: {
      value: plaintextCrc32c,
    },
  });

  const ciphertext = encryptResponse.ciphertext;

  // Optional, but recommended: perform integrity verification on encryptResponse.
  // For more details on ensuring E2E in-transit integrity to and from Cloud KMS visit:
  // https://cloud.google.com/kms/docs/data-integrity-guidelines
  if (!encryptResponse.verifiedPlaintextCrc32c) {
    throw new Error('Encrypt: request corrupted in-transit');
  }
  if (
    crc32c.calculate(ciphertext) !==
    Number(encryptResponse.ciphertextCrc32c.value)
  ) {
    throw new Error('Encrypt: response corrupted in-transit');
  }

  console.log(`Ciphertext: ${ciphertext.toString('base64')}`);
  return ciphertext;
}

return encryptSymmetric();

use Google\Cloud\Kms\V1\Client\KeyManagementServiceClient;
use Google\Cloud\Kms\V1\EncryptRequest;

function encrypt_symmetric(
    string $projectId = 'my-project',
    string $locationId = 'us-east1',
    string $keyRingId = 'my-key-ring',
    string $keyId = 'my-key',
    string $plaintext = '...'
) {
    // Create the Cloud KMS client.
    $client = new KeyManagementServiceClient();

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

    // Call the API.
    $encryptRequest = (new EncryptRequest())
        ->setName($keyName)
        ->setPlaintext($plaintext);
    $encryptResponse = $client->encrypt($encryptRequest);
    printf('Ciphertext: %s' . PHP_EOL, $encryptResponse->getCiphertext());

    return $encryptResponse;
}

# Import base64 for printing the ciphertext.
import base64

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


def encrypt_symmetric(
    project_id: str, location_id: str, key_ring_id: str, key_id: str, plaintext: str
) -> bytes:
    """
    Encrypt plaintext using a symmetric key.

    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').
        plaintext (string): message to encrypt

    Returns:
        bytes: Encrypted ciphertext.

    """

    # Convert the plaintext to bytes.
    plaintext_bytes = plaintext.encode("utf-8")

    # Optional, but recommended: compute plaintext's CRC32C.
    # See crc32c() function defined below.
    plaintext_crc32c = crc32c(plaintext_bytes)

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

    # Build the key name.
    key_name = client.crypto_key_path(project_id, location_id, key_ring_id, key_id)

    # Call the API.
    encrypt_response = client.encrypt(
        request={
            "name": key_name,
            "plaintext": plaintext_bytes,
            "plaintext_crc32c": plaintext_crc32c,
        }
    )

    # Optional, but recommended: perform integrity verification on encrypt_response.
    # For more details on ensuring E2E in-transit integrity to and from Cloud KMS visit:
    # https://cloud.google.com/kms/docs/data-integrity-guidelines
    if not encrypt_response.verified_plaintext_crc32c:
        raise Exception("The request sent to the server was corrupted in-transit.")
    if not encrypt_response.ciphertext_crc32c == crc32c(encrypt_response.ciphertext):
        raise Exception(
            "The response received from the server was corrupted in-transit."
        )
    # End integrity verification

    print(f"Ciphertext: {base64.b64encode(encrypt_response.ciphertext)}")
    return encrypt_response


def crc32c(data: bytes) -> int:
    """
    Calculates the CRC32C checksum of the provided data.

    Args:
        data: the bytes over which the checksum should be calculated.

    Returns:
        An int representing the CRC32C checksum of the provided bytes.
    """
    import crcmod  # type: ignore

    crc32c_fun = crcmod.predefined.mkPredefinedCrcFun("crc-32c")
    return crc32c_fun(data)

# 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"
# plaintext  = "..."

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

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

# Build the parent key name.
key_name = client.crypto_key_path project:    project_id,
                                  location:   location_id,
                                  key_ring:   key_ring_id,
                                  crypto_key: key_id

# Call the API.
response = client.encrypt name: key_name, plaintext: plaintext
puts "Ciphertext: #{Base64.strict_encode64 response.ciphertext}"

using Google.Cloud.Kms.V1;
using Google.Protobuf;
using System.Text;

public class DecryptSymmetricSample
{
    public string DecryptSymmetric(
      string projectId = "my-project", string locationId = "us-east1", string keyRingId = "my-key-ring", string keyId = "my-key",
      byte[] ciphertext = null)
    {
        // Create the client.
        KeyManagementServiceClient client = KeyManagementServiceClient.Create();

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

        // Call the API.
        DecryptResponse result = client.Decrypt(keyName, ByteString.CopyFrom(ciphertext));

        // Get the plaintext. Cryptographic plaintexts and ciphertexts are
        // always byte arrays.
        byte[] plaintext = result.Plaintext.ToByteArray();

        // Return the result.
        return Encoding.UTF8.GetString(plaintext);
    }
}

import (
	"context"
	"fmt"
	"hash/crc32"
	"io"

	kms "cloud.google.com/go/kms/apiv1"
	"cloud.google.com/go/kms/apiv1/kmspb"
	"google.golang.org/protobuf/types/known/wrapperspb"
)

// decryptSymmetric will decrypt the input ciphertext bytes using the specified symmetric key.
func decryptSymmetric(w io.Writer, name string, ciphertext []byte) error {
	// name := "projects/my-project/locations/us-east1/keyRings/my-key-ring/cryptoKeys/my-key"
	// ciphertext := []byte("...")  // result of a symmetric encryption call

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

	// Optional, but recommended: Compute ciphertext's CRC32C.
	crc32c := func(data []byte) uint32 {
		t := crc32.MakeTable(crc32.Castagnoli)
		return crc32.Checksum(data, t)
	}
	ciphertextCRC32C := crc32c(ciphertext)

	// Build the request.
	req := &kmspb.DecryptRequest{
		Name:             name,
		Ciphertext:       ciphertext,
		CiphertextCrc32C: wrapperspb.Int64(int64(ciphertextCRC32C)),
	}

	// Call the API.
	result, err := client.Decrypt(ctx, req)
	if err != nil {
		return fmt.Errorf("failed to decrypt ciphertext: %w", err)
	}

	// Optional, but recommended: perform integrity verification on result.
	// For more details on ensuring E2E in-transit integrity to and from Cloud KMS visit:
	// https://cloud.google.com/kms/docs/data-integrity-guidelines
	if int64(crc32c(result.Plaintext)) != result.PlaintextCrc32C.Value {
		return fmt.Errorf("Decrypt: response corrupted in-transit")
	}

	fmt.Fprintf(w, "Decrypted plaintext: %s", result.Plaintext)
	return nil
}

import com.google.cloud.kms.v1.CryptoKeyName;
import com.google.cloud.kms.v1.DecryptResponse;
import com.google.cloud.kms.v1.KeyManagementServiceClient;
import com.google.protobuf.ByteString;
import java.io.IOException;

public class DecryptSymmetric {

  public void decryptSymmetric() 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";
    byte[] ciphertext = null;
    decryptSymmetric(projectId, locationId, keyRingId, keyId, ciphertext);
  }

  // Decrypt data that was encrypted using a symmetric key.
  public void decryptSymmetric(
      String projectId, String locationId, String keyRingId, String keyId, byte[] ciphertext)
      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, and
      // key.
      CryptoKeyName keyName = CryptoKeyName.of(projectId, locationId, keyRingId, keyId);

      // Decrypt the response.
      DecryptResponse response = client.decrypt(keyName, ByteString.copyFrom(ciphertext));
      System.out.printf("Plaintext: %s%n", response.getPlaintext().toStringUtf8());
    }
  }
}

//
// 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';
// Ciphertext must be either a Buffer object or a base-64 encoded string
// const ciphertext = Buffer.from('...');

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

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

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

// Optional, but recommended: compute ciphertext's CRC32C.
const crc32c = require('fast-crc32c');
const ciphertextCrc32c = crc32c.calculate(ciphertext);

async function decryptSymmetric() {
  const [decryptResponse] = await client.decrypt({
    name: keyName,
    ciphertext: ciphertext,
    ciphertextCrc32c: {
      value: ciphertextCrc32c,
    },
  });

  // Optional, but recommended: perform integrity verification on decryptResponse.
  // For more details on ensuring E2E in-transit integrity to and from Cloud KMS visit:
  // https://cloud.google.com/kms/docs/data-integrity-guidelines
  if (
    crc32c.calculate(decryptResponse.plaintext) !==
    Number(decryptResponse.plaintextCrc32c.value)
  ) {
    throw new Error('Decrypt: response corrupted in-transit');
  }

  const plaintext = decryptResponse.plaintext.toString();

  console.log(`Plaintext: ${plaintext}`);
  return plaintext;
}

return decryptSymmetric();

use Google\Cloud\Kms\V1\Client\KeyManagementServiceClient;
use Google\Cloud\Kms\V1\DecryptRequest;

function decrypt_symmetric(
    string $projectId = 'my-project',
    string $locationId = 'us-east1',
    string $keyRingId = 'my-key-ring',
    string $keyId = 'my-key',
    string $ciphertext = '...'
) {
    // Create the Cloud KMS client.
    $client = new KeyManagementServiceClient();

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

    // Call the API.
    $decryptRequest = (new DecryptRequest())
        ->setName($keyName)
        ->setCiphertext($ciphertext);
    $decryptResponse = $client->decrypt($decryptRequest);
    printf('Plaintext: %s' . PHP_EOL, $decryptResponse->getPlaintext());

    return $decryptResponse;
}

from google.cloud import kms


def decrypt_symmetric(
    project_id: str, location_id: str, key_ring_id: str, key_id: str, ciphertext: bytes
) -> kms.DecryptResponse:
    """
    Decrypt the ciphertext using the symmetric key

    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').
        ciphertext (bytes): Encrypted bytes to decrypt.

    Returns:
        DecryptResponse: Response including plaintext.

    """

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

    # Build the key name.
    key_name = client.crypto_key_path(project_id, location_id, key_ring_id, key_id)

    # Optional, but recommended: compute ciphertext's CRC32C.
    # See crc32c() function defined below.
    ciphertext_crc32c = crc32c(ciphertext)

    # Call the API.
    decrypt_response = client.decrypt(
        request={
            "name": key_name,
            "ciphertext": ciphertext,
            "ciphertext_crc32c": ciphertext_crc32c,
        }
    )

    # Optional, but recommended: perform integrity verification on decrypt_response.
    # For more details on ensuring E2E in-transit integrity to and from Cloud KMS visit:
    # https://cloud.google.com/kms/docs/data-integrity-guidelines
    if not decrypt_response.plaintext_crc32c == crc32c(decrypt_response.plaintext):
        raise Exception(
            "The response received from the server was corrupted in-transit."
        )
    # End integrity verification

    print(f"Plaintext: {decrypt_response.plaintext!r}")
    return decrypt_response


def crc32c(data: bytes) -> int:
    """
    Calculates the CRC32C checksum of the provided data.
    Args:
        data: the bytes over which the checksum should be calculated.
    Returns:
        An int representing the CRC32C checksum of the provided bytes.
    """
    import crcmod  # type: ignore

    crc32c_fun = crcmod.predefined.mkPredefinedCrcFun("crc-32c")
    return crc32c_fun(data)

# 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"
# ciphertext  = "..."

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

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

# Build the parent key name.
key_name = client.crypto_key_path project:    project_id,
                                  location:   location_id,
                                  key_ring:   key_ring_id,
                                  crypto_key: key_id

# Call the API.
response = client.decrypt name: key_name, ciphertext: ciphertext
puts "Plaintext: #{response.plaintext}"