Generating random bytes

This topic shows you how to retrieve random bytes from the random number generator in Cloud HSM.

Before you begin

• Grant the cloudkms.locations.generateRandomBytes permission in the cloud location(s) where your service will be generating random bytes. You can learn about permissions in Cloud Key Management Service at Permissions and roles.

Generating random bytes

C#

To run this code, first set up a C# development environment and install the Cloud KMS C# SDK.

using Google.Api.Gax.ResourceNames;
using Google.Cloud.Kms.V1;

public class GenerateRandomBytesSample
{
    public byte[] GenerateRandomBytes(
      string projectId = "my-project", string locationId = "us-east1", int numBytes = 256)
    {
        // Create the client.
        KeyManagementServiceClient client = KeyManagementServiceClient.Create();

        // Build the location name.
        LocationName locationName = new LocationName(projectId, locationId);

        // Call the API.
        GenerateRandomBytesResponse result = client.GenerateRandomBytes(locationName.ToString(), numBytes, ProtectionLevel.Hsm);

        // The data comes back as raw bytes, which may include non-printable
        // characters. To print the result, you could encode it as base64.
        // string encodedData = result.Data.ToBase64();

        return result.Data.ToByteArray();
    }
}

Go

To run this code, first set up a Go development environment and install the Cloud KMS Go SDK.

import (
	"context"
	"encoding/base64"
	"fmt"
	"io"

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

// generateRandomBytes generates random bytes with entropy sourced from the
// given location.
func generateRandomBytes(w io.Writer, location string, numBytes int32) error {
	// name := "projects/my-project/locations/us-east1"
	// numBytes := 256

	// 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.GenerateRandomBytesRequest{
		Location:        location,
		LengthBytes:     numBytes,
		ProtectionLevel: kmspb.ProtectionLevel_HSM,
	}

	// Generate random bytes.
	result, err := client.GenerateRandomBytes(ctx, req)
	if err != nil {
		return fmt.Errorf("failed to generate random bytes: %w", err)
	}

	// The data comes back as raw bytes, which may include non-printable
	// characters. This base64-encodes the result so it can be printed below.
	encodedData := base64.StdEncoding.EncodeToString(result.Data)

	fmt.Fprintf(w, "Random bytes: %s", encodedData)
	return nil
}

Java

To run this code, first set up a Java development environment and install the Cloud KMS Java SDK.

import com.google.cloud.kms.v1.GenerateRandomBytesResponse;
import com.google.cloud.kms.v1.KeyManagementServiceClient;
import com.google.cloud.kms.v1.LocationName;
import com.google.cloud.kms.v1.ProtectionLevel;
import java.io.IOException;
import java.util.Base64;

public class GenerateRandomBytes {

  public void generateRandomBytes() throws IOException {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    String locationId = "us-east1";
    int numBytes = 256;
    generateRandomBytes(projectId, locationId, numBytes);
  }

  // Create a new key for use with MacSign.
  public void generateRandomBytes(String projectId, String locationId, int numBytes)
      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 for the location.
      LocationName locationName = LocationName.of(projectId, locationId);

      // Generate the bytes.
      GenerateRandomBytesResponse response =
          client.generateRandomBytes(locationName.toString(), numBytes, ProtectionLevel.HSM);

      // The data comes back as raw bytes, which may include non-printable
      // characters. This base64-encodes the result so it can be printed below.
      String encodedData = Base64.getEncoder().encodeToString(response.getData().toByteArray());

      System.out.printf("Random bytes: %s", encodedData);
    }
  }
}

Node.js

To run this code, first set up a Node.js development environment and install the Cloud KMS Node.js SDK.

//
// TODO(developer): Uncomment these variables before running the sample.
//
// const projectId = 'my-project';
// const locationId = 'us-east1';
// const numBytes = 256;

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

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

// Build the location name
const locationName = client.locationPath(projectId, locationId);

async function generateRandomBytes() {
  const [randomBytesResponse] = await client.generateRandomBytes({
    location: locationName,
    lengthBytes: numBytes,
    protectionLevel: 'HSM',
  });

  console.log(`Random bytes: ${randomBytesResponse.data.toString('base64')}`);
  return randomBytesResponse;
}

return generateRandomBytes();

PHP

To run this code, first learn about using PHP on Google Cloud and install the Cloud KMS PHP SDK.

use Google\Cloud\Kms\V1\Client\KeyManagementServiceClient;
use Google\Cloud\Kms\V1\GenerateRandomBytesRequest;
use Google\Cloud\Kms\V1\ProtectionLevel;

/**
 * Generate a random byte string using Cloud KMS.
 *
 * @param string $projectId The Google Cloud project ID.
 * @param string $locationId The location ID (e.g. us-east1).
 * @param int $numBytes The number of bytes to generate.
 */
function generate_random_bytes(
    string $projectId,
    string $locationId = 'us-east1',
    int $numBytes = 256
) {
    // Create the Cloud KMS client.
    $client = new KeyManagementServiceClient();

    // Build the parent name.
    $locationName = $client->locationName($projectId, $locationId);

    // Call the API.
    $generateRandomBytesRequest = (new GenerateRandomBytesRequest())
        ->setLocation($locationName)
        ->setLengthBytes($numBytes)
        ->setProtectionLevel(ProtectionLevel::HSM);
    $randomBytesResponse = $client->generateRandomBytes($generateRandomBytesRequest);

    // The data comes back as raw bytes, which may include non-printable
    // characters. This base64-encodes the result so it can be printed below.
    $encodedData = base64_encode($randomBytesResponse->getData());
    printf('Random bytes: %s' . PHP_EOL, $encodedData);

    return $randomBytesResponse;
}

Python

To run this code, first set up a Python development environment and install the Cloud KMS Python SDK.

# Import base64 for encoding the bytes for printing.
import base64

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


def generate_random_bytes(project_id: str, location_id: str, num_bytes: int) -> bytes:
    """
    Generate random bytes with entropy sourced from the given location.

    Args:
        project_id (string): Google Cloud project ID (e.g. 'my-project').
        location_id (string): Cloud KMS location (e.g. 'us-east1').
        num_bytes (integer): number of bytes of random data.

    Returns:
        bytes: Encrypted ciphertext.

    """

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

    # Build the location name.
    location_name = client.common_location_path(project_id, location_id)

    # Call the API.
    protection_level = kms.ProtectionLevel.HSM
    random_bytes_response = client.generate_random_bytes(
        request={
            "location": location_name,
            "length_bytes": num_bytes,
            "protection_level": protection_level,
        }
    )

    print(f"Random bytes: {base64.b64encode(random_bytes_response.data)}")
    return random_bytes_response

Ruby

To run this code, first set up a Ruby development environment and install the Cloud KMS Ruby SDK.

# TODO(developer): uncomment these values before running the sample.
# project_id  = "my-project"
# location_id = "us-east1"
# num_bytes = 256

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

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

# Build the parent location name.
location_name = client.location_path project:    project_id,
                                     location:   location_id

# Call the API.
response = client.generate_random_bytes location: location_name, length_bytes: num_bytes, protection_level: :HSM

# The data comes back as raw bytes, which may include non-printable
# characters. This base64-encodes the result so it can be printed below.
encoded_data = Base64.strict_encode64 response.data

puts "Random bytes: #{encoded_data}"

Known limitations

• The GenerateRandomBytes API call can produce at most 1024 bytes of randomness per call. To generate more bytes of randomness, you can make multiple API calls.

• The GenerateRandomBytes API call is not supported for the Software or External protection levels.