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Muestra de código

C#

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Cloud KMS, consulta las bibliotecas cliente de Cloud KMS.

Para autenticarte en Cloud KMS, configura las credenciales predeterminadas de la aplicación. Si deseas obtener más información, consulta Configura la autenticación para un entorno de desarrollo local.


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);
    }
}

Go

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Cloud KMS, consulta las bibliotecas cliente de Cloud KMS.

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
}

Java

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Cloud KMS, consulta las bibliotecas cliente de Cloud KMS.

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());
    }
  }
}

Node.js

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Cloud KMS, consulta las bibliotecas cliente de Cloud KMS.

//
// 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();

PHP

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Cloud KMS, consulta las bibliotecas cliente de Cloud KMS.

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;
}

Python

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Cloud KMS, consulta las bibliotecas cliente de Cloud KMS.

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)

Ruby

Para obtener información sobre cómo instalar y usar la biblioteca cliente de Cloud KMS, consulta las bibliotecas cliente de Cloud KMS.

# 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}"

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