Encripta y desencripta datos con una clave simétrica

En este tema, te mostramos cómo hacer lo siguiente:

  • Encriptar texto o contenido binario (texto sin formato) con una clave de Cloud KMS
  • Desencriptar cifrado que estaba encriptado con una clave de Cloud KMS

Configuración

  • Antes de encriptar o desencriptar datos, debes crear un llavero de claves y una clave tal como se describe en Crea claves y llaveros de claves.

    Por motivos de seguridad, el material sin procesar de clave criptográfica representado por una clave de Cloud KMS nunca puede visualizarse ni exportarse. Solo un usuario autorizado puede usarlo para encriptar o desencriptar datos cuando invoca la API de Cloud KMS.

  • Asegúrate de que el usuario que llama a los métodos de encriptación y desencriptación tiene los permisos de cloudkms.cryptoKeyVersions.useToEncrypt y cloudkms.cryptoKeyVersions.useToDecrypt de la clave que se usó para encriptar o desencriptar el contenido.

    Una forma de permitirle a un usuario que encripte o desencripte contenido con una clave es si se lo agrega a las funciones IAM roles/cloudkms.cryptoKeyEncrypter, roles/cloudkms.cryptoKeyDecrypter o roles/cloudkms.cryptoKeyEncrypterDecrypter de esa clave. Consulta Permisos y funciones para obtener más información.

  • Si vas a usar las bibliotecas cliente de Cloud KMS, deberás instalar la biblioteca cliente de tu idioma de preferencia.

  • Si vas a usar la herramienta de la línea de comandos de gcloud para Cloud KMS, deberás instalar el SDK de Google Cloud.

Encripta

Línea de comandos

Para encriptar datos, proporciona la información de clave correcta, especifica el nombre del archivo de texto sin formato que encriptarás y también el nombre del archivo que incluirá el contenido encriptado.

gcloud kms encrypt \
  --location=[LOCATION]  \
  --keyring=[KEY_RING] \
  --key=[KEY] \
  --plaintext-file=[FILEPATH_AND_FILENAME_TO_ENCRYPT] \
  --ciphertext-file=[FILEPATH_AND_FILENAME].enc

El tamaño del archivo de texto sin formato no debe superar los 64 KiB.

El comando encrypt admite la marca opcional --additional-authenticated-data- file que permite especificar un archivo que contenga datos autenticados adicionales. El tamaño del archivo de datos autenticados adicionales no debe superar los 64 KiB.

Si configuras las marcas --plaintext-file o --additional-authenticated-data-file como -, el archivo se lee desde stdin. De manera similar, si configuras la marca --ciphertext-file como -, el cifrado se escribe en stdout.

El comando encrypt admite la marca opcional --version para indicar la versión de la clave que se debe usar para la desencriptación. Según la configuración predeterminada, se usa la versión principal.

En el siguiente ejemplo de encrypt, se muestra cómo especificar una versión de clave y los datos autenticados adicionales.

gcloud kms encrypt \
  --location=[LOCATION]  \
  --keyring=[KEY_RING] \
  --key=[KEY] \
  --version=[KEY_VERSION] \
  --additional-authenticated-data-file=[ADDITIONAL_AUTHENTICATED_DATA_FILEPATH_AND_FILENAME] \
  --plaintext-file=[FILEPATH_AND_FILENAME_TO_ENCRYPT] \
  --ciphertext-file=[FILEPATH_AND_FILENAME].enc

Protocolo

El contenido que se debe encriptar y que se envía a Cloud KMS en formato JSON debe estar codificado en Base 64. Para obtener más información sobre la codificación y decodificación con Base 64, consulta Codificación Base 64.

Para encriptar los datos, realiza una solicitud POST, proporciona la información del proyecto y la clave que corresponda, y especifica el texto codificado en Base 64 que se encriptará en el campo plaintext del cuerpo de la solicitud. Reemplaza API_KEY por una clave de API válida. Consulta Accede a la API para obtener información sobre cómo generar una clave de API.

POST https://cloudkms.googleapis.com/v1/projects/[PROJECT_ID]/locations/[LOCATION]/keyRings/[keyring_name]/cryptoKeys/[key_name]:encrypt&key=API_KEY
{
  "plaintext": "U3VwZXIgc2VjcmV0IHRleHQgdGhhdCBtdXN0IGJlIGVuY3J5cHRlZAo=",
}

En este ejemplo, se usa curl:

curl -s -X POST "https://cloudkms.googleapis.com/v1/projects/[PROJECT_ID]/locations/[LOCATION]/keyRings/[KEYRING_NAME]/cryptoKeys/[KEY_NAME]:encrypt" \
  -d "{\"plaintext\":\"[BASE64_ENCODED_INPUT]\"}" \
  -H "Authorization:Bearer [API_KEY]"\
  -H "Content-Type:application/json"

C#

        public static object Encrypt(string projectId, string locationId, string keyRingId, string cryptoKeyId,
string plaintextFile, string ciphertextFile)
        {
            var cloudKms = CreateAuthorizedClient();
            // Generate the full path of the crypto key to use for encryption.
            var cryptoKey = $"projects/{projectId}/locations/{locationId}/keyRings/{keyRingId}/cryptoKeys/{cryptoKeyId}";
            EncryptRequest encryptRequest = new EncryptRequest();
            byte[] plaintext = File.ReadAllBytes(plaintextFile);
            encryptRequest.Plaintext = Convert.ToBase64String(plaintext);
            Console.WriteLine($"dataToEncrypt.Plaintext: {encryptRequest.Plaintext}");
            var result = cloudKms.Projects.Locations.KeyRings.CryptoKeys.Encrypt(name: cryptoKey, body: encryptRequest).Execute();
            // Output encrypted data to a file.
            File.WriteAllBytes(ciphertextFile, Convert.FromBase64String(result.Ciphertext));
            Console.Write($"Encrypted file created: {ciphertextFile}");
            return 0;
        }

Go

func encrypt(projectID, locationID, keyRingID, cryptoKeyID string, plaintext []byte) ([]byte, error) {
	ctx := context.Background()
	client, err := google.DefaultClient(ctx, cloudkms.CloudPlatformScope)
	if err != nil {
		return nil, err
	}

	cloudkmsService, err := cloudkms.New(client)
	if err != nil {
		return nil, err
	}

	parentName := fmt.Sprintf("projects/%s/locations/%s/keyRings/%s/cryptoKeys/%s",
		projectID, locationID, keyRingID, cryptoKeyID)

	req := &cloudkms.EncryptRequest{
		Plaintext: base64.StdEncoding.EncodeToString(plaintext),
	}
	resp, err := cloudkmsService.Projects.Locations.KeyRings.CryptoKeys.Encrypt(parentName, req).Do()
	if err != nil {
		return nil, err
	}

	return base64.StdEncoding.DecodeString(resp.Ciphertext)
}

Java

/**
 * Encrypts the given plaintext using the specified crypto key.
 */
public static byte[] encrypt(
    String projectId, String locationId, String keyRingId, String cryptoKeyId, byte[] plaintext)
    throws IOException {
  // The resource name of the cryptoKey
  String resourceName = String.format(
      "projects/%s/locations/%s/keyRings/%s/cryptoKeys/%s",
      projectId, locationId, keyRingId, cryptoKeyId);

  // Create the Cloud KMS client.
  CloudKMS kms = createAuthorizedClient();

  EncryptRequest request = new EncryptRequest().encodePlaintext(plaintext);
  EncryptResponse response = kms.projects().locations().keyRings().cryptoKeys()
      .encrypt(resourceName, request)
      .execute();

  return response.decodeCiphertext();
}

Node.js

async function encrypt(
  projectId = 'your-project-id', // Your GCP projectId
  keyRingId = 'my-key-ring', // Name of the crypto key's key ring
  cryptoKeyId = 'my-key', // Name of the crypto key, e.g. "my-key"
  plaintextFileName = './path/to/plaintext.txt',
  ciphertextFileName = './path/to/plaintext.txt.encrypted'
) {
  const fs = require('fs');
  const {promisify} = require('util');

  // Import the library and create a client
  const kms = require('@google-cloud/kms');
  const client = new kms.KeyManagementServiceClient();

  // The location of the crypto key's key ring, e.g. "global"
  const locationId = 'global';

  // Reads the file to be encrypted
  const readFile = promisify(fs.readFile);
  const contentsBuffer = await readFile(plaintextFileName);
  const plaintext = contentsBuffer.toString('base64');
  const name = client.cryptoKeyPath(
    projectId,
    locationId,
    keyRingId,
    cryptoKeyId
  );

  // Encrypts the file using the specified crypto key
  const [result] = await client.encrypt({name, plaintext});
  const writeFile = promisify(fs.writeFile);
  await writeFile(ciphertextFileName, Buffer.from(result.ciphertext, 'base64'));
  console.log(`Encrypted ${plaintextFileName} using ${result.name}.`);
  console.log(`Result saved to ${ciphertextFileName}.`);
}

PHP

/**
 * Encrypt a text file.
 *
 * @param string $projectId
 * @param string $keyRingId
 * @param string $cryptoKeyId
 * @param string $plaintextFileName The path to the file containing plaintext to encrypt.
 * @param string $ciphertextFileName The path to write the ciphertext.
 * @param string $locationId [optional]
 * @return null
 */
function encrypt($projectId, $keyRingId, $cryptoKeyId, $plaintextFileName, $ciphertextFileName, $locationId = 'global')
{
    // Instantiate the client, authenticate, and add scopes.
    $client = new Google_Client();
    $client->useApplicationDefaultCredentials();
    $client->addScope('https://www.googleapis.com/auth/cloud-platform');

    // Create the Cloud KMS client.
    $kms = new Google_Service_CloudKMS($client);

    // The resource name of the cryptokey.
    $name = sprintf('projects/%s/locations/%s/keyRings/%s/cryptoKeys/%s',
        $projectId,
        $locationId,
        $keyRingId,
        $cryptoKeyId
    );

    // Use the KMS API to encrypt the text.
    $encoded = base64_encode(file_get_contents($plaintextFileName));
    $request = new Google_Service_CloudKMS_EncryptRequest();
    $request->setPlaintext($encoded);
    $response = $kms->projects_locations_keyRings_cryptoKeys->encrypt(
        $name,
        $request
    );

    // Write the encrypted text to a file.
    file_put_contents($ciphertextFileName, base64_decode($response['ciphertext']));
    printf('Saved encrypted text to %s' . PHP_EOL, $ciphertextFileName);
}

Python

def encrypt(project_id, location_id, key_ring_id, crypto_key_id,
            plaintext_file_name, ciphertext_file_name):
    """Encrypts data from plaintext_file_name using the provided CryptoKey and
    saves it to ciphertext_file_name so it can only be recovered with a call to
    decrypt.
    """

    # Creates an API client for the KMS API.
    kms_client = googleapiclient.discovery.build('cloudkms', 'v1')

    # The resource name of the CryptoKey.
    name = 'projects/{}/locations/{}/keyRings/{}/cryptoKeys/{}'.format(
        project_id, location_id, key_ring_id, crypto_key_id)

    # Read data from the input file.
    with io.open(plaintext_file_name, 'rb') as plaintext_file:
        plaintext = plaintext_file.read()

    # Use the KMS API to encrypt the data.
    crypto_keys = kms_client.projects().locations().keyRings().cryptoKeys()
    request = crypto_keys.encrypt(
        name=name,
        body={'plaintext': base64.b64encode(plaintext).decode('ascii')})
    response = request.execute()
    ciphertext = base64.b64decode(response['ciphertext'].encode('ascii'))

    # Write the encrypted data to a file.
    with io.open(ciphertext_file_name, 'wb') as ciphertext_file:
        ciphertext_file.write(ciphertext)

    print('Saved ciphertext to {}.'.format(ciphertext_file_name))

Ruby

# project_id      = "Your Google Cloud project ID"
# location_id     = "The location of the key ring"
# key_ring_id     = "The ID of the key ring"
# crypto_key_id   = "The ID of the crypto key"
# plaintext_file  = "File to encrypt"
# ciphertext_file = "File to store encrypted input data"

require "google/apis/cloudkms_v1"

# Initialize the client and authenticate with the specified scope
Cloudkms = Google::Apis::CloudkmsV1
kms_client = Cloudkms::CloudKMSService.new
kms_client.authorization = Google::Auth.get_application_default(
  "https://www.googleapis.com/auth/cloud-platform"
)

# The resource name of the crypto key
resource = "projects/#{project_id}/locations/#{location_id}/" +
           "keyRings/#{key_ring_id}/cryptoKeys/#{crypto_key_id}"

# Read the secret data from the file
plaintext = File.read plaintext_file

request = Cloudkms::EncryptRequest.new plaintext: plaintext

# Use the KMS API to encrypt the data
response = kms_client.encrypt_crypto_key resource, request

# Write the encrypted text to the output file
File.write ciphertext_file, response.ciphertext

puts "Saved encrypted #{plaintext_file} as #{ciphertext_file}"

Desencripta

Línea de comandos

Para desencriptar los datos, proporciona la información de la clave adecuada, especifica el nombre del archivo encriptado (archivo cifrado) que se desencriptará y el nombre del archivo en el que se guardará el contenido desencriptado.

gcloud kms decrypt \
  --location=[LOCATION] \
  --keyring=[KEY_RING] \
  --key=[KEY] \
  --ciphertext-file=[FILEPATH_AND_FILENAME_TO_DECRYPT] \
  --plaintext-file=[FILEPATH_AND_FILENAME_TO_DECRYPT].dec

El comando decrypt admite la marca opcional --additional-authenticated-data- file que permite especificar un archivo que contenga datos autenticados adicionales. El tamaño del archivo de datos autenticados adicionales no debe superar los 64 KiB.

Si configuras las marcas --ciphertext-file o --additional-authenticated-data-file como -, el archivo se lee desde stdin. De manera similar, si configuras la marca --plaintext-file como -, el texto sin formato desencriptado se escribe en stdout.

En el siguiente ejemplo de decrypt, se muestra cómo especificar los datos autenticados adicionales.

gcloud kms decrypt \
  --location=[LOCATION] \
  --keyring=[KEY_RING] \
  --key=[KEY] \
  --additional-authenticated-data-file=[ADDITIONAL_AUTHENTICATED_DATA_FILEPATH_AND_FILENAME] \
  --ciphertext-file=[FILEPATH_AND_FILENAME_TO_DECRYPT] \
  --plaintext-file=[FILEPATH_AND_FILENAME_TO_DECRYPT].dec

Protocolo

El texto desencriptado que se muestra en el archivo JSON de Cloud KMS tiene la codificación Base 64. Para obtener más información sobre la codificación y decodificación con Base 64, consulta Codificación Base 64.

Para desencriptar datos encriptados, haz una solicitud POST y proporciona la información de proyecto y clave que corresponda, y especifica el texto encriptado (cifrado) que se desencriptará en el campo ciphertext del cuerpo de la solicitud. Reemplaza API_KEY por una clave de API válida. Consulta Accede a la API para obtener información sobre cómo generar una clave de API.

POST https://cloudkms.googleapis.com/v1/projects/[PROJECT_ID]/locations/[LOCATION]/keyRings/[KEYRING_NAME]/cryptoKeys/[KEY_NAME]:decrypt&key=API_KEY
{
  "ciphertext": "CiQAhMwwBo61cHas7dDgifrUFs5zNzBJ2uZtVFq4ZPEl6fUVT4kSmQ...",
}

En este ejemplo, se usa curl:

curl -s -X POST "https://cloudkms.googleapis.com/v1/projects/[PROJECT_ID]/locations/[LOCATION]/keyRings/[KEYRING_NAME]/cryptoKeys/[KEY_NAME]:decrypt" \
  -d "{\"ciphertext\":\"[ENCRYPTED_CONTENT]\"}" \
  -H "Authorization:Bearer [API_KEY]"\
  -H "Content-Type:application/json"

C#

    public static object Decrypt(string projectId, string locationId, string keyRingId, string cryptoKeyId,
string ciphertextFile, string plaintextFile)
    {
        var cloudKms = CreateAuthorizedClient();
        // Generate the full path of the crypto key to use for encryption.
        var cryptoKey = $"projects/{projectId}/locations/{locationId}/keyRings/{keyRingId}/cryptoKeys/{cryptoKeyId}";
        DecryptRequest decryptRequest = new DecryptRequest();
        byte[] ciphertext = File.ReadAllBytes(ciphertextFile);
        decryptRequest.Ciphertext = Convert.ToBase64String(ciphertext);
        Console.WriteLine($"dataToDecrypt.Ciphertext: {decryptRequest.Ciphertext}");
        var result = cloudKms.Projects.Locations.KeyRings.CryptoKeys.Decrypt(name: cryptoKey, body: decryptRequest).Execute();
        // Output decrypted data to a file.
        File.WriteAllBytes(plaintextFile, Convert.FromBase64String(result.Plaintext));
        Console.Write($"Decrypted file created: {plaintextFile}");
        return 0;
    }

Go

func decrypt(projectID, locationID, keyRingID, cryptoKeyID string, ciphertext []byte) ([]byte, error) {
	ctx := context.Background()
	client, err := google.DefaultClient(ctx, cloudkms.CloudPlatformScope)
	if err != nil {
		return nil, err
	}

	cloudkmsService, err := cloudkms.New(client)
	if err != nil {
		return nil, err
	}

	parentName := fmt.Sprintf("projects/%s/locations/%s/keyRings/%s/cryptoKeys/%s",
		projectID, locationID, keyRingID, cryptoKeyID)

	req := &cloudkms.DecryptRequest{
		Ciphertext: base64.StdEncoding.EncodeToString(ciphertext),
	}
	resp, err := cloudkmsService.Projects.Locations.KeyRings.CryptoKeys.Decrypt(parentName, req).Do()
	if err != nil {
		return nil, err
	}
	return base64.StdEncoding.DecodeString(resp.Plaintext)
}

Java

/**
 * Decrypts the provided ciphertext with the specified crypto key.
 */
public static byte[] decrypt(String projectId, String locationId, String keyRingId,
    String cryptoKeyId, byte[] ciphertext)
    throws IOException {
  // Create the Cloud KMS client.
  CloudKMS kms = createAuthorizedClient();

  // The resource name of the cryptoKey
  String cryptoKeyName = String.format(
      "projects/%s/locations/%s/keyRings/%s/cryptoKeys/%s",
      projectId, locationId, keyRingId, cryptoKeyId);

  DecryptRequest request = new DecryptRequest().encodeCiphertext(ciphertext);
  DecryptResponse response = kms.projects().locations().keyRings().cryptoKeys()
      .decrypt(cryptoKeyName, request)
      .execute();

  return response.decodePlaintext();
}

Node.js

async function decrypt(
  projectId = 'your-project-id', // Your GCP projectId
  keyRingId = 'my-key-ring', // Name of the crypto key's key ring
  cryptoKeyId = 'my-key', // Name of the crypto key, e.g. "my-key"
  ciphertextFileName = './path/to/plaintext.txt.encrypted',
  plaintextFileName = './path/to/plaintext.txt.decrypted'
) {
  const fs = require('fs');
  const {promisify} = require('util');

  // Import the library and create a client
  const kms = require('@google-cloud/kms');
  const client = new kms.KeyManagementServiceClient();

  // The location of the crypto key's key ring, e.g. "global"
  const locationId = 'global';

  // Reads the file to be decrypted
  const readFile = promisify(fs.readFile);
  const contentsBuffer = await readFile(ciphertextFileName);
  const name = client.cryptoKeyPath(
    projectId,
    locationId,
    keyRingId,
    cryptoKeyId
  );
  const ciphertext = contentsBuffer.toString('base64');

  // Dencrypts the file using the specified crypto key
  const [result] = await client.decrypt({name, ciphertext});

  // Writes the dencrypted file to disk
  const writeFile = promisify(fs.writeFile);
  await writeFile(plaintextFileName, Buffer.from(result.plaintext, 'base64'));
  console.log(
    `Decrypted ${ciphertextFileName}, result saved to ${plaintextFileName}.`
  );
}

PHP

/**
 * Decrypt a text file.
 *
 * @param string $projectId
 * @param string $keyRingId
 * @param string $cryptoKeyId
 * @param string $ciphertextFileName The path to the ciphertext file to decrypt.
 * @param string $plaintextFileName The path to write the decrypted plaintext file.
 * @param string $locationId [optional]
 * @return null
 */
function decrypt($projectId, $keyRingId, $cryptoKeyId, $ciphertextFileName, $plaintextFileName, $locationId = 'global')
{
    // Instantiate the client, authenticate, and add scopes.
    $client = new Google_Client();
    $client->useApplicationDefaultCredentials();
    $client->addScope('https://www.googleapis.com/auth/cloud-platform');

    // Create the Cloud KMS client.
    $kms = new Google_Service_CloudKMS($client);

    // The resource name of the cryptokey.
    $name = sprintf('projects/%s/locations/%s/keyRings/%s/cryptoKeys/%s',
        $projectId,
        $locationId,
        $keyRingId,
        $cryptoKeyId
    );

    // Use the KMS API to decrypt the text.
    $ciphertext = base64_encode(file_get_contents($ciphertextFileName));
    $request = new Google_Service_CloudKMS_DecryptRequest();
    $request->setCiphertext($ciphertext);
    $response = $kms->projects_locations_keyRings_cryptoKeys->decrypt(
        $name,
        $request
    );

    // Write the decrypted text to a file.
    file_put_contents($plaintextFileName, base64_decode($response['plaintext']));
    printf('Saved decrypted text to %s' . PHP_EOL, $plaintextFileName);
}

Python

def decrypt(project_id, location_id, key_ring_id, crypto_key_id,
            ciphertext_file_name, plaintext_file_name):
    """Decrypts data from ciphertext_file_name that was previously encrypted
    using the provided CryptoKey and saves it to plaintext_file_name."""

    # Creates an API client for the KMS API.
    kms_client = googleapiclient.discovery.build('cloudkms', 'v1')

    # The resource name of the CryptoKey.
    name = 'projects/{}/locations/{}/keyRings/{}/cryptoKeys/{}'.format(
        project_id, location_id, key_ring_id, crypto_key_id)

    # Read encrypted data from the input file.
    with io.open(ciphertext_file_name, 'rb') as ciphertext_file:
        ciphertext = ciphertext_file.read()

    # Use the KMS API to decrypt the data.
    crypto_keys = kms_client.projects().locations().keyRings().cryptoKeys()
    request = crypto_keys.decrypt(
        name=name,
        body={'ciphertext': base64.b64encode(ciphertext).decode('ascii')})
    response = request.execute()
    plaintext = base64.b64decode(response['plaintext'].encode('ascii'))

    # Write the decrypted data to a file.
    with io.open(plaintext_file_name, 'wb') as plaintext_file:
        plaintext_file.write(plaintext)

    print('Saved plaintext to {}.'.format(plaintext_file_name))

Ruby

# project_id    = "Your Google Cloud project ID"
# location_id   = "The location of the key ring"
# key_ring_id   = "The ID of the key ring"
# crypto_key_id = "The ID of the crypto key"
# ciphertext_file = "File to decrypt"
# plaintext_file  = "File to store decrypted data"

require "google/apis/cloudkms_v1"

# Initialize the client and authenticate with the specified scope
Cloudkms = Google::Apis::CloudkmsV1
kms_client = Cloudkms::CloudKMSService.new
kms_client.authorization = Google::Auth.get_application_default(
  "https://www.googleapis.com/auth/cloud-platform"
)

# The resource name of the crypto key
resource = "projects/#{project_id}/locations/#{location_id}/" +
           "keyRings/#{key_ring_id}/cryptoKeys/#{crypto_key_id}"

# Read the encrypted data from the file
ciphertext = File.read ciphertext_file

request = Cloudkms::DecryptRequest.new ciphertext: ciphertext

# Use the KMS API to decrypt the data
response = kms_client.decrypt_crypto_key resource, request

# Write the decrypted text to the output file
File.write plaintext_file, response.plaintext

puts "Saved decrypted #{ciphertext_file} as #{plaintext_file}"

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