Uso del almacenamiento en caché de claves de datos: S tep-by-step Ejemplo de almacenamiento en caché de claves de datos: cifrado de una cadena

Cómo utilizar el almacenamiento en caché de claves de datos

En este tema se muestra cómo usar el almacenamiento en caché de claves de datos en las aplicaciones. Recorremos el proceso paso a paso. A continuación, combinaremos todo el procedimiento en un ejemplo sencillo que utiliza el almacenamiento en caché de claves de datos en una operación para cifrar una cadena.

Los ejemplos en esta sección muestran cómo usar la versión 2.0.x y posterior del AWS Encryption SDK. Para ver ejemplos que utilizan versiones anteriores, busca tu versión en la lista de versiones del GitHub repositorio de tu lenguaje de programación.

Para ver ejemplos completos y probados del uso del almacenamiento en caché de claves de datos en el AWS Encryption SDK, consulte:

La AWS Encryption SDK para .NET no admite el almacenamiento en caché de claves de datos.

Temas

Uso del almacenamiento en caché de claves de datos: S tep-by-step
Ejemplo de almacenamiento en caché de claves de datos: cifrado de una cadena

Uso del almacenamiento en caché de claves de datos: S tep-by-step

Estas step-by-step instrucciones le muestran cómo crear los componentes que necesita para implementar el almacenamiento en caché de claves de datos.

Crear una caché de clave de datos. En estos ejemplos, utilizamos la caché local que proporciona AWS Encryption SDK. Limitamos la caché a 10 claves de datos.

Cree un proveedor de claves maestras (Java y Python) o un anillo de claves (C y JavaScript). Estos ejemplos utilizan un proveedor de claves maestras AWS Key Management Service (AWS KMS) o un llavero de AWS KMS compatible.

C


// Create an AWS KMS keyring
//   The input is the Amazon Resource Name (ARN) 
//   of an AWS KMS key

struct aws_cryptosdk_keyring *kms_keyring = Aws::Cryptosdk::KmsKeyring::Builder().Build(kms_key_arn);

Java

En el siguiente ejemplo se utiliza la versión 2. x delSDK de cifrado de AWS para Java. Versión 3. x del SDK de cifrado de AWS para Java CMM de almacenamiento en caché de claves de datos está en desuso. Con la versión 3. x, también puede utilizar el llavero AWS KMS jerárquico, una solución alternativa de almacenamiento en caché de materiales criptográficos.


// Create an AWS KMS master key provider
//   The input is the Amazon Resource Name (ARN) 
//   of an AWS KMS key

MasterKeyProvider<KmsMasterKey> keyProvider = KmsMasterKeyProvider.builder().buildStrict(kmsKeyArn);

JavaScript Browser

En el navegador, debe insertar las credenciales de forma segura. En este ejemplo se definen las credenciales de un paquete web (kms.webpack.config) que resuelve las credenciales en tiempo de ejecución. Crea una instancia de proveedor cliente de AWS KMS a partir de un cliente de AWS KMS y las credenciales. Luego, cuando crea el llavero, este pasa el proveedor del cliente al constructor junto con el AWS KMS key (generatorKeyId).


const { accessKeyId, secretAccessKey, sessionToken } = credentials

const clientProvider = getClient(KMS, {
    credentials: {
      accessKeyId,
      secretAccessKey,
      sessionToken
    }
  })

/*  Create an AWS KMS keyring
 *  You must configure the AWS KMS keyring with at least one AWS KMS key
 *  The input is the Amazon Resource Name (ARN) 
 */ of an AWS KMS key

const keyring = new KmsKeyringBrowser({
    clientProvider,
    generatorKeyId,
    keyIds,
  })

JavaScript Node.js


/* Create an AWS KMS keyring
 *   The input is the Amazon Resource Name (ARN) 
*/   of an AWS KMS key

const keyring = new KmsKeyringNode({ generatorKeyId })

Python


# Create an AWS KMS master key provider
#  The input is the Amazon Resource Name (ARN) 
#  of an AWS KMS key

key_provider = aws_encryption_sdk.StrictAwsKmsMasterKeyProvider(key_ids=[kms_key_arn])

Crear un administrador de materiales criptográficos de almacenamiento (CMM de almacenamiento en caché).

Asocie el CMM de almacenamiento en caché con la caché y con el proveedor de claves maestras o llavero. A continuación, establezca los umbrales de seguridad de la caché en el CMM de almacenamiento en caché.

C

En el SDK de cifrado de AWS para C, puede crear un CMM de almacenamiento en caché a partir de un CMM subyacente, como el CMM predeterminado, o a partir de un llavero. En este ejemplo se crea el CMM de almacenamiento en caché a partir de un llavero.

Después de crear el CMM de almacenamiento en caché, puede liberar sus referencias al llavero y a la caché. Para más información, consulte Recuento de referencias.


// Create the caching CMM
//   Set the partition ID to NULL.
//   Set the required maximum age value to 60 seconds.
struct aws_cryptosdk_cmm *caching_cmm = aws_cryptosdk_caching_cmm_new_from_keyring(allocator, cache, kms_keyring, NULL, 60, AWS_TIMESTAMP_SECS);

// Add an optional message threshold
//   The cached data key will not be used for more than 10 messages.
aws_status = aws_cryptosdk_caching_cmm_set_limit_messages(caching_cmm, 10);

// Release your references to the cache and the keyring.
aws_cryptosdk_materials_cache_release(cache);
aws_cryptosdk_keyring_release(kms_keyring);

Java

En el siguiente ejemplo se utiliza la versión 2. x delSDK de cifrado de AWS para Java. Versión 3. x of the SDK de cifrado de AWS para Java no admite el almacenamiento en caché de claves de datos, pero sí es compatible con el anillo de claves AWS KMS jerárquico, una solución alternativa de almacenamiento en caché de materiales criptográficos.


/*
 * Security thresholds
 *   Max entry age is required. 
 *   Max messages (and max bytes) per entry are optional
 */
int MAX_ENTRY_AGE_SECONDS = 60;
int MAX_ENTRY_MSGS = 10;
       
//Create a caching CMM
CryptoMaterialsManager cachingCmm =
    CachingCryptoMaterialsManager.newBuilder().withMasterKeyProvider(keyProvider)
                                 .withCache(cache)
                                 .withMaxAge(MAX_ENTRY_AGE_SECONDS, TimeUnit.SECONDS)
                                 .withMessageUseLimit(MAX_ENTRY_MSGS)
                                 .build();

JavaScript Browser


/*
 * Security thresholds
 *   Max age (in milliseconds) is required.
 *   Max messages (and max bytes) per entry are optional.
 */
const maxAge = 1000 * 60
const maxMessagesEncrypted = 10

/* Create a caching CMM from a keyring  */
const cachingCmm = new WebCryptoCachingMaterialsManager({
  backingMaterials: keyring,
  cache,
  maxAge,
  maxMessagesEncrypted
})

JavaScript Node.js


/*
 * Security thresholds
 *   Max age (in milliseconds) is required.
 *   Max messages (and max bytes) per entry are optional.
 */
const maxAge = 1000 * 60
const maxMessagesEncrypted = 10

/* Create a caching CMM from a keyring  */
const cachingCmm = new NodeCachingMaterialsManager({
  backingMaterials: keyring,
  cache,
  maxAge,
  maxMessagesEncrypted
})

Python


# Security thresholds
#   Max entry age is required. 
#   Max messages (and max bytes) per entry are optional
#
MAX_ENTRY_AGE_SECONDS = 60.0
MAX_ENTRY_MESSAGES = 10
       
# Create a caching CMM
caching_cmm = CachingCryptoMaterialsManager(
    master_key_provider=key_provider,
    cache=cache,
    max_age=MAX_ENTRY_AGE_SECONDS,
    max_messages_encrypted=MAX_ENTRY_MESSAGES
)

Es todo lo que tiene que hacer. Luego solo tiene que dejar que el AWS Encryption SDK se encargue de administrar la caché, o bien agregar su propia lógica de administración de la caché.

Cuando desee utilizar el almacenamiento de claves de datos en una llamada para cifrar o descifrar datos, especifique el CMM de almacenamiento en caché en lugar del proveedor de claves maestras u otro CMM.

nota

Si va a cifrar secuencias de datos o datos de tamaño desconocido, asegúrese de especificar el tamaño de los datos en la solicitud. El AWS Encryption SDK no utiliza el almacenamiento en caché de claves de datos para cifrar datos de tamaño desconocido.

C

En el SDK de cifrado de AWS para C, cree una sesión con el CMM de almacenamiento en caché y luego procese la sesión.

De forma predeterminada, cuando el tamaño de mensaje es desconocido e ilimitado, el AWS Encryption SDK no almacena en caché las claves de datos. Para permitir el almacenamiento en caché cuando no se conoce el tamaño exacto de los datos, utilice el método aws_cryptosdk_session_set_message_bound para establecer un tamaño máximo para el mensaje. Defina el límite en un tamaño mayor que el tamaño estimado del mensaje. Si el tamaño real del mensaje supera el límite, la operación de cifrado genera un error.


/* Create a session with the caching CMM. Set the session mode to encrypt. */
struct aws_cryptosdk_session *session = aws_cryptosdk_session_new_from_cmm_2(allocator, AWS_CRYPTOSDK_ENCRYPT, caching_cmm);

/* Set a message bound of 1000 bytes */
aws_status = aws_cryptosdk_session_set_message_bound(session, 1000);

/* Encrypt the message using the session with the caching CMM */
aws_status = aws_cryptosdk_session_process(
             session, output_buffer, output_capacity, &output_produced, input_buffer, input_len, &input_consumed);

/* Release your references to the caching CMM and the session. */
aws_cryptosdk_cmm_release(caching_cmm);
aws_cryptosdk_session_destroy(session);

Java

En el siguiente ejemplo, se utiliza la versión 2. x delSDK de cifrado de AWS para Java. Versión 3. x del SDK de cifrado de AWS para Java CMM de almacenamiento en caché de claves de datos está en desuso. Con la versión 3. x, también puede utilizar el llavero AWS KMS jerárquico, una solución alternativa de almacenamiento en caché de materiales criptográficos.


// When the call to encryptData specifies a caching CMM,
// the encryption operation uses the data key cache
final AwsCrypto encryptionSdk = AwsCrypto.standard();
return encryptionSdk.encryptData(cachingCmm, plaintext_source).getResult();

JavaScript Browser


const { result } = await encrypt(cachingCmm, plaintext)

JavaScript Node.js

Cuando utiliza el CMM de almacenamiento en caché en el SDK de cifrado de AWS para JavaScript para Node.js, el método de encrypt necesita la longitud del texto no cifrado. Si no la proporciona, la clave de datos no se almacena en caché. Si proporciona una longitud, pero los datos en texto no cifrado que proporciona superan esa longitud, se producirá un error en la operación de cifrado. Si no sabe la longitud exacta del texto no cifrado, como cuando transmite datos, proporcione el valor esperado más grande.


const { result } = await encrypt(cachingCmm, plaintext, { plaintextLength: plaintext.length })

Python


# Set up an encryption client
client = aws_encryption_sdk.EncryptionSDKClient()

# When the call to encrypt specifies a caching CMM,
# the encryption operation uses the data key cache
#
encrypted_message, header = client.encrypt(
    source=plaintext_source,
    materials_manager=caching_cmm
)

Ejemplo de almacenamiento en caché de claves de datos: cifrado de una cadena

Este ejemplo de código sencillo utiliza el almacenamiento en caché de claves de datos al cifrar una cadena. Combina el código del step-by-step procedimiento en un código de prueba que puede ejecutar.

El ejemplo crea una caché local y un proveedor de claves maestras o un llavero para un AWS KMS key. A continuación, se utiliza la caché local y un proveedor de claves maestras o llavero para crear un CMM de almacenamiento en caché con los umbrales de seguridad adecuados. En Java y Python, la solicitud de cifrado especifica el CMM de almacenamiento en caché, los datos en texto no cifrado que hay que cifrar y un contexto de cifrado. En C, el CMM de almacenamiento en caché se especifica en la sesión y la sesión se proporciona a la solicitud de cifrado.

Para ejecutar estos ejemplos, debe proporcionar el Nombre de recurso de Amazon (ARN) de un AWS KMS key. Compruebe de tenga permiso para utilizar la AWS KMS key para generar una clave de datos.

Para obtener ejemplos reales más detallados de cómo crear y usar una caché de claves de datos, consulte Ejemplo de almacenamiento en caché de claves de datos.

C


/*
 * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"). You may not use
 * this file except in compliance with the License. A copy of the License is
 * located at
 *
 *     http://aws.amazon.com/apache2.0/
 *
 * or in the "license" file accompanying this file. This file is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <aws/cryptosdk/cache.h>
#include <aws/cryptosdk/cpp/kms_keyring.h>
#include <aws/cryptosdk/session.h>

void encrypt_with_caching(
    uint8_t *ciphertext,     // output will go here (assumes ciphertext_capacity bytes already allocated)
    size_t *ciphertext_len,  // length of output will go here
    size_t ciphertext_capacity,
    const char *kms_key_arn,
    int max_entry_age,
    int cache_capacity) {
    const uint64_t MAX_ENTRY_MSGS = 100;

    struct aws_allocator *allocator = aws_default_allocator();
    
    // Load error strings for debugging
    aws_cryptosdk_load_error_strings();

    // Create a keyring
    struct aws_cryptosdk_keyring *kms_keyring = Aws::Cryptosdk::KmsKeyring::Builder().Build(kms_key_arn);

    // Create a cache
    struct aws_cryptosdk_materials_cache *cache = aws_cryptosdk_materials_cache_local_new(allocator, cache_capacity);

    // Create a caching CMM
    struct aws_cryptosdk_cmm *caching_cmm = aws_cryptosdk_caching_cmm_new_from_keyring(
        allocator, cache, kms_keyring, NULL, max_entry_age, AWS_TIMESTAMP_SECS);
    if (!caching_cmm) abort();

    if (aws_cryptosdk_caching_cmm_set_limit_messages(caching_cmm, MAX_ENTRY_MSGS)) abort();

    // Create a session
    struct aws_cryptosdk_session *session =        
        aws_cryptosdk_session_new_from_cmm_2(allocator, AWS_CRYPTOSDK_ENCRYPT, caching_cmm);
    if (!session) abort();

    // Encryption context
    struct aws_hash_table *enc_ctx = aws_cryptosdk_session_get_enc_ctx_ptr_mut(session);
    if (!enc_ctx) abort();
    AWS_STATIC_STRING_FROM_LITERAL(enc_ctx_key, "purpose");
    AWS_STATIC_STRING_FROM_LITERAL(enc_ctx_value, "test");
    if (aws_hash_table_put(enc_ctx, enc_ctx_key, (void *)enc_ctx_value, NULL)) abort();

    // Plaintext data to be encrypted
    const char *my_data = "My plaintext data";
    size_t my_data_len  = strlen(my_data);
    if (aws_cryptosdk_session_set_message_size(session, my_data_len)) abort();

    // When the session uses a caching CMM, the encryption operation uses the data key cache
    // specified in the caching CMM.
    size_t bytes_read;
    if (aws_cryptosdk_session_process(
            session,
            ciphertext,
            ciphertext_capacity,
            ciphertext_len,
            (const uint8_t *)my_data,
            my_data_len,
            &bytes_read))
        abort();
    if (!aws_cryptosdk_session_is_done(session) || bytes_read != my_data_len) abort();

    aws_cryptosdk_session_destroy(session);
    aws_cryptosdk_cmm_release(caching_cmm);
    aws_cryptosdk_materials_cache_release(cache);
    aws_cryptosdk_keyring_release(kms_keyring);
}

Java


// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

package com.amazonaws.crypto.examples;

import com.amazonaws.encryptionsdk.AwsCrypto;
import com.amazonaws.encryptionsdk.CryptoMaterialsManager;
import com.amazonaws.encryptionsdk.MasterKeyProvider;
import com.amazonaws.encryptionsdk.caching.CachingCryptoMaterialsManager;
import com.amazonaws.encryptionsdk.caching.CryptoMaterialsCache;
import com.amazonaws.encryptionsdk.caching.LocalCryptoMaterialsCache;
import com.amazonaws.encryptionsdk.kmssdkv2.KmsMasterKey;
import com.amazonaws.encryptionsdk.kmssdkv2.KmsMasterKeyProvider;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.Map;
import java.util.concurrent.TimeUnit;

/**
 * <p>
 * Encrypts a string using an &KMS; key and data key caching
 *
 * <p>
 * Arguments:
 * <ol>
 * <li>KMS Key ARN: To find the Amazon Resource Name of your &KMS; key,
 *     see 'Find the key ID and ARN' at https://docs.aws.amazon.com/kms/latest/developerguide/find-cmk-id-arn.html
 * <li>Max entry age: Maximum time (in seconds) that a cached entry can be used
 * <li>Cache capacity: Maximum number of entries in the cache
 * </ol>
 */
public class SimpleDataKeyCachingExample {

    /*
     * Security thresholds
     *   Max entry age is required.
     *   Max messages (and max bytes) per data key are optional
     */
    private static final int MAX_ENTRY_MSGS = 100;

    public static byte[] encryptWithCaching(String kmsKeyArn, int maxEntryAge, int cacheCapacity) {
        // Plaintext data to be encrypted
        byte[] myData = "My plaintext data".getBytes(StandardCharsets.UTF_8);

        // Encryption context
        // Most encrypted data should have an associated encryption context
        // to protect integrity. This sample uses placeholder values.
        // For more information see:
        // blogs.aws.amazon.com/security/post/Tx2LZ6WBJJANTNW/How-to-Protect-the-Integrity-of-Your-Encrypted-Data-by-Using-AWS-Key-Management
        final Map<String, String> encryptionContext = Collections.singletonMap("purpose", "test");

        // Create a master key provider
        MasterKeyProvider<KmsMasterKey> keyProvider = KmsMasterKeyProvider.builder()
            .buildStrict(kmsKeyArn);

        // Create a cache
        CryptoMaterialsCache cache = new LocalCryptoMaterialsCache(cacheCapacity);

        // Create a caching CMM
        CryptoMaterialsManager cachingCmm =
            CachingCryptoMaterialsManager.newBuilder().withMasterKeyProvider(keyProvider)
                .withCache(cache)
                .withMaxAge(maxEntryAge, TimeUnit.SECONDS)
                .withMessageUseLimit(MAX_ENTRY_MSGS)
                .build();

        // When the call to encryptData specifies a caching CMM,
        // the encryption operation uses the data key cache
        final AwsCrypto encryptionSdk = AwsCrypto.standard();
        return encryptionSdk.encryptData(cachingCmm, myData, encryptionContext).getResult();
    }
}

JavaScript Browser


// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

/* This is a simple example of using a caching CMM with a KMS keyring
 * to encrypt and decrypt using the AWS Encryption SDK for Javascript in a browser.
 */

import {
  KmsKeyringBrowser,
  KMS,
  getClient,
  buildClient,
  CommitmentPolicy,
  WebCryptoCachingMaterialsManager,
  getLocalCryptographicMaterialsCache,
} from '@aws-crypto/client-browser'
import { toBase64 } from '@aws-sdk/util-base64-browser'

/* This builds the client with the REQUIRE_ENCRYPT_REQUIRE_DECRYPT commitment policy,
 * which enforces that this client only encrypts using committing algorithm suites
 * and enforces that this client
 * will only decrypt encrypted messages
 * that were created with a committing algorithm suite.
 * This is the default commitment policy
 * if you build the client with `buildClient()`.
 */
const { encrypt, decrypt } = buildClient(
  CommitmentPolicy.REQUIRE_ENCRYPT_REQUIRE_DECRYPT
)

/* This is injected by webpack.
 * The webpack.DefinePlugin or @aws-sdk/karma-credential-loader will replace the values when bundling.
 * The credential values are pulled from @aws-sdk/credential-provider-node
 * Use any method you like to get credentials into the browser.
 * See kms.webpack.config
 */
declare const credentials: {
  accessKeyId: string
  secretAccessKey: string
  sessionToken: string
}

/* This is done to facilitate testing. */
export async function testCachingCMMExample() {
  /* This example uses an &KMS; keyring. The generator key in a &KMS; keyring generates and encrypts the data key.
   * The caller needs kms:GenerateDataKey permission on the &KMS; key in generatorKeyId.
   */
  const generatorKeyId =
    'arn:aws:kms:us-west-2:658956600833:alias/EncryptDecrypt'

  /* Adding additional KMS keys that can decrypt.
   * The caller must have kms:Encrypt permission for every &KMS; key in keyIds.
   * You might list several keys in different AWS Regions.
   * This allows you to decrypt the data in any of the represented Regions.
   * In this example, the generator key
   * and the additional key are actually the same &KMS; key.
   * In `generatorId`, this &KMS; key is identified by its alias ARN.
   * In `keyIds`, this &KMS; key is identified by its key ARN.
   * In practice, you would specify different &KMS; keys,
   * or omit the `keyIds` parameter.
   * This is *only* to demonstrate how the &KMS; key ARNs are configured.
   */
  const keyIds = [
    'arn:aws:kms:us-west-2:658956600833:key/b3537ef1-d8dc-4780-9f5a-55776cbb2f7f',
  ]

  /* Need a client provider that will inject correct credentials.
   * The credentials here are injected by webpack from your environment bundle is created
   * The credential values are pulled using @aws-sdk/credential-provider-node.
   * See kms.webpack.config
   * You should inject your credential into the browser in a secure manner
   * that works with your application.
   */
  const { accessKeyId, secretAccessKey, sessionToken } = credentials

  /* getClient takes a KMS client constructor
   * and optional configuration values.
   * The credentials can be injected here,
   * because browsers do not have a standard credential discovery process the way Node.js does.
   */
  const clientProvider = getClient(KMS, {
    credentials: {
      accessKeyId,
      secretAccessKey,
      sessionToken,
    },
  })

  /* You must configure the KMS keyring with your &KMS; keys */
  const keyring = new KmsKeyringBrowser({
    clientProvider,
    generatorKeyId,
    keyIds,
  })

  /* Create a cache to hold the data keys (and related cryptographic material).
   * This example uses the local cache provided by the Encryption SDK.
   * The `capacity` value represents the maximum number of entries
   * that the cache can hold.
   * To make room for an additional entry,
   * the cache evicts the oldest cached entry.
   * Both encrypt and decrypt requests count independently towards this threshold.
   * Entries that exceed any cache threshold are actively removed from the cache.
   * By default, the SDK checks one item in the cache every 60 seconds (60,000 milliseconds).
   * To change this frequency, pass in a `proactiveFrequency` value
   * as the second parameter. This value is in milliseconds.
   */
  const capacity = 100
  const cache = getLocalCryptographicMaterialsCache(capacity)

  /* The partition name lets multiple caching CMMs share the same local cryptographic cache.
   * By default, the entries for each CMM are cached separately. However, if you want these CMMs to share the cache,
   * use the same partition name for both caching CMMs.
   * If you don't supply a partition name, the Encryption SDK generates a random name for each caching CMM.
   * As a result, sharing elements in the cache MUST be an intentional operation.
   */
  const partition = 'local partition name'

  /* maxAge is the time in milliseconds that an entry will be cached.
   * Elements are actively removed from the cache.
   */
  const maxAge = 1000 * 60

  /* The maximum number of bytes that will be encrypted under a single data key.
   * This value is optional,
   * but you should configure the lowest practical value.
   */
  const maxBytesEncrypted = 100

  /* The maximum number of messages that will be encrypted under a single data key.
   * This value is optional,
   * but you should configure the lowest practical value.
   */
  const maxMessagesEncrypted = 10

  const cachingCMM = new WebCryptoCachingMaterialsManager({
    backingMaterials: keyring,
    cache,
    partition,
    maxAge,
    maxBytesEncrypted,
    maxMessagesEncrypted,
  })

  /* Encryption context is a *very* powerful tool for controlling
   * and managing access.
   * When you pass an encryption context to the encrypt function,
   * the encryption context is cryptographically bound to the ciphertext.
   * If you don't pass in the same encryption context when decrypting,
   * the decrypt function fails.
   * The encryption context is ***not*** secret!
   * Encrypted data is opaque.
   * You can use an encryption context to assert things about the encrypted data.
   * The encryption context helps you to determine
   * whether the ciphertext you retrieved is the ciphertext you expect to decrypt.
   * For example, if you are are only expecting data from 'us-west-2',
   * the appearance of a different AWS Region in the encryption context can indicate malicious interference.
   * See: https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#encryption-context
   *
   * Also, cached data keys are reused ***only*** when the encryption contexts passed into the functions are an exact case-sensitive match.
   * See: https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/data-caching-details.html#caching-encryption-context
   */
  const encryptionContext = {
    stage: 'demo',
    purpose: 'simple demonstration app',
    origin: 'us-west-2',
  }

  /* Find data to encrypt. */
  const plainText = new Uint8Array([1, 2, 3, 4, 5])

  /* Encrypt the data.
   * The caching CMM only reuses data keys
   * when it know the length (or an estimate) of the plaintext.
   * However, in the browser,
   * you must provide all of the plaintext to the encrypt function.
   * Therefore, the encrypt function in the browser knows the length of the plaintext
   * and does not accept a plaintextLength option.
   */
  const { result } = await encrypt(cachingCMM, plainText, { encryptionContext })

  /* Log the plain text
   * only for testing and to show that it works.
   */
  console.log('plainText:', plainText)
  document.write('</br>plainText:' + plainText + '</br>')

  /* Log the base64-encoded result
   * so that you can try decrypting it with another AWS Encryption SDK implementation.
   */
  const resultBase64 = toBase64(result)
  console.log(resultBase64)
  document.write(resultBase64)

  /* Decrypt the data.
   * NOTE: This decrypt request will not use the data key
   * that was cached during the encrypt operation.
   * Data keys for encrypt and decrypt operations are cached separately.
   */
  const { plaintext, messageHeader } = await decrypt(cachingCMM, result)

  /* Grab the encryption context so you can verify it. */
  const { encryptionContext: decryptedContext } = messageHeader

  /* Verify the encryption context.
   * If you use an algorithm suite with signing,
   * the Encryption SDK adds a name-value pair to the encryption context that contains the public key.
   * Because the encryption context might contain additional key-value pairs,
   * do not include a test that requires that all key-value pairs match.
   * Instead, verify that the key-value pairs that you supplied to the `encrypt` function are included in the encryption context that the `decrypt` function returns.
   */
  Object.entries(encryptionContext).forEach(([key, value]) => {
    if (decryptedContext[key] !== value)
      throw new Error('Encryption Context does not match expected values')
  })

  /* Log the clear message
   * only for testing and to show that it works.
   */
  document.write('</br>Decrypted:' + plaintext)
  console.log(plaintext)

  /* Return the values to make testing easy. */
  return { plainText, plaintext }
}

JavaScript Node.js


// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

import {
  KmsKeyringNode,
  buildClient,
  CommitmentPolicy,
  NodeCachingMaterialsManager,
  getLocalCryptographicMaterialsCache,
} from '@aws-crypto/client-node'

/* This builds the client with the REQUIRE_ENCRYPT_REQUIRE_DECRYPT commitment policy,
 * which enforces that this client only encrypts using committing algorithm suites
 * and enforces that this client
 * will only decrypt encrypted messages
 * that were created with a committing algorithm suite.
 * This is the default commitment policy
 * if you build the client with `buildClient()`.
 */
const { encrypt, decrypt } = buildClient(
  CommitmentPolicy.REQUIRE_ENCRYPT_REQUIRE_DECRYPT
)

export async function cachingCMMNodeSimpleTest() {
  /* An &KMS; key is required to generate the data key.
   * You need kms:GenerateDataKey permission on the &KMS; key in generatorKeyId.
   */
  const generatorKeyId =
    'arn:aws:kms:us-west-2:658956600833:alias/EncryptDecrypt'

  /* Adding alternate &KMS; keys that can decrypt.
   * Access to kms:Encrypt is required for every &KMS; key in keyIds.
   * You might list several keys in different AWS Regions.
   * This allows you to decrypt the data in any of the represented Regions.
   * In this example, the generator key
   * and the additional key are actually the same &KMS; key.
   * In `generatorId`, this &KMS; key is identified by its alias ARN.
   * In `keyIds`, this &KMS; key is identified by its key ARN.
   * In practice, you would specify different &KMS; keys,
   * or omit the `keyIds` parameter.
   * This is *only* to demonstrate how the &KMS; key ARNs are configured.
   */
  const keyIds = [
    'arn:aws:kms:us-west-2:658956600833:key/b3537ef1-d8dc-4780-9f5a-55776cbb2f7f',
  ]

  /* The &KMS; keyring must be configured with the desired &KMS; keys
   * This example passes the keyring to the caching CMM
   * instead of using it directly.
   */
  const keyring = new KmsKeyringNode({ generatorKeyId, keyIds })

  /* Create a cache to hold the data keys (and related cryptographic material).
   * This example uses the local cache provided by the Encryption SDK.
   * The `capacity` value represents the maximum number of entries
   * that the cache can hold.
   * To make room for an additional entry,
   * the cache evicts the oldest cached entry.
   * Both encrypt and decrypt requests count independently towards this threshold.
   * Entries that exceed any cache threshold are actively removed from the cache.
   * By default, the SDK checks one item in the cache every 60 seconds (60,000 milliseconds).
   * To change this frequency, pass in a `proactiveFrequency` value
   * as the second parameter. This value is in milliseconds.
   */
  const capacity = 100
  const cache = getLocalCryptographicMaterialsCache(capacity)

  /* The partition name lets multiple caching CMMs share the same local cryptographic cache.
   * By default, the entries for each CMM are cached separately. However, if you want these CMMs to share the cache,
   * use the same partition name for both caching CMMs.
   * If you don't supply a partition name, the Encryption SDK generates a random name for each caching CMM.
   * As a result, sharing elements in the cache MUST be an intentional operation.
   */
  const partition = 'local partition name'

  /* maxAge is the time in milliseconds that an entry will be cached.
   * Elements are actively removed from the cache.
   */
  const maxAge = 1000 * 60

  /* The maximum amount of bytes that will be encrypted under a single data key.
   * This value is optional,
   * but you should configure the lowest value possible.
   */
  const maxBytesEncrypted = 100

  /* The maximum number of messages that will be encrypted under a single data key.
   * This value is optional,
   * but you should configure the lowest value possible.
   */
  const maxMessagesEncrypted = 10

  const cachingCMM = new NodeCachingMaterialsManager({
    backingMaterials: keyring,
    cache,
    partition,
    maxAge,
    maxBytesEncrypted,
    maxMessagesEncrypted,
  })

  /* Encryption context is a *very* powerful tool for controlling
   * and managing access.
   * When you pass an encryption context to the encrypt function,
   * the encryption context is cryptographically bound to the ciphertext.
   * If you don't pass in the same encryption context when decrypting,
   * the decrypt function fails.
   * The encryption context is ***not*** secret!
   * Encrypted data is opaque.
   * You can use an encryption context to assert things about the encrypted data.
   * The encryption context helps you to determine
   * whether the ciphertext you retrieved is the ciphertext you expect to decrypt.
   * For example, if you are are only expecting data from 'us-west-2',
   * the appearance of a different AWS Region in the encryption context can indicate malicious interference.
   * See: https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#encryption-context
   *
   * Also, cached data keys are reused ***only*** when the encryption contexts passed into the functions are an exact case-sensitive match.
   * See: https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/data-caching-details.html#caching-encryption-context
   */
  const encryptionContext = {
    stage: 'demo',
    purpose: 'simple demonstration app',
    origin: 'us-west-2',
  }

  /* Find data to encrypt.  A simple string. */
  const cleartext = 'asdf'

  /* Encrypt the data.
   * The caching CMM only reuses data keys
   * when it know the length (or an estimate) of the plaintext.
   * If you do not know the length,
   * because the data is a stream
   * provide an estimate of the largest expected value.
   *
   * If your estimate is smaller than the actual plaintext length
   * the AWS Encryption SDK will throw an exception.
   *
   * If the plaintext is not a stream,
   * the AWS Encryption SDK uses the actual plaintext length
   * instead of any length you provide.
   */
  const { result } = await encrypt(cachingCMM, cleartext, {
    encryptionContext,
    plaintextLength: 4,
  })

  /* Decrypt the data.
   * NOTE: This decrypt request will not use the data key
   * that was cached during the encrypt operation.
   * Data keys for encrypt and decrypt operations are cached separately.
   */
  const { plaintext, messageHeader } = await decrypt(cachingCMM, result)

  /* Grab the encryption context so you can verify it. */
  const { encryptionContext: decryptedContext } = messageHeader

  /* Verify the encryption context.
   * If you use an algorithm suite with signing,
   * the Encryption SDK adds a name-value pair to the encryption context that contains the public key.
   * Because the encryption context might contain additional key-value pairs,
   * do not include a test that requires that all key-value pairs match.
   * Instead, verify that the key-value pairs that you supplied to the `encrypt` function are included in the encryption context that the `decrypt` function returns.
   */
  Object.entries(encryptionContext).forEach(([key, value]) => {
    if (decryptedContext[key] !== value)
      throw new Error('Encryption Context does not match expected values')
  })

  /* Return the values so the code can be tested. */
  return { plaintext, result, cleartext, messageHeader }
}

Python


# Copyright 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file is
# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
# ANY KIND, either express or implied. See the License for the specific
# language governing permissions and limitations under the License.
"""Example of encryption with data key caching."""
import aws_encryption_sdk
from aws_encryption_sdk import CommitmentPolicy


def encrypt_with_caching(kms_key_arn, max_age_in_cache, cache_capacity):
    """Encrypts a string using an &KMS; key and data key caching.

    :param str kms_key_arn: Amazon Resource Name (ARN) of the &KMS; key
    :param float max_age_in_cache: Maximum time in seconds that a cached entry can be used
    :param int cache_capacity: Maximum number of entries to retain in cache at once
    """
    # Data to be encrypted
    my_data = "My plaintext data"

    # Security thresholds
    #   Max messages (or max bytes per) data key are optional
    MAX_ENTRY_MESSAGES = 100

    # Create an encryption context
    encryption_context = {"purpose": "test"}

    # Set up an encryption client with an explicit commitment policy. Note that if you do not explicitly choose a
    # commitment policy, REQUIRE_ENCRYPT_REQUIRE_DECRYPT is used by default.
    client = aws_encryption_sdk.EncryptionSDKClient(commitment_policy=CommitmentPolicy.REQUIRE_ENCRYPT_REQUIRE_DECRYPT)

    # Create a master key provider for the &KMS; key
    key_provider = aws_encryption_sdk.StrictAwsKmsMasterKeyProvider(key_ids=[kms_key_arn])

    # Create a local cache
    cache = aws_encryption_sdk.LocalCryptoMaterialsCache(cache_capacity)

    # Create a caching CMM
    caching_cmm = aws_encryption_sdk.CachingCryptoMaterialsManager(
        master_key_provider=key_provider,
        cache=cache,
        max_age=max_age_in_cache,
        max_messages_encrypted=MAX_ENTRY_MESSAGES,
    )

    # When the call to encrypt data specifies a caching CMM,
    # the encryption operation uses the data key cache specified
    # in the caching CMM
    encrypted_message, _header = client.encrypt(
        source=my_data, materials_manager=caching_cmm, encryption_context=encryption_context
    )

    return encrypted_message

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Convenciones del documento

Almacenamiento en caché de claves de datos

Configuración de los umbrales de seguridad de la caché