Componente Crypt

Resumen

NOTE: Requires PHP’s openssl extension to be present in the system

DOES NOT support insecure algorithms with modes:

des*, rc2*, rc4*, des*, *ecb

Phalcon provides encryption facilities via the Phalcon\Crypt component. This class offers simple object-oriented wrappers to the openssl PHP’s encryption library.

By default, this component utilizes the AES-256-CFB cipher.

The cipher AES-256 is used among other places in SSL/TLS across the Internet. It’s considered among the top ciphers. In theory it’s not crackable since the combinations of keys are massive. Although NSA has categorized this in Suite B, they have also recommended using higher than 128-bit keys for encryption.

NOTE: You must use a key length corresponding to the current algorithm. For the default algorithm aes-256-cfb the default key length is 32 bytes.

Uso básico

This component is designed to be very simple to use:

<?php

use Phalcon\Crypt;

$key = "12345"; // Your luggage combination

$crypt     = new Crypt();
$text      = 'This is the text that you want to encrypt.';
$encrypted = $crypt->encrypt($text, $key);

echo $crypt->decrypt($encrypted, $key);

If no parameters are passed in the constructor, the component will use the aes-256-cfb cipher with signing by default. You can always change the cipher as well as disable signing.

<?php

use Phalcon\Crypt;

$key = "12345"; // Your luggage combination

$crypt     = new Crypt();

$crypt
    ->setCipher('aes-256-gcm')
    ->useSigning(false)
;

$text      = 'This is the text that you want to encrypt.';
$encrypted = $crypt->encrypt($text, $key);

echo $crypt->decrypt($encrypted, $key);

Encrypt

The encrypt() method encrypts a string. The component will use the previously set cipher, which has been set in the constructor or explicitly. If no key is passed in the parameter, the previously set key will be used.

<?php

use Phalcon\Crypt;

$key = "12345"; // Your luggage combination

$crypt = new Crypt();
$crypt->setKey($key);

$text      = 'This is the text that you want to encrypt.';
$encrypted = $crypt->encrypt($text);

or using the key as the second parameter

<?php

use Phalcon\Crypt;

$key = "12345"; // Your luggage combination

$crypt     = new Crypt();
$text      = 'This is the text that you want to encrypt.';
$encrypted = $crypt->encrypt($text, $key);

The method will also internally use signing by default. You can always use useSigning(false) prior to the method call to disable it.

Decrypt

The decrypt() method decrypts a string. Similar to encrypt() the component will use the previously set cipher, which has been set in the constructor or explicitly. If no key is passed in the parameter, the previously set key will be used.

<?php

use Phalcon\Crypt;

$key = "12345"; // Your luggage combination

$crypt = new Crypt();
$crypt->setKey($key);

$text      = 'T4\xb1\x8d\xa9\x98\x05\\\x8c\xbe\x1d\x07&[\x99\x18\xa4~Lc1\xbeW\xb3';
$encrypted = $crypt->decrypt($text);

or using the key as the second parameter

<?php

use Phalcon\Crypt;

$key = "12345"; // Your luggage combination

$crypt     = new Crypt();
$crypt->setKey($key);

$text      = 'T4\xb1\x8d\xa9\x98\x05\\\x8c\xbe\x1d\x07&[\x99\x18\xa4~Lc1\xbeW\xb3';
$encrypted = $crypt->decrypt($text, $key);

The method will also internally use signing by default. You can always use useSigning(false) prior to the method call to disable it.

Base64 Encrypt

The encryptBase64() can be used to encrypt a string in a URL friendly way. It uses encrypt() internally and accepts the text and optionally the key of the element to encrypt. There is also a third parameter safe (defaults to false) which will perform string replacements for non URL friendly characters such as + or /.

Base64 Decrypt

The decryptBase64() can be used to decrypt a string in a URL friendly way. Similar to encryptBase64() it uses decrypt() internally and accepts the text and optionally the key of the element to encrypt. There is also a third parameter safe (defaults to false) which will perform string replacements for previously replaced non URL friendly characters such as + or /.

Exceptions

Exceptions thrown in the Phalcon\Crypt component will be of type [Phalcon\Crypt\Exception][config-exception]. If however you are using signing and the calculated hash for decrypt() does not match, Phalcon\Crypt\Mismatch will be thrown. You can use these exceptions to selectively catch exceptions thrown only from this component.

<?php

use Phalcon\Crypt\Mismatch;
use Phalcon\Mvc\Controller;

class IndexController extends Controller
{
    public function index()
    {
        try {
            // Get some configuration values
            $this->crypt->decrypt('hello');
        } catch (Mismatch $ex) {
            echo $ex->getMessage();
        }
    }
}

Functionality

Ciphers

The getter getCipher() returns the currently selected cipher. If none has been explicitly defined either by the setter setCipher() or the constructor of the object the aes-256-cfb is selected by default. The aes-256-gcm is the preferable cipher.

You can always get an array of all the available ciphers for your system by calling getAvailableCiphers().

Hash Algorithm

The getter getHashAlgo() returns the hashing algorithm use by the component. If none has been explicitly defined by the setter setHashAlgo() the sha256 will be used. If the hash algorithm defined is not available in the system or is wrong, a [Phalcon\Crypt\Exception][crypt=exception] will be thrown.

You can always get an array of all the available hashing algorithms for your system by calling getAvailableHashAlgos().

Keys

The component offers a getter and a setter for the key to be used. Once the key is set, it will be used for any encrypting or decrypting operation (provided that the key parameter is not defined when using these methods).

• getKey(): Returns the encryption key.
• setKey() Sets the encryption key.

You should always create as secure keys as possible. 12345 might be good for your luggage combination, or password1 for your email, but for your application you should try something a lot more complex. The longer and more random the key is the better. The length of course depends on the chosen cipher.

Several online services can generate a random and strong text that can be used for a key. Alternatively you can always use the hash() methods from the Phalcon\Security component, which can offer a strong key by hashing a string.

Signing

To instruct the component to use signing or not, useSigning is available. It accepts a boolean which sets a flag internally, specifying whether signing will be used or not.

Auth Data

If the cipher selected is of type gcm or ccm (what the cipher name ends with), auth data is required for the component to correctly encrypt or decrypt data. The methods available for this operation are:

• setAuthTag()
• setAuthData()
• setAuthTagLength() - defaults to 16

Padding

You can also set the padding used by the component by using setPadding(). By default the component will use PADDING_DEFAULT. The available padding constants are:

• PADDING_ANSI_X_923
• PADDING_DEFAULT
• PADDING_ISO_10126
• PADDING_ISO_IEC_7816_4
• PADDING_PKCS7
• PADDING_SPACE
• PADDING_ZERO

Inyección de Dependencias

As with most Phalcon components, you can store the Phalcon\Crypt object in your Phalcon\Di container. By doing so, you will be able to access your configuration object from controllers, models, views and any component that implements Injectable.

An example of the registration of the service as well as accessing it is below:

<?php

use Phalcon\Di\FactoryDefault;
use Phalcon\Crypt;

// Create a container
$container = new FactoryDefault();

$container->set(
    'crypt',
    function () {
        $crypt = new Crypt();

        // Set a global encryption key
        $crypt->setKey(
            "T4\xb1\x8d\xa9\x98\x05\\\x8c\xbe\x1d\x07&[\x99\x18\xa4~Lc1\xbeW\xb3"
        );

        return $crypt;
    },
    true
);

The component is now available in your controllers using the crypt key

<?php

use MyApp\Models\Secrets;
use Phalcon\Crypt;
use Phalcon\Http\Request;
use Phalcon\Mvc\Controller;

/**
 * @property Crypt   $crypt
 * @property Request $request
 */
class SecretsController extends Controller
{
    public function saveAction()
    {
        $secret = new Secrets();

        $text = $this->request->getPost('text');

        $secret->content = $this->crypt->encrypt($text);

        if ($secret->save()) {
            $this->flash->success(
                'Secret was successfully created!'
            );
        }
    }
}

Enlaces

• Advanced Encryption Standard (AES)
• What is block cipher
• Introduction to Blowfish
• CTR-Mode Encryption
• Recommendation for Block Cipher Modes of Operation: Methods and Techniques
• Counter (CTR) mode