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Security Utility

.. php:namespace:: Cake\Utility


.. php:class:: Security

The security library handles basic security measures such as providing methods for hashing and encrypting data.

Encrypting and Decrypting Data

.. php:staticmethod:: encrypt($text, $key, $hmacSalt = null)

.. php:staticmethod:: decrypt($cipher, $key, $hmacSalt = null)

Encrypt $text using AES-256. The $key should be a value with a lots of variance in the data much like a good password. The returned result will be the encrypted value with an HMAC checksum.

The openssl extension is required for encrypting/decrypting.

An example use would be:

// Assuming key is stored somewhere it can be re-used for
// decryption later.
$key = 'wt1U5MACWJFTXGenFoZoiLwQGrLgdbHA';
$result = Security::encrypt($value, $key);

If you do not supply an HMAC salt, the value of Security::getSalt() will be used. Encrypted values can be decrypted using :php:meth:`Cake\\Utility\\Security::decrypt()`.

This method should never be used to store passwords.

Decrypt a previously encrypted value. The $key and $hmacSalt parameters must match the values used to encrypt or decryption will fail. An example use would be:

// Assuming the key is stored somewhere it can be re-used for
// Decryption later.
$key = 'wt1U5MACWJFTXGenFoZoiLwQGrLgdbHA';

$cipher = $user->secrets;
$result = Security::decrypt($cipher, $key);

If the value cannot be decrypted due to changes in the key or HMAC salt false will be returned.

Hashing Data

.. php:staticmethod:: hash( $string, $type = NULL, $salt = false )

Create a hash from string using given method. Fallback on next available method. If $salt is set to true, the application's salt value will be used:

// Using the application's salt value
$sha1 = Security::hash('CakePHP Framework', 'sha1', true);

// Using a custom salt value
$sha1 = Security::hash('CakePHP Framework', 'sha1', 'my-salt');

// Using the default hash algorithm
$hash = Security::hash('CakePHP Framework');

The hash() method supports the following hashing strategies:

  • md5
  • sha1
  • sha256

And any other hash algorithm that PHP's hash() function supports.

Warning

You should not be using hash() for passwords in new applications. Instead you should use the DefaultPasswordHasher class which uses bcrypt by default.

Getting Secure Random Data

.. php:staticmethod:: randomBytes($length)

Get $length number of bytes from a secure random source. This function draws data from one of the following sources:

  • PHP's random_bytes function.
  • openssl_random_pseudo_bytes from the SSL extension.

If neither source is available a warning will be emitted and an unsafe value will be used for backwards compatibility reasons.

.. php:staticmethod:: randomString($length)

Get a random string $length long from a secure random source. This method draws from the same random source as randomBytes() and will encode the data as a hexadecimal string.