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<?php namespace Laravel; defined('DS') or die('No direct script access.');
class Crypter {
/**
* The encryption cipher.
*
* @var string
*/
public static $cipher = MCRYPT_RIJNDAEL_256;
/**
* The encryption mode.
*
* @var string
*/
public static $mode = MCRYPT_MODE_CBC;
/**
* The block size of the cipher.
*
* @var int
*/
public static $block = 32;
/**
* Encrypt a string using Mcrypt.
*
* The string will be encrypted using the AES-256 scheme and will be base64 encoded.
*
* @param string $value
* @return string
*/
public static function encrypt($value)
{
$iv = mcrypt_create_iv(static::iv_size(), static::randomizer());
$value = static::pad($value);
$value = mcrypt_encrypt(static::$cipher, static::key(), $value, static::$mode, $iv);
return base64_encode($iv.$value);
}
/**
* Decrypt a string using Mcrypt.
*
* @param string $value
* @return string
*/
public static function decrypt($value)
{
$value = base64_decode($value);
// To decrypt the value, we first need to extract the input vector and
// the encrypted value. The input vector size varies across different
// encryption ciphers and modes, so we'll get the correct size.
$iv = substr($value, 0, static::iv_size());
$value = substr($value, static::iv_size());
// Once we have the input vector and the value, we can give them both
// to Mcrypt for decryption. The value is sometimes padded with \0,
// so we will trim all of the padding characters.
$key = static::key();
$value = mcrypt_decrypt(static::$cipher, $key, $value, static::$mode, $iv);
return static::unpad($value);
}
/**
* Get the most secure random number generator for the system.
*
* @return int
*/
public static function randomizer()
{
// There are various sources from which we can get random numbers
// but some are more random than others. We'll choose the most
// random source we can for this server environment.
if (defined('MCRYPT_DEV_URANDOM'))
{
return MCRYPT_DEV_URANDOM;
}
elseif (defined('MCRYPT_DEV_RANDOM'))
{
return MCRYPT_DEV_RANDOM;
}
// When using the default random number generator, we'll seed
// the generator on each call to ensure the results are as
// random as we can possibly get them.
else
{
mt_srand();
return MCRYPT_RAND;
}
}
/**
* Get the input vector size for the cipher and mode.
*
* @return int
*/
protected static function iv_size()
{
return mcrypt_get_iv_size(static::$cipher, static::$mode);
}
/**
* Add PKCS7 compatible padding on the given value.
*
* @param string $value
* @return string
*/
protected static function pad($value)
{
$pad = static::$block - (Str::length($value) % static::$block);
return $value .= str_repeat(chr($pad), $pad);
}
/**
* Remove the PKCS7 compatible padding from the given value.
*
* @param string $value
* @return string
*/
protected static function unpad($value)
{
$pad = ord($value[($length = Str::length($value)) - 1]);
if ($pad and $pad < static::$block)
{
// If the correct padding is present on the string, we will remove
// it and return the value. Otherwise, we'll throw an exception
// as the padding appears to have been changed.
if (preg_match('/'.chr($pad).'{'.$pad.'}$/', $value))
{
return substr($value, 0, $length - $pad);
}
// If the padding characters do not match the expected padding
// for the value we'll bomb out with an exception since the
// encrypted value seems to have been changed.
else
{
throw new \Exception("Decryption error. Padding is invalid.");
}
}
return $value;
}
/**
* Get the encryption key from the application configuration.
*
* @return string
*/
protected static function key()
{
return Config::get('application.key');
}
}
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