Sometimes two way encryption is very much important when it comes in storing credential information. Credit Card, Bank account information, digital signature etc are very important information of user and strongly discouraged to store in plain text. These data should always be stored in encrypted format. PCI has a very strict guideline and policy for storing Credit Card Information in database or file.

This class is very handy to solve this type of situation.

Features:

- Simple & Easy to use from anywhere in your application with a single line of code.
- Easily configurable & can work without any configuration.
- Support multiple salt configurations
- Requires PHP Mcrypt library installed
- Static method for encryption and decryption
- Light Weight

Method:

- RayCrypt::encrypt();
- RayCrypt::decrypt();
- RayCrypt::config();
- RayCrypt::padString();

Class:

File: raycrypt.php

<?php
/**
 * Two way Encryption and Decryption Class.
 *
 * Suitable for storing credential information like credit card, bank account information into the database
 *
 * PHP version 5+
 * - require Mcrypt library installed
 *
 * @package     raynux
 * @subpackage  raynux.labs.crypt
 * @version     1.0
 * @author	Md. Rayhan Chowdhury
 * @license     MIT License http://www.opensource.org/licenses/mit-license.php
 */

/**
 * Encrypt & Decrypt Using PHP MCrypt Library
 *
 * @package     raynux
 * @subpackage  raynux.labs.crypt
 * @author      Md. Rayhan Chowdhury
 */
class RayCrypt{

    /**
     * RayCrypt Instances
     *
     * @var RayCrypt
     */
    protected static $_instances = array();

    /**
     * Secret Salt generated from the key
     *
     * @var string
     */
    protected $_secretKey;

    /**
     * Default Configuration Array
     *
     * @var array
     */
    protected $_defaults = array(
                                    'returnPlainText' => true,
                                    'salt' => '7$e4!158f6$%#be533.!@a066!#35428^#%&$*&faa91:!982*#!e07'
                                );

    /**
     * Hold Run-time configuration
     *
     * @var array
     */
    protected $_configs = array();

    /**
     * Class Constructor
     *
     * @param array $options
     */
    private function __construct($options = null) {
        $this->_setConfig($options);
    }

    /**
     * Get Instance of RayCrypt
     *
     * @param string $configName
     * @param array $options
     * @return RayCrypt
     */
    private static function &_getInstance($configName = null, $options = null) {

        if (empty($configName)) {
            $configName = 'default';
        }

        if (empty(self::$_instances[$configName])) {
            self::$_instances[$configName] = new self($options);
        }

        return self::$_instances[$configName];
    }

    /**
     * Configure the class instance
     *
     * @param array $options  array('salt' => '', 'returnPlainText' => true)
     * @return RayCrypt
     */
    protected function &_setConfig($options = null) {

        if (empty($options) || !is_array($options)) {
            $options = array();
        }

        $this->_configs = array_merge($this->_defaults, $options);

        if (!empty($this->_configs['salt'])) {
            $this->_setSecretKey($this->_configs['salt']);
        }

        return $this;
    }

    /**
     * Set secret salt for encryption algorithm
     * @param string $key
     * @return RayCrypt
     * @access protected
     */
    protected function &_setSecretKey($key) {
        $this->_secretKey = md5(substr(sha1($key), 0, 32));
        return $this;
    }

    /**
     *
     * @param  $configName
     * @param  $options
     */
    public static function config($configName, $options = null) {
        $_this = self::_getInstance($configName, $options);
    }

    /**
     * Encrypt using Mcrypt PHP Library
     *
     * @param string $value
     * @param string $configName
     * @return string
     * @access public
     * @static
     */
    public static function encrypt($value, $configName = null) {

        $_this = self::_getInstance($configName);
        $key = $_this->_secretKey;

        $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
        $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
        $encryped = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $value, MCRYPT_MODE_ECB, $iv);
        if (!empty($_this->_configs['returnPlainText'])) {
            $encryped = base64_encode($encryped);
        }

        return $encryped;
    }

    /**
     * Decrypt Using Mcrypt
     *
     * @param string $value
     * @param string $configName
     * @return string
     * @access public
     * @static
     */
    public static function decrypt($value, $configName = null) {
        $_this = self::_getInstance($configName);
        $key = $_this->_secretKey;

        if (!empty($_this->_configs['returnPlainText'])) {
            $value = base64_decode($value);
        }

        $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
        $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
        return rtrim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $value, MCRYPT_MODE_ECB, $iv), "\0\4");
    }

    /**
     * Masks Important Information Padding String
     *
     * helpful in displaying a part of credit card information like
     * 01234567890 will result xxxxxxx7890
     *
     * @param string $string
     * @param integer $length specify negative length to mask from backward
     * @param mask character $maskCharacter
     * @return string
     * @access public
     * @static
     */
    public static function padString($string, $length, $maskCharacter = 'X') {
        $maskString = substr($string, 0, $length);
        $maskString = preg_replace('(.)', $maskCharacter, $maskString);
        $string = $maskString . substr($string, $length);
        return $string;
    }

}

?>

Usage Example: some quick examples are given below to introduce you with the class and it’s methods.

<?php
/**
 * RayCrypt Example File
 */

/**
 * Load RayCrypt Library
 */
include_once 'raycrypt.php';

/**
 * Basic debug function
 *
 * @param mixed $value
 */
function dump ($value) {
    printf('<pre>%s</pre>', var_export($value, true));
};

/**
 * Use RayCrypt without any configuration, it uses default configuration
 */
$data = 'My important data';
$encrypted = RayCrypt::encrypt($data);
$decrypted = RayCrypt::decrypt($encrypted);
dump(array('data' => $data, 'encrypted' => $encrypted, 'decrypted' => $decrypted));

/**
 * Output
 array (
  'data' => 'My important data',
  'encrypted' => 'JBtn3msE0QIAei/v9oHP5nW2xasbdSeVhAb4nPXqiUA=',
  'decrypted' => 'My important data',
)
 */

/**
 * Use RayCrypt with a separate configuration salt for creditCard information
 */
RayCrypt::config('creditCard', array('salt' => 'jdfjsddfsdf!$#fjsdkjfsdfi7*@(@sdhf'));
$data = '01234567890';
$encrypted = RayCrypt::encrypt($data, 'creditCard');
$decrypted = RayCrypt::decrypt($encrypted, 'creditCard');
dump(array('data' => $data, 'encrypted' => $encrypted, 'decrypted' => $decrypted));

/**
 * Output
array (
  'data' => '01234567890',
  'encrypted' => 'E9FO62vScqmObOlIXso70Hx8JpEqzVOiac8yuk3/4yM=',
  'decrypted' => '01234567890',
)
 */

/**
 * Use RayCrypt with a another configuration for bank information
 */
RayCrypt::config('bank', array('salt' => 'Nothing wrong'));
$data = '884585847';
$encrypted = RayCrypt::encrypt($data, 'bank');
$decrypted = RayCrypt::decrypt($encrypted, 'bank');
dump(array('data' => $data, 'encrypted' => $encrypted, 'decrypted' => $decrypted));

/**
 * Output
array (
  'data' => '884585847',
  'encrypted' => 'BnDAjNJq/ZrwEKT9yLVFEVZO0b4/uu2AWRGVhX3mVRw=',
  'decrypted' => '884585847',
)
 */

dump(RayCrypt::padString('0123456789', -4)); // output 'XXXXXX6789'

?>

Please let me know if you find this class helpful for you..

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