Encryption

encryption.php

<?php
class Crypto {
  /**
     * Encrypt using 3DES
     *
     * @param string $clear clear text input
     * @param string $key encryption key to retrieve from the configuration, defaults to 'des_key'
     * @param boolean $base64 whether or not to base64_encode() the result before returning
     *
     * @return string encrypted text
     */
    public function encrypt($clear, $key = 'des_key', $base64 = true)
    {
        if (!$clear) {
            return '';
        }

        /*-
         * Add a single canary byte to the end of the clear text, which
         * will help find out how much of padding will need to be removed
         * upon decryption; see http://php.net/mcrypt_generic#68082
         */
        $clear = pack("a*H2", $clear, "80");

        if (function_exists('mcrypt_module_open') &&
            ($td = mcrypt_module_open(MCRYPT_TripleDES, "", MCRYPT_MODE_CBC, ""))
        ) {
            $iv = $this->create_iv(mcrypt_enc_get_iv_size($td));
            mcrypt_generic_init($td, $this->config->get_crypto_key($key), $iv);
            $cipher = $iv . mcrypt_generic($td, $clear);
            mcrypt_generic_deinit($td);
            mcrypt_module_close($td);
        }
        else {
            @include_once 'des.inc';

            if (function_exists('des')) {
                $des_iv_size = 8;
                $iv = $this->create_iv($des_iv_size);
                $cipher = $iv . des($this->config->get_crypto_key($key), $clear, 1, 1, $iv);
            }
            else {
                self::raise_error(array(
                    'code' => 500, 'type' => 'php',
                    'file' => __FILE__, 'line' => __LINE__,
                    'message' => "Could not perform encryption; make sure Mcrypt is installed or lib/des.inc is available"
                    ), true, true);
            }
        }

        return $base64 ? base64_encode($cipher) : $cipher;
    }


    /**
     * Decrypt 3DES-encrypted string
     *
     * @param string $cipher encrypted text
     * @param string $key encryption key to retrieve from the configuration, defaults to 'des_key'
     * @param boolean $base64 whether or not input is base64-encoded
     *
     * @return string decrypted text
     */
    public function decrypt($cipher, $key = 'des_key', $base64 = true)
    {
        if (!$cipher) {
            return '';
        }

        $cipher = $base64 ? base64_decode($cipher) : $cipher;

        if (function_exists('mcrypt_module_open') &&
            ($td = mcrypt_module_open(MCRYPT_TripleDES, "", MCRYPT_MODE_CBC, ""))
        ) {
            $iv_size = mcrypt_enc_get_iv_size($td);
            $iv = substr($cipher, 0, $iv_size);

            // session corruption? (#1485970)
            if (strlen($iv) < $iv_size) {
                return '';
            }

            $cipher = substr($cipher, $iv_size);
            mcrypt_generic_init($td, $this->config->get_crypto_key($key), $iv);
            $clear = mdecrypt_generic($td, $cipher);
            mcrypt_generic_deinit($td);
            mcrypt_module_close($td);
        }
        else {
            @include_once 'des.inc';

            if (function_exists('des')) {
                $des_iv_size = 8;
                $iv = substr($cipher, 0, $des_iv_size);
                $cipher = substr($cipher, $des_iv_size);
                $clear = des($this->config->get_crypto_key($key), $cipher, 0, 1, $iv);
            }
            else {
                self::raise_error(array(
                    'code' => 500, 'type' => 'php',
                    'file' => __FILE__, 'line' => __LINE__,
                    'message' => "Could not perform decryption; make sure Mcrypt is installed or lib/des.inc is available"
                    ), true, true);
            }
        }

        /*-
         * Trim PHP's padding and the canary byte; see note in
         * rcube::encrypt() and http://php.net/mcrypt_generic#68082
         */
        $clear = substr(rtrim($clear, "\0"), 0, -1);

        return $clear;
    }


    /**
     * Generates encryption initialization vector (IV)
     *
     * @param int Vector size
     *
     * @return string Vector string
     */
    private function create_iv($size)
    {
        // mcrypt_create_iv() can be slow when system lacks entrophy
        // we'll generate IV vector manually
        $iv = '';
        for ($i = 0; $i < $size; $i++) {
            $iv .= chr(mt_rand(0, 255));
        }

        return $iv;
    }
}
}