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Filename : CBC.php
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<?php

/**
 * Class to emulate Perl's Crypt::CBC module
 *
 * Blowfish support that is compatable with Perl requires libmcrypt >= 2.4.9.
 * If you are using libmcrypt <= 2.4.8, Blowfish encryption will work,
 * but your data will not be readable by Perl scripts.  It will work
 * "internally" .. i.e. this class will be able to encode/decode the data.
 *
 * Blowfish support that is compatable with PHP applications using
 * libmcrypt <= 2.4.8 requies you to use 'BLOWFISH-COMPAT' when
 * specifying the cipher.  Check the libmcrypt docs when in doubt.
 *
 * This class no longer works with libmcrypt 2.2.x versions.
 *
 * NOTE: the cipher names in this class may change depending on how
 * the author of libcrypt decides to name things internally.
 *
 *
 * @category  Encryption
 * @package   Crypt_CBC
 * @author    Colin Viebrock <colin@viebrock.com>
 * @copyright 2002-2012 Colin Viebrock
 * @version   $Revision: 322853 $
 * @license   http://www.opensource.org/licenses/bsd-license.php BSD
 * @link      http://pear.php.net/package/Crypt_CBC
 */

require_once 'PEAR.php';

class Crypt_CBC extends PEAR {

    /**
    * supported procedures
    * @var array
    */
    var $known_ciphers = array (
        'DES'               => MCRYPT_DES,
        'BLOWFISH'          => MCRYPT_BLOWFISH,
        'BLOWFISH-COMPAT'   => MCRYPT_BLOWFISH_COMPAT,
    );

    /**
    * used cipher
    * @var string
    */
    var $cipher;

    /**
    * crypt resource, for 2.4.x
    * @var string
    */
    var $TD;

    /**
    * crypt deinit function, for backwards compatability
    * @var string
    */
    var $deinit_function;

    /**
    * blocksize of cipher
    * @var string
    */
    var $blocksize;

    /**
    * keysize of cipher
    * @var int
    */
    var $keysize;

    /**
    * mangled key
    * @var string
    */
    var $keyhash;

    /**
    * source type of the initialization vector for creation
    * possible types are MCRYPT_RAND or MCRYPT_DEV_URANDOM or MCRYPT_DEV_RANDOM
    * @var int
    */
    var $rand_source    = MCRYPT_RAND;

    /**
    * header
    * @var string
    */
    var $header_spec    = 'RandomIV';

    /**
    * debugging
    * @var string
    */
    var $_last_clear;

    /**
    * debugging
    * @var string
    */
    var $_last_crypt;

    /**
    * Constructor
    * $key is the key to use for encryption. $cipher can be DES, BLOWFISH or
    * BLOWFISH-COMPAT
    *
    * @param    $key        encryption key
    * @param    $cipher     which algorithm to use, defaults to DES
    *
    * @return   $return     either a PEAR error or true
    *
    * @access   public
    *
    */

    function Crypt_CBC ($key, $cipher='DES')
    {

        if (!extension_loaded('mcrypt')) {
            return $this->raiseError('mcrypt module is not compiled into PHP', null,
                PEAR_ERROR_DIE, null, 'compile PHP using "--with-mcrypt"' );
        }
        if (!function_exists('mcrypt_module_open')) {
            return $this->raiseError('libmcrypt version insufficient', null,
                PEAR_ERROR_DIE, null, 'this class requires libmcrypt >= 2.4.x, preferably >= 2.5.5' );
        }
        if (function_exists('mcrypt_generic_deinit')) {
			$this->deinit_function = 'mcrypt_generic_deinit';
		} else if (function_exists('mcrypt_generic_end')) {
			$this->deinit_function = 'mcrypt_generic_end';
		} else {
            return $this->raiseError('PHP version insufficient', null,
                PEAR_ERROR_DIE, null, 'this class requires PHP >= 4.0.2, preferably >= 4.1.1' );
        }


        /* initialize */

        $this->header_spec = 'RandomIV';

        /* check for key */

        if (!$key) {
            return $this->raiseError('no key specified');
        }

        /* check for cipher */

        $cipher = strtoupper($cipher);
        if (!isset($this->known_ciphers[$cipher])) {
            return $this->raiseError('unknown cipher "'.$cipher.'"' );
        }

        $this->cipher = $this->known_ciphers[$cipher];

        /* initialize cipher */

        $this->TD = mcrypt_module_open ($this->cipher, '', 'ecb', '');
        $this->blocksize = mcrypt_enc_get_block_size($this->TD);
        $this->keysize = mcrypt_enc_get_key_size($this->TD);

        /* mangle key with MD5 */

        $this->keyhash = $this->_md5perl($key);
        while( strlen($this->keyhash) < $this->keysize ) {
            $this->keyhash .= $this->_md5perl($this->keyhash);
        }

        $this->key = substr($this->keyhash, 0, $this->keysize);

        return true;

    }


    /**
    * Destructor
    *
    */

    function _Crypt_CBC ()
    {
        @mcrypt_module_close($this->TD);
    }


    /**
    * Encryption method
    *
    * @param    $clear      plaintext
    *
    * @return   $crypt      encrypted text, or PEAR error
    *
    * @access   public
    *
    */

    function encrypt($clear)
    {

        $this->last_clear = $clear;

        /* new IV for each message */

        $iv = mcrypt_create_iv($this->blocksize, $this->rand_source);

        /* create the message header */

        $crypt = $this->header_spec . $iv;

        /* pad the cleartext */

        $padsize = $this->blocksize - (strlen($clear) % $this->blocksize);
        $clear .= str_repeat(pack ('C*', $padsize), $padsize);


        /* do the encryption */

        $start = 0;
        while ( $block = substr($clear, $start, $this->blocksize) ) {
            $start += $this->blocksize;
            if (mcrypt_generic_init($this->TD, $this->key, $iv) < 0 ) {
                return $this->raiseError('mcrypt_generic_init failed' );
            }
            $cblock = mcrypt_generic($this->TD, $iv^$block );
            $iv = $cblock;
            $crypt .= $cblock;
            call_user_func($this->deinit_function, $this->TD);
        }

        $this->last_crypt = $crypt;
        return $crypt;

    }



    /**
    * Decryption method
    *
    * @param    $crypt      encrypted text
    *
    * @return   $clear      plaintext, or PEAR error
    *
    * @access   public
    *
    */

    function decrypt($crypt) {

        $this->last_crypt = $crypt;

        /* get the IV from the message header */

        $iv_offset = strlen($this->header_spec);
        $header = substr($crypt, 0, $iv_offset);
        $iv = substr ($crypt, $iv_offset, $this->blocksize);
        if ( $header != $this->header_spec ) {
            return $this->raiseError('no initialization vector');
        }

        $crypt = substr($crypt, $iv_offset+$this->blocksize);

        /* decrypt the message */

        $start = 0;
        $clear = '';

        while ( $cblock = substr($crypt, $start, $this->blocksize) ) {
            $start += $this->blocksize;
            if (mcrypt_generic_init($this->TD, $this->key, $iv) < 0 ) {
                return $this->raiseError('mcrypt_generic_init failed' );
            }
            $block = $iv ^ mdecrypt_generic($this->TD, $cblock);
            $iv = $cblock;
            $clear .= $block;
            call_user_func($this->deinit_function, $this->TD);
        }

        /* remove the padding from the end of the cleartext */

        $padsize = ord(substr($clear, -1));
        $clear = substr($clear, 0, -$padsize);

        $this->last_clear = $clear;
        return $clear;

    }



    /**
    * Emulate Perl's MD5 function, which returns binary data
    *
    * @param    $string     string to MD5
    *
    * @return   $hash       binary hash
    *
    * @access private
    *
    */

    function _md5perl($string)
    {
        return pack('H*', md5($string));
    }
}
?>