/RNA/crypt.php

<?php

define("MODE_ECB",0);

define("MODE_CBC",1);



/**

  * An abstract layer class to encrypt data.

  *

  * This class is class is used to encrypt and decrypt data using different algorithms

  * and modes.

  *

  * @author  Igor Ribeiro de Assis <igor21@terra.com.br>

  * @version 1.0-beta

  * @access  public

  * @package Perfect Crypt

  */



class pcrypt

{

    /** Encryption Block Mode: ECB, CBC actually.

      *

      * @var    int the mode used 

      * @access private

      */

    var $blockmode = MODE_ECB;

    

    /** Key for Encryption

      *

      * @var    string the key used in encryption and decryption

      * @access public

      */

    var $key = null;



    /** IV - Initialization Vector String

      *

      * @var    string initialization vector for some modes (CBC)

      * @access public

      */

    var $iv  = "z4c8e7gh"; 

    

    /** Methods */

    

    /** Constructor of the class.

      * 

      * The constructor initialize some important vars and include the algorithm

      * file.

      *

      * @access public

      * @param  int $blockmode the blockmode to use

      * @param  string $cipher the algorithm used to crypt

      * @param  string $key the ley used to crypt

      * 

      * @return void

      */

    

    function pcrypt($blockmode = MODE_ECB, $cipher = 'BLOWFISH', $key = null, $array = false)

    {

        // Include cipher_class file

        $cipher = strtolower($cipher);

        if (!file_exists("./cipher/".$cipher.".php")) 

        {

            $this->error("Unknown Cipher ".$cipher);

        }

        include_once "./cipher/".$cipher.".php";

        

        // Load cipher_class

        if (!class_exists("pcrypt_".$cipher))

        {

            $this->error("Class pcrypt_".$cipher." doesn't exists");

        }

        

        $class  = "pcrypt_".$cipher;

        $this->cipher = new $class($key, $array);

        

        // Initialize Vars

        $this->blockmode = $blockmode;

        $this->key = $key;

    }

    

    /** Crypt data using the selected algorithm

      * 

      * This method encrypt data using the selected algorithm and mode:

      *    Algorithms: Blowfish

      *    Modes: ECB, CBC

      * For a description about algorithms and modes see: 

      * Applied Cryptography by Bruce Schneier

      *

      * @access public

      * @param  string $plain  the plain text to be encrypted

      * @return string $cipher the plain text encrypted

      */

    function encrypt($plain)

    {

        if (empty($plain))

        {

            $this->error("Empty Plain Text");

        }

        

        // Encrypt using the correct mode

        switch($this->blockmode) {

        case MODE_ECB:

            $cipher = $this->_ecb_encrypt($plain);

            break;

        

        case MODE_CBC:

            $cipher = $this->_cbc_encrypt($plain);

            break;



        default:

            $this->error("Invalid mode ".$this->blockmode);

        }

        

        return $cipher;

    }



    /** Decrypt using the selected algorithm

      *

      * This method decrypt data using the selected algorithm and mode.

      * TODO: Discover the algorithm and mode auto

      *

      * @access public

      * @param  string $cipher the crypted data to be decrypted

      * @return string $plain  the cipher text decrypted

      */

    function decrypt($cipher)

    {

        if (empty($cipher))

        {

            $this->error("Invalid Cipher Text");

        }

        

        // Decrypt with the correct mode        

        switch($this->blockmode) {

        case MODE_ECB:

            $plain = $this->_ecb_decrypt($cipher);

            break;

        

        case MODE_CBC:

            $plain = $this->_cbc_decrypt($cipher);

            break;



        default:

            $this->error("Invalid mode ".$this->blockmode);

        }

        

        return $plain;

    }

    

    function getlen($len){

    	if(method_exists($this->cipher, "_getlen"))

    		return $this->cipher->_getlen($len);    		

    	

    	return -1;

    }

    

    /** Method to encrypt using ECB mode.

      * 

      * In ECB mode the blocks are encrypted independently 

      *

      * @access private

      * @param  string $plain  the plain text to be encrypted

      * @return string $cipher the plain text encrypted

      */

    function _ecb_encrypt($plain)

    {

        $blocksize = $this->cipher->blocksize;

        $plainsize = strlen($plain);

        $cipher    = array();

       

        for($i = 0;$i < $plainsize;$i = $i + $blocksize)

        {

            $block = substr($plain,$i,$blocksize); 

            

            while(strlen($block) < $blocksize)

            {

                // pad block with '\0'

                $block .= "\0";

            }

            $cipher = array_merge($cipher, $this->cipher->_encrypt($block));

        }

        

        return $cipher;

    }

    

    /** Method to decrypt using ECB mode.

      *

      * @access private

      * @param  string $cipher the cipher text

      * @return string $plain  the cipher text decrypted

      */

    function _ecb_decrypt($cipher)

    {

        $blocksize  = $this->cipher->blocksize;

        $ciphersize = strlen($cipher);

        $plain      = array(); 

        

        for($i = 0;$i < $ciphersize;$i = $i + $blocksize)

        {

            $block = substr($cipher,$i,$blocksize); 

            $block = $this->cipher->_decrypt($block);

            

            // Remove padded chars 

            for($n = 0; $n < $blocksize; $n++){

            	if($block[$n] == "\0")

                	$block[$n] = 0;

            }

            $plain = array_merge($plain, $block);

        }

        

        return $plain;

    }

    

    /** This method encrypt using CBC mode.

      *

      * In CBC mode each block is xored with the last. This function use $iv as

      * first block.

      *

      * @access private

      * @param  string $plain  the plain text to be decrypted

      * @return string $cipher the plain text encrypted

      */

    function _cbc_encrypt($plain)

    {

        $blocksize = $this->cipher->blocksize;

        $plainsize = strlen($plain);

        $cipher    = '';

        $lcipher   = $this->iv;

        

        // encrypt each block

        for($i = 0;$i < $plainsize;$i = $i + $blocksize)

        {

            $block = substr($plain,$i,$blocksize); 

            if(strlen($block) < $blocksize)

            {

                // pad block with '\0' 

                $block = str_pad($block,$blocksize,"\0",STR_PAD_LEFT);

            }

            // crypt the block xored with the last cipher block

            $lcipher = $this->cipher->_encrypt($block ^ $lcipher);

            $cipher .= $lcipher;

        }

        

        return $cipher;

    }

    

    /** This method decrypt using CBC.

      *

      * @access private

      * @param  string $cipher the cipher text

      * @return string $plain  the cipher text decrypted

      */

    function _cbc_decrypt($cipher)

    {

        // get the block size of the cipher

        $blocksize  = $this->cipher->blocksize;

        $ciphersize = strlen($cipher);

        $plain      = '';

        $lcipher    = $this->iv;

        

        for($i = 0;$i < $ciphersize;$i = $i + $blocksize)

        {

            $block   = substr($cipher,$i,$blocksize); 

            

            // xor the block with the last cipher block

            $dblock  = $lcipher ^ $this->cipher->_decrypt($block);

            $lcipher = $block;

            

            // Remove padded chars 

            while(substr($dblock,0,1) == "\0")

            {

                $dblock = substr($dblock,1);

            }

            $plain .= $dblock;

        }

        

        return $plain;

    }

    

    /**

      * A simple function for error handling.

      * 

      * TODO: Improve the error handling of the class 

      *

      * @access private

      * @param  string $message erro message

      * @return boolean true

      */

    function error($message)

    {

        echo "Error: ".$message."<br>";       



        return 1;

    }

}

?>