Subversion Repositories cheapmusic

<?php

/**

 * Pure-PHP implementation of Triple DES.

 *

 * Uses mcrypt, if available, and an internal implementation, otherwise.  Operates in the EDE3 mode (encrypt-decrypt-encrypt).

 *

 * PHP version 5

 *

 * Here's a short example of how to use this library:

 * <code>

 * <?php

 *    include 'vendor/autoload.php';

 *

 *    $des = new \phpseclib\Crypt\TripleDES();

 *

 *    $des->setKey('abcdefghijklmnopqrstuvwx');

 *

 *    $size = 10 * 1024;

 *    $plaintext = '';

 *    for ($i = 0; $i < $size; $i++) {

 *        $plaintext.= 'a';

 *    }

 *

 *    echo $des->decrypt($des->encrypt($plaintext));

 * ?>

 * </code>

 *

 * @category  Crypt

 * @package   TripleDES

 * @author    Jim Wigginton <terrafrost@php.net>

 * @copyright 2007 Jim Wigginton

 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License

 * @link      http://phpseclib.sourceforge.net

 */

namespace phpseclib\Crypt;

/**

 * Pure-PHP implementation of Triple DES.

 *

 * @package TripleDES

 * @author  Jim Wigginton <terrafrost@php.net>

 * @access  public

 */

class TripleDES extends DES

{

    /**

     * Encrypt / decrypt using inner chaining

     *

     * Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (self::MODE_CBC3).

     */

    const MODE_3CBC = -2;

    /**

     * Encrypt / decrypt using outer chaining

     *

     * Outer chaining is used by SSH-2 and when the mode is set to \phpseclib\Crypt\Base::MODE_CBC.

     */

    const MODE_CBC3 = Base::MODE_CBC;

    /**

     * Key Length (in bytes)

     *

     * @see \phpseclib\Crypt\TripleDES::setKeyLength()

     * @var int

     * @access private

     */

    var $key_length = 24;

    /**

     * The default salt used by setPassword()

     *

     * @see \phpseclib\Crypt\Base::password_default_salt

     * @see \phpseclib\Crypt\Base::setPassword()

     * @var string

     * @access private

     */

    var $password_default_salt = 'phpseclib';

    /**

     * The mcrypt specific name of the cipher

     *

     * @see \phpseclib\Crypt\DES::cipher_name_mcrypt

     * @see \phpseclib\Crypt\Base::cipher_name_mcrypt

     * @var string

     * @access private

     */

    var $cipher_name_mcrypt = 'tripledes';

    /**

     * Optimizing value while CFB-encrypting

     *

     * @see \phpseclib\Crypt\Base::cfb_init_len

     * @var int

     * @access private

     */

    var $cfb_init_len = 750;

    /**

     * max possible size of $key

     *

     * @see self::setKey()

     * @see \phpseclib\Crypt\DES::setKey()

     * @var string

     * @access private

     */

    var $key_length_max = 24;

    /**

     * Internal flag whether using self::MODE_3CBC or not

     *

     * @var bool

     * @access private

     */

    var $mode_3cbc;

    /**

     * The \phpseclib\Crypt\DES objects

     *

     * Used only if $mode_3cbc === true

     *

     * @var array

     * @access private

     */

    var $des;

    /**

     * Default Constructor.

     *

     * Determines whether or not the mcrypt extension should be used.

     *

     * $mode could be:

     *

     * - \phpseclib\Crypt\Base::MODE_ECB

     *

     * - \phpseclib\Crypt\Base::MODE_CBC

     *

     * - \phpseclib\Crypt\Base::MODE_CTR

     *

     * - \phpseclib\Crypt\Base::MODE_CFB

     *

     * - \phpseclib\Crypt\Base::MODE_OFB

     *

     * - \phpseclib\Crypt\TripleDES::MODE_3CBC

     *

     * If not explicitly set, \phpseclib\Crypt\Base::MODE_CBC will be used.

     *

     * @see \phpseclib\Crypt\DES::__construct()

     * @see \phpseclib\Crypt\Base::__construct()

     * @param int $mode

     * @access public

     */

    function __construct($mode = Base::MODE_CBC)

    {

        switch ($mode) {

            // In case of self::MODE_3CBC, we init as CRYPT_DES_MODE_CBC

            // and additional flag us internally as 3CBC

            case self::MODE_3CBC:

                parent::__construct(Base::MODE_CBC);

                $this->mode_3cbc = true;

                // This three $des'es will do the 3CBC work (if $key > 64bits)

                $this->des = array(

                    new DES(Base::MODE_CBC),

                    new DES(Base::MODE_CBC),

                    new DES(Base::MODE_CBC),

                );

                // we're going to be doing the padding, ourselves, so disable it in the \phpseclib\Crypt\DES objects

                $this->des[0]->disablePadding();

                $this->des[1]->disablePadding();

                $this->des[2]->disablePadding();

                break;

            // If not 3CBC, we init as usual

            default:

                parent::__construct($mode);

        }

    }

    /**

     * Test for engine validity

     *

     * This is mainly just a wrapper to set things up for \phpseclib\Crypt\Base::isValidEngine()

     *

     * @see \phpseclib\Crypt\Base::__construct()

     * @param int $engine

     * @access public

     * @return bool

     */

    function isValidEngine($engine)

    {

        if ($engine == self::ENGINE_OPENSSL) {

            $this->cipher_name_openssl_ecb = 'des-ede3';

            $mode = $this->_openssl_translate_mode();

            $this->cipher_name_openssl = $mode == 'ecb' ? 'des-ede3' : 'des-ede3-' . $mode;

        }

        return parent::isValidEngine($engine);

    }

    /**

     * Sets the initialization vector. (optional)

     *

     * SetIV is not required when \phpseclib\Crypt\Base::MODE_ECB is being used.  If not explicitly set, it'll be assumed

     * to be all zero's.

     *

     * @see \phpseclib\Crypt\Base::setIV()

     * @access public

     * @param string $iv

     */

    function setIV($iv)

    {

        parent::setIV($iv);

        if ($this->mode_3cbc) {

            $this->des[0]->setIV($iv);

            $this->des[1]->setIV($iv);

            $this->des[2]->setIV($iv);

        }

    }

    /**

     * Sets the key length.

     *

     * Valid key lengths are 64, 128 and 192

     *

     * @see \phpseclib\Crypt\Base:setKeyLength()

     * @access public

     * @param int $length

     */

    function setKeyLength($length)

    {

        $length >>= 3;

        switch (true) {

            case $length <= 8:

                $this->key_length = 8;

                break;

            case $length <= 16:

                $this->key_length = 16;

                break;

            default:

                $this->key_length = 24;

        }

        parent::setKeyLength($length);

    }

    /**

     * Sets the key.

     *

     * Keys can be of any length.  Triple DES, itself, can use 128-bit (eg. strlen($key) == 16) or

     * 192-bit (eg. strlen($key) == 24) keys.  This function pads and truncates $key as appropriate.

     *

     * DES also requires that every eighth bit be a parity bit, however, we'll ignore that.

     *

     * If the key is not explicitly set, it'll be assumed to be all null bytes.

     *

     * @access public

     * @see \phpseclib\Crypt\DES::setKey()

     * @see \phpseclib\Crypt\Base::setKey()

     * @param string $key

     */

    function setKey($key)

    {

        $length = $this->explicit_key_length ? $this->key_length : strlen($key);

        if ($length > 8) {

            $key = str_pad(substr($key, 0, 24), 24, chr(0));

            // if $key is between 64 and 128-bits, use the first 64-bits as the last, per this:

            // http://php.net/function.mcrypt-encrypt#47973

            $key = $length <= 16 ? substr_replace($key, substr($key, 0, 8), 16) : substr($key, 0, 24);

        } else {

            $key = str_pad($key, 8, chr(0));

        }

        parent::setKey($key);

        // And in case of self::MODE_3CBC:

        // if key <= 64bits we not need the 3 $des to work,

        // because we will then act as regular DES-CBC with just a <= 64bit key.

        // So only if the key > 64bits (> 8 bytes) we will call setKey() for the 3 $des.

        if ($this->mode_3cbc && $length > 8) {

            $this->des[0]->setKey(substr($key,  0, 8));

            $this->des[1]->setKey(substr($key,  8, 8));

            $this->des[2]->setKey(substr($key, 16, 8));

        }

    }

    /**

     * Encrypts a message.

     *

     * @see \phpseclib\Crypt\Base::encrypt()

     * @access public

     * @param string $plaintext

     * @return string $cipertext

     */

    function encrypt($plaintext)

    {

        // parent::en/decrypt() is able to do all the work for all modes and keylengths,

        // except for: self::MODE_3CBC (inner chaining CBC) with a key > 64bits

        // if the key is smaller then 8, do what we'd normally do

        if ($this->mode_3cbc && strlen($this->key) > 8) {

            return $this->des[2]->encrypt(

                $this->des[1]->decrypt(

                    $this->des[0]->encrypt(

                        $this->_pad($plaintext)

                    )

                )

            );

        }

        return parent::encrypt($plaintext);

    }

    /**

     * Decrypts a message.

     *

     * @see \phpseclib\Crypt\Base::decrypt()

     * @access public

     * @param string $ciphertext

     * @return string $plaintext

     */

    function decrypt($ciphertext)

    {

        if ($this->mode_3cbc && strlen($this->key) > 8) {

            return $this->_unpad(

                $this->des[0]->decrypt(

                    $this->des[1]->encrypt(

                        $this->des[2]->decrypt(

                            str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, "\0")

                        )

                    )

                )

            );

        }

        return parent::decrypt($ciphertext);

    }

    /**

     * Treat consecutive "packets" as if they are a continuous buffer.

     *

     * Say you have a 16-byte plaintext $plaintext.  Using the default behavior, the two following code snippets

     * will yield different outputs:

     *

     * <code>

     *    echo $des->encrypt(substr($plaintext, 0, 8));

     *    echo $des->encrypt(substr($plaintext, 8, 8));

     * </code>

     * <code>

     *    echo $des->encrypt($plaintext);

     * </code>

     *

     * The solution is to enable the continuous buffer.  Although this will resolve the above discrepancy, it creates

     * another, as demonstrated with the following:

     *

     * <code>

     *    $des->encrypt(substr($plaintext, 0, 8));

     *    echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));

     * </code>

     * <code>

     *    echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));

     * </code>

     *

     * With the continuous buffer disabled, these would yield the same output.  With it enabled, they yield different

     * outputs.  The reason is due to the fact that the initialization vector's change after every encryption /

     * decryption round when the continuous buffer is enabled.  When it's disabled, they remain constant.

     *

     * Put another way, when the continuous buffer is enabled, the state of the \phpseclib\Crypt\DES() object changes after each

     * encryption / decryption round, whereas otherwise, it'd remain constant.  For this reason, it's recommended that

     * continuous buffers not be used.  They do offer better security and are, in fact, sometimes required (SSH uses them),

     * however, they are also less intuitive and more likely to cause you problems.

     *

     * @see \phpseclib\Crypt\Base::enableContinuousBuffer()

     * @see self::disableContinuousBuffer()

     * @access public

     */

    function enableContinuousBuffer()

    {

        parent::enableContinuousBuffer();

        if ($this->mode_3cbc) {

            $this->des[0]->enableContinuousBuffer();

            $this->des[1]->enableContinuousBuffer();

            $this->des[2]->enableContinuousBuffer();

        }

    }

    /**

     * Treat consecutive packets as if they are a discontinuous buffer.

     *

     * The default behavior.

     *

     * @see \phpseclib\Crypt\Base::disableContinuousBuffer()

     * @see self::enableContinuousBuffer()

     * @access public

     */

    function disableContinuousBuffer()

    {

        parent::disableContinuousBuffer();

        if ($this->mode_3cbc) {

            $this->des[0]->disableContinuousBuffer();

            $this->des[1]->disableContinuousBuffer();

            $this->des[2]->disableContinuousBuffer();

        }

    }

    /**

     * Creates the key schedule

     *

     * @see \phpseclib\Crypt\DES::_setupKey()

     * @see \phpseclib\Crypt\Base::_setupKey()

     * @access private

     */

    function _setupKey()

    {

        switch (true) {

            // if $key <= 64bits we configure our internal pure-php cipher engine

            // to act as regular [1]DES, not as 3DES. mcrypt.so::tripledes does the same.

            case strlen($this->key) <= 8:

                $this->des_rounds = 1;

                break;

            // otherwise, if $key > 64bits, we configure our engine to work as 3DES.

            default:

                $this->des_rounds = 3;

                // (only) if 3CBC is used we have, of course, to setup the $des[0-2] keys also separately.

                if ($this->mode_3cbc) {

                    $this->des[0]->_setupKey();

                    $this->des[1]->_setupKey();

                    $this->des[2]->_setupKey();

                    // because $des[0-2] will, now, do all the work we can return here

                    // not need unnecessary stress parent::_setupKey() with our, now unused, $key.

                    return;

                }

        }

        // setup our key

        parent::_setupKey();

    }

    /**

     * Sets the internal crypt engine

     *

     * @see \phpseclib\Crypt\Base::__construct()

     * @see \phpseclib\Crypt\Base::setPreferredEngine()

     * @param int $engine

     * @access public

     * @return int

     */

    function setPreferredEngine($engine)

    {

        if ($this->mode_3cbc) {

            $this->des[0]->setPreferredEngine($engine);

            $this->des[1]->setPreferredEngine($engine);

            $this->des[2]->setPreferredEngine($engine);

        }

        return parent::setPreferredEngine($engine);

    }

}