Subversion Repositories oidplus

<?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 \phpseclib3\Crypt\TripleDES('ctr');

 *

 *    $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 phpseclib3\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 \phpseclib3\Crypt\Common\BlockCipher::MODE_CBC.

     */

    const MODE_CBC3 = self::MODE_CBC;

    /**

     * Key Length (in bytes)

     *

     * @see \phpseclib3\Crypt\TripleDES::setKeyLength()

     * @var int

     * @access private

     */

    protected $key_length = 24;

    /**

     * The mcrypt specific name of the cipher

     *

     * @see \phpseclib3\Crypt\DES::cipher_name_mcrypt

     * @see \phpseclib3\Crypt\Common\SymmetricKey::cipher_name_mcrypt

     * @var string

     * @access private

     */

    protected $cipher_name_mcrypt = 'tripledes';

    /**

     * Optimizing value while CFB-encrypting

     *

     * @see \phpseclib3\Crypt\Common\SymmetricKey::cfb_init_len

     * @var int

     * @access private

     */

    protected $cfb_init_len = 750;

    /**

     * max possible size of $key

     *

     * @see self::setKey()

     * @see \phpseclib3\Crypt\DES::setKey()

     * @var string

     * @access private

     */

    protected $key_length_max = 24;

    /**

     * Internal flag whether using self::MODE_3CBC or not

     *

     * @var bool

     * @access private

     */

    private $mode_3cbc;

    /**

     * The \phpseclib3\Crypt\DES objects

     *

     * Used only if $mode_3cbc === true

     *

     * @var array

     * @access private

     */

    private $des;

    /**

     * Default Constructor.

     *

     * Determines whether or not the mcrypt or OpenSSL extensions should be used.

     *

     * $mode could be:

     *

     * - ecb

     *

     * - cbc

     *

     * - ctr

     *

     * - cfb

     *

     * - ofb

     *

     * - 3cbc

     *

     * - cbc3 (same as cbc)

     *

     * @see \phpseclib3\Crypt\DES::__construct()

     * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct()

     * @param string $mode

     * @access public

     */

    public function __construct($mode)

    {

        switch (strtolower($mode)) {

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

            // and additional flag us internally as 3CBC

            case '3cbc':

                parent::__construct('cbc');

                $this->mode_3cbc = true;

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

                $this->des = [

                    new DES('cbc'),

                    new DES('cbc'),

                    new DES('cbc'),

                ];

                // we're going to be doing the padding, ourselves, so disable it in the \phpseclib3\Crypt\DES objects

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

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

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

                break;

            case 'cbc3':

                $mode = 'cbc';

                // fall-through

            // If not 3CBC, we init as usual

            default:

                parent::__construct($mode);

                if ($this->mode == self::MODE_STREAM) {

                    throw new BadModeException('Block ciphers cannot be ran in stream mode');

                }

        }

    }

    /**

     * Test for engine validity

     *

     * This is mainly just a wrapper to set things up for \phpseclib3\Crypt\Common\SymmetricKey::isValidEngine()

     *

     * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct()

     * @param int $engine

     * @access protected

     * @return bool

     */

    protected function isValidEngineHelper($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::isValidEngineHelper($engine);

    }

    /**

     * Sets the initialization vector.

     *

     * SetIV is not required when \phpseclib3\Crypt\Common\SymmetricKey::MODE_ECB is being used.

     *

     * @see \phpseclib3\Crypt\Common\SymmetricKey::setIV()

     * @access public

     * @param string $iv

     */

    public 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 128 and 192 bits.

     *

     * If you want to use a 64-bit key use DES.php

     *

     * @see \phpseclib3\Crypt\Common\SymmetricKey:setKeyLength()

     * @access public

     * @throws \LengthException if the key length is invalid

     * @param int $length

     */

    public function setKeyLength($length)

    {

        switch ($length) {

            case 128:

            case 192:

                break;

            default:

                throw new \LengthException('Key size of ' . $length . ' bits is not supported by this algorithm. Only keys of sizes 128 or 192 bits are supported');

        }

        parent::setKeyLength($length);

    }

    /**

     * Sets the key.

     *

     * Triple DES can use 128-bit (eg. strlen($key) == 16) or 192-bit (eg. strlen($key) == 24) keys.

     *

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

     *

     * @access public

     * @see \phpseclib3\Crypt\DES::setKey()

     * @see \phpseclib3\Crypt\Common\SymmetricKey::setKey()

     * @throws \LengthException if the key length is invalid

     * @param string $key

     */

    public function setKey($key)

    {

        if ($this->explicit_key_length !== false && strlen($key) != $this->explicit_key_length) {

            throw new \LengthException('Key length has already been set to ' . $this->explicit_key_length . ' bytes and this key is ' . strlen($key) . ' bytes');

        }

        switch (strlen($key)) {

            case 16:

                $key .= substr($key, 0, 8);

                break;

            case 24:

                break;

            default:

                throw new \LengthException('Key of size ' . strlen($key) . ' not supported by this algorithm. Only keys of sizes 16 or 24 are supported');

        }

        // copied from self::setKey()

        $this->key = $key;

        $this->key_length = strlen($key);

        $this->changed = $this->nonIVChanged = true;

        $this->setEngine();

        if ($this->mode_3cbc) {

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

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

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

        }

    }

    /**

     * Encrypts a message.

     *

     * @see \phpseclib3\Crypt\Common\SymmetricKey::encrypt()

     * @access public

     * @param string $plaintext

     * @return string $cipertext

     */

    public 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 \phpseclib3\Crypt\Common\SymmetricKey::decrypt()

     * @access public

     * @param string $ciphertext

     * @return string $plaintext

     */

    public 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 \phpseclib3\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 \phpseclib3\Crypt\Common\SymmetricKey::enableContinuousBuffer()

     * @see self::disableContinuousBuffer()

     * @access public

     */

    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 \phpseclib3\Crypt\Common\SymmetricKey::disableContinuousBuffer()

     * @see self::enableContinuousBuffer()

     * @access public

     */

    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 \phpseclib3\Crypt\DES::setupKey()

     * @see \phpseclib3\Crypt\Common\SymmetricKey::setupKey()

     * @access private

     */

    protected 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 \phpseclib3\Crypt\Common\SymmetricKey::__construct()

     * @see \phpseclib3\Crypt\Common\SymmetricKey::setPreferredEngine()

     * @param int $engine

     * @access public

     */

    public function setPreferredEngine($engine)

    {

        if ($this->mode_3cbc) {

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

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

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

        }

        parent::setPreferredEngine($engine);

    }

}