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Diffstat (limited to 'phpsec/Crypt/TripleDES.php')
| -rw-r--r-- | phpsec/Crypt/TripleDES.php | 690 |
1 files changed, 690 insertions, 0 deletions
diff --git a/phpsec/Crypt/TripleDES.php b/phpsec/Crypt/TripleDES.php new file mode 100644 index 000000000..4d0dbbca0 --- /dev/null +++ b/phpsec/Crypt/TripleDES.php @@ -0,0 +1,690 @@ +<?php
+/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
+
+/**
+ * Pure-PHP implementation of Triple DES.
+ *
+ * Uses mcrypt, if available, and an internal implementation, otherwise. Operates in the EDE3 mode (encrypt-decrypt-encrypt).
+ *
+ * PHP versions 4 and 5
+ *
+ * Here's a short example of how to use this library:
+ * <code>
+ * <?php
+ * include('Crypt/TripleDES.php');
+ *
+ * $des = new Crypt_TripleDES();
+ *
+ * $des->setKey('abcdefghijklmnopqrstuvwx');
+ *
+ * $size = 10 * 1024;
+ * $plaintext = '';
+ * for ($i = 0; $i < $size; $i++) {
+ * $plaintext.= 'a';
+ * }
+ *
+ * echo $des->decrypt($des->encrypt($plaintext));
+ * ?>
+ * </code>
+ *
+ * LICENSE: This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ *
+ * @category Crypt
+ * @package Crypt_TripleDES
+ * @author Jim Wigginton <terrafrost@php.net>
+ * @copyright MMVII Jim Wigginton
+ * @license http://www.gnu.org/licenses/lgpl.txt
+ * @version $Id: TripleDES.php,v 1.13 2010/02/26 03:40:25 terrafrost Exp $
+ * @link http://phpseclib.sourceforge.net
+ */
+
+/**
+ * Include Crypt_DES
+ */
+require_once 'DES.php';
+
+/**
+ * Encrypt / decrypt using inner chaining
+ *
+ * Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (CRYPT_DES_MODE_CBC3).
+ */
+define('CRYPT_DES_MODE_3CBC', 3);
+
+/**
+ * Encrypt / decrypt using outer chaining
+ *
+ * Outer chaining is used by SSH-2 and when the mode is set to CRYPT_DES_MODE_CBC.
+ */
+define('CRYPT_DES_MODE_CBC3', CRYPT_DES_MODE_CBC);
+
+/**
+ * Pure-PHP implementation of Triple DES.
+ *
+ * @author Jim Wigginton <terrafrost@php.net>
+ * @version 0.1.0
+ * @access public
+ * @package Crypt_TerraDES
+ */
+class Crypt_TripleDES {
+ /**
+ * The Three Keys
+ *
+ * @see Crypt_TripleDES::setKey()
+ * @var String
+ * @access private
+ */
+ var $key = "\0\0\0\0\0\0\0\0";
+
+ /**
+ * The Encryption Mode
+ *
+ * @see Crypt_TripleDES::Crypt_TripleDES()
+ * @var Integer
+ * @access private
+ */
+ var $mode = CRYPT_DES_MODE_CBC;
+
+ /**
+ * Continuous Buffer status
+ *
+ * @see Crypt_TripleDES::enableContinuousBuffer()
+ * @var Boolean
+ * @access private
+ */
+ var $continuousBuffer = false;
+
+ /**
+ * Padding status
+ *
+ * @see Crypt_TripleDES::enablePadding()
+ * @var Boolean
+ * @access private
+ */
+ var $padding = true;
+
+ /**
+ * The Initialization Vector
+ *
+ * @see Crypt_TripleDES::setIV()
+ * @var String
+ * @access private
+ */
+ var $iv = "\0\0\0\0\0\0\0\0";
+
+ /**
+ * A "sliding" Initialization Vector
+ *
+ * @see Crypt_TripleDES::enableContinuousBuffer()
+ * @var String
+ * @access private
+ */
+ var $encryptIV = "\0\0\0\0\0\0\0\0";
+
+ /**
+ * A "sliding" Initialization Vector
+ *
+ * @see Crypt_TripleDES::enableContinuousBuffer()
+ * @var String
+ * @access private
+ */
+ var $decryptIV = "\0\0\0\0\0\0\0\0";
+
+ /**
+ * The Crypt_DES objects
+ *
+ * @var Array
+ * @access private
+ */
+ var $des;
+
+ /**
+ * mcrypt resource for encryption
+ *
+ * The mcrypt resource can be recreated every time something needs to be created or it can be created just once.
+ * Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode.
+ *
+ * @see Crypt_AES::encrypt()
+ * @var String
+ * @access private
+ */
+ var $enmcrypt;
+
+ /**
+ * mcrypt resource for decryption
+ *
+ * The mcrypt resource can be recreated every time something needs to be created or it can be created just once.
+ * Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode.
+ *
+ * @see Crypt_AES::decrypt()
+ * @var String
+ * @access private
+ */
+ var $demcrypt;
+
+ /**
+ * Does the (en|de)mcrypt resource need to be (re)initialized?
+ *
+ * @see setKey()
+ * @see setIV()
+ * @var Boolean
+ * @access private
+ */
+ var $changed = true;
+
+ /**
+ * Default Constructor.
+ *
+ * Determines whether or not the mcrypt extension should be used. $mode should only, at present, be
+ * CRYPT_DES_MODE_ECB or CRYPT_DES_MODE_CBC. If not explictly set, CRYPT_DES_MODE_CBC will be used.
+ *
+ * @param optional Integer $mode
+ * @return Crypt_TripleDES
+ * @access public
+ */
+ function Crypt_TripleDES($mode = CRYPT_DES_MODE_CBC)
+ {
+ if ( !defined('CRYPT_DES_MODE') ) {
+ switch (true) {
+ case extension_loaded('mcrypt'):
+ // i'd check to see if des was supported, by doing in_array('des', mcrypt_list_algorithms('')),
+ // but since that can be changed after the object has been created, there doesn't seem to be
+ // a lot of point...
+ define('CRYPT_DES_MODE', CRYPT_DES_MODE_MCRYPT);
+ break;
+ default:
+ define('CRYPT_DES_MODE', CRYPT_DES_MODE_INTERNAL);
+ }
+ }
+
+ if ( $mode == CRYPT_DES_MODE_3CBC ) {
+ $this->mode = CRYPT_DES_MODE_3CBC;
+ $this->des = array(
+ new Crypt_DES(CRYPT_DES_MODE_CBC),
+ new Crypt_DES(CRYPT_DES_MODE_CBC),
+ new Crypt_DES(CRYPT_DES_MODE_CBC)
+ );
+
+ // we're going to be doing the padding, ourselves, so disable it in the Crypt_DES objects
+ $this->des[0]->disablePadding();
+ $this->des[1]->disablePadding();
+ $this->des[2]->disablePadding();
+
+ return;
+ }
+
+ switch ( CRYPT_DES_MODE ) {
+ case CRYPT_DES_MODE_MCRYPT:
+ switch ($mode) {
+ case CRYPT_DES_MODE_ECB:
+ $this->mode = MCRYPT_MODE_ECB;
+ break;
+ case CRYPT_DES_MODE_CTR:
+ $this->mode = 'ctr';
+ break;
+ case CRYPT_DES_MODE_CBC:
+ default:
+ $this->mode = MCRYPT_MODE_CBC;
+ }
+
+ break;
+ default:
+ $this->des = array(
+ new Crypt_DES(CRYPT_DES_MODE_ECB),
+ new Crypt_DES(CRYPT_DES_MODE_ECB),
+ new Crypt_DES(CRYPT_DES_MODE_ECB)
+ );
+
+ // we're going to be doing the padding, ourselves, so disable it in the Crypt_DES objects
+ $this->des[0]->disablePadding();
+ $this->des[1]->disablePadding();
+ $this->des[2]->disablePadding();
+
+ switch ($mode) {
+ case CRYPT_DES_MODE_ECB:
+ case CRYPT_DES_MODE_CTR:
+ case CRYPT_DES_MODE_CBC:
+ $this->mode = $mode;
+ break;
+ default:
+ $this->mode = CRYPT_DES_MODE_CBC;
+ }
+ }
+ }
+
+ /**
+ * Sets the key.
+ *
+ * Keys can be of any length. Triple DES, itself, can use 128-bit (eg. strlen($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 zero's.
+ *
+ * @access public
+ * @param String $key
+ */
+ function setKey($key)
+ {
+ $length = strlen($key);
+ if ($length > 8) {
+ $key = str_pad($key, 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);
+ }
+ $this->key = $key;
+ switch (true) {
+ case CRYPT_DES_MODE == CRYPT_DES_MODE_INTERNAL:
+ case $this->mode == CRYPT_DES_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));
+ }
+ $this->changed = true;
+ }
+
+ /**
+ * Sets the initialization vector. (optional)
+ *
+ * SetIV is not required when CRYPT_DES_MODE_ECB is being used. If not explictly set, it'll be assumed
+ * to be all zero's.
+ *
+ * @access public
+ * @param String $iv
+ */
+ function setIV($iv)
+ {
+ $this->encryptIV = $this->decryptIV = $this->iv = str_pad(substr($iv, 0, 8), 8, chr(0));
+ if ($this->mode == CRYPT_DES_MODE_3CBC) {
+ $this->des[0]->setIV($iv);
+ $this->des[1]->setIV($iv);
+ $this->des[2]->setIV($iv);
+ }
+ $this->changed = true;
+ }
+
+ /**
+ * Generate CTR XOR encryption key
+ *
+ * Encrypt the output of this and XOR it against the ciphertext / plaintext to get the
+ * plaintext / ciphertext in CTR mode.
+ *
+ * @see Crypt_DES::decrypt()
+ * @see Crypt_DES::encrypt()
+ * @access public
+ * @param Integer $length
+ * @param String $iv
+ */
+ function _generate_xor($length, &$iv)
+ {
+ $xor = '';
+ $num_blocks = ($length + 7) >> 3;
+ for ($i = 0; $i < $num_blocks; $i++) {
+ $xor.= $iv;
+ for ($j = 4; $j <= 8; $j+=4) {
+ $temp = substr($iv, -$j, 4);
+ switch ($temp) {
+ case "\xFF\xFF\xFF\xFF":
+ $iv = substr_replace($iv, "\x00\x00\x00\x00", -$j, 4);
+ break;
+ case "\x7F\xFF\xFF\xFF":
+ $iv = substr_replace($iv, "\x80\x00\x00\x00", -$j, 4);
+ break 2;
+ default:
+ extract(unpack('Ncount', $temp));
+ $iv = substr_replace($iv, pack('N', $count + 1), -$j, 4);
+ break 2;
+ }
+ }
+ }
+
+ return $xor;
+ }
+
+ /**
+ * Encrypts a message.
+ *
+ * @access public
+ * @param String $plaintext
+ */
+ function encrypt($plaintext)
+ {
+ if ($this->mode != CRYPT_DES_MODE_CTR && $this->mode != 'ctr') {
+ $plaintext = $this->_pad($plaintext);
+ }
+
+ // if the key is smaller then 8, do what we'd normally do
+ if ($this->mode == CRYPT_DES_MODE_3CBC && strlen($this->key) > 8) {
+ $ciphertext = $this->des[2]->encrypt($this->des[1]->decrypt($this->des[0]->encrypt($plaintext)));
+
+ return $ciphertext;
+ }
+
+ if ( CRYPT_DES_MODE == CRYPT_DES_MODE_MCRYPT ) {
+ if ($this->changed) {
+ if (!isset($this->enmcrypt)) {
+ $this->enmcrypt = mcrypt_module_open(MCRYPT_3DES, '', $this->mode, '');
+ }
+ mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV);
+ $this->changed = false;
+ }
+
+ $ciphertext = mcrypt_generic($this->enmcrypt, $plaintext);
+
+ if (!$this->continuousBuffer) {
+ mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV);
+ }
+
+ return $ciphertext;
+ }
+
+ if (strlen($this->key) <= 8) {
+ $this->des[0]->mode = $this->mode;
+
+ return $this->des[0]->encrypt($plaintext);
+ }
+
+ // we pad with chr(0) since that's what mcrypt_generic does. to quote from http://php.net/function.mcrypt-generic :
+ // "The data is padded with "\0" to make sure the length of the data is n * blocksize."
+ $plaintext = str_pad($plaintext, ceil(strlen($plaintext) / 8) * 8, chr(0));
+
+ $des = $this->des;
+
+ $ciphertext = '';
+ switch ($this->mode) {
+ case CRYPT_DES_MODE_ECB:
+ for ($i = 0; $i < strlen($plaintext); $i+=8) {
+ $block = substr($plaintext, $i, 8);
+ $block = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT);
+ $block = $des[1]->_processBlock($block, CRYPT_DES_DECRYPT);
+ $block = $des[2]->_processBlock($block, CRYPT_DES_ENCRYPT);
+ $ciphertext.= $block;
+ }
+ break;
+ case CRYPT_DES_MODE_CBC:
+ $xor = $this->encryptIV;
+ for ($i = 0; $i < strlen($plaintext); $i+=8) {
+ $block = substr($plaintext, $i, 8) ^ $xor;
+ $block = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT);
+ $block = $des[1]->_processBlock($block, CRYPT_DES_DECRYPT);
+ $block = $des[2]->_processBlock($block, CRYPT_DES_ENCRYPT);
+ $xor = $block;
+ $ciphertext.= $block;
+ }
+ if ($this->continuousBuffer) {
+ $this->encryptIV = $xor;
+ }
+ break;
+ case CRYPT_DES_MODE_CTR:
+ $xor = $this->encryptIV;
+ for ($i = 0; $i < strlen($plaintext); $i+=8) {
+ $key = $this->_generate_xor(8, $xor);
+ $key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT);
+ $key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT);
+ $key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT);
+ $block = substr($plaintext, $i, 8);
+ $ciphertext.= $block ^ $key;
+ }
+ if ($this->continuousBuffer) {
+ $this->encryptIV = $xor;
+ }
+ }
+
+ return $ciphertext;
+ }
+
+ /**
+ * Decrypts a message.
+ *
+ * @access public
+ * @param String $ciphertext
+ */
+ function decrypt($ciphertext)
+ {
+ if ($this->mode == CRYPT_DES_MODE_3CBC && strlen($this->key) > 8) {
+ $plaintext = $this->des[0]->decrypt($this->des[1]->encrypt($this->des[2]->decrypt($ciphertext)));
+
+ return $this->_unpad($plaintext);
+ }
+
+ // we pad with chr(0) since that's what mcrypt_generic does. to quote from http://php.net/function.mcrypt-generic :
+ // "The data is padded with "\0" to make sure the length of the data is n * blocksize."
+ $ciphertext = str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, chr(0));
+
+ if ( CRYPT_DES_MODE == CRYPT_DES_MODE_MCRYPT ) {
+ if ($this->changed) {
+ if (!isset($this->demcrypt)) {
+ $this->demcrypt = mcrypt_module_open(MCRYPT_3DES, '', $this->mode, '');
+ }
+ mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV);
+ $this->changed = false;
+ }
+
+ $plaintext = mdecrypt_generic($this->demcrypt, $ciphertext);
+
+ if (!$this->continuousBuffer) {
+ mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV);
+ }
+
+ return $this->mode != 'ctr' ? $this->_unpad($plaintext) : $plaintext;
+ }
+
+ if (strlen($this->key) <= 8) {
+ $this->des[0]->mode = $this->mode;
+
+ return $this->_unpad($this->des[0]->decrypt($plaintext));
+ }
+
+ $des = $this->des;
+
+ $plaintext = '';
+ switch ($this->mode) {
+ case CRYPT_DES_MODE_ECB:
+ for ($i = 0; $i < strlen($ciphertext); $i+=8) {
+ $block = substr($ciphertext, $i, 8);
+ $block = $des[2]->_processBlock($block, CRYPT_DES_DECRYPT);
+ $block = $des[1]->_processBlock($block, CRYPT_DES_ENCRYPT);
+ $block = $des[0]->_processBlock($block, CRYPT_DES_DECRYPT);
+ $plaintext.= $block;
+ }
+ break;
+ case CRYPT_DES_MODE_CBC:
+ $xor = $this->decryptIV;
+ for ($i = 0; $i < strlen($ciphertext); $i+=8) {
+ $orig = $block = substr($ciphertext, $i, 8);
+ $block = $des[2]->_processBlock($block, CRYPT_DES_DECRYPT);
+ $block = $des[1]->_processBlock($block, CRYPT_DES_ENCRYPT);
+ $block = $des[0]->_processBlock($block, CRYPT_DES_DECRYPT);
+ $plaintext.= $block ^ $xor;
+ $xor = $orig;
+ }
+ if ($this->continuousBuffer) {
+ $this->decryptIV = $xor;
+ }
+ break;
+ case CRYPT_DES_MODE_CTR:
+ $xor = $this->decryptIV;
+ for ($i = 0; $i < strlen($ciphertext); $i+=8) {
+ $key = $this->_generate_xor(8, $xor);
+ $key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT);
+ $key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT);
+ $key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT);
+ $block = substr($ciphertext, $i, 8);
+ $plaintext.= $block ^ $key;
+ }
+ if ($this->continuousBuffer) {
+ $this->decryptIV = $xor;
+ }
+ }
+
+ return $this->mode != CRYPT_DES_MODE_CTR ? $this->_unpad($plaintext) : $plaintext;
+ }
+
+ /**
+ * 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 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 Crypt_TripleDES::disableContinuousBuffer()
+ * @access public
+ */
+ function enableContinuousBuffer()
+ {
+ $this->continuousBuffer = true;
+ if ($this->mode == CRYPT_DES_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 Crypt_TripleDES::enableContinuousBuffer()
+ * @access public
+ */
+ function disableContinuousBuffer()
+ {
+ $this->continuousBuffer = false;
+ $this->encryptIV = $this->iv;
+ $this->decryptIV = $this->iv;
+
+ if ($this->mode == CRYPT_DES_MODE_3CBC) {
+ $this->des[0]->disableContinuousBuffer();
+ $this->des[1]->disableContinuousBuffer();
+ $this->des[2]->disableContinuousBuffer();
+ }
+ }
+
+ /**
+ * Pad "packets".
+ *
+ * DES works by encrypting eight bytes at a time. If you ever need to encrypt or decrypt something that's not
+ * a multiple of eight, it becomes necessary to pad the input so that it's length is a multiple of eight.
+ *
+ * Padding is enabled by default. Sometimes, however, it is undesirable to pad strings. Such is the case in SSH1,
+ * where "packets" are padded with random bytes before being encrypted. Unpad these packets and you risk stripping
+ * away characters that shouldn't be stripped away. (SSH knows how many bytes are added because the length is
+ * transmitted separately)
+ *
+ * @see Crypt_TripleDES::disablePadding()
+ * @access public
+ */
+ function enablePadding()
+ {
+ $this->padding = true;
+ }
+
+ /**
+ * Do not pad packets.
+ *
+ * @see Crypt_TripleDES::enablePadding()
+ * @access public
+ */
+ function disablePadding()
+ {
+ $this->padding = false;
+ }
+
+ /**
+ * Pads a string
+ *
+ * Pads a string using the RSA PKCS padding standards so that its length is a multiple of the blocksize (8).
+ * 8 - (strlen($text) & 7) bytes are added, each of which is equal to chr(8 - (strlen($text) & 7)
+ *
+ * If padding is disabled and $text is not a multiple of the blocksize, the string will be padded regardless
+ * and padding will, hence forth, be enabled.
+ *
+ * @see Crypt_TripleDES::_unpad()
+ * @access private
+ */
+ function _pad($text)
+ {
+ $length = strlen($text);
+
+ if (!$this->padding) {
+ if (($length & 7) == 0) {
+ return $text;
+ } else {
+ user_error("The plaintext's length ($length) is not a multiple of the block size (8)", E_USER_NOTICE);
+ $this->padding = true;
+ }
+ }
+
+ $pad = 8 - ($length & 7);
+ return str_pad($text, $length + $pad, chr($pad));
+ }
+
+ /**
+ * Unpads a string
+ *
+ * If padding is enabled and the reported padding length is invalid the encryption key will be assumed to be wrong
+ * and false will be returned.
+ *
+ * @see Crypt_TripleDES::_pad()
+ * @access private
+ */
+ function _unpad($text)
+ {
+ if (!$this->padding) {
+ return $text;
+ }
+
+ $length = ord($text[strlen($text) - 1]);
+
+ if (!$length || $length > 8) {
+ return false;
+ }
+
+ return substr($text, 0, -$length);
+ }
+}
+
+// vim: ts=4:sw=4:et:
+// vim6: fdl=1:
\ No newline at end of file |