RC4.php
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<?php
/**
* PHPExcel_Reader_Excel5_RC4
*
* Copyright (c) 2006 - 2015 PHPExcel
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* @category PHPExcel
* @package PHPExcel_Reader_Excel5
* @copyright Copyright (c) 2006 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
* @license http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt LGPL
* @version ##VERSION##, ##DATE##
*/
class PHPExcel_Reader_Excel5_RC4
{
// Context
protected $s = array();
protected $i = 0;
protected $j = 0;
/**
* RC4 stream decryption/encryption constrcutor
*
* @param string $key Encryption key/passphrase
*/
public function __construct($key)
{
$len = strlen($key);
for ($this->i = 0; $this->i < 256; $this->i++) {
$this->s[$this->i] = $this->i;
}
$this->j = 0;
for ($this->i = 0; $this->i < 256; $this->i++) {
$this->j = ($this->j + $this->s[$this->i] + ord($key[$this->i % $len])) % 256;
$t = $this->s[$this->i];
$this->s[$this->i] = $this->s[$this->j];
$this->s[$this->j] = $t;
}
$this->i = $this->j = 0;
}
/**
* Symmetric decryption/encryption function
*
* @param string $data Data to encrypt/decrypt
*
* @return string
*/
public function RC4($data)
{
$len = strlen($data);
for ($c = 0; $c < $len; $c++) {
$this->i = ($this->i + 1) % 256;
$this->j = ($this->j + $this->s[$this->i]) % 256;
$t = $this->s[$this->i];
$this->s[$this->i] = $this->s[$this->j];
$this->s[$this->j] = $t;
$t = ($this->s[$this->i] + $this->s[$this->j]) % 256;
$data[$c] = chr(ord($data[$c]) ^ $this->s[$t]);
}
return $data;
}
}