82 lines
2.5 KiB
PHP
82 lines
2.5 KiB
PHP
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<?php
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/**
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* PHPExcel_Reader_Excel5_RC4
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*
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* Copyright (c) 2006 - 2015 PHPExcel
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* @category PHPExcel
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* @package PHPExcel_Reader_Excel5
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* @copyright Copyright (c) 2006 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
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* @license http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt LGPL
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* @version ##VERSION##, ##DATE##
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*/
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class PHPExcel_Reader_Excel5_RC4
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{
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// Context
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protected $s = array();
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protected $i = 0;
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protected $j = 0;
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/**
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* RC4 stream decryption/encryption constrcutor
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*
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* @param string $key Encryption key/passphrase
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*/
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public function __construct($key)
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{
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$len = strlen($key);
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for ($this->i = 0; $this->i < 256; $this->i++) {
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$this->s[$this->i] = $this->i;
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}
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$this->j = 0;
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for ($this->i = 0; $this->i < 256; $this->i++) {
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$this->j = ($this->j + $this->s[$this->i] + ord($key[$this->i % $len])) % 256;
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$t = $this->s[$this->i];
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$this->s[$this->i] = $this->s[$this->j];
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$this->s[$this->j] = $t;
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}
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$this->i = $this->j = 0;
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}
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/**
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* Symmetric decryption/encryption function
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*
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* @param string $data Data to encrypt/decrypt
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*
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* @return string
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*/
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public function RC4($data)
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{
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$len = strlen($data);
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for ($c = 0; $c < $len; $c++) {
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$this->i = ($this->i + 1) % 256;
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$this->j = ($this->j + $this->s[$this->i]) % 256;
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$t = $this->s[$this->i];
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$this->s[$this->i] = $this->s[$this->j];
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$this->s[$this->j] = $t;
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$t = ($this->s[$this->i] + $this->s[$this->j]) % 256;
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$data[$c] = chr(ord($data[$c]) ^ $this->s[$t]);
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}
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return $data;
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}
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}
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