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142 lines
3.3 KiB
142 lines
3.3 KiB
<?php
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/*
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* Author: Ryan Gilfether
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* URL: http://www.gilfether.com/phpCrypt
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* Date: Sep 4, 2005
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* Copyright (C) 2005 Ryan Gilfether
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*
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* This file is part of phpCrypt
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*
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* phpCrypt is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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namespace PHP_CRYPT;
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require_once(dirname(__FILE__)."/../Cipher.php");
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require_once(dirname(__FILE__)."/../Mode.php");
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require_once(dirname(__FILE__)."/../phpCrypt.php");
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/**
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* Implements Electronic Code Book (ECB) block cipher mode
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*
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* @author Ryan Gilfether
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* @link http://www.gilfether.com/phpcrypt
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* @copyright 2005 Ryan Gilfether
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*/
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class Mode_ECB extends Mode
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{
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/**
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* Constructor
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* Sets the cipher object that will be used for encryption
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*
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* @param object $cipher one of the phpCrypt encryption cipher objects
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* @param int $block_size The size of blocks (in bits) used for encryption
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* @return void
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*/
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public function __construct($cipher)
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{
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parent::__construct(PHP_Crypt::MODE_ECB, $cipher);
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// this works with only block Ciphers
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if($cipher->type() != Cipher::BLOCK)
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trigger_error("ECB mode requires a block cipher", E_USER_WARNING);
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}
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/**
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* Destructor
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*
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* @return void
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*/
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public function __destruct()
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{
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parent::__destruct();
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}
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/**
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* Encrypts an the entire string $plain_text using the cipher passed
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* to the constructor in ECB mode
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*
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* @param string $text The string to be encrypted in ECB mode
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* @return boolean Returns true
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*/
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public function encrypt(&$text)
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{
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$this->pad($text);
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$blocksz = $this->cipher->blockSize();
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$max = strlen($text) / $blocksz;
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for($i = 0; $i < $max; ++$i)
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{
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// get the current position within $text
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$pos = $i * $blocksz;
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// grab a block of text
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$block = substr($text, $pos, $blocksz);
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// encrypt the block
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$this->cipher->encrypt($block);
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// replace the plain text with the cipher text
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$text = substr_replace($text, $block, $pos, $blocksz);
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}
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return true;
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}
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/**
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* Decrypts an the entire string $plain_text using the cipher passed
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* to the constructor in ECB mode
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*
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* @param string $text The string to be decrypted in ECB mode
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* @return boolean Returns true
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*/
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public function decrypt(&$text)
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{
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$blocksz = $this->cipher->blockSize();
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$max = strlen($text) / $blocksz;
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for($i = 0; $i < $max; ++$i)
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{
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// get the current position within $text
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$pos = $i * $blocksz;
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// get a block of cipher text
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$block = substr($text, $pos, $blocksz);
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// decrypt the block
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$this->cipher->decrypt($block);
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// replace the block of cipher text with plain text
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$text = substr_replace($text, $block, $pos, $blocksz);
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}
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$this->strip($text);
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return true;
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}
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/**
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* This mode does not require an IV
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*
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* @return boolean Returns false
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*/
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public function requiresIV()
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{
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return false;
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}
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}
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?>
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