Author URI: http://sw-guide.de/ Version: 2.0 Copyright © 2006-2010, all rights reserved This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program 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 General Public License for more details. */ class MathCheck { /** * GenerateValues * */ function MathCheck_GenerateValues($input_numbers = '1~1, 2~2, 3~3, 4~4, 5~5, 6~6, 7~7, 8~8, 9~9, 10~10', $unique_key = 'LnfvpVZmsSCfLf0WxXN0') { // Get numbers in array $num_array = $this->MathCheck_Aux_NumberToArray($input_numbers); // Get random keys $rand_keys = array_rand($num_array, 2); // Operands for displaying... $resultArray = array( 'operand1' => $num_array[$rand_keys[0]], 'operand2' => $num_array[$rand_keys[1]], 'result' => $this->MathCheck_Aux_GenerateHash($rand_keys[0] + $rand_keys[1], date('j'), $unique_key), ); return $resultArray; } /** * InputValidation * * Input validation. Returns an empty string if validation passed or an * error string if not passed. */ function MathCheck_InputValidation($actualResult, $userEntered, $unique_key = 'LnfvpVZmsSCfLf0WxXN0') { $error = ''; // Case 1: User has not entered an answer at all: if ($error == '' && $userEntered == '') { $error = 'No answer'; } $userEntered = preg_replace('/[^0-9]/', '', $userEntered); // Remove everything except numbers if ($error == '' && $actualResult != $this->MathCheck_Aux_GenerateHash($userEntered, date(j), $unique_key) ) { if ( ( date('G') <= 1 ) AND ( $actualResult == $this->MathCheck_Aux_GenerateHash($userEntered, (intval(date(j))-1), $unique_key ) ) ) { // User has just passed midnight while writing the comment. We consider // the time between 0:00 and 1:59 still as the day before to avoid // error messages if user visited page on 23:50 but pressed the "Submit Comment" // button on 0:15. } else { $error = 'Wrong answer'; } } return $error; } /*** * MathCheck_Aux_NumberToArray * * Converts the input string, e.g. "1~one, 2~two, 3~three, 4~four, ..." * into an array, e.g.: Array([1] => one, [2] => two, [3] => three, ...) */ function MathCheck_Aux_NumberToArray($input) { $input = str_replace(' ', '', $input); // Strip whitespace $sourcearray = explode(',', $input); // Create array foreach ($sourcearray as $loopval) { $temparr = explode('~', $loopval); $targetarray[$temparr[0]] = $temparr[1]; } return $targetarray; } /*** * MathCheck_Aux_GenerateHash * * Generate hash */ function MathCheck_Aux_GenerateHash($inputstring, $day, $unique) { // If using WordPress: many people have defined a WP_SECRET sting in // wp-config.php, so we add it if it exists if ( defined('WP_SECRET') ) $inputstring .= WP_SECRET; // Adds the file modification time of this file $inputstring .= filemtime(__FILE__); // Adds a unique value $inputstring .= $unique; // Add the IP address of the server under which the current script is executing. $inputstring .= getenv('SERVER_ADDR'); // Add date $inputstring .= $day . date('ny'); // Get MD5 and reverse it $enc = strrev(md5($inputstring)); // Get only a few chars out of the string $enc = substr($enc, 28, 1) . substr($enc, 9, 1) . substr($enc, 21, 1) . substr($enc, 15, 1) . substr($enc, 7, 1); // Return result return $enc; } } ?>