/scalr-2/tags/scalr-2.0.0/app/src/Lib/Graphics/Captcha/class.Captcha.php

<?php

  /******************************************************************

   Projectname:   CAPTCHA 2
   Version:	  0.9	
   Author:        Cristian Navalici cristian.navalici at gmail dot com
   Last modified: 22-feb-2007
   Copyright (C): 2007 Cristian Navalici, All Rights Reserved

   * GNU General Public License (Version 2, June 1991)
   *
   * 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.

   Description:
   This class can generate CAPTCHAs, see README for more details!

   28.02.2007 - added Windows specifications for MCRYPT_RAND 

  ******************************************************************/

class Captcha {

// here you can make some adjustments
private $font_size 	= 18; // if GD2 in points / GD1 in pixels
private $font 		= 'fonts/Gibberish.ttf';
private $img_height 	= 50;
private $save_path	= 'captcha'; // without trailing slash
private $secret_key	= 'JKHuioashdfiasjbnd';

private $use_windows = 0; // 1 - if you'll use windows   0 - if don't
// until here

private $gd_enabled = true;
private $allow_jpg_output = false;
private $allow_png_output = false;
private $length;

//======================================================================
//	CONSTRUCTOR
//======================================================================
function __construct ($length = 6, $type = 'png', $letter = '') {

	$this->font = dirname(__FILE__)."/fonts/Gibberish.ttf";
    
    $check_gd = gd_info();
	if (!$check_gd['GD Version']) {
		$this->gd_enabled = false;
	}
	
	// check for JPG capability
	if ($check_gd['JPG Support']) {
		$this->allow_jpg_output = true;
	}
	
	// check for PNG capability
	if ($check_gd['PNG Support']) {
		$this->allow_png_output = true;
	}
	
	if(!session_id()){
		session_start();
	} else {
		session_regenerate_id();
	}
}

//======================================================================
// MAIN FUNCTION: createCaptcha
// create a captcha image based on supplied arguments
// if GD is not enabled it switch to TEXT MODE
//
// @arg:	$length (int) - length of generated string
//		$type (string) - type of generated picture (jpg or png)
//		$draw_lines (bool) - optional lines on picture
// @return:	none (picture saved)
//======================================================================
public function createCaptcha($length = 6, $type = 'png', $draw_lines = 'true') {

if ($this->gd_enabled) {
	$img_length = $length * ($this->font_size+5);
	$image       = imagecreatetruecolor($img_length, $this->img_height) or die("Cannot Initialize new GD image stream");;

	//  ----- TRANSFORMATIONS PART -----------------------------------
	// set background
	$bgcolor     = imagecolorallocate($image, 255, 255, 255);
	imagefill($image,0,0,$bgcolor);
	
	$random_pixels = $img_length * $this->img_height / 2;

        for ($i = 0; $i < $random_pixels; $i++) {
		$color_pixel  = ImageColorAllocate($image, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
		ImageSetPixel($image, rand(0, $img_length), rand(0, $this->img_height), $color_pixel);
        }
	
	// smooth image
        imagefilter($image, IMG_FILTER_SMOOTH, 10);
	
	// add text
	$gens = $this->stringGenerator($length);
	
	for ($i = 0 ; $i < $length ; $i++) 
	{	    
	    $stringcolor = imagecolorallocate($image, mt_rand(0, 180), mt_rand(0, 100), mt_rand(0, 180));
		imagettftext($image, $this->font_size, mt_rand(-40,40), 10 + (($this->font_size + 4) * $i), mt_rand(20, 40),
                   $stringcolor,
                   $this->font,
                   $gens[$i]);
	}

	// default draw lines
	if ((bool)$draw_lines) {
		$img = $this->drawLines ($image, $img_length);
	} else {
		$img = $image;
	}
	
	//  ----- EOS TRANSFORMATIONS PART -----------------------------------

	//create name for saved files (must be unique)
	$sname = $this->save_path .'/'. substr(time(), -5);

	// if you want a jpeg or png but the option is not available
	// automated change to the other type
	if ((!$this->allow_jpg_output) && (!$this->allow_png_output)) {
		echo "We have a problem! We can't save jpg or png either. Check your GD configuration.";
		exit (0);
	} else {
		if ($type == 'jpeg') {
			if ($this->allow_jpg_output) { 
				$sname .= '.jpg';
        			imagejpeg($img, $sname);
        		} else {
        			$sname .= '.png';
        			imagepng($img, $sname);
        		}
		} elseif ($type == 'png') {
	        	if ($this->allow_png_output) { 
        			$sname .= '.png';
        			imagepng($img, $sname);
        		} else {
				$sname .= '.jpg';
        			imagejpeg($img, $sname);
        		}
		}
	} // if-else
	
	$_SESSION['savedfile'] = $sname;
	imagedestroy($img);
} else { 
	// if GD in not installed we switch to text mode
	echo $this->stringGenerator($length);
}// ifelse ($gd_enabled)
	
}

//======================================================================
// SHOW CAPTCHA
// function to show captcha image on website page
// 
// @arg:	none
// @return:	echo image
//======================================================================
public function showCaptcha() {

	return "<img src='/" .$_SESSION['savedfile']. "' border='0' alt='captcha code' title='captcha code' />";

}

//======================================================================
// VERIFY CAPTCHA
//
// @arg:	$txt (string) - entered string from user
// @return:	bool (true / false)
//======================================================================
public function verifyCaptcha($txt) {

	// remove generated image
	if (is_file($_SESSION['savedfile'])) unlink ($_SESSION['savedfile']);
	
	// DECRYPTION PART
	$decrypted_data = $this->cryptDecrypt($_SESSION['captcha'], 'DECRYPT');

	return (strcmp ($txt, $decrypted_data) == 0) ? true : false;

}


//============================================================================================
//	P R I V A T E    F U N C T I O N S
//============================================================================================

//======================================================================
// STRING GENERATOR
// generates a random string of alphanumerics for captcha
//
// @arg:	$length (integer) - length of generated string
// @return:	$gen_string (string) - generated string (mixture of alphanumerics)
//======================================================================
private function stringGenerator($length) {

	// mix some letters and some digits
	$alphanumerics   = array_merge(range('A', 'Z'), range(2, 9));
	$alphanumerics_len = count($alphanumerics) - 1;

	$gen_string = '';
	for ($i = 0; $i < $length; $i++) {
		$gen_string .= $alphanumerics[mt_rand(0, $alphanumerics_len)];
	}
	
	// ENCRYPTION PART 
	$encrypted_data = $this->cryptDecrypt($gen_string, 'CRYPT');
	$_SESSION['captcha'] = $encrypted_data;
	
	return $gen_string;
	
}

//======================================================================
// DRAW SOME LINES ON PICTURE
// draw some lines to image to make it more complicated
//
// @arg:	$image (resource)
//		$imagelength (int)
// @return:	$image (resource) - an image painted with lines
//======================================================================
private function drawLines($image, $imagelength) {
	
	for ($i =0 ; $i<4 ; $i++) {
		// define random colors  for lines
		$cColor = imagecolorallocate($image,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255));
		
		// first coodinates are in the first half of image
		$x0coordonate = mt_rand (0, 0.5 * $imagelength);
		$y0coordonate = mt_rand (0, $this->img_height);
		// second coodinates are in the second half of image
		$x1coordonate = mt_rand (0.5 * $imagelength,$imagelength);
		$y1coordonate = mt_rand (0, $this->img_height);
		
		imageline ($image, $x0coordonate, $y0coordonate, $x1coordonate, $y1coordonate,$cColor );
		imageline ($image, $x0coordonate-1, $y0coordonate-1, $x1coordonate-1, $y1coordonate-1,$cColor );
	}
	
	return $image;
}

//======================================================================
// CRYPT OR DECRYPT A STRING
// 
// we encrypt the string with libmcrypt > 2.4.x
// @arg:	$txt (string) string in clear text
//		$flag (constant) CRYPT | DECRYPT
// @return:	$result (string) encoded string
//======================================================================
private function cryptDecrypt($txt, $flag) {
	$td = mcrypt_module_open('tripledes', '', 'ecb', '');
	
        // windows OS supports only MCRYPT_RAND
	if (!$this->use_windows) {
		$iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_DEV_RANDOM);
	} else {
		srand ( ( (int) ( (double) microtime() * 1000003)) ); // good seed 1000003 is prime number
		$iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
	}
   	$ks = mcrypt_enc_get_key_size($td);
	
   	$key = substr(md5($this->secret_key), 0, $ks); 
	
	// Intialize encryption 
   	mcrypt_generic_init($td, $key, $iv);

	switch ($flag) {
		case 'CRYPT': 	$result = mcrypt_generic($td, $txt); break;
		case 'DECRYPT': $result = trim (mdecrypt_generic($td, $txt)); break;
	}

   	// Terminate encryption handler 
	mcrypt_generic_deinit($td);
   	mcrypt_module_close($td);
   	
   	return $result;
}


} // EOF class

?>