PHP: Creating a simple Captcha

Question

I have created a simple captcha generator, but won't show captcha-image :

index.php :

<?php
session_start();
$_SESSION['captcha'] = rand(1000, 9999);
?>

<img src="generator.inc.php" />

generator.inc.php :

<?php
session_start();
header('Content-type: image/jpeg');

$text = $_SESSION['captcha'];

$font_size = 30;
$image_width = 160;
$image_height = 50;

$image = imagecreate($image_width, $image_height);

imagecolorallocate($image, 200, 200, 200);

$font_color = imagecolorallocate($image, 20 , 20 , 20);

imagettftext($image, $font_size, 0, 15, 30, $font_color, 'BYekan.ttf', $text);

imagejpeg($image);
?>

Please tell me what am i doing wrong?

P.S :

I'm using Lamp server on Linux.

What happens when you view the image? Also, don't use a custom-made captcha in production code. There's a good chance that it'll be trivial to break. — Blender
– Blender, Commented Aug 4, 2013 at 11:09
how you can access BYekan.ttf ? I mean where is the font file ? — Janith Chinthana
– Janith Chinthana, Commented Aug 4, 2013 at 11:22
@Blender When implemented properly, I doubt that, especially since there is less benefit for malicious hackers to break it if it's not widely used. — GolezTrol
– GolezTrol, Commented Aug 4, 2013 at 11:22

Hamed Kamrava · Accepted Answer · 2014-07-25 14:40:22Z

1

Probably GD library is not installed.

Also check in php.ini and make sure GD line be uncommented.

answered Jul 25, 2014 at 14:40

Hamed Kamrava

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Comments

Hieu Le · Accepted Answer · 2013-08-04 11:25:51Z

0

I remove the header function call in your script and found an error that you have not defined the $image_height variable. In your script, you duplicate the $image_width assignment.

answered Aug 4, 2013 at 11:25

Hieu Le

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1 Comment

Hieu Le Over a year ago

Can you remove the header function and let me know what appear in the screen when your navigate to the generator.inc.php file from the browser?

Conrad Lotz · Accepted Answer · 2013-08-04 11:37:11Z

My suggestion would be to try 2 things:

I have read and seen before that people suggest to place the content type header('Content-type: image/jpeg'); just before the imagejpeg($image);. To back this up here is an article profing it: http://php.net/manual/en/function.imagejpeg.php

My other suggestion would be to base64_encode the file. If header('Content-type: image/jpeg'); produces an error suggestion "header() must be called before any actual output is sent" then base64_encode allows one to create an image with specifying the content type. Remove the header code and then add the following code when imagejpeg($image); is called.

ob_start();
imagejpeg($image); //your code
$img = ob_get_contents();
ob_end_clean();
echo '<img src="data:image/jpeg;base64,'.base64_encode($img).'" />';

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