are you a human?

PHP Graphical Distorted Text Example

<?php

//php5-curl must be installed

function HandleRequest()
{

//
	// All requests start here. If values are provided for the 'id' and 'code'
	// parameters, we assume the user is attempting to pass the CAPTCHA. If
	// the 'code' is not provided, it's assumed we need to present the user 
	// with the form and CAPTCHA 
	//

$key = $_GET['id'];
	$code = $_GET['code'];
	$user = $_GET['user'];

if((!is_null($key)) && (!is_null($code)))
	{
		if(ValidateCode($key, $code))
		{
			CreateAccount($user);
		}
		else
		{
			ShowEnterCodeForm("Invalid Code Entered");
		}
	}
	else
	{
		ShowEnterCodeForm("");
	}
}

function ValidateCode($key, $code)
{
	//
	// The id and code sent via the ShowCodeForm end up here.
	// These values are used to make a request to the CAPTCHA system.
	// If the code matches, the CAPTCHA system returns 'success'
	//

$resp = GetData("https://areyouahuman.org/captcha.pl?id=$key&code=$code&type=IMAGE");

if(strcmp($resp, 'success') == 0)
	{
		return 1;
	}	
	else
	{
		return 0;
	}
}

function CreateAccount($user)
{
	// add logic here to create user account
	
	$content = "
			<html>
			<body>
			<title>Bogus account creation page</title>
			<center>
			Account Created!
			</center>
			</body>
			<html>";
	
	SendData($content);
}

function SendData($content)
{
	print $content;
}

function GetData($url)
{

// you will need php5-curl install for this work. 
	// on debian, it's apt-get install php5-curl.
	// be sure to run apt-get update first :)

$c = curl_init();
	
	curl_setopt($c, CURLOPT_URL, $url);
	curl_setopt($c, CURLOPT_RETURNTRANSFER, 1);

// Download the godaddy CA cert and tell curl about it via:
	// curl_setopt($c, CURLOPT_CAINFO, "/path/to/cert");
	// Once this is done, change CUROPT_SSL_VERIFYPEER to 1
	//
	// See http://curl.rtin.bz/docs/sslcerts.html for more info

curl_setopt($c, CURLOPT_SSL_VERIFYPEER, 0);
	curl_setopt($c, CURLOPT_SSL_VERIFYHOST, 2);

$response = curl_exec($c);
	curl_close($c);

return $response;

}

function ShowEnterCodeForm($msg)
{
	$key = GenerateRandomKey();

//
	// This represnts a typical "create an account" form.
	// The portions of this form that are specific to the CAPTCHA
	// are the 'id' and 'code' fields.
	//

$content = "
			<html>
			<body>
			<title>Bogus account creation page</title>
			<center>
			<img src='/captcha.pl?id=$key'/><br/>
			<form action='gdtExample.php' method='GET'>
				Username: <input type='text' name='user' id='user'/><br/>
				<input type='hidden' name='id' value='$key'/>
				Enter Code:<input type='text' name='code'/><br/>
				<input type='submit' value='Create Account'/>
			</form>
			<br/>
			$msg
			</center>
			</body>
			<html>";
			
	SendData($content);
}

function GenerateRandomKey()
{
	//
	// Generate a 32-byte alphanumeric ID that is passed to the CAPTCHA system
	//

$key = "";
	$alphabet = array();
	$i = 0;

//0 - 9
	for($i = ord('0'); $i <= ord('9'); $i++)
	{
		$alphabet[] = chr($i);
	}

//a - z
	for($i = ord('a'); $i <= ord('z'); $i++)
	{
		$alphabet[] = chr($i);
	}

//A - Z
	for($i = ord('A'); $i <= ord('Z'); $i++)
	{
		$alphabet[] = chr($i);
	}

while(strlen($key) < 32)
	{
		$key .= $alphabet[(int)rand(0, sizeof($alphabet))];
	}

return $key;
}

HandleRequest();