CAPTCHA

Instructions:
Create the following SQL table:
CREATE TABLE captcha (
confirm_id char(32) DEFAULT ” NOT NULL,
session_id char(32) DEFAULT ” NOT NULL,
code char(8) DEFAULT ” NOT NULL,
PRIMARY KEY (session_id,confirm_id)
);

Modify the settings in the script.

This script uses TTF fonts to display the code. You can upload your own fonts to use. Just be sure to change $font_dir to wherever your fonts are stored. (A default font without rotation is used if none are available.)

Snippet

1. <?php

2. //

3. // Settings

4. //

5. $dbhost = ‘localhost’;

6. $dbuser = ‘username’;

7. $dbpass = ‘password’;

8. $database = ‘database’;

9. $min_char = 4;

10. $max_char = 8;

11. $font_dir = ‘./*.ttf’;

12. //

13. // Initial start

14. //

15. mysql_connect($dbhost, $dbuser, $dbpass);

16. mysql_select_db($database);

17. session_start();

18. //

19. // Initiate image

20. //

21. header(“content-type: image/png”);

22. header(“Cache-control: no-cache, no-store”);

23. $width = rand(200, 300);

24. $height = rand(50, 70);

25. $img = imagecreate($width, $height);

26. $background = imagecolorallocate($img, rand(200, 255), rand(200, 255), rand(200, 255));

27. //

28. // Compile code

29. //

30. $array = array();

31. for ($i = 0; $i < $max_char; $i++)

32. {

33.   $alpha = chr(rand(1, 26) + 64);

34.   $numeric = rand(0, 9);

35.   $array[] = (rand(0, 1) == 0 || count($array) < $min_char) ? ((rand(0, 1) == 0) ? $alpha : $numeric) : ”;

36. }

37. $code = str_replace(‘0′, ‘Z’, implode(”, $array));

38. //

39. // Query database

40. //

41. $confirm_id = (eregi(‘^[a-z0-9]{32}$’, $_GET['id'])) ? $_GET['id'] : md5(uniqid($_SERVER['REMOTE_ADDR']));

42. $session_id = (eregi(“^[a-z0-9]{32}$”, session_id())) ? session_id() : ”;

43. mysql_query(“DELETE FROM captcha WHERE session_id = ‘$session_id’”);

44. mysql_query(“INSERT INTO captcha (confirm_id, session_id, code) VALUES (‘$confirm_id’, ‘$session_id’, ‘$code’)”);

45. //

46. // Create background

47. //

48. for ($i = 0; $i < rand(5, 20); $i++)

49. {

50.   $color = imagecolorallocate($img, rand(0, 255), rand(0, 255), rand(0, 255));

51.   $loc_x = rand(-100, $width + 100);

52.   $loc_y = rand(-50, $height + 50);

53.   $end_x = rand(-100, $width + 100);

54.   $end_y = rand(-50, $height + 50);

55.   // Background shapes

56.   $shape = rand(1, 3);

57.   switch ($shape)

58.   {

59.     case 1:

60.       // Draw an ellipse

61.       imageellipse($img, $loc_x, $loc_y, rand(100, 400), rand(50, 400), $color);

62.     break;

63.     case 2:

64.       // Draw a rectangle

65.       imagerectangle($img, $loc_x, $loc_y, $end_x, $end_y, $color);

66.     break;

67.     case 3:

68.       // Draw a line

69.       imageline($img, $loc_x, $loc_y, $end_x, $end_y, $color);

70.     break;

71.   }

72. }

73. //

74. // Compile image

75. //

76. $x_move = $width / (strlen($code) + 1);

77. $current_pos = rand(0, $x_move / 2);

78. $less_rotate = array(‘N’, ‘Z’, ‘6′, ‘9′);

79. for ($i = 0; $i < strlen($code); $i++)

80. {

81.   $size = rand(15, 20);

82.   $angle = (in_array($code[$i], $less_rotate)) ? rand(-15, 15) : rand(-30, 30);

83.   $x_pos = $current_pos + rand($size + 1, $x_move);

84.   $y_pos = $height/2 + rand(-8, 8);

85.   $current_pos = $x_pos;

86.   $fonts = glob($font_dir);

87.   $font = $fonts[array_rand($fonts)];

88.   $color = imagecolorallocate($img, rand(0, 127), rand(0, 127), rand(0, 127));

89.   if (!empty($font))

90.     imagettftext($img, $size, $angle, $x_pos, $y_pos, $color, $font, $code[$i]);

91.   else

92.     imagestring($img, 5, $x_pos, $y_pos, $code[$i], $color);

93. }

94. //

95. // Create image

96. //

97. imagepng($img);

98. imagedestroy($img);

99. /* —— MySQL Query ——

100. CREATE TABLE captcha (

101. confirm_id char(32) DEFAULT ” NOT NULL,

102. session_id char(32) DEFAULT ” NOT NULL,

103. code char(8) DEFAULT ” NOT NULL,

104. PRIMARY KEY  (session_id,confirm_id)

105. );

106. */

107. ?>

108. ### TEST PAGE ###

109. <?php

110. mysql_connect(‘localhost’, ‘username’, ‘password’);

111. mysql_select_db(‘database’);

112. session_start();

113. if (isset($_POST['submit']))

114. {

115.   $confirm_id = (eregi(‘^[a-z0-9]{32}$’, $_POST['confirm_id'])) ? $_POST['confirm_id'] : ”;

116.   $result = mysql_query(“SELECT * FROM captcha WHERE confirm_id = ‘$confirm_id’ LIMIT 1″);

117.   $row = mysql_fetch_assoc($result);

118.   if (!$row || $_POST['confirm'] !== $row['code'])

119.   {

120.     echo ‘<b>Invalid Code:</b>’;

121.   }

122.   else

123.   {

124.     $session_id = (eregi(“^[a-z0-9]{32}$”, session_id())) ? session_id() : ”;

125.     mysql_query(“DELETE FROM captcha WHERE session_id = ‘$session_id’”);

126.     session_destroy();

127.     echo ‘<b>Valid:</b>’;

128.   }

129.   echo $_POST['confirm'] . ‘|’ . $row['code'] . ‘<br />’;

130. }

131. $confirm_id = md5(uniqid($_SERVER['REMOTE_ADDR']));

132. ?>

133. <img src=“captcha.php?id=<?php echo $confirm_id; ?>”>

134. <form method=“post”>

135. <input type=“hidden” name=“confirm_id” value=“<?php echo $confirm_id; ?>”>

136. <input type=“text” name=“confirm” size=“30″>

137. <input type=“submit” name=“submit” value=“Submit”>

138. </form>