and alike. User input is veryfied with captcha::check().
You should leave the sample COLLEGE.ttf next to this script, else you
have to define the _FONT_DIR constant correctly. Use only one type.
Includes a sluggish workaround for Internet Explorer; but this script
must reside in a www-accessible directory then.
Public Domain, available via http://freshmeat.net/p/captchaphp
*/
#-- config
define("EWIKI_FONT_DIR", dirname(__FILE__)); // which fonts to use
define("CAPTCHA_INVERSE", 0); // white or black(=1)
define("CAPTCHA_TIMEOUT", 5000); // in seconds (=max 4 hours)
/* static - (you could instantiate it, but...) */
class captcha {
/* gets parameter from $_REQUEST[] array (POST vars) and so can
verify input, @returns boolean
*/
function check() {
if (($hash = $_REQUEST["captcha_hash"])
and ($pw = trim($_REQUEST["captcha_input"]))) {
return((captcha::hash($pw)==$hash) || (captcha::hash($pw,-1)==$hash));
}
}
/* yields
END;
}
$html = "$html
";
return($html);
}
/* generates alternative (non-graphic), human-understandable
representation of the passphrase
*/
function textual_riddle($phrase) {
$symbols0 = '"\'-/_:';
$symbols1 = array("\n,", "\n;", ";", "\n&", "\n-", ",", ",", "\nand then", "\nfollowed by", "\nand", "\nand not a\n\"".chr(65+rand(0,26))."\",\nbut");
$s = "Guess the letters and numbers\n(passphrase riddle)\n--\n";
for ($p=0; $p= 'A') {
$type = ($c >= 'a' ? "small " : "");
do {
$n = rand(-3,3);
$c2 = chr((ord($c) & 0x5F) + $n);
}
while (($c2 < 'A') || ($c2 > 'Z'));
if ($n < 0) {
$n = -$n;
$add .= "$type'$c2' +$n letters";
}
else {
$add .= "$n chars before $type$c2";
}
}
#-- number
else {
$add = "???";
$n = (int) $c;
do {
do { $x = rand(1, 10); } while (!$x);
$op = rand(0,11);
if ($op <= 2) {
$add = "($add * $x)"; $n *= $x;
}
elseif ($op == 3) {
$x = 2 * rand(1,2);
$add = "($add / $x)"; $n /= $x;
}
elseif ($sel % 2) {
$add = "($add + $x)"; $n += $x;
}
else {
$add = "($add - $x)"; $n -= $x;
}
}
while (rand(0,1));
$add .= " = $n";
}
$s .= "$add";
$s .= $symbols1[rand(0,count($symbols1)-1)] . "\n";
}
return($s);
}
/* returns jpeg file stream with unscannable letters encoded
in front of colorful disturbing background
*/
function image($phrase, $width=200, $height=60, $inverse=0, $maxsize=0xFFFFF) {
#-- initialize in-memory image with gd library
srand(microtime()*21017);
$img = imagecreatetruecolor($width, $height);
$R = $inverse ? 0xFF : 0x00;
imagefilledrectangle($img, 0,0, $width,$height, captcha::random_color($img, 222^$R, 255^$R));
$c1 = rand(150^$R, 185^$R);
$c2 = rand(195^$R, 230^$R);
#-- configuration
$fonts = array(
// "COLLEGE.ttf",
);
$fonts += glob(EWIKI_FONT_DIR."/*.ttf");
#-- encolour bg
$wd = 20;
$x = 0;
while ($x < $width) {
imagefilledrectangle($img, $x, 0, $x+=$wd, $height, captcha::random_color($img, 222^$R, 255^$R));
$wd += max(10, rand(0, 20) - 10);
}
#-- make interesting background I, lines
$wd = 4;
$w1 = 0;
$w2 = 0;
for ($x=0; $x<$width; $x+=(int)$wd) {
if ($x < $width) { // verical
imageline($img, $x+$w1, 0, $x+$w2, $height-1, captcha::random_color($img,$c1,$c2));
}
if ($x < $height) { // horizontally ("y")
imageline($img, 0, $x-$w2, $width-1, $x-$w1, captcha::random_color($img,$c1,$c2));
}
$wd += rand(0,8) - 4;
if ($wd < 1) { $wd = 2; }
$w1 += rand(0,8) - 4;
$w2 += rand(0,8) - 4;
if (($x > $height) && ($y > $height)) {
break;
}
}
#-- more disturbing II, random letters
$limit = rand(30,90);
for ($n=0; $n<$limit; $n++) {
$letter = "";
do {
$letter .= chr(rand(31,125)); // random symbol
} while (rand(0,1));
$size = rand(5, $height/2);
$half = (int) ($size / 2);
$x = rand(-$half, $width+$half);
$y = rand(+$half, $height);
$rotation = rand(60, 300);
$c1 = captcha::random_color($img, 130^$R, 240^$R);
$font = $fonts[rand(0, count($fonts)-1)];
imagettftext($img, $size, $rotation, $x, $y, $c1, $font, $letter);
}
#-- add the real text to it
$len = strlen($phrase);
$w1 = 10;
$w2 = $width / ($len+1);
for ($p=0; $p<$len; $p++) {
$letter = $phrase[$p];
$size = rand(18, $height/2.2);
$half = (int) $size / 2;
$rotation = rand(-33, 33);
$y = rand($size+3, $height-3);
$x = $w1 + $w2*$p;
$w1 += rand(-$width/90, $width/40); // @BUG: last char could be +30 pixel outside of image
$font = $fonts[rand(0, count($fonts)-1)];
$r=rand(30,99); $g=rand(30,99); $b=rand(30,99); // two colors for shadow
$c1 = imagecolorallocate($img, $r*1^$R, $g*1^$R, $b*1^$R);
$c2 = imagecolorallocate($img, $r*2^$R, $g*2^$R, $b*2^$R);
imagettftext($img, $size, $rotation, $x+1, $y, $c2, $font, $letter);
imagettftext($img, $size, $rotation, $x, $y-1, $c1, $font, $letter);
}
#-- let JFIF stream be generated
/* Drop down quality if browser is MSIE */
if (preg_match('|MSIE ([0-9].[0-9]{1,2})|',$_SERVER["HTTP_USER_AGENT"],$matched)){
$quality = 8;
} else {
$quality = 100;
}
$s = array();
do {
ob_start(); ob_implicit_flush(0);
imagejpeg($img, "", (int)$quality);
$jpeg = ob_get_contents(); ob_end_clean();
$size = strlen($jpeg);
$s_debug[] = ((int)($quality*10)/10) . "%=$size";
$quality = $quality * ($maxsize/$size) * 0.93 - 1.7; // -($quality/7.222)*
}
while (($size > $maxsize) && ($quality >= 16));
imagedestroy($img);
#print_r($s_debug);
return($jpeg);
}
/* helper code */
function random_color($img, $a,$b) {
return imagecolorallocate($img, rand($a,$b), rand($a,$b), rand($a,$b));
}
/* unreversable hash from passphrase, with time() slice encoded */
function hash($text, $dtime=0) {
$text = strtolower($text);
$pfix = (int) (time() / CAPTCHA_TIMEOUT) + $dtime;
return md5("captcha::$pfix:$text::".__FILE__.":$_SERVER[SERVER_NAME]:80");
}
/* makes string of random letters for embedding into image and for
encoding as hash, later verification
*/
function mkpass() {
$s = "";
for ($n=0; $n<10; $n++) {
$s .= chr(rand(0, 255));
}
$s = base64_encode($s); // base64-set, but filter out unwanted chars
$s = preg_replace("/[+\/=IG0ODQR]/i", "", $s); // (depends on YOUR font)
$s = substr($s, 0, rand(5,7));
return($s);
}
}
#-- IE workaround
if (isset($_REQUEST["_ddu"])) {
header("Content-Type: image/jpeg");
die(base64_decode(substr($_REQUEST["_ddu"], 0)));
}
?>