<?php
============= 文件: validate_image.php ================
/*
不用 session 实现的图片认证码
作者: 暖阳
*/
$validateCodeKeepTime = 60 * 5; //验证码有效时间,秒
function validateCode($string,$action="ENCODE"){ //字符串加密和解密
$secret_string = 'd0nf873498**&^%$JHJK'; //绝密字符串,可以任意设定
if($string=="") return "";
if($action=="ENCODE") $crc32="@".crc32($string);
else list($string,$crc32)=split("@",$string);
$key = substr(md5($_SERVER["HTTP_USER_AGENT"].$secret_string.filemtime(str_replace('\\','/',__FILE__))),8,18);
$string = ($action=="ENCODE"?$string:base64_decode($string));
$len = strlen($key);
$code = "";
for($i=0; $i<strlen($string); $i++){
$k = $i%$len;
$code .= $string[$i]^$key[$k];
}
$code = ($action == "DECODE" ? (crc32($code)==$crc32?$code:NULL) : base64_encode($code)."$crc32");
return $code;
}
function randString($len=4){ //产生随机字符串
$chars="23456789ABCDEFGHJKLMNPRSTWXY"; //验证码可取的字符,去掉不易辨认的字符
$string="";
for($i=0;$i<$len;$i++){
srand((double)microtime()*1000000);
$rand=rand(0,strlen($chars)-1);
$string.=substr($chars,$rand,1);
}
return strtoupper($string);
}
//输出图片
if(strtolower(str_replace('\\','/',__FILE__))==strtolower(str_replace('\\','/',$_SERVER['SCRIPT_FILENAME']))){
$decode = validateCode($_GET["secretCode"],"DECODE");
list($string,$mytime)=split('@',$decode);
if(!$string) $string=' ';
Header("Content-type: image/gif");
$imageWidth = strlen($string)*20;
$imageHeight = 20;
$im = imagecreate($imageWidth,$imageHeight);
$backColor = ImageColorAllocate($im, rand(220,255),rand(220,255),rand(220,255)); //背景色
imagefilledrectangle($im, 0, 0, $imageWidth, $imageHeight, $backColor);
for($i=0;$i<100;$i++){ //画斑点
$dotColor = ImageColorAllocate($im, rand(0,255),rand(0,255),rand(0,255)); //点色
$x = rand(0,$imageWidth); $y = rand(0,$imageHeight);
imagesetpixel($im, $x, $y, $dotColor);
}
for($i=0;$i<strlen($string);$i++){ //写字
$frontColor = ImageColorAllocate($im, rand(0,120),rand(0,120),rand(0,120)); //字色
imagestring($im, 5, rand(20*$i+1,20*$i+10), rand(0,5), substr($string,$i,1),$frontColor);
}
imagepng($im);
imagedestroy($im);
exit;
}
?>
========================================实例=========================================
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>faisun@sina.com</title>
<style type="text/css">
body,td{ font-size:12px; }
</style>
</head>
<body>
<?
include("validate_image.php");
if($_REQUEST[action]=="confirm"){
list($mycode,$mytime)=split('@',validateCode($_POST["secretCode"],"DECODE"));
if(time()-$mytime>$validateCodeKeepTime){
echo "验证码已过期!";
exit;
}elseif(!$_POST["secretCode"]||strtoupper($_POST[ValidateCode])!=$mycode){
echo "验证码错误!";
exit;
}else{
echo "验证码输入正确."; //改为你其他的处理代码.
}
}else{
?>
<form name="form1" method="post" action="">
<table width="300" border="0" cellspacing="0" cellpadding="3">
<tr>
<td width="110" align="right">验证码:</td>
<td width="178">
<?
$secretCode = validateCode(randString(4)."@".time());
?>
<input name="ValidateCode" type="text" id="ValidateCode" size="10">
<img src="validate_image.php?secretCode=<?=urlencode($secretCode);?>" align="absmiddle">
<input type='hidden' name='secretCode' value='<?=$secretCode;?>'>
</td>
</tr>
<tr>
<td> </td>
<td> </td>
</tr>
<tr>
<td> </td>
<td><input name="action" type="hidden" id="action" value="confirm">
<input type="submit" name="Submit" value="确定"></td>
</tr>
</table>
</form>
<?
}
?>
</body>
</html>
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