在登陆时加上验证码，怎么用程序来实现校验呢？

[websherry]

这个验证码是系统随机产生的，可是这怎么来实现安全登陆呢？一时搞不懂是什么原理，在程序上如何控制这个验证码，请各位高手帮帮忙，先谢谢大家了！

[causky]

<?php
while( $randomed < 4096 || $randomed > 65535 )
{
srand ( ( double ) microtime ( ) * 1000000 );
$randval = rand ( );
$randomed = 一个ＩＮＴ型 ^ $randval;
}
print ( "附加码： <img src=\"png.php?random=".$randomed."\" align=\"bottom\">" );
print ( "<input name=\"adcode\" type=\"hidden\" value=".$randval.">" );
?>
//--------png.php---------
<?
$random = dechex ( $_GET['random'] );
for ( $i = 0; $i < strlen ( $random ); $i ++ )
{
srand ( ( double ) microtime ( ) * 1000000 );
$randval2 = rand();
$randval2 %= 4;
imagestring ( $Image, 5, 10 + $i * 20, $randval2, $random[ $i ], $black );
}
ImagePNG ( $Image );
ImageDestroy( $Image );
?>
//--check程序
if ( ( hexdec ( $g_user[aid] ) ^ $g_user[adcode] ) != 上面那个ＩＮＴ型 )
{
／／附加码错误
}

[bonniewater]

把这个验证码存成session，然后在判断页面判断就可以了

[mrsun]

在生成验证码的页面包含一个hidden隐藏变量，然后一起传到下页
把用户填写的和生成的比较一下就可以了

[xuzuning]

开玩笑！"在生成验证码的页面包含一个hidden隐藏变量"这样做不是形同虚设吗？

[zhaobohao]

就是,你一定要记住,特别重要的东西,要保存成session,别用什么hidden,或者cookies,我到一些要密码的网站..他们很多密码都保存在javascript,hidden,cookies,我都能弄来..不用注册..哈哈...

[vitalgg]

<?
/* login.php */
session_start();
?>
<FORM METHOD=POST ACTION="ii.php">
<input type=text name=number maxlength=4><img src="yan.php">
<INPUT TYPE="submit" name="sub">
</FORM>

<?
if(isset($_POST["sub"])){
if($_POST["number"]!=$_SESSION["auth"]||empty($_POST["number"])){
echo "验证码错误" ;
unset($_SESSION['auth']);
}else{
echo"验证码正确";
unset($_SESSION['auth']);
};
};
?>
====================
yan.php
<?php
session_start();
srand((double)microtime()*1000000);

while(($authnum=rand()%10000)<1000);//生成四位随机整数验证码
$_SESSION['auth']=$authnum;

//生成验证码图片
Header("Content-type: image/PNG");
$im = imagecreate(50,20);
$black = ImageColorAllocate($im, 200,10,0);
$white = ImageColorAllocate($im, 255,255,255);
$gray = ImageColorAllocate($im, 230,230,230);
imagefill($im,68,30,$gray);

//将四位整数验证码绘入图片
//位置交错
for ($i = 0; $i < strlen($authnum); $i++) {
if ($i%2 == 0) $top = 1;
else $top = 5;
imagestring($im, 5, 10*$i+6, $top, substr($authnum,$i,1), $black);
}

for($i=0;$i<150;$i++) //加入干扰象素
{
imagesetpixel($im, rand()%70 , rand()%30 , $black);
}

ImagePNG($im);
ImageDestroy($im);

?>

[zxlh]

xbm.asp

<!--#include file="numcode.asp"-->
<%
Response.Buffer = True
With Response
.Expires = -1
.AddHeader "Pragma","no-cache"
.AddHeader "cache-ctrol","no-cache"
End With

Dim num
Randomize
num = Int(7999 * Rnd + 2000)
Session("validateCode") = num

Dim Image
Dim Width, Height
Dim digtal
Dim Length
Dim sort
Dim hc
Length = 4
hc = chr(13) & chr(10)

Redim sort(Length)

digital = ""
For I = 1 To Length - Len(num)
digital = digital & "0"
Next
For I = 1 To Len(num)
digital = digital & Mid(num, I, 1)
Next
For I = 1 To Len(digital)
sort(I) = Mid(digital, I, 1)
Next
Width = 8 * Len(digital)
Height = 10

Response.ContentType = "image/x-xbitmap"

Image = "#define counter_width " & Width & hc
Image = Image & "#define counter_height " & Height & hc
Image = Image & "static unsigned char counter_bits[] = {" & hc

For I = 1 To Height
For J = 1 To Length
Image = Image & a(sort(J),I) & ","
Next
Next

Image = Left(Image, Len(Image) - 1)
Image = Image & "};" & hc

Response.Write Image
%>

numcode.asp


<%
Dim a(10,10)

a(0,1) = "0x3c" '数字0
a(0,2) = "0x66"
a(0,3) = "0xc3"
a(0,4) = "0xc3"
a(0,5) = "0xc3"
a(0,6) = "0xc3"
a(0,7) = "0xc3"
a(0,8) = "0xc3"
a(0,9) = "0x66"
a(0,10)= "0x3c"

a(1,1) = "0x18" '数字1
a(1,2) = "0x1c"
a(1,3) = "0x18"
a(1,4) = "0x18"
a(1,5) = "0x18"
a(1,6) = "0x18"
a(1,7) = "0x18"
a(1,8) = "0x18"
a(1,9) = "0x18"
a(0,10)= "0x7e"

a(2,1) = "0x3c" '数字2
a(2,2) = "0x66"
a(2,3) = "0x60"
a(2,4) = "0x60"
a(2,5) = "0x30"
a(2,6) = "0x18"
a(2,7) = "0x0c"
a(2,8) = "0x06"
a(2,9) = "0x06"
a(2,10)= "0x7e"

a(3,1) = "0x3c" '数字3
a(3,2) = "0x66"
a(3,3) = "0xc0"
a(3,4) = "0x60"
a(3,5) = "0x1c"
a(3,6) = "0x60"
a(3,7) = "0xc0"
a(3,8) = "0xc0"
a(3,9) = "0x66"
a(3,10)= "0x38"

a(4,1) = "0x38" '数字4
a(4,2) = "0x3c"
a(4,3) = "0x36"
a(4,4) = "0x33"
a(4,5) = "0x33"
a(4,6) = "0x33"
a(4,7) = "0xff"
a(4,8) = "0x30"
a(4,9) = "0x30"
a(4,10)= "0xfe"

a(5,1) = "0xfe" '数字5
a(5,2) = "0xfe"
a(5,3) = "0x06"
a(5,4) = "0x06"
a(5,5) = "0x3e"
a(5,6) = "0x60"
a(5,7) = "0xc0"
a(5,8) = "0xc3"
a(5,9) = "0x66"
a(5,10)= "0x3c"

a(6,1) = "0x60" '数字6
a(6,2) = "0x30"
a(6,3) = "0x18"
a(6,4) = "0x0c"
a(6,5) = "0x3e"
a(6,6) = "0x63"
a(6,7) = "0xc3"
a(6,8) = "0xc3"
a(6,9) = "0x66"
a(6,10) ="0x3c"

a(7,1) = "0xff" '数字7
a(7,2) = "0xc0"
a(7,3) = "0x60"
a(7,4) = "0x30"
a(7,5) = "0x18"
a(7,6) = "0x18"
a(7,7) = "0x18"
a(7,8) = "0x18"
a(7,9) = "0x18"
a(7,10)= "0x18"

a(8,1) = "0x3c" '数字8
a(8,2) = "0x66"
a(8,3) = "0xc3"
a(8,4) = "0x66"
a(8,5) = "0x3c"
a(8,6) = "0x66"
a(8,7) = "0xc3"
a(8,8) = "0xc3"
a(8,9) = "0x66"
a(8,10)= "0x3c"

a(9,1) = "0x3c" '数字9
a(9,2) = "0x66"
a(9,3) = "0xc3"
a(9,4) = "0xc3"
a(9,5) = "0x66"
a(9,6) = "0x3c"
a(9,7) = "0x18"
a(9,8) = "0x0c"
a(9,9) = "0x06"
a(9,10)= "0x03"
%>

[zzmpower]

我想用session 是再适合不过了，
session_is_register("$dd");

[AgathaZ]

TO:zhaobohao(中文字符)
不用注册就能把密码弄过来？？？？怎么弄啊？？？！！！！