Graphic digit verification code

Graphic digit verification code
Code:
 
<?
/*
* Filename: authpage. php
*/
Srand (double) microtime () * 1000000 );
// Verify that the user input is consistent with the verification code
If (isset ($ _ POST ['authinput'])
{
If (strcmp ($ _ POST ['authnum'], $ _ POST ['authinput']) = 0)
Echo "verification successful! ";
Else
Echo "verification failed! ";
}
// Generate a new four-digit integer verification code
While ($ authnum = rand () % 10000) <1000 );
?>
<Form action = authpage. php method = post>
<Table>
Enter the verification code: <input type = text name = authinput style = "width: 80px"> <br>
<Input type = submit name = "verify" value = "submit verification code">
<Input type = hidden name = authnum value = <? Echo $ authnum;?>

</Table>
</Form>
Bytes -------------------------------------------------------------------------------------------------------------
<?
/*
* Filename: authimg. php
*/
// Generate a verification code Image
Header ("Content-type: image/PNG ");
Srand (double) microtime () * 1000000 );
$ Im = imagecreate (58,28 );
$ Black = ImageColorAllocate ($ im, 0, 0 );
$ White = ImageColorAllocate ($ im, 255,255,255 );
$ Gray = ImageColorAllocate ($ im, 200,200,200 );
Imagefill ($ im, 68, 30, $ gray );
// Print the four-digit integer verification code into the image
Imagestring ($ im, 5, 10, 8, $ HTTP_GET_VARS ['authnum'], $ white );
For ($ I = 0; $ I <50; $ I ++) // add interference pixels
{
Imagesetpixel ($ im, rand () % 70, rand () % 30, $ gray );
}
ImagePNG ($ im );
ImageDestroy ($ im );