[kompadre]

<?php
if ($user = $_GET["user"] == "") die ("Chto-to s vashey formochkoy... :(");
$pass = $_REQUEST["pass"];
$e_user = "";  $e_pass = ""; 

$fh = fopen ('paroli.txt', 'r');

while (($e_user != $user)&&(!feof($fh))) {
  list($e_user, $e_pass) = explode(':',fgets($fh, 1024));
}

if ((feof($fh))&&($e_user != $user)) echo "Netu takogo usera ...";
else if ($pass == $e_pass) echo "Uspeh !"; 
else echo "Takoy user uzhe yest no parol k nemu ne podhodit"; 
fclose($fh);
?>

А в текстовике
Юзер:инкрипченный пароль (в данном случае - md5)
=====================
user1:b85b28ca50e30f48442d84417e3c729a
user2:b85b28ca50e30f48442d84417e3c729a (flasher.ru)