$salt = 'csdnfgksdgojnmfnb';

$password = md5($salt.$_POST['password']);
$result = mysql_query("SELECT id FROM users
                       WHERE username = '".mysql_real_escape_string($_POST['username'])."'
                       AND password = '$password'");

if (mysql_num_rows($result) < 1) {
    /* Access denied */
    echo "The username or password you entered is incorrect.";

} else {
    $_SESSION['id'] = mysql_result($result, 0, 'id');
    #header("Location: ./");
    echo "Hello $_SESSION[id]!";
}

require('PasswordHash.php');

$pwdHasher = new PasswordHash(8, FALSE);

// $hash is what you would store in your database
$hash = $pwdHasher->HashPassword( $password );

// $hash would be the $hashed stored in your database for this user
$checked = $pwdHasher->CheckPassword($password, $hash);
if ($checked) {
    echo 'password correct';
} else {
    echo 'wrong credentials';
}

<?php
// generates a 8 character hexadecimal CRC32 string
function crc($o){
  return str_pad(dechex(crc32($o)), 8, 0, STR_PAD_LEFT);
}

$salt = crc(mt_rand() . time); // a unique fixed length salt
$hash = sha1($password . $salt) . $salt; // generates a 40 character hash (32+8)

?>

<?php

$hash = $TheHashFromDatabase;

$salt = substr($hash, -8);
$generated_hash = sha1($_POST['user_pwd'] . $salt) . $salt;

if($generated_hash == $hash){
  // logged in - password is correct
}

?>