Hi everybody,
I would like to implement an authentication scheme that is used in PHP
websites all the time, but I can't seem to figure out how to make a
Java equivelant.
The PHP code is really simple:

/ Get the two character salt from the username
 $salt = substr($loginName, 0, 2);

 // Encrypt the password
 $crypted_password = crypt($loginPassword, $salt);
 
 // Formulate the SQL query to find the user
 $query = "SELECT password FROM customers
              WHERE email = '$loginName'
           AND password = '$crypted_password'";

 // Execute the query
 $result = @ mysql_query ($query,
                          $connection)
 or showerror();
 
 // exactly one row? then we have found the user
 if (mysql_num_rows($result) != 1 || $already_logged===true)
   return false;
 else
   return true;

As you can see, nothing shocking is happening there. A password is
encrypted using a salt (first two letters of the login name). It is
then checked whether this password is in the database for the user
that is trying to log in. This has the advantage that the password is
stored in the database in encrypted form meaning that even if the
database is comprimized the users passwords are still safe.

In other words, what I'm looking for is an encryption method that
simply encrypts using a salt (and thus produces the same
encrypted_string every time given a certain password/salt
combination). No decryption is ever needed. However, all the examples
on encryption that I find on the Net are all regarding public and
secret keys and make things way too complicated for my humble needs.

Does anybody have a simple example on how to do this in Java or know
of a URL where such an example is posted?

Any help is much appreciated, thanks, Jonck