mysql> select uid, username, password from userdb;
+-----+------------+------------------------------------------------+
| uid | username   | password                                       |
+-----+------------+------------------------------------------------+
|   2 | hesco      | password                                       |
|  35 | md5        | 05;X@9WL<JL&TU3!8@`L&[P``
                     |
|  36 | md5_hex    | @-35B93(P-C<W8C%C86%C,6(T9#4S,#4X.#`P8C`V968`
 |
|  37 | md5_base64 | 65F(T9UHS<V-Q<T<P,51"66=!<T<W=P``
             |
+-----+------------+------------------------------------------------+
4 rows in set (0.00 sec)

##</code><code>##

sub CreateUser {
  my($userdb,$username,$password)=@_;
  print STDERR "Running Create User Subroutine.\n";
  # store md5 hash of password
  # my $digest = md5($password);
  # my $digest = md5_hex($password);
  # my $digest = md5_base64($password);

  # my $user = { username => $username, password => $digest };
  my $user = { username => $username, password => $password };
  $user = $userdb->user_create( $user );
  return;
}

##</code><code>##

  DRIVER => [ 'DBI',
    DBH         => $authdb,
    TABLE       => 'userdb',
    CONSTRAINTS => {
      'userdb.username' => '__CREDENTIAL_1__',
      'userdb.password' => '__CREDENTIAL_2__'
      # 'MD5:userdb.password' => '__CREDENTIAL_2__'
      # 'MD5_hex:userdb.password' => '__CREDENTIAL_2__'
      # 'MD5_base64:userdb.password' => '__CREDENTIAL_2__'
    },
  ],