Michael Robinton > Crypt-License-2.04 > Crypt::License



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Crypt::License - Perl extension to examine a license file.


There are two modes of operation:

        use Crypt::License;1;
        encrypted module here...

The calling routine should define an anonymous hash pointed to by the variable $ptr2_License. i.e.

 use vars qw( $ptr2_License );
 $ptr2_License = {
        'private'       => 'name1, name2,...',  # use private key 
                                                # module name
        'path'          => 'path to License file',
 require licensed_module_name;

Or, for nested modules, a reference pointer to point back to the originating module containing the License information.

 use vars qw( $ptr2_License );
 $ptr2_License = { 'next' => 'any value will do', };
 require licensed_module_name;

        Seconds remaining until License expiration are returned in
        $ptr2_License{expires} unless there is no expiration

        Warnings if any will be in $ptr2_License->{warn}

        It is important the 'require' instead of 'use' loads the module
        so that $ptr2_License is visible to the loader and not forgotton
        in the case of mod-perl so don't enclose a in BEGIN{} block.

        Version checking is not supported via 'use' like statement. It
        can be done by examining the module contents.

More automated setup can be accomplished with the Crypt::License::Util tools.

  use Crypt::License::Util;

See Crypt::License::Util documentation for complete description

The second module mode is for development use and just loads the module so its objects can be accessed;

  use Crypt::License;

  $time = Crypt::License::date2time(date string);

  @file_text = Crypt::License::get_file(file_path);

  $first_tag_number = Crypt::License::extract(\@file_text,\%parms);



Crypt::License decodes an encrypted file and attempts to decrypt it by first, looking for a hash pointer in the caller program called $ptr2_License. The hash contains the path to the License file and an optional 'private' key list of modules which will decrypt only with the 'private' key. OR, a hash key of 'next' with no particular value that indicates to look to the next caller on the stack for the License pointer. If the pointer is not present or the License file is not found successfully, then no further action is taken. If the License file is successfully opened, and the contents validated then the attached encrypted module is loaded and the seconds remaining until License expiration are returned or now() in the case of no expiration. Undef is returned for an expired license (module fails to load).

This is what is in a certificate
 License Text followed by:
 ID:    :unique licensee identifier, date code is fine
 NAME:  :company or entity name
 ADD1:  :address line 1
 ADD2:  :address line 2
 CITY:  :city
 STATE: :state or province
 ZIP:   :postal code
 CTRY:  :country
 TEL:   :telephone number
 FAX:   fax number
 CONT:  :contact person
 MAIL:  :email addy of contact
 SERV:  :http server name       * optional
 HOST:  :hostname               * optional Sys::Hostname
 USER:  :calling user           * optional
 GROUP: :calling group          * optional
 HOME:  :called from within this path   * optional
 DATE:  :creation date, mm-dd-yy | yyyy  or mmm dd yy | yyyy
 EXP:   :expiration             * optional
 KEY:   :hex key
 PKEY:  :hex public key
$time = Crypt::License::date2time(date string)

Converts a string into a numeric time value as returned by the perl function 'time' else 0;

 * acceptable date formats
        mm dd yy
        month day year          month = text or digits
        month day, year

actually any combination of separators [/- ] will work commas are always deleted, white space compressed, etc...

@file_text = Crypt::License::get_file(file_path)

Takes the file path/name as its argument. Returns the stripped file contents suitable for MAC calculation in an array. On failure, returns an empty array.

MAC calculation

The MAC signature is created by taking the MD5 sum of the file less MAC the line (if present). Leading blank lines are removed, all tabs are converted to single spaces and trailing white space is snipped to avoid complications caused by cut and paste operations. MAC calculation is only done on the text portion of the file.

$first_tag_num = Crypt::License::extract(\@file_text,\%parms)

extract takes an input array consisting of the lines of text in the License and returns the \%parms hash filled with the values present in the License file. The return value is the pointer to the first tag of the array.

MAC calculation described above will only be done on the text portion of the array.


The following fields are returned to the %chk_vals hash from the host platform unless the fields are not present in the License file:

 SERV:  :http server name
 HOST:  :hostname as returned by Sys::Hostname::hostname
 USER:  :user
 GROUP: :user
 HOME:  :server document root
 EXP:   :time since epcoch time ins seconds


The target module distribution for License encryption should be modified as follows:


For installation with programs called by apache that are installed using PerlModule or PerlRequire commands, there are several requirements.

1 The server will need a License with a public key. The License needs to be loaded in the startup.pl script.
2 The handlers loaded from the PerlRequire or PerlModule directives need a next $ptr2_License so that on startup they will decrypt and when called from user space will point back to the user License.
3 Any routine which calls handler directives needs a next $ptr2_License even if the module is not actually loaded in the routine. i.e. some handlers, like Apache::AuthCookie, force the loading of the user's handlers so the call to 'use UserHandler' is unnecessary.
4 Specifically for modules like Apache::AuthCookie, this module calls Licensed modules by virtue of the PerlRequire or PerlModule directives in the users config file. BECAUSE of this, the AuthCookie module MUST have a next $ptr2_License inserted in the beginning statements.

HINT use the Crypt::License::Util routines to insert the necessary pointer after a standard module is "used" but before the code is called.

  use Apache;
  use Apache::Constants qw(:common :response :http);
  use Apache::AuthCookie;
  use vars qw($VERSION @ISA);
  $VERSION = 1.00;
  @ISA = qw(Apache::AuthCookie);
  use Crypt::License::Util;
5 With all this accomplished, crypted modules should load and de-crypt without problem.


None by default.


  makeCert.pl     makes a License document
  makeLicenseMod.pl     makes only unsplit Licensed modules
  makeCrypt.pl    makes a split Licensed module
  makePOD.pl      separates POD from mixed module
  mod_parser.pl   used by makeCrypt, makePOD, makeLicenseMod


Michael Robinton, michael@bizsystems.com



  Copyright 2002 Michael Robinton, BizSystems.

This module is free software; you can redistribute it and/or modify it under the terms of either:

  a) the GNU General Public License as published by the Free Software
  Foundation; either version 1, or (at your option) any later version,


  b) the "Artistic License" which comes with this module.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See either the GNU General Public License or the Artistic License for more details.

You should have received a copy of the Artistic License with this module, in the file ARTISTIC. If not, I'll be glad to provide one.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA


Crypt::License::Notice(3), Crypt::License::Util(3)

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