Extension:PageProtectionPlus

Welcome to the MediaWiki extension for protecting pages.

PageProtectionPlus (a.k.a PPP) has been created on the base called PageProtection written by Fabian Schmitt. If you are using PageProtection and you are interested why this is a branch and what are the differences please see further section called  Why branch?.

The extension is implemented as parser and hook in AlternateEdit. You can have multiple protected and unprotected areas on a single article where only allowed users see the protected areas, all other users see the rest.

Requirements
0. PHP 5

1. PEAR and PEAR/Crypt_RSA packages.


 * Crypt_RSA – http://pear.php.net/package/Crypt_RSA (1.2 or later; pear installs 1.0 by default)
 * Pear-Base – http://pear.php.net/package/PEAR

2. Additionaly, you'll need one of these:


 * GMP system library – http://www.swox.com/gmp/
 * bin_int PHP's package/extension – http://pecl.php.net/package/big_int
 * bcmath PHP's extension

3. You also need cryptographic engine(s):


 * PHP with libmcrypt – http://mcrypt.sourceforge.net (very ok to have it)
 * and/or
 * Crypt_Blowfish – http://pear.php.net/package/Crypt_Blowfish (version 1.1.0RC1 or higher!)

4. Older MediaWiki installations may need ExtensionFunctions.php to be installed.

You can get more info in the /Installation Guide/

Getting
The whole code with installation guide is now available for download from the following locations:
 * http://entropy.echelon.pl/people/siefca/software/PageProtectionPlus-2.3b.tar.gz
 * ftp://ep09.pld-linux.org/people/siefca/software/PageProtectionPlus-2.3b.tar.gz
 * ftp://ftp.pld-linux.org/people/siefca/software/PageProtectionPlus-2.3b.tar.gz

How it works
This is a  cryptographic  engine used  to protect  articles and/or articles' sections of MediaWiki. It uses public-key cryptography combined  with symmetric-key  cryptography  to achieve good  safety/time factor. In order to work properly it needs  RSA  key  pairs  present  in  PEM  files  on  the application server, which handles encryption and decryption.

When you edit a page
It encrypts sections of  text in  the articles  just before they are put in to  the database. To recognize parts which should be encrypted it looks for XML  tag called 'protect'. Whenever it finds the opening tag it performs encryption of the text up to the closing tag.

When you read a page
It seeks for  'protect' XML  tags and  extracts information enclosed within them. It then checks  whether  a user  is allowed to read a certain part of  a text. If that is so, it runs decryption engine and replaces cryptograms  with plain texts. To decrypt a cryptogram (an encrypted  text in other words) it  needs a valid RSA  key pair present in  the keys' heap - a directory containing PEM files.

Tags
This extension allows protecting  single areas  by spanning them with   -tags. The  tag  has   the  following parameters:


 * users – Comma-separated list of  usernames who are allowed to read and edit the area.


 * groups – Comma-separated  list of groupnames who  are allowed to read and edit the area.


 * show – Defines,  what to do  when user  has no access  to the area. Possible Values:
 * warning –   Error-message with list of permissions.
 * none –   Nothing is displayed.
 * crypt –  Encrpyted text is shown.
 * page –   Page in "errorpage" is displayed.
 * text –   Protected text is displayed (the section is marked as readonly).


 * errorpage – Page to be shown when show=page is set.

Valid  ciphers  can   be   found   on  specialpage   called Special:PageProtectionCipherSuite.
 * cipher – Defines cipher   to  be   used  for   encryption.


 * You can put  'rsa' string as a value,  which will enable encryption of  the whole text with  the RSA  public key  without symmetric  cipher in  the middle layer.  It is powerful,  but very very slow  (and not recommended for larger pages).

The text between the opening and closing 'protect'-tags will be hidden for users not in the specified  lists. Members of 'sysop' always have access.

Example:  Database-Settings ;Server : localhost ...

Why there is a directory for keys, not a one file?
It allows you to generate new RSA key and  still be able to read pages  encrypted by one  of the keys used  before. Keys are identified by their IDs (which are parts of fingerprints), so  filenames doesn't matter.

There are two exceptions, where the names have matter.


 * One  is  the  name   default.pem  (or  other   set  in $wgPEMfile).  The file  named like  that should  contain the default key used for encryption. If you'll change its name, the routine find it in other file and use it when decrypting pages previously encrypted using it. However, a new key pair will  be generated  for encryption  and placed  in the  file saved under that name.


 * Second exception is the name lite.pem (or  other set in $wgPEMlite_file). The  file named  like that  should contain the  default key  used  for encryption  by  using so  called 'Pure-RSA' method.  If you'll  change its name,  the routine use it to decrypt pages  previously encrypted with it, but a new key pair  will be generated for  Pure-RSA encryption and placed in the file saved  under the name lite.pem or other set in $wgPEMlite_file.

Am I able to decrypt pages from PageProtection?
Yes, the  PageProtectionPlus  can decrypt  pages  encrypted using PageProtection.

Am I able to encrypt pages using RSA?
Yes. Pure-RSA is supported, but  you won't be able  to read the pages encrypted  in that  way under  PageProtection (in case of downgrade, reinstall).

Why branch?
PageProtectionPlus is a branch, since it differs in the most common operations from  PageProtection. It uses symmetric encryption for a text  and RSA  for encryption  of randomly generated symmetric key delivered within a header preceding an encrypted text data.

Original PageProtection uses pure RSA encryption,  which is strong but  it fails with  some requirements I needed  to be enforced:


 * The need of using strong RSA key (more than 2048 bits)
 * The need to be able to exchange the default RSA key periodically
 * The need that encryption/decryption should be performed fast
 * The need that the editor can choose symmetric cipher

Major differences

 * RSA encrypts only the random, symmetric key (by default)
 * Texts are encrypted using random, symmetric keys
 * There is a key heap - directory containing all RSA keys that are in use
 * Asymmetric keys (RSA) are identfied by their IDs
 * Encrypted text sections keept in the database have headers

Minor differences

 * Code for encryption/decryption is modular – you can adapt a new cipher engine in minutes
 * Editor can decide, which symmetric algorithm will be used (the cipher attribute for the protect tag)
 * Added i18n
 * Added special page containing list of supported ciphers (Special:PageProtectionPlusCipherSuite)
 * Texts are passed in binary format to the crypto-engines (base64 enc/dec and headers are handled by new classes)
 * ProtectionParser class was forced to not repeat decryption for text areas where it was done already
 * classes that are parsing tags were changed a bit to handle new attribute for the protect tag called 'cipher'

Result:


 * On Xeon(TM) CPU 2.70GHz RSA-encryption of one page (7kB) has taken about 90 seconds before, and now using Blowfish+RSA it takes 3 seconds.

Credits
Active help:


 * Magdalena Madeja, documentation reviews
 * Zbigniew Sobiecki, RSA-fingerprints discussion
 * Mike Dillon, important parser fix
 * Maik Hentsche, important accesslist fix

Pasive help:


 * Tomek Kaczmarek (tolerance)
 * Robert Grobelny (good mood)
 * Marcin Gołuch (idea of preventing access in our wiki)

Copyright
This extension is released under the terms of GPL version 2 or higher.


 * Copyright (C) 2006, 2007 Pawel Wilk (pw at gnu.org)
 * Portions Copyright (C) 2006, 2007 Fabian Schmitt (fs at u4m.de)