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+
+   ffff  
+  ff    firma -  
+  ffff  encrypted mailing list manager
+  ff    - a firma cai mas nao quebra
+  ff    
+
+Index
+-----
+
+ 1 - The concept
+ 2 - Everyone has the private key X The server has the private key
+ 3 - Why bash
+ 4 - Development Guidelines
+ 5 - Setup
+ 6 - Tips
+ 7 - Design and features
+ 8 - Caveats
+ 9 - Contact
+
+The concept
+-----------
+
+ In portuguese, "firma" means for signature, signature and trust checking and
+ is a slang for strength and enterprise.
+
+ All this together just can be one thing: an encrypted mailing list manager :P
+
+ In the streets, the expression "a firma cai mas nao quebra" (the enterprise
+ falls but does not breaks) is commonly used to talk about the strength of a
+ group that operates in secrecy. To our list manager, this concept says that
+ your encrypted mailing list can stops to work -- if the server goes offline
+ or abducted by aliens -- but the system can never be broken. With firma, we
+ are trying to follow this philosophy.
+
+ Firma is based on the gpgmailalias.pl perl script, hosted at
+ http://www.rediris.es/app/pgplist/index.en.html, but completely rewritten
+ in bash.
+
+ Firma works as a command line and MTA pipe alias tool that receives an
+ email message in its input, grab the encrypted/signed message, re-encrypt
+ and send it to each subscriber.
+
+ In the server you just need the script, a keyring with the list keypair
+ and two config files. When mail arrives, it is redirected by the MTA to the
+ script and it process the message if its properly encrypted and signed.
+ No temporary files are written during a message processing and no default
+ message archive, so no messages -- encrypted or not -- rest on your system
+ in all steps of the process.
+
+Everyone has the private key X The server has the private key
+-------------------------------------------------------------
+
+ When using a encrypted mailing list software, one must choose between
+ keeping the private key in the server or send it to each of the
+ subscribers. We'll not consider the case where every subscribers encrypt
+ the message to all recipients cause this has none automation in the
+ process we are looking for.
+
+ For the first there are some options:
+
+   - Schleuder
+     http://schleuder2.nadir.org/
+
+   - GPG Mailman
+     http://medien.informatik.uni-ulm.de/~stefan/gpg-mailman.xhtml
+
+   - Crypt-ML - gpg-ezmlm
+     http://www.synacklabs.net/projects/crypt-ml/
+
+   - Secure Email List Services (SELS)
+     http://sels.ncsa.illinois.edu/
+
+ For the second option there is the NAH6 Mailman patch,
+ http://mail.python.org/pipermail/mailman-coders/2003-June/000506.html
+
+ For the firsts releases of Firma, we choose to use just the first option.
+ In the future the code should contain support for an one-keypair list,
+ but this is not the main behavior we want in an encrypted mailing list.
+ This is a question of centralized versus decentralized vulnerability.
+
+ An one-keypair list is more or less just like a mail alias: someone
+ send an encrypted email to the list address and the manager just forwards
+ that encrypted email to the lists subscribers, optionally removing some
+ headers and performing some security auditing. Every user has the list
+ private key, so if someone lost it to the world then one must regenerate
+ a keypair and send again to every subscriber.
+
+ In the case of a keypair stored in the server, where subscribers has just
+ the list pubkey, the list admin just need to remove the correspondent pubkey
+ from the list's keyring with in case some user has its keypair compromised.
+
+ These two approaches has a similar external hole of some private key turned
+ public. Designing Firma, we decided for the centralized model, for three main
+ reasons:
+
+  1 - A server can be safer than any user's ordinary computer.
+
+  2 - Automation: when some user is removed from the list, we just remove their
+      key from the list keyring; in the decentralized approach, the list admin
+      needs to regenerate a new list keypair, otherwise the unsubscribed user
+      can still decrypt list messages if he can sniff the mail server traffic.
+
+  3 - Use a public-key and all info stored onto it as the subscriber info.
+
+Why Bash
+--------
+
+ You may ask why we choose bash. Its really strange a crypto project using
+ shell scripting language. But bash has many advantages:
+
+ - Bash is found in almost all unix-like systems
+
+ - Small dependencies: firma needs just tools like sed, awk, grep, cut and
+   gpg itself. Look at the file "GUIDELINES" to see a complete list of all
+   unix commands needed to run firma.
+
+ - You can easily put all the tools, scripts and config files in a read-only
+   media to protect against cracks such as rootkits.
+
+ - Keeping your encrypted list manager out from a huge and sometimes bugged
+   mail software prevents insecure use of your mailing list by an excess of
+   unwanted functions and routines.
+
+ - Firma has a total KISS design, and bash helps to keep it simple.
+
+ - Firma adopted the style suggested in the Advanced Bash-Scripting Guide,
+   http://www.tldp.org/LDP/abs/html/scrstyle.html
+
+Development Guidelines
+----------------------
+
+ As a security project we made a restricted set of guidelines / design policy,
+ attempting to get a clean, bug-free and high quality code. We choose a slow
+ development rather than sit-and-code. These rules are detailed in the file
+ GUIDELINES.
+
+Setup
+-----
+
+ Note for Debian users: you'll need the "expect" package to run firma.
+
+ Firma installation is quite simple:
+
+ 1 - Create a folder to store lists; by default firma use /var/lib/firma/lists
+     but you can use anything, just edit firma and change FIRMA_LIST_PATH
+     variable.
+
+ 2 - Copy firma script to whatever you like, e.g. /usr/local/bin and check that
+     it has no write permission
+
+ 3 - Create a list-wide config file (default is /var/lib/firma/firma.conf) with
+     the common definitions for all lists. You might just copy the sample
+     firma.conf.dist and edit according to your needs.
+
+     All config variables can be overwritten at each list's own config file;
+     firma.conf should be chmoded as 600, chowned nobody.nobody or whatever
+     user your MTA runs. If you run postfix, the user is specified by the
+     main.cf parameter "default_privs".
+
+     For a list of all config parameters, type
+
+       firma --help config
+
+ 4 - Then create your lists with the command
+
+       firma -c your-list
+
+     Then firma will ask some questions and create a gpg keyring and a config
+     file with the following variables:
+
+       LIST_ADDRESS= list's email address
+       LIST_ADMIN= list's administrators email addresses (space separated)
+       LIST_HOMEDIR= list's GnuPG homedir, where the list's keyrings are located
+       PASSPHRASE= passphrase for the list's private keyring
+
+     Then a gpg keypair and a config file are automatically generated;
+     the owner of the config file and keyring should be nobody.nobody
+     (or the user your MTA run as) and its permissions must be 600.
+
+     After that you can add some optional parameters on this list config file:
+
+       SUBJECT_PREFIX= prefix to be included in the subject of list messages
+
+       REMOVE_THESE_HEADERS= headers that should be stripped from list messages
+                             (space separated case-insensitive entries)
+                             (may include regexps (e.g., X-.*)
+
+       REPLIES_SHOULD_GO_TO_LIST= set to '1' to add a Reply-To header containing the
+                                  list address
+
+       SILENTLY_DISCARD_INVALID_MESSAGES= set to '1' to silently discard invalid
+                                          messages (message not signed/encrypted,
+                                          sender not subscribed to the list, etc.)
+                                          instead of sending bounces back to sender
+
+       KEYSERVER= default keyserver to import/export keys
+                  (defaults to keyserver.noreply.org)
+
+       REQUIRE_SIGNATURE= whether messages sent to the list should be (1) or don't
+                          need to be (0) signed to be processed; defaults to '1';
+                          this doesn't affect the way email administration works,
+                          when signature is mandatory
+
+     For a list of all config parameters, type
+
+       firma --help config
+
+ 5 - Create an alias to the list at your MTA; on sendmail or postfix,
+     add this to your aliases file:
+
+       your-list: "| /usr/local/bin/firma -p your-list"
+       your-list-request: "| /usr/local/bin/firma -e your-list"
+
+     and then run the command
+
+       newaliases
+
+     alternatively, you can use a virtual mailbox table if you want
+     to easily host a lot of encrypted mailing lists.
+
+ 6 - Admin tasks are performed through aliases like your-list-request@yourmachine
+     or via command-line:
+
+       firma -a your-list
+
+     inside this command or encrypted in your mailing list request, use the
+     following commands:
+
+       sub keyserver|keyfile key-id
+
+         subscribe key-id pubkey from file or keyserver (currently not
+         implemented)
+
+       unsub email-address
+
+          unsubscribe all keys with email-address IDs (currently not
+          implemented)
+
+       use email-address
+
+          uses the given address for message delivery instead
+          of the primary address of a subscribed key
+
+ 7 - To subscribe and unsubscribe manually the users and the list admins on, use
+     a command line like
+
+       gpg --homedir [path-to-your-list-keyring] --import < file
+
+     and be sure that after this command the list keyring is owned by nobody.nobody.
+
+ 8 - Send encrypted AND signed messages to your-list@yourmachine and look
+     what happens :)
+
+Tips
+----
+
+ - Use an encrypted swap memory
+ - Use a read-only media to store firma and its needed apps
+ - Use ramdisk to FIRMA_LIST_PATH so all keys and passwords vanishes if the server is shutdown
+ - Use a big PASSPHRASE, 25+ chars with alpha-numeric and special ascii keys
+
+Design and features (OUTDATED)
+-------------------
+
+ Firma is simple but its simplicity doesn't reflect in lack of design.
+
+ - Uses a gpg keyring to store both the keys and the subscribers options
+
+ - Command line is simple to avoid admin tasks resting in some .bash_history
+
+ - Non-pgp blocks in a message are discarded since we don't want to deal with
+   unencrypted content
+
+ - All unwanted email headers are striped as a privacy measure for who sends
+   the message
+
+ - Firma doesn't use any disk write when processing a message; no temp files
+   that may rest in the system; everything goes in memory (but take care,
+   sometimes it will use the swap and then is best to make it encrypted)
+
+ - By default it doesn't archive messages in the server
+
+ - By default it removes the Subject header and put it inside the encrypted
+   message, as Subject are outside the PGP/MIME context
+
+ - Messages appear to be sent To: Undisclosed Recipients
+
+ Major features are:
+
+ - Keyring support
+
+ - Administration through email or command-line
+
+8 - Caveats
+
+ People that uses Sylpheed should config the list to accept messages that
+ arent signed. Thats because currently firma depends that the encrypted
+ and signed parts come in the same PGP block and Sylpheed splits the
+ encrypted message and the signature in two separate blocks. Thats a
+ firma and not Sylpheed issue. The PGP/MIME spec allows one to send
+ the PGP/MIME encrypted message in two separate blocks. We hope to fix
+ this someday :)
+
+9 - Contact
+
+ Contact: firma (@) firma.sarava.org
+
+ Messages should be encrypted with the list pubkey
+ 3DF104314023E18358EFDD270D51B4E79E693CF7 found at keys.indymedia.org.
+