gnupg/mailing-list-test

After making sure a gpg2 with mailing list support is in your patch,
run test.sh as follows (when you run it, it will ask for two
passwords, use the password 'a'):

  # ./test.sh
  ***************
  Generating a user key (use a password of 'a').
  ***************
  'Some User <some@user.org>'

  ***************
  Importing some public keys.
    Running: gpg2 --batch --import keys.gpg
  ***************

  ***************
  Set the password to 'a'
  ***************

  ***************
  Creating mailing list.
    Running: gpg2 --batch --quick-gen-mailing-list-key gnupg-devel <gnupg-devel@gnupg.org>
  ***************
  'gnupg-devel <gnupg-devel@gnupg.org>'

  ...

To get more verbose output, run test.sh with the -v flag.  To get even
more output, change the gpg2 invocations to include --debug=packet.

A summary of the commands:

  --mailing-list-key-gen
  --quick-gen-mailing-list-key 'Name <mailing-list@example.com>'

    Create a new mailing list key.

  --mailing-list-add-sub ML-KEYID SUB-KEYID...
  --mailing-list-add-rm ML-KEYID SUB-KEYID...

    Add or remove one or more subscribers from the mailing list.

  --mailing-list-subs ML-KEYID

    List the subscribers (using their decryted keyids!)

    Compare:

      $ gpg2 -k 2A08A54D
      pub   rsa2048/2A08A54D 2016-02-08 [SC]
      uid         [ultimate] gnupg-devel <gnupg-devel@gnupg.org> (mailing list)
      sub   rsa2048/ED2D0863 2016-02-08 [E]
      sub   rsa2/7C03B9E1 2016-02-08 [E]
      sub   rsa2/83BCEFE4 2016-02-08 [E]
      sub   rsa2/04A1E753 2016-02-08 [E]
      sub   rsa2/535EB487 2016-02-08 [E]

    The above 2-bit RSA keys!  These are the encrypted keys.  Here are
    the real subscribers:

      $ gpg2 --mailing-list-subs 2A08A54D
      D1B030E3
      AA45C71F
      94244910
      95A0BEEA
        4 subscribers.

To encrypt to a mailing list, just do: gpg2 -r ML-KEYID -e and a gnupg
with encrypted mailing list support will automatically encrypt to the
list of current subscribers.