Using caff to sign lots of keys
-------------------------------

If you have loads of keys to sign (sometimes, there are keysigning parties with
more than 100 participants), keysigning can be awkward, even with caff. It gets
worse if you have multiple local keys and want to sign with all.

Some hints to get the signing done faster:

* Use fingerprints instead of key ids.

  caff and gpg allow you to specify the full fingerprint. This will save you
  from having to check the fingerprint yourself. If you have a text file with
  all fingerprints, use that and then run

  $ xargs caff <options> <ksp-fingerprints.txt

  For convenience, caff also allows spaces in fingerprints/keyids as output by
  gpg --fingerprint.

* Use gpgparticipants(1) formated input when possible.

  When the KSP organizer provides a gpgparticipants(1) compatible list
  of all the participants, it can be convenient to transcribe the
  annotations made on the spot on the printout back to the digital copy.
  Then you can run

  $ caff <options> <ksp-annotated.txt

  caff will ignore participants for which both the "ID" and
  "Fingerprint" checkboxes are not *both* marked with an 'x'.
  (Moreover, keys are selected using their 40-hex digits fingerprint,
  which must be present in the list.)

* If you prefer to do the signing offline.

  You'll have to make caff's GNUPGHOME know the keys that are to be
  signed, somehow.  A possibility is to run multiple passes as explained
  below.  However if the keyring of all participants has been provided
  by the KSP organizers, then --key-file can be enough:

  $ caff <options> --no-download --key-file keyring.asc <ksp-annotated.txt

  Note however that if keys in keyring.asc were stripped off all (non
  self-)signatures, for instance if keyring.asc was created with
  '--export-options export-minimal', caff won't be able to detect your
  old signatures unless they are already present in its own keyring
  (which should be the case if signing is never done without caff).

  Note also that if keys in keyring.asc were stripped off their
  encryption subkeys (which fortunately gpg never does when exporting,
  but which a zealous KSP organizer could have done manually to reduce
  the file size), caff may send unencrypted mails.

* v3 keys are evil.

  V3 keys (pgp 2.6x keys) are deprecated.  Not only do they rely on md5 for
  their fingerprint and signatures, they also use the patented IDEA algorithm
  for encryption.  Also, there are several attacks that make creating new keys
  with the same keyid trivial.  Others make it possible to create different
  keys with the same fingerprint (tho the key will not actually contain valid
  RSA parameters).

  Because of these problems a lot of people (like caff's author) refuse to sign
  v3 keys these days.

  If you still want to sign v3 keys, sign v3 separately. Batch processing does
  not work. See README.v3-keys.

* Use multiple passes.

  Going through retrieving, signing, and mailing keys can help, e.g.:

  $ xargs caff --no-sign --no-export-old --no-mail     <ksp-fingerprints.txt
  $ xargs caff --no-download --no-export-old --no-mail <ksp-fingerprints.txt
  $ xargs caff --no-download --no-sign --no-export-old <ksp-fingerprints.txt

* If you have multiple local keys, use -u <mykey1>,<mykey2>.

  $ caff -u <mykey1>,<mykey2> <keyids to sign>

* Use gpg-agent.

  See README.gpg-agent.

* Use gpg-sign-args.

  $CONFIG{'gpg-sign-args'} = "save";

  This automatically saves the key after signing in gpg. The advantage is that
  you do not have to type "save" for each key. The disadvantage is that you
  cannot choose which UIDs to sign by answering "no" at the "Really sign?"
  prompt any more; you will have *not* to send out some mails. (And you have
  unwanted signatures lingering around in ~/.caff/gnupghome/pubring.gpg.)

 -- Guilhem Moulin <guilhem@guilhem.org>  Thu, 03 Apr 2014 12:43:13 +0200