This module is currently able to enqueue IP addresses of your visitors. It automatically sends them, 15 at a time, as specified by the documentation of the API it uses, to the webservice of http://www.stopforumspam.com/ in cron.
The result it gets is then evaluated using configurable settings, such as frequency (amount of times a 'hit' is made) and confidence (how confident the webservice is this is a spammer). Whether it is a spammer or hammer, the result is stored/cached for a configurable amount of time in the database.
The IP addresses get automatically added to the blocklist if safe mode is disabled and they get auto-removed when the status has expired.
Planned features for now:
Report spammers to the webservice
From experience, the hook_cron is too slow
Implement own cron, e.g. run every 5 minutes, configurable
Send specifiable amount of requests per cron run
If you wish to become a co-maintainer please contact me using the form provided by drupal.org.
This is experimental code for a 7.x version of the https://drupal.org/project/openpgp module. I hope this sandbox will be somewhat short-lived as I would much rather see this rolled into the main module.
The code is mostly untested, and I can personally only take credit for a few tweaks. This 7.x port is based on the code that Jeriatrix posted to github and announced here: https://drupal.org/node/1155042#comment-6583806
In addition to the work that was done before I found it, I've made modifications to fix one of the admin pages (see #1967426: Configuration Error) cleaned up some queries to be compatible with Drupal 7, and added support for signing outgoing mail with PGP signatures if encryption is used (see #682452: Support for PGP signatures).