This module sets the security status of s2s connections to invalid if their key is too small and their certificate was issued after 2014, per CA/B Forum guidelines.
Certificate Authorities were no longer allowed to issue certificates with public keys smaller than 2048 bits (for RSA) after December 31 2013. This module was written to enforce this, as there were some CAs that were slow to comply. As of 2015, it might not be very relevant anymore, but still useful for anyone who wants to increase their security levels.
When a server is determined to have a "too small" key, this module sets its chain and identity status to "invalid", so Prosody will treat it as a self-signed certificate istead.
The definition of "too small" is based on the key type and is taken from [RFC 4492].
Works with Prosody 0.9 and later. Requires LuaSec with support for inspecting public keys.