DDSSEC12 — Size of permission file sent on authentication can exceed max IP packet size

The Permission File is an XML file. The signature is also encoded as text. For large systems with a lot of Topics the size can grow to be quite big. This is amplified by the fact that it is possible and convenient to combine the permissions of multiple participants into a single file. This size can exceed the 64KB max size of IP.

An additional problem is that the permissions file is sent during the authentication handshake. The authentication handshake uses a special "best efforts stateless" that does not support fragmentation of large packets. This is done on purpose to make the channel to be robust to sequence number attacks but it results on the inability to send these large permission files.

This could be addressed by separating the permissions from the authentication handshake and there is already an issue filed for this, see DDSSEC12-13.

However there is a simple solution that can make the current approach more scalable. The proposed approach is to send the Permissions document compressed rather than in their current text form.

Users are already hitting this limit so this issue requests that capability to send the permissions compressed is added with high priority, even if later a more general solution is developed as requested in DDSSEC12-13.