As
Ultralights,
De_flieger and others have noted, metadata is powerfull.
It can be used to create any almost any scenario desired by those in the shadows.
The situation is not helped when you look at
https://www.ag.gov.au/NationalSecuri...s/Default.aspx
where on one hand (in the sample datasets) they state that
For internet access services, the Bill explicitly excludes anything that is web-browsing history or could amount to web-browsing history, such as a URL or IP address to which a subscriber has browsed.
yet on the other hand they want
any other service or device identifier known to the provider that uniquely identifies the destination of the communication.
which effectively means the destination IP address, hence they then have a pretty good idea of your web-browsing history.
If CASA wants the metadata then they really should state
why they want such easy access to it.
Convenience (to CASA, by not having to get an actual warrant) is
not an acceptable reason.