[Cryptography] Signal Security / Secure Chat Metadata Traffic Analysis Generally

[arxlight]

As some belated follow-up on this topic, this declassified infographic 
on "lawful access" to chat programs was developed by the FBI:

https://propertyofthepeople.org/document-detail/?doc-id=21114562

It's dated way back in 2021 but I had never seen it before. On the 
assumption the list hasn't either, I thought it worth linking to.