When doing my work on the filtering proxy, I did think about whether it could be made to work with HTTPS as well. The only useful plain text part of a HTTPS connection is the domain, so that seems to be a limiting factor on what I could do, just block domains. Obviously the rest of the data going through the proxy would be encrypted, but as my computer was the sender and intended recipient, surely I could decrypt it. As it turns out, Chrome (not my go to browser) can be configured to output a file containing they keys it uses in HTTPS. I discovered while using wireshark on another project. Wireshark can use this file to let you inspect HTTPS streams. Maybe my proxy could be updated to use this file (and parallels in other browsers if they’re there) to allow filtering for HTTPS.