[zamadatix]

500 isn't really asking for much, Signal does up to 1,000 in a group using standard direct messaging encryption (client side fanout). Whatsapp uses a shared hash ratchet and just spins up new keys when someone leaves, this allows it to do 10,000.

Discord gets to 25,000 active users before they move to throwing resources at the problem for a hard max of 500,000 total users able to join (but not be active at once, that number is a little fluffy) so it doesn't seem e2ee is really slamming the breaks on scaling vs how far you could normally get.

Signals approach https://signal.org/blog/private-groups/

Whatsapps approach https://scontent.whatsapp.net/v/t39.8562-34/122249142_469857...

Finally if you allow tying and verifying to real world identity and don't require forward secrecy then the encryption side of the problem is no more difficult than PGP.

[DenseComet]

Discord doesn't do E2E encryption, although those numbers for Signal and Whatsapp are pretty impressive.

[zamadatix]

I probably wasn't as clear as I could have been on that. The Discord numbers were meant to provide a point of comparison on how little e2ee really impacts scaling active users vs a traditional system but I wasn't very explicit that's why it was being mentioned.