On: Show HN: A journaling service that runs over WhatsApp

[pricechild]

WhatsApp lets you link multiple devices now - I have the same account on an android and spare iPhone.

The main restrictions are that you have to use the main device every 14 days and can only have ~4 linked devices.

https://faq.whatsapp.com/378279804439436/?helpref=faq_conten...

[notpushkin → pricechild]

> The main restrictions are that you have to use the main device every 14 days and can only have ~4 linked devices.

I’m trying to think of a rationale and really can’t. Any ideas?

[lxgr → notpushkin]

Due to the way WhatsApp does (person to person, not group) chat encryption, the number of messages scales linearly with the number of devices of either party to the conversation.

They probably want to put a cap on how much data/CPU the sending device has to expend per message.

[notpushkin → lxgr]

Hmmm. Couldn’t they just use their group protocol for private chats, too?

[lxgr → notpushkin]

I'm not too sure, but I suspect that due to how they do group vs. individual message encryption, this might decrease forward secrecy somewhat.

[faangguyindia → pricechild]

It's just not same. Telegram has different instances in different devices.

While WhatsApp simply uses instance on your phone via webapi on your desktop.