Signal does have sync, but it works exactly the same way as Whatsapp's does, requiring your phone to be on and connected

Telegram's secret chats are also client-specific and not synced, and I have no idea how it would even be possible to have e2e chats synced on multiple devices without having a "main" device that's doing the actual crypto or sharing the secret key

If you're interested in learning how to implement end-to-end chats with multiple devices, checkout out Wire security whitepaper (https://wire.com/resource/Wire%20Security%20Whitepaper/downl...) for one way of doing it.

Hopefully, OpenWhisperSystems will release documentation about their implementation in Signal (note: it doesn't require phone, unlike WhatsApp)

Thanks! Will definitely read this.

I got fooled by Signal's requirement of a phone for the activation and thought it was also required for normal usage, I guess that's better than Whatsapp, though being able to register and use it without a phone at all would be even better (even Telegram doesn't do this though, IIRC it requires a phone number)

You can just use a one time VoiP phone number if you want to use Signal without your real phone number. That's not optimal, but its pretty neat.

Agreed on phone numbers. Speaking of Wire, it doesn't require them.

You are totally wrong. The phone number aspect has absolutely nothing to do with the e2e client problem.

Its possible to have e2e on multiple clients, with or without a phone number attached to it. There are multiple chat clients that can do it, some with, some without phone number. Signal requires phone number and does it, Wire and Riot do it without a phone number.

Telegram just don't actually care about security or privacy. Unencrypted defaults, all conversation saved on the server, even if you use their 'roll your own' crypt secret chats you lose most of the functionality that actually go people to use Telegram in the first place.

Telegram essentially has no usable e2e crypto to speak off. Secret chats are a usability and security nightmare.

People should use Riot (Matrix) or Wire. Those are much better.

> Signal does have sync, but it works exactly the same way as Whatsapp's does, requiring your phone to be on and connected

It doesn't. The phone is only needed for initial setup.