>> reasonably privacy-friendly
> Telegram still has no E2E encryption by default
Not leaking your personal data, identity or telephone number, and with whom you communicate is often more important.
With significantly worse UX.
> still has no E2E encryption by default
This doesn't make it not reasonably secure in my mind. While the TG people will be able to access your messages, they can also process them, making stuff like large groups even possible (imagine the distribution hell otherwise).
I do tend to think that there's not much of a down side to E2E for private chats though, since you can still share private keys between devices to enable sync.
> So it's worth nothing if no one use it.
Telegram is way more than secret chats.
So your standard for “reasonably secure” communications is Facebook Messenger?
It's not perfect, nothing is. But it makes better compromises than others.
i'd rather have a foundation of properly functioning, award winning cryptography than "features" designed for people who haven't thought through their threat model sufficiently.
castles made of sand melt into the sea eventually
Signal also makes trade offs in order to het crypto to the masses.
Again, crypto is either broken or not. Telegram crypto is not broken. It's fine. Not everyone might like it, but that does not matter. I don't know story about CIA (although I wouldn't be surprised to find out that Signal is honeypot), so can't comment about that.
Security is not a yes/no thing. It is equal to the price to break it. If the cryptography is well-tested for decades, the price is much higher. This is not true for Telegram. It does not matter how good its creators are.
There is another unique identifier that's stored in the local contact list: email addresses.
Use either email address or a phone number as an identifier, and you've no longer built a offensively privacy-violating service but have exactly the same distributed property.
If you only have access to one phone number and not giving it out is critical, then Signal might not be the right choice for you. But you won’t find a more secure channel that collects less metadata anywhere else.
There's no property of the latter that makes them a better choice than the former, but the existing ecosystem makes a disposable or role email address a much easier thing to obtain, and in general leaking an email address a far-less-damaging privacy violation than leaking a phone number, which can so easily be used to harass and directly track you.
In many parts of the world, disposable mobile numbers are very definitely not a practical thing. The correct starting point here is to use either an email or a telephone number as an external ID. It's still not perfect, but at least it's not a complete disaster any more.
Alas they've been 'working on it' for a very long time now, and are likely to fail because of this painfully slow progress.
Perhaps if they'd pissed around less with trivia like cryptographically secure stickers, they might have increased their chances of becoming a useful product before they end up surrendering the space to an inferior product which gains too much market share to overcome before they're even properly off the starting blocks.
I criticise Signal here because I like the design and hate their botched execution, not because I dislike the protocol. On the contrary, I dearly want something that competent to succeed, but fear we're rapidly losing the chance of that happening because they have launched a privacy-disaster product and most of the potential market will have seen that, dismissed it and forgotten about it before they pull their finger out and fix it.