> They're apparently "encrypted", but the keys are controlled by Telegram.
Yes, but they take steps to ensure they cannot easily be forced to decrypt chats via a court order in a single country. From the Telegram FAQ:
To protect the data that is not covered by end-to-end encryption, Telegram uses a distributed infrastructure. Cloud chat data is stored in multiple data centers around the globe that are controlled by different legal entities spread across different jurisdictions. The relevant decryption keys are split into parts and are never kept in the same place as the data they protect. As a result, several court orders from different jurisdictions are required to force us to give up any data.
> Furthermore, they frequently "ban" channels that they deem contain "inappropriate" or "adult" content. Clearly they're reviewed by either humans or AI of some sort. So... that makes me uncomfortable.
AFAIK messages are only forwarded to Telegram support if they are reported by users. Chats spreading pornographic content are often banned on iOS due to the App Store guidelines (and in certain countries due to local laws), but illegal channels (e.g. CP) may be blocked globally.
> Also, this means that anyone who has your phone number is told you're on the app and given your username, which you may not want for privacy reasons.
This is not true anymore, a while ago they added new privacy settings that allow you to prevent others from finding you unless they are in your Telegram contact list. (Of course, this means if you don't want anyone in your phone's contacts to be able to find you on Telegram, you should deny the app contacts permission.)
IMO it's a reasonable trade-off for general use as a chat platform with public groups and all, you can use secret chats if you really want to be confident in your privacy. Maybe they could add support for end-to-end encrypted groups though.
> Yes, but they take steps to ensure they cannot easily be forced to decrypt chats via a court order in a single country. From the Telegram FAQ
Again, this is just what they claim. Doesn't mean they don't read chats because they feel like it. And this doesn't mean that they won't cooperate with other entities in the future. Or that the keys won't get leaked.
Your data being encrypted is pointless if it's stored one someone else's servers, and they have the keys to it.
If we are going with a conspiracy theory that whatsapp deliberately included a buffer overrun bug as a backdoor... then why the heck would we trust telegram about this?
I see no reason why open source helps here. Closed source clients aren't black boxes. You can examine the bytecode. You can decompile the binaries.
I see no reason why a conspiracy dedicated enough to hide a backdoor as a buffer overrun wouldn't also be capable of making the Telegram server store key material in a single country to make it available to legal requests (since, as you say. the back-end software isn't open source).
Bytecode is basically the same as source. Decompiled binaries are harder to read, but there are oodles of professionals who are very skilled at reading decompiled code. The actual structure of the program itself plays (to me) a much bigger role in the auditability of a system.
Yes, but they take steps to ensure they cannot easily be forced to decrypt chats via a court order in a single country. From the Telegram FAQ:
To protect the data that is not covered by end-to-end encryption, Telegram uses a distributed infrastructure. Cloud chat data is stored in multiple data centers around the globe that are controlled by different legal entities spread across different jurisdictions. The relevant decryption keys are split into parts and are never kept in the same place as the data they protect. As a result, several court orders from different jurisdictions are required to force us to give up any data.
https://telegram.org/faq#q-do-you-process-data-requests
> Furthermore, they frequently "ban" channels that they deem contain "inappropriate" or "adult" content. Clearly they're reviewed by either humans or AI of some sort. So... that makes me uncomfortable.
AFAIK messages are only forwarded to Telegram support if they are reported by users. Chats spreading pornographic content are often banned on iOS due to the App Store guidelines (and in certain countries due to local laws), but illegal channels (e.g. CP) may be blocked globally.
> Also, this means that anyone who has your phone number is told you're on the app and given your username, which you may not want for privacy reasons.
This is not true anymore, a while ago they added new privacy settings that allow you to prevent others from finding you unless they are in your Telegram contact list. (Of course, this means if you don't want anyone in your phone's contacts to be able to find you on Telegram, you should deny the app contacts permission.)