I'm referring to two things(although really just one) here
- WhatsApp claims to store messages only as long as they are undelivered, after which they are purged from their servers. Even if they are retained, they are e2e encrypted. Telegram on the other hand, from what I can see, store all messages in plaintext or in an encrypted-at-rest form where they control and have access to the keys. It comes down to whether I trust them, and I have no reason to.
- Tying back into the encryption point, in the event of a breach or an MITM, whoever intercepts or accesses WhatsApp messages will get encrypted dumps, while my Telegram messages are pretty much going to be in plaintext.
Also, the option to delete on a periodic basis is not an alternative to not having things stored in the first place. That said, there is no way you can verify that copies are not retained on the servers in either case (WhatsApp or Telegram) so there's not much to argue there.
Clients are open-source, so you can see the code for e2e encryption.
> That said, there is no way you can verify that copies are not retained on the servers in either case (WhatsApp or Telegram) so there's not much to argue there.
This is exactly true, so I actually prefer Matrix.
Also adding to this, there is certainly more nuance to it and WhatsApp is certainly far from perfect in that you still trust them to implement E2EE correctly without incompetence or malice, and then there's the whole other issue of their cloud backups being entirely unencrypted by design. Thankfully the latter can be turned off for now.
- Tying back into the encryption point, in the event of a breach or an MITM, whoever intercepts or accesses WhatsApp messages will get encrypted dumps, while my Telegram messages are pretty much going to be in plaintext.