The news is out, WhatsApp switched on encryption for a billion people. It supports all devices and encrypts texts, photos, videos and calls.
There are so many questions that just came to my mind that I really would like to get answered. Since the news is so fresh, there isn't any more information online yet. I do hope that there are not too many questions in this one question format.
- How does such a system work to support all devices?
- What encryption do they use? PGP? RSA/AES-hybrid? Other?
- How strong is the encryption and when do the keypairs even get generated?
- Why can group chats be encrypted as well as 1:1 conversations?
- When and how does the verification of the public key happen?
- Where is the private key stored?
- Is it possible to extract the private key?
- What happens when I change my phone?
- Are backups encrypted too?
- Is supporting the past unencrypted chat history not a security concern? Or do they even encrypt the chat history?
- Is the design of the system really secure when the app sais
"when possible, the messages you send and your calls are secured with end-to-end encryption"
Thank you very much. I know that some points might only be speculation, but a good thought on how it could be implemented is just as fine.