I implemented the Diffie-Hellman Key Exchange algorithm but, I was wondering how to handle if one of the parties lost his key.
Let's take a chat app as an example, Bob and Alice they used to have a shared key, but sadly Alice changed his device, and what if Bob sent a message to her encrypted with the shared key while she was offline. How can this be handled?
Not Sure about this solution: Can I once Alice logs in with the new mobile device it requests from her room users to re-authenticate? and how about that message that Bob sent pre-re-authentication?
Thanks in advance. :)
As @kelalaka said, I can send an excuse to bob by re-auth and resending the message from his device.