To achieve forward secrecy and backward secrecy in the end-to-end encryption algorithm, the encryption keys are continuously updated. This means that each Keychat client is stateful. This state cannot be synchronized across two devices, as doing so would compromise the forward and backward secrecy of the end-to-end encryption.

One possible solution is that, if Alice and Bob are both using Keychat on two devices (a phone and a computer), we can create a pairwise group for these four devices. We still need some time to implement this.