[whispersystems] Automatically reset secure sessions?

[Johan Wevers]

Hello,

If one copies Signal on 2 different phones with the same keys and number
(with Titanium Backup for example), it will cause synchronisation issues
if one phone receives a new message and one wishes to continue the
conversation on the other device. A manual reset of the secure session
is required. Otherwise decryption errors arise.

However, when experimenting with Whatsapp, it does not suffer from this.
How is this achieved? I assume the receiving device sends back a
"decryption OK" status to the sender, if a "decryption error" is sent
back one of the parties initiates a reset of the secure session and the
message gets resent, all without user interaction.

Can this mechanism be built in in Signal as wel? It would make Signal
more robust and prevent angering developers when words like "Titanium
Backup" are mentioned in a bug report. :-)