[messaging] Forward secrecy and multiple devices
nadim at nadim.computer
Fri Oct 31 06:04:29 PDT 2014
I've been wondering about how to make asynchronous forward-secret
messaging systems work when the user is accessing message history from
Say I send a bunch of messages from computer A to another user's
Later, I buy myself a new computer B on which I want to download and
decrypt my message history.
If the messages I sent all relied on my long-term identity, then I can
just use my long-term key pair to decrypt the messages on computer B and
there wouldn't be a problem.
However, I am wondering how that would work in case I was using
forward-secret session keys that changed message by message. How would
the session secrets be communicated across devices? How would computer B
be able to decrypt my forward-secret messages sent from computer A?
It would be great to hear the opinion of the many experts on this list
regarding this matter.
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