[messaging] Forward secrecy and multiple devices

Ben Harris mail at bharr.is
Fri Oct 31 06:50:29 PDT 2014

Computer A encrypts message with a personal key and stores the message in
the cloud. The personal key is never shared so it can't be attacked,
computer B gets the messages and decrypts with the personal key.w

On 31 October 2014 21:04, Nadim Kobeissi <nadim at nadim.computer> wrote:

> Hi everyone,
> I've been wondering about how to make asynchronous forward-secret
> messaging systems work when the user is accessing message history from
> multiple devices.
> Say I send a bunch of messages from computer A to another user's computer
> U.
> 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.
> Regards,
> NK
> _______________________________________________
> Messaging mailing list
> Messaging at moderncrypto.org
> https://moderncrypto.org/mailman/listinfo/messaging
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://moderncrypto.org/mail-archive/messaging/attachments/20141031/7552fbdd/attachment.html>

More information about the Messaging mailing list