Re:The Security, Usability and Multi-Device-Problem of Messa...
by zeveb on Thursday December 17, 2015 @02:11PM
(#10753673)
You never want to share keys if you can get away with it.
Your suggestion also doesn't solve the problem of lost, compromised or destroyed devices.
If I have one phone and one computer, no algorithmic solution can determine if the person holding my phone is me, and the person holding my laptop is a thief, or if the person holding my phone is a thief and the person holding my laptop is me.
Honestly, even majority vote is insufficient: is there any reason to trust the person holding my phone and laptop over the person holding my computer? What if my home just burned down?
What's needed is for each device to have its own keys, and for messages to 'you' to really be sent to each device. And when you lose a device, you have to let your friends know, and they have to manually verify which of your devices to no longer trust. This can be presented in a pleasing fashion, but you can't eliminate the need for human judgement.
Your suggestion also doesn't solve the problem of lost, compromised or destroyed devices.
If I have one phone and one computer, no algorithmic solution can determine if the person holding my phone is me, and the person holding my laptop is a thief, or if the person holding my phone is a thief and the person holding my laptop is me.
Honestly, even majority vote is insufficient: is there any reason to trust the person holding my phone and laptop over the person holding my computer? What if my home just burned down?
What's needed is for each device to have its own keys, and for messages to 'you' to really be sent to each device. And when you lose a device, you have to let your friends know, and they have to manually verify which of your devices to no longer trust. This can be presented in a pleasing fashion, but you can't eliminate the need for human judgement.