I have another idea for SkySigner and I would like to hear your thoughts.
For those who haven't heard of it before, SkySigner is a Nostr signer I have been developing. The idea is to let Nostr clients and websites request signatures without giving them direct access to the private key.
So far I have been experimenting with NIP-07 and NIP-46 and testing how SkySigner works with different Nostr clients.
Now I am wondering if I could turn SkySigner into a portable USB signing device.
My idea is to plug a USB drive into a computer and use SkySigner to approve signing requests while keeping the private key separate from the applications requesting signatures.
I know a regular USB drive is not a hardware wallet and simply running an application from USB doesn't automatically make it secure.
That made me think about another possibility. What if SkySigner ran inside its own bootable Linux environment on the USB drive instead?
Of course there would still be security questions to solve. But I find the idea interesting enough to experiment with.
Has anyone tried building something similar for Nostr?
Would you go with a portable application or a bootable USB system? And what security problems should I be looking out for?
You're still loading the key into memory on the system you plug it into, so the USB stick is no different than an encrypted VM image on the main disk.
OS kernel level virtualization can demarcate the memory between the host and VM, but then again the USB stick isn't adding anything, it's just a backup of that VM.
Encrypted VM's are good for a lot of things like reducing footprint for the host to be pwned or apps from pwning each other, I think there's a few QubesOS lurkers here even, but the usb-on-host doesn't do much if the host itself is the risk.
There are these things:
https://m.stacker.news/162472
It's not just a USB stick, its basically a mini PC that uses USB for power and could run as an appliance without a host dependency.
I have not tinkered with one, I assume the supply chains are sketchy and storage is too weak for a Lightning node which is my interest, but might work for a simple signer.
Might even be able to hack something onto a Roku stick, those are abundant and cheap.