BashLogic wroteHey Nuc, nice to see that you have been tinkering ;)
beyond the question of key encryption type, what takes into account usb sniffing?
If computer is compromised (thats only way to install sniffer), attacker might get password to access keychain, but not a key itself.
So technically if he get physical access and previously sniff password - he own everything. WIthout custom hardware it is impossible to protect from such breach.