Bingo. It would be interesting if there was a sort of generic touchscreen device that acted as a USB firewall. It would prompt you and display the data before a

Bingo. It would be interesting if there was a sort of generic touchscreen device that acted as a USB firewall. It would prompt you and display the data before allowing it to go through. But even if such a device existed, how would you tell whether a transaction signature is really a signature of your transaction and not some encoding of your seed? It seems that no matter how you look at it, there will always be some level of trust involved[0]. For maximum security, the best would probably be to use an airgaped/secured/encrypted general-purpose computer and use a SD card to transmit transaction data. You could even use pre-bitcoin computer hardware if you are super paranoid. Also, if I recall correctly, there are fully open source hardware wallets like Trezor. In theory, you could review the firmware and flash it yourself. You then just need to trust the hardware isn't backdoored to steal Bitcoin seeds. But that would require some rather large companies like ARM to get in the Bitcoin seed stealing business (and for your computer to be infected by ARM-developed seed stealing malware). [0] https://www.cs.cmu.edu/~rdriley/487/papers/Thompson_1984_ReflectionsonTrustingTrust.pdf https://www.cs.cmu.edu/~rdriley/487/papers/Thompson_1984_Ref...