General-Purpose Hardware Wallet Fundamentally, crypto-currency hardware wallets are just devices that securely generate public/private key pairs, and sign input data when approved using a password and physical approval mechanism, right?

This seems like a generally useful capability, though as far as I can tell, the only devices available are purpose-built for a specific set of crypto-currency protocols, or some other protocol like U2F on the YubiKey.  I don't want my $100 Ledger wallet to become useless if its supported currencies (or the entire market) fall into disuse.  So is there any way to either:


Use (or modify to use) the Ledger to perform general key generation and signing?
Buy a general-purpose keygen + signing device that supports crypto-currency signature methods?
Use (or modify to use) the Ledger to perform general key generation and signing?


Yes. The things that the Ledger support are not specific to cryptocurrencies. You can write applications for the Ledger that do other things, so long as the firmware supports the cryptographic operations that are necessary.


  : Buy a general-purpose keygen + signing device that supports crypto-currency signature methods?


Yes. The cryptocurrency stuff happens externally to the cryptography. You can write an application that offloads the cryptography to a general purpose keygen and signing device (usually HSMs) and handles the remaining cryptocurrency stuff (transaction construction, node, etc.) on a general purpose computer.



Hardware wallets are really generic HSMs (although the Trezor does not contain a secure element like Ledger Nano S's do) that have had specific cryptocurrency applications built into them. They can be used for general cryptography things too, you just need to write software for that, and possibly modify firmware.