OSHW USB token for Passkeys (FIDO2, U2F, WebAuthn) and PGP by duwe

Description

The idea to carry your precious key material along in a specially secured hardware item is almost as old as public keys themselves, starting with the OpenPGP card. Nowadays, an USB plug or NFC are the hardware interfaces of choice, and password-less log-ins are fortunately becoming more popular and standardised.

Meanwhile there are a few products available in that field, for example

• yubikey - the "market leader", who continues to sell off buggy, allegedly unfixable firmware ROMs from old stock. Needless to say, it's all but open source, so assume backdoors.

• nitrokey - the "start" variant is open source, but the hardware was found to leak its flash ROM content via the SWD debugging interface (even when the flash is read protected !)

• solokey(2) - quite neat hardware, with a secure enclave called "TrustZone-M". Unfortunately, the OSS firmware development is stuck in a rusty dead end and cannot use it.

I plan to base this project on the not-so-tiny USB stack, which is extremely easy to retarget, and to rewrite / refactor the crypto protocols to use the keys only via handles, so the actual key material can be stored securely. My Initial testbed is the devkit for the solokey2, the NXP LPCXpresso55S69.

Goals

Create a proof-of-concept item that can provide a second factor for logins and/or decrypt a PGP mail with your private key without disclosing the key itself. Implement or at least show a migration path to store the private key in a location with elevated hardware security.

Resources

LPCXpresso55S69, tropicsquare tropic01, arm-none cross toolchain