While public keys are deterministic and can be spot checked, the use of synthetic nonces in signing protocols makes them inherently non-deterministic and unverifiable. Spot checking is a weak defense as devices may behave differently over time. However, retroactive and thorough spot checking can still be done through non-hardened derivation paths. Both the pubkey and signature issues need to be fully addressed, but the proposal for a non-deterministic signature scheme is far more severe as it removes the possibility of spot checks altogether. The hope is to standardize a scheme with the advantages of non-determinism while avoiding covert channels.