Metadata Signatures

[pgebheim]

@Wolog2021 -- Can you update this issue to include a description?

TLDR; Signed transaction metadata would allow the ledger to validate the metadata without having it all hardcoded on device. This could be extended with FLIP-934 if that gets the relevant support.

Assuming support for FLIP-934 this might be an answer to #33

[relatko]

Each transaction type has metadata associated with it. It consists of

• script hash
• transaction name to be displayed on the device
• argument information (type + string to be displayed on the device)
  As of now, these data are hardcoded in the app. Instead, the app may contain a set of public keys and it will receive the metadata signed with one of these public keys. Then the app may validate the signature (and possibly show the authority that signed the metadata) and use the metadata to process the transaction.

A decision was made to implement Merkle trees solution first. But this is something that we expect to develop this year.