Using ION/Sidetree about health-cards

[jmandel]

Thanks for these comments. Please note that the current Health Cards spec is based on the expectation that all participants will support "long-form" ion DIDs, and participants are not required to resolve ion DIDs against a a blockchain-anchored ledger (see the "Long-form vs. Short-form DIDs" note under https://healthwallet.cards/#protocol-details).

The plan is to start with did:ion because it (1) gives us the ability to describe sets of public keys + service endpoints in a consistent format, for issuers as well as (optionally) holders, and (2) it provides -- or at least may well provide -- a glide path to future capabilities like permission-less key rotation and updates, if/when we adopt full resolution.