Proof of Ownership should be required

[ChristopherA]

ATTN: @talltree, @msporny

In https://github.com/WebOfTrustInfo/rebooting-the-web-of-trust-fall2016/blob/master/topics-and-advance-readings/did-spec-working-draft-03.md#54-proof-of-ownership-optional

I don't believe that proof of ownership is optional, as you need at least one key to sign the DDO that strongly verifies that the a DDO is owned by the DID registered in a ledger (the reason why it is called proof of ownership). There needs to be at minimum one.

[msporny]

Proof of ownership isn't optional in many cases. You need it when transmitting verifiable claims to inspectors.

That said, we do have use cases where proof of ownership is always delegated (such as in identifying flex ledgers). You could argue that delegated proof of ownership is still proof of ownership, so it's not optional.

There is only one use case where you may not want proof of ownership, and that's a one-time claim of space in the DID ledger to ensure you won't get collisions w/ the DID you chose for some purpose. I'm unsure of the utility of doing this... one could argue that's junk data in the ledger. Then again, one could always claim a did w/ a proof of ownership and then throw away the key or set it to something impossible like "FFFFFFFFFFFFFFF".

[ChristopherA]

I can except that proof of ownership can be delegated but it is still required because without it the data on the blockchain that is called a DID is no valid.