Use protobuf public key in BaseAccount

[aaronc]

As a temporary measure in #5682, we decided to use amino-encoded bytes for the BaseAccount pub_key in protobuf. We can't cut a release without fixing this.

We have a cosmos.crypto.PublicKey proto type which we can use on BaseAccount.

The biggest glitch is that the AccountI interface has Get/SetPubKey methods which take crypto.PubKey interfaces.

I see two solutions:

1. change AccountI.Get/SetPubKey to use cosmos.crypto.PublicKey proto type and then use PublicKeyCodec wherever a conversion to crypto.PubKey is needed
2. find some magic way to cache crypto.PubKey on the BaseAccount struct (maybe with a hidden field)

My preference is to go with approach 1. Thoughts? @alexanderbez ?

[alexanderbez]

I also believe that approach (1) is the cleaner and more intuitive approach. Let's go with that if we can.

[aaronc]

PubKey bech32 encoding is still using amino. I'm assuming we should update that as well to use protobuf?

[aaronc]

Oh no... the whole keyring is still using amino. What do we do? Leave it like that?

[alexanderbez]

Yikes! I would rather avoid using Amino in the Keybase in favor of Proto if we can. However, this may require too much work before Stargate.

I would consider, instead:

1. Quickly tweak keys add to save key material using Proto such that the existing logic can tell the difference between existing amino-encoded vs newly proto-encoded key material (e.g. using a byte prefix or something). This paves the way for use of Proto only since all new keys will be Proto-encoded.
2. Introduce a new command, keys reformat, that takes existing amino-encoded key material and reformates it to proto-encoded key material. Operators will have ample time to reformat all their keys such that in the next major release, we remove amino support entirely.

Other ideas?

/cc @alessio

[aaronc]

Can someone explain how bech32 pubkeys are used? That's one hard piece of this refactoring.

[alexanderbez]

We need to avoid Bech32 pubkey encoding at all costs.

[aaronc]

Oh so we can just delete that code?

[alexanderbez]

Which code specifically?

[aaronc]

Bech32ifyPubKey and all that other pub key stuff in types/address.go

[alexanderbez]

Yeah all of that should be removed IMHO.