[More Research Required] Multi-Phase Signing

[patrick-ogrady]

Sometimes, transaction construction requires signing a payload that is comprised of the signature of another payload (i.e. iterative transaction construction). Specifically, this would unblock blockchains that allow delegating "voting" operations to a separate key (but require a "proof of ownership" signature during construction from the new "voting" key). It is possible that some multi-sig constructions also require multiple phases.