@ValarDragon suggested to remove the Version field from the Canonical(Vote/Proposal) altogether and let the KMS (instead of the HSM) make sure (via an initial handshake) that it doesn't sign any message while "talking to a different version".

This would have the following advantages:

• less communication overhead when sending Votes/Proposals
• less bytes to sign inside the HSM
• no need to change Vote/Proposal structs (or the Signable interface)

This would change the offsets though (cc @jleni)
(related: #2545)