In this commit, we begin implementing the latest spec change to reduce
the attack surface on online channels. In this commit, we introduce a
distinct HTLC base point which will be used to sign the second-level
HTLC transactions for each active HLTC on the commitment transaction of
the remote node. With this, we allow the commitment key to remain
offline, as it isn’t needed in routine channel updates, unless we need
to go to chain.
In this commit we reverse the ordering of the MinAcceptDepth and
HltcMinimum fields within the AcceptChannel message. Previously, the
order of these two fields were reversed, meaning the remote peer
would’ve attempted to parse the MinAcceptDepth (as we intended), as
part of the HtlcMinimum, leading to a garbage value.
This commit adds the new set of single funder messages from the
specification. As a result, after this commit and a follow up, all of
our messages will directly line up with those that are detailed within
the specification.
The new set of funding messages are very similar to our prior ones,
aside from the main difference of the addition of several channel level
constraints that give nodes control over their exposure, throughput,
and other values.
