As I am sure you are aware, for the last 5 months work has been on-going to
create a relative lock-time proposal using sequence numbers. The
implementation can be found at https://github.com/bitcoin/bitcoin/pull/6312.
The current implementation is "mempool-only" and the soft-fork would be
deployed
Tamas,
You could use a key for both signing and for derivation of a deeper
level (and perhaps there are some applications for this, if you think of
any please let me know), but the use cases being considered involve
generation of signing key sequences from seeds that are easy to backup
and
