Both sides elect a commitment fee, and the lowest is chosen. That means
you can't game the other side (but if you offer too low, then can error
out of course).
Fees are split 50-50 if possible: originally the whole fee has to be
paid by the (single) funder. Neither side can withdraw funds which
would make them unable to pay fees.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Most complex change was gather_updates(), which handles all the "what
is the current state of the channel" logic for our dumb test utils.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
As documented in the paper; it's also two bytes shorter, and allows
us to use the exact same script for three cases.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
StephenM347 on #lightning-dev indicated it could be clearer that
this is all about changing commitment transactions.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
It's slightly clearer to do the "2" outside the branch.
Also, spending it requires the extra 0 due to OP_CHECKMULTISIG bug.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
As reported by mmeijeri on r/Bitcoin:
https://www.reddit.com/r/Bitcoin/comments/3dlxw4/reaching_the_ground_with_lightning_lightning/ct80xpp
As the signature doesn't cover the input itself, you could replace the
secret key from the escape transaction with 0, and it will use the "A and B"
branch of the output.
(This also fixes a bug in the anchor output where the OP_IF consumed the
secret).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Alpha has segregated witnesses, so txid doesn't include the inputs.
That means we can create the first commit transaction before we sign
the anchor tx.
Bitcoin will need to do this differently: presumbly via new sipops
(a OP_CHECKSIG2VERIFY I imagine).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Which emerged clearly when setting one side's locktime differently than
the other.
Each side specifies the (minimum) time they need to notice a fraud attempt:
this constrains the *other* side.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
It doesn't matter until we start setting sequence numbers properly,
so hasn't been noticed until now.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
... Which reveals it wasn't paying a fee. So update fix that, and
initialize the alpha tx fields while we're there.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The even-S check was based on https://github.com/sipa/bitcoin/commit/a81cd9680
which was replaced by a low-S check in commit e0e14e43d9586409e42919f6cb955540134cda2a
Abstract out and fix the check.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Rusty Russell