Hi all,
There have been a number of suggested changes to the commitment
transaction format:
1. Rather than trying to agree on what fees will be in the future, we
should use an OP_TRUE-style output to allow CPFP (Roasbeef)
2. The `remotepubkey` should be a BIP-32-style, to avoid the
option_data_loss_protect "please tell me your current
per_commitment_point" problem[1]
3. The CLTV timeout should be symmetrical to avoid trying to game the
peer into closing. (Connor IIRC?).
It makes sense to combine these into a single `commitment_style2`
feature, rather than having a testing matrix of all these disabled and
enabled.
BOLT #2:
- If `commitment_style2` negotiated, update_fee is a protocol error.
This mainly changes BOLT #3:
- The feerate for commitment transactions is always 253 satoshi/Sipa.
- Commitment tx always has a P2WSH OP_TRUE output of 1000 satoshi.
- Fees, OP_TRUE are always paid by the initial funder, because it's simple,
unless they don't have funds (eg. push_msat can do this, unless we remove it?)
- HTLC-timeout and HTLC-success txs sigs are
SIGHASH_ANYONECANPAY|SIGHASH_SINGLE, so you can Bring Your Own Fees.
- `localpubkey`, `remotepubkey`, `local_htlcpubkey`,
`remote_htlcpubkey`, `local_delayedpubkey`, and `remote_delayedpubkey`
derivation now uses a two-stage unhardened BIP-32 derivation based on
the commitment number. Two-stage because we can have 2^48 txs and
BIP-32 only supports 2^31: the first 17 bits are used to derive the
parent for the next 31 bits?
- `to_self_delay` for both sides is the maximum of either the
`open_channel` or `accept_channel`.
- `to_remote` is now a P2WSH of:
`to_self_delay` OP_CSV OP_DROP <remotepubkey> OP_CHECKSIG
Cheers,
Rusty.
[1] I recently removed checking this field from c-lightning, as I
couldn't get it to reliably work under stress-test. I may just have
a bug, but we could just fix the spec instead, then we can get our
funds back even if we never talk to the peer.
_______________________________________________
Lightning-dev mailing list
Lightning-dev@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/lightning-dev
