The Bitcoin Optech newsletter provides readers with a top-level summary of the most important technical news happening in Bitcoin, along with resources that help them learn more. To help our readers stay up-to-date with Bitcoin, we’re republishing the latest issue of this newsletter below. Remember to subscribe to receive this content straight to your inbox.
This week’s newsletter encourages miners to start signaling for taproot and describes continued discussion about closing lost LN channels using only a wallet seed. Also included are our regular sections with announcements of releases and release candidates, plus notable changes to popular Bitcoin infrastructure software.
- Miners encouraged to start signaling for taproot: miners who expect to be willing to enforce the new consensus rules for taproot are encouraged to begin signaling and to ensure they’ll be able to run Bitcoin Core 0.21.1 (described below) or other compatible taproot-enforcing software by the minimum activation block specified in BIP341.
Anyone wanting to trustlessly monitor signaling progress can upgrade to Bitcoin Core 0.21.1 and use the getblockchaininfo RPC. For example, the following command line prints the number of blocks in the current retarget period, the number of those blocks which have signaled, and whether it’s possible for taproot to activate in this period (assuming there’s no reorg):
$ bitcoin-cli getblockchaininfo
| jq ‘.softforks.taproot.bip9.statistics | .elapsed,.count,.possible’
- If you prefer a graphical representation with supplementary information about miner progress and don’t need to use your own node, we recommend taproot.watch by Hampus Sjöberg.
- Closing lost channels with only a BIP32 seed: as described in Newsletter #128, Lloyd Fournier proposed a method for creating new channels that would allow a user who lost all information except for their BIP32 wallet seed to re-discover their peers using only public information about the LN network. Once the user found their peers, they could request the peers close their mutual channels using the BOLT2 data loss protection protocol (see Newsletter #31). The proposed method isn’t perfect—users should still create backups1 and replicate them across independent systems—but Fournier’s proposal provides additional redundancy that would be especially useful for everyday users.
Two weeks ago, Rusty Russell restarted the thread after trying to specify and implement the idea. After some additional mailing list discussion with Fournier and a group conversation in the weekly LN protocol development meeting, Russell indicated he was leaning against the idea, saying “I see encrypted backups as a more-likely-to-be-implemented solution though. Because they’re useful to send to places other than peers, and they can also contain HTLC information if you want.” Being able to contain HTLC information would allow settling payments that were pending at that time, which is a capability no recovery mechanism based solely on a BIP32 seed could provide.
Releases and release candidates
New releases and release candidates for popular Bitcoin infrastructure projects. Please consider upgrading to new releases or helping to test release candidates.
- Bitcoin Core 0.21.1 is a new version of Bitcoin Core that contains activation logic for the proposed taproot soft fork. Taproot uses schnorr signatures and allows the use of tapscript. These are, respectively, specified by BIPs 341, 340, and 342. Also included is the ability to pay bech32m addresses specified by BIP350, although bitcoins spent to such addresses on mainnet will not be secure until activation of a soft fork using such addresses, such as taproot. The release additionally includes bug fixes and minor improvements.
Note: due to a problem with the certificate authority that provides the code signing certificates for the Windows versions of Bitcoin Core, users on Windows will need to click through an extra…