[Bitcoin-segwit2x] Notes on segwit2x and anti-replay methods

Given recent threads, it seemed useful to summarize the status of segwit2x vis anti-replay. 1) Thanks to all for some healthy debate on btc1 Slack's #debate channel, as well as in public. 2) anti-replay is currently an open issue: https://github.com/btc1/bitcoin/issues/34 Being an open issue implies that we are actively soliciting suggestions and solutions. 3) In informal discussions, I've termed segwit2x a "node HF", meaning that it is somewhat of a hybrid fork, somewhere between soft fork and hard fork. 3a) In a soft fork, nodes and SPV wallets auto-accept new rules (*opt-out*). At most a "new rules!" warning is emitted, but operation otherwise continues under the new ruleset. 3b) In a "pure" hard fork, nodes and SPV wallets do not auto-accept new rules, and must upgrade to adopt (*opt-in*). 3c) In segwit2x, nodes and SPV wallets split the difference. nodes do not auto-accept new rules, but many wallets, notably SPV wallets, will. 4) It is good to provide some sort of facility such that SPV wallets may also emit a "new rules" warning for the segwit2x 2M HF upgrade, to match the experience of an opt-out soft fork upgrade. James Hilliard's PR was re-opened for this purpose: https://github.com/btc1/bitcoin/pull/46 5) It is *not* good to include a change that breaks all wallets (meaning, requires upgrade to continue working post-2M HF). The likely case is that the NYA participants and 80+% hashpower will upgrade to 2M BBSI. Thus, in the the likely "one chain" outcome, a break-all-wallets change would be unnecessarily disruptive to users (to make a large understatement). 6) This leaves us with a range of solutions that include opt-in replay protection (#34) and HF visibility via block version bit (#46). Gavin's suggestion is in #34. Sergio had another suggestion on twitter last night. Both seem viable, because they are opt-in. -- Jeff Garzik CEO and Co Founder Bloq, Inc. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.linuxfoundation.org/pipermail/bitcoin-segwit2x/attachments/20170727/1a9c7b7c/attachment.html>