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dara=google.com ARC-Authentication-Results: i=1; gmr-mx.google.com; dkim=pass header.i=@mail.wpsoftware.net header.s=default header.b=k+Afimub; spf=pass (google.com: domain of apoelstra@wpsoftware.net designates 66.183.0.205 as permitted sender) smtp.mailfrom=apoelstra@wpsoftware.net; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=wpsoftware.net Received: from mail.wpsoftware.net ([66.183.0.205]) by gmr-mx.google.com with ESMTP id s92-20020a25aa65000000b00dc657e7de95si647200ybi.0.2024.04.01.07.20.55 for ; Mon, 01 Apr 2024 07:20:55 -0700 (PDT) Received-SPF: pass (google.com: domain of apoelstra@wpsoftware.net designates 66.183.0.205 as permitted sender) client-ip=66.183.0.205; Received: from camus (camus-andrew.lan [192.168.0.190]) by mail.wpsoftware.net (Postfix) with ESMTPSA id 8DBAB400DD for ; Mon, 1 Apr 2024 14:20:54 +0000 (UTC) Date: Mon, 1 Apr 2024 14:20:53 +0000 From: Andrew Poelstra To: bitcoindev@googlegroups.com Subject: Re: [bitcoindev] The Future of Bitcoin Testnet Message-ID: References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="C/AxekDA4/AqNTHA" Content-Disposition: inline In-Reply-To: X-Original-Sender: apoelstra@wpsoftware.net X-Original-Authentication-Results: gmr-mx.google.com; dkim=pass header.i=@mail.wpsoftware.net header.s=default header.b=k+Afimub; spf=pass (google.com: domain of apoelstra@wpsoftware.net designates 66.183.0.205 as permitted sender) smtp.mailfrom=apoelstra@wpsoftware.net; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=wpsoftware.net Precedence: list Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com List-ID: X-Google-Group-Id: 786775582512 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , X-Spam-Score: -0.8 (/) --C/AxekDA4/AqNTHA Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Apr 01, 2024 at 01:37:59PM +0000, Pieter Wuille wrote: >=20 > As for using other measures to prevent too large difficulty variations...= I'm not sure that's desirable, because it always cuts both ways (nicely de= monstrated by the "allow difficulty 1 rule" on testnet3 backfiring and enab= ling block storms!). For applications that actually need very predictable b= lock rate, there is signet. For others, just the normal mainnet rules are p= robably not too terrible. I would be ok with having a somewhat reduced bloc= k interval (say a few days instead of 2 weeks) if that's not deemed to comp= lex to implement across the ecosystem, but I don't think it's that importan= t. > I really like this. For my part (rust-bitcoin) this would be as simple as adding an extra parameter to my blockparams structure. Possibly one already exists, I'd have to check. This would be much easier than the existing situation where we have special-case logic for testnet the difficulty-1 target. It would also limit the amount of bikeshedding possible, since there aren't too many conflicting goals regarding the retargeting window... unlike tweaking the existing logic where there's a tradeoff between "we should make this never happen" and "it should happen often enough that it doesn't break people's code" and "it should happen if blocks slow down to like, 1/50th their normal rate even if they are still technically being produced" and "it shouldn't be possible to trigger it within the 2-hour timestamp-faking window" etc. And questions about whether we should fix/redesign the interaction between the reset rule and the normal difficulty retarget. OTOH, since we already have the special logic, I'd also be happy with tweaking the existing rule. My specific proposal (after reading Jameson's post, which has some nice graphs of difficulty) would be * increase the reset threshold from 20 minutes to 6 hours, which is (a) well outside the 2-hour window in which miners can easily fake timestamps, and (b) will basically never be hit by accident * increase the reset difficulty from 1 to 1MM, which is an rough lower bound on the "normal" testnet difficulty seen historically Which puts us in the "this rule would never be triggered unless literally everyone stopped mining" corner of the design space. --=20 Andrew Poelstra Director of Research, Blockstream Email: apoelstra at wpsoftware.net Web: https://www.wpsoftware.net/andrew The sun is always shining in space -Justin Lewis-Webster --=20 You received this message because you are subscribed to the Google Groups "= Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to bitcoindev+unsubscribe@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/= bitcoindev/ZgrCxWxMkiAt2Tg2%40camus. --C/AxekDA4/AqNTHA Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkPnKPD7Je+ki35VexYjWPOQbl8EFAmYKwsQACgkQxYjWPOQb l8F37Af/eKhN/8c40ez2uDx8/jUtklkrvnyzK9tD9Exlqg8seQ8f3kanK6opkcie dA2ZiI5PbWnTujNHwyi0Aa9quJbJg3ostQCWzYu8wASNAprQelCI5jP5fAZAp9h6 JyqUsrvjzWSBYPNaa596qYaMOKcup2kPZ5zxzmU0wueycaBaRQoevxQx9xAWlyFU IKUiAWwi0Ep5eNrADYGEs0gxDp4E6XmCER7CM35fkvLzUr2WSeHFjpQOQI3dVExY jUWWUTtX3obRYT1UOMcpX5ueHgabf6t01p6dqBZ5Rf9PWwILLGu2yUvZMcCssVD5 ZDmiU8yC52XRvFoZz6xrKKeWP0b5Zw== =jegM -----END PGP SIGNATURE----- --C/AxekDA4/AqNTHA--