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[202.12.124.150]) by gmr-mx.google.com with ESMTPS id af79cd13be357-8c530a7d2d9si6232685a.1.2026.01.14.02.15.57 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Jan 2026 02:15:57 -0800 (PST) Received-SPF: pass (google.com: domain of sjors@sprovoost.nl designates 202.12.124.150 as permitted sender) client-ip=202.12.124.150; Received: from phl-compute-01.internal (phl-compute-01.internal [10.202.2.41]) by mailfout.stl.internal (Postfix) with ESMTP id 5CAC01D0012E; Wed, 14 Jan 2026 05:15:57 -0500 (EST) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-01.internal (MEProxy); Wed, 14 Jan 2026 05:15:57 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgdduvddvleduucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucenucfjughrpegtggfuhfgjffevgffkfhfvofesthhqmh dthhdtjeenucfhrhhomhepufhjohhrshcurfhrohhvohhoshhtuceoshhjohhrshesshhp rhhovhhoohhsthdrnhhlqeenucggtffrrghtthgvrhhnpeejtedthfejkefhvdfgveettd ffgeevfeevveelleehieeggfelveeluddvieeiveenucffohhmrghinhepghhithhhuhgs rdgtohhmnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomh epshhjohhrshesshhprhhovhhoohhsthdrnhhlpdhnsggprhgtphhtthhopedvpdhmohgu vgepshhmthhpohhuthdprhgtphhtthhopegsihhttghoihhnuggvvhesghhoohhglhgvgh hrohhuphhsrdgtohhmpdhrtghpthhtohepmhhurhgthhesmhhurhgthhdrohhnvg X-ME-Proxy: Feedback-ID: ie5e042df:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 14 Jan 2026 05:15:56 -0500 (EST) Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.300.41.1.7\)) Subject: Re: [bitcoindev] Addressing remaining points on BIP 54 From: Sjors Provoost In-Reply-To: <492f9bba-8a1f-4fa2-8618-98bd564a6178@murch.one> Date: Wed, 14 Jan 2026 11:15:45 +0100 Cc: Murch Content-Transfer-Encoding: quoted-printable Message-Id: <1B807731-DC2A-4E59-B462-5C210EF1FB73@sprovoost.nl> References: <05f5b0ee-b487-4733-9860-ac0705b6b901n@googlegroups.com> <9C946151-D6DD-4CB7-B524-15FD9F625D9D@sprovoost.nl> <492f9bba-8a1f-4fa2-8618-98bd564a6178@murch.one> To: bitcoindev@googlegroups.com X-Mailer: Apple Mail (2.3864.300.41.1.7) X-Original-Sender: sjors@sprovoost.nl X-Original-Authentication-Results: gmr-mx.google.com; dkim=pass header.i=@sprovoost.nl header.s=fm3 header.b=c7RQ0bQC; dkim=pass header.i=@messagingengine.com header.s=fm2 header.b=OutJoAww; spf=pass (google.com: domain of sjors@sprovoost.nl designates 202.12.124.150 as permitted sender) smtp.mailfrom=sjors@sprovoost.nl; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=sprovoost.nl 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 (/) Hi Murch, You're referring to the "serialization with witness data" defined in BIP 14= 1. But that's not how the transaction is serialised in a block, since the witn= ess is segregated. > The witness is committed in a tree that is nested into the block's existi= ng merkle root via the coinbase transaction for the purpose of making this BIP soft fork compatible. A future hard fork can place this tree in its own bra= nch. As long as the miner doesn't touch the SegWit OP_RETURN , which also commit= s to the coinbase witness, it can safely use the legacy transaction serialisa= tion. - Sjors [0] https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki#transact= ion-id > Op 14 jan 2026, om 01:23 heeft Murch het volgende gesch= reven: >=20 > Hi Sjors, >=20 > On 2026-01-08 00:30, Sjors Provoost wrote: >> The approach suggested by Towns [4] of appending a 0-sat OP_RETURN outpu= t with >> padding so a 4-byte nonce lands in the final 64-byte SHA256 chunk is pro= bably >> better, but not because like nLockTime it has a small hashing midstate >> benefit. It's easier to implement. > I can=E2=80=99t access Delving right now to read AJ=E2=80=99s comment, bu= t a small nit on the idea of using an additional output: BIP=E2=80=AF141 re= quires coinbase transaction inputs to have a 32-byte witness. Since the wit= ness section follows the outputs in the serialization, the bytes before the= `nLocktime` in a coinbase transaction are the witness of the coinbase inpu= t, not the last output script. >=20 > -Murch --=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 visit https://groups.google.com/d/msgid/bitcoindev/= 1B807731-DC2A-4E59-B462-5C210EF1FB73%40sprovoost.nl.