Return-Path: Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 11EBFC0032 for ; Tue, 5 Sep 2023 18:00:39 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id CC76640153 for ; Tue, 5 Sep 2023 18:00:38 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org CC76640153 Authentication-Results: smtp2.osuosl.org; dkim=pass (2048-bit key, unprotected) header.d=messagingengine.com header.i=@messagingengine.com header.a=rsa-sha256 header.s=fm1 header.b=PPqCPycH X-Virus-Scanned: amavisd-new at osuosl.org X-Spam-Flag: NO X-Spam-Score: -2.602 X-Spam-Level: X-Spam-Status: No, score=-2.602 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id UXn9-YGRHGVX for ; Tue, 5 Sep 2023 18:00:38 +0000 (UTC) Received: from wout2-smtp.messagingengine.com (wout2-smtp.messagingengine.com [64.147.123.25]) by smtp2.osuosl.org (Postfix) with ESMTPS id EB47240134 for ; Tue, 5 Sep 2023 18:00:37 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org EB47240134 Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailout.west.internal (Postfix) with ESMTP id 164673200950; Tue, 5 Sep 2023 14:00:35 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute5.internal (MEProxy); Tue, 05 Sep 2023 14:00:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm1; t=1693936834; x=1694023234; bh=1/G7F3CGCc/wO HdCY1NHbreGkamLDkVig7JUwWFCOTE=; b=PPqCPycHKZJ1SyFyLWkLThhhUt3SG z9FQvE9Oj7RH8Ppwus7u4dILPVy2CpassCIoJbZthLY98sJsfFayqHUhWFiIHsz/ 7VApmUpLE2YbJv2R4P+pVgbBJV6UX0JFD5d/5OgHN4Lk2btDbHznM5RRRGIPz88i vPnt1k2tbhif1KRwsmktwBZhlBDo22pR4OOo9zltLr0gXfPer+C7bX9FJ/asFX6o zaW6dHLVPh1njdo3UMG6hV6eEjNIohCBOMkJU+5acNOSm+PpUKuDh2QisHf6IFvV RA4sd7ZwIGD+VfYCGlbRQOYG6XJKB0RXHb1ZHE+aqa6ALiO1nNiYima3A== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedviedrudehuddgleejucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvfevuffkfhggtggujgesghdtreertddtvdenucfhrhhomheprfgvthgv rhcuvfhougguuceophgvthgvsehpvghtvghrthhouggurdhorhhgqeenucggtffrrghtth gvrhhnpeelvdellefftddukeduffejgfefjeeuheeileeftdfgteduteeggeevueethfej tdenucffohhmrghinhepphgvthgvrhhtohguugdrohhrghenucevlhhushhtvghrufhiii gvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehpvghtvgesphgvthgvrhhtohguugdr ohhrgh X-ME-Proxy: Feedback-ID: i525146e8:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 5 Sep 2023 14:00:32 -0400 (EDT) Received: by localhost (Postfix, from userid 1000) id 418235F82B; Tue, 5 Sep 2023 18:00:33 +0000 (UTC) Date: Tue, 5 Sep 2023 18:00:33 +0000 From: Peter Todd To: Andrew Poelstra , Bitcoin Protocol Discussion Message-ID: References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="jhBCJUTj0zdymhQa" Content-Disposition: inline In-Reply-To: Subject: Re: [bitcoin-dev] Compressed Bitcoin Transactions X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 05 Sep 2023 18:00:40 -0000 --jhBCJUTj0zdymhQa Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Sep 01, 2023 at 01:56:18PM +0000, Andrew Poelstra via bitcoin-dev w= rote: > We can swag what the space savings would be: there are 122MM utxos right > now, which is a bit under 2^27. So assuming a uniform distribution of > prefixes we'd need to specify 28 bits to identify a UTXO. To contrast, > to identify a blockheight we need 20 bits and then maybe 12 more bits to > specify a TXO within a block. Plus whatever varint overhead we have. > (I've been working on this project but busy with family stuff and don't > remember exactly where we landed on the varints for this. I think we > agreed that there was room for improvement but didn't want to hold up > posting the rest of the concept because of it.) Since most transactions spend txouts that are similar in height to each oth= er, you could save further bits by specifying a reference height and then encod= ing the exact txout with a delta. If you're sending multiple txins or multiple transactions in a single packe= t, you could achieve this by starting the packet with the reference block heig= ht. If your application tends to send just a single transaction, you could use a reference height that is a function of the current time. Since sender and receiver might not agree on the exact time, you could try slightly differen= ce reference heights via bruteforcing until the transaction signatures validat= e. --=20 https://petertodd.org 'peter'[:-1]@petertodd.org --jhBCJUTj0zdymhQa Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE0RcYcKRzsEwFZ3N5Lly11TVRLzcFAmT3bL8ACgkQLly11TVR LzdQGQ/8DEjgazwJ82CA5NG5djwTF1pybNs3bjowdFC8uLmUjSGeK3Mwjve9M7Pl irN6qMKwGtgoMCbRJvUVxuqgkra7LEy8wR+Z/e36AeP9oFDq3k6gzU5UtLnnQeqM LMLofg9f9xrf8NKo1zC/DOAQ+jAH0RYZhHBlNFRYQEo0VpViKByqhSsKaCZarpCh H4dHMof/j1x0AIVnqvdSKR8kb0PUm22RHLIgVZVzrecJarAkO91unDvJnq+1N1tX /AAmIaJLVjhO9q2V1i2vW+q6n9wxJYdDiwEHoMnR0QkO0qMm5XjlFCnETPiWy3Zh WkEBcIqZgXuZlTrSzpQaizQb4FyIB+hE9lihaZ9Xz2/DxfkmqtOqh7FG8xCLRiVi Kpx/J0ZDLm+L13c7GmQaLLonfarx6iRRIf/F30R6GuvuUepN7qZ2BEGpNg7plDMq KTthYUoKbuBZCO4GwtoM71JOAv/Sa3915+7G5hc4Gh0YZg7TkpwAb3CPVDlMsRM+ lCfrH06Xw7yGcmD+vbiR7G8r7fN0J5PzNrXnWyButiz/RfsiYkkv0cOdbDk4ylS+ qej3V1sL4/B1GGUrtXctr8ajowVtfblhhpuqvsEKlh48FTn3Cn2pV9BE9ywlEPox UC281gECd6piiU0Oo3AtUIGT1qmHwM6mHUw8owrcpiblMn3a/WQ= =jT/j -----END PGP SIGNATURE----- --jhBCJUTj0zdymhQa--