Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 7FF564A6 for ; Wed, 21 Nov 2018 11:20:59 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ed1-f48.google.com (mail-ed1-f48.google.com [209.85.208.48]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 113456C5 for ; Wed, 21 Nov 2018 11:20:58 +0000 (UTC) Received: by mail-ed1-f48.google.com with SMTP id h50so4574128ede.5 for ; Wed, 21 Nov 2018 03:20:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:in-reply-to:references:date:message-id:mime-version; bh=qkSQQ3XNGSBL3XGwlWOcVh75WBLQeNt2Ahp5/dnuUao=; b=sy+6zNkkOdAuLOlqWZwyVphPVoQBNSX0SaPYY3tcedKC2pPfo3qgl+AjAzJ/YbfSN2 EDCRiW5+NoGRXcES7saV2AJdG2qHkbmVKyZHSOIkhG2xAL7Q+h02RjbverppejOwCzN0 YlUzm+TXG9/lcQpZ4ouWyPAnuCMuC4Nh9p2rMO3gYDkYRXS9ueUXIMj8y7mI8GEJzQAh UZ44qt97JZd+UqB5MkOR1nupR6k97G3ZEeDDqdARuAl91i1FAH48MZf1imvJIFShlGyI dwduy/GiByQFPcxm01xeq0LCWYEWU9eib1eekPInirWOVh4ckCyY9MO/NJgNUZ6cSS+4 e9hw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:in-reply-to:references:date :message-id:mime-version; bh=qkSQQ3XNGSBL3XGwlWOcVh75WBLQeNt2Ahp5/dnuUao=; b=nec3uP7kzVwwJ8bJMg5kkYjAyvSxFio4dqCa3B5E8IIf+zmYNVkLm01snaWJZdMsqy Ou1yB6FxsGAcxnEAOQPcjppqjRvohxi/OocctNfWGWkFJnTOf2QDCDxMHs11kjWo9b4K ypyX4XCBESo+3+g4PF3QwxAy398QYe5iLodKHpEEngiSz05QdWm/5nid9451qAZej+Ka 6Ruq9kMzVoAaBNil3MIaif7NNMkFdD02mt7P2rtWPUrx4J2vssmeaWSw/JEmcj0xcreN LkfF9nn4gmVCnc2svTMqZgmFKS+vXd8fg9uC2Uw77ItnJwP2oNb/Abe1p28Px04rlN1f xmTg== X-Gm-Message-State: AA+aEWaQL/m1sFK0dPMRT3tHFnACgWnW0cuefTnrXde8nuD9PZCEJIH+ sKLSqchJvb/ZX8nvBuXZR/jJfYNW X-Google-Smtp-Source: AFSGD/VPtYku7vfKmyKMWHktn2wL9zNXbZE6GoFBR2OiGrOXhX4M95IuI8bsueTE8FRQQcF4RFgbfg== X-Received: by 2002:a50:b1db:: with SMTP id n27mr5528232edd.65.1542799257601; Wed, 21 Nov 2018 03:20:57 -0800 (PST) Received: from localhost ([2a02:aa16:1102:5480:1115:8f2f:6db1:5c0a]) by smtp.gmail.com with ESMTPSA id r8sm648407edo.11.2018.11.21.03.20.56 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 21 Nov 2018 03:20:57 -0800 (PST) From: Christian Decker To: Anthony Towns , Bitcoin Protocol Discussion , Pieter Wuille , Bitcoin Protocol Discussion In-Reply-To: <20181120202904.gmbg5ebegvsgqfys@erisian.com.au> References: <20181120202904.gmbg5ebegvsgqfys@erisian.com.au> Date: Wed, 21 Nov 2018 12:20:44 +0100 Message-ID: <87h8gad6cz.fsf@gmail.com> MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Thu, 22 Nov 2018 14:08:02 +0000 Subject: Re: [bitcoin-dev] Safer sighashes and more granular SIGHASH_NOINPUT X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Nov 2018 11:20:59 -0000 Anthony Towns via bitcoin-dev writes: > Given this implementation, NOINPUT effectively implies ANYONECANPAY, > I think. (I think that is also true of BIP 118's NOINPUT spec) I mentioned this in my reply to Pieter, but this may not be true if we remove the blanking of the `hashSequence` field. Anyonecanpay would allow changing the number of inputs in an arbitrary fashion, while `noinput` without the blanking would (in a weird roundabout way) still commit to the number of inputs. Maybe we want to make that more explicit by also hashing the number of inputs? But I can't think of a good usecase for keeping that, with noinput. Cheers, Christian