From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 6AB2711B6 for ; Sat, 24 Feb 2018 18:59:02 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-vk0-f45.google.com (mail-vk0-f45.google.com [209.85.213.45]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 2EF3B466 for ; Sat, 24 Feb 2018 18:59:01 +0000 (UTC) Received: by mail-vk0-f45.google.com with SMTP id x135so7515448vkd.5 for ; Sat, 24 Feb 2018 10:59:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to; bh=i1YjNWIAsU6l0EZes5Yu3I7uFVEEEmGMJh0gE3tnF40=; b=acMdHMJSPUtdW/dRmBDc4mM29jNARnEo0j8tufNsXk4b6Szd4LdBFyOxwbWgJ8Z8Hr 6SMcuodDkJcnA/uYcOK0snYlt4nTK8uduiSUP3PUPbtCLwPbC4P1R+CTxswoglV/Mzj5 1k5PElASw0JRyqbPPbKRTi1RyTtQhHzfClCE6BmcEN/moZYjN7SZP8hzJxe0vacodro1 BFre382vuV/4qshyygNQMjCP2xU3RvdvkBhrKRRDrWeG/mSSZv2irQ9XF7/Coojwx1Fp OGuD/MnWF5DtP95XKNFOP2DUIx/V1uWqp3E+V+uI7+/zE9EHKso0tUZe+XpiFBzuSrAJ PObA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to; bh=i1YjNWIAsU6l0EZes5Yu3I7uFVEEEmGMJh0gE3tnF40=; b=hjNHoN1DV+CjZsBeuO+1h96DBJA9BhrNCnP16ugvV7CEg/qxEkFEjbgPRxdTsbMMuV 0snK1L3AysGQk6w9yYqhNRK5kPGytNnHwTRLlrBtKQqN+2lXds892XiFUmM1B8ZAIvhf xo0U5MGqXTbtibWRHcqrkoA6P08kRSGScEMMxHK1mTCRgtVQI82oRHQ2OXU+BJQOTO1v YXiz0tMX4myevM+x/QTIytilLUQGFF4EbC6Uwm5gvLKz+G48WTaAZhONeDbWLJdwIjqW NGXDC41qafCpDiQG0h6prHx17FLY/T1FekpSjX6huvCKJXdfSvPn6rLJC0ApN109anwa jneQ== X-Gm-Message-State: APf1xPDv1lKKfd9PXW/btRM+c2Iax407r6a3m+Y4nSV5cOPub3kka+R8 2FTtLNCdlaRNO9LoVW2o5KFgNxgUZwofxnuzd8EWoQ== X-Google-Smtp-Source: AG47ELsuCj44RI/V+lR5uGRUtiX2r5/w/+YFZA9Kq/cefFcDqKFEf9HXI8oXwk7Ud2Mm6L0isUUxcvioDgH0YJZqpBA= X-Received: by 10.31.100.10 with SMTP id y10mr2323123vkb.55.1519498740316; Sat, 24 Feb 2018 10:59:00 -0800 (PST) MIME-Version: 1.0 Sender: gmaxwell@gmail.com Received: by 10.103.97.70 with HTTP; Sat, 24 Feb 2018 10:58:59 -0800 (PST) In-Reply-To: <1519328661.898070.1280084352.71F1C1C3@webmail.messagingengine.com> References: <1519328661.898070.1280084352.71F1C1C3@webmail.messagingengine.com> From: Gregory Maxwell Date: Sat, 24 Feb 2018 18:58:59 +0000 X-Google-Sender-Auth: zVxtgkkGhEGhrwlrc7x6R6c1swc Message-ID: To: Daniel Edgecumbe , Bitcoin Protocol Discussion Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, 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 Subject: Re: [bitcoin-dev] Graftroot: Private and efficient surrogate scripts under the taproot assumption 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: Sat, 24 Feb 2018 18:59:02 -0000 On Thu, Feb 22, 2018 at 7:44 PM, Daniel Edgecumbe via bitcoin-dev wrote: > I don't think that binding grafts to a particular transaction requires this aggregation. > It seems to me that you could just sign H(txid, script) rather than H(script). > I'm not aware of whether this would break aggregation. That would require that you know the txid in advance. Sometimes you do-- and a graftroot sighash flag could handle that... but usually you wouldn't. The case where you already do know it can sort of be covered today without using the graftroot: Sign a transaction spending the multisig coin to the graft. This isn't a strict alternative however, because it's not atomic: you could imagine that txn being announced and then the graft not being spent, while someone would like to spend a different graft. That non-atomiticity could be addressed by making the graft spends an OR of all the other graft spends but that isn't scalable or private. Regardless, still doesn't work if the graft isn't created after the fact. The aggregation bit has the property of working just in time, even on grafts created in advance.