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 D59B5EE4; Mon, 30 Sep 2019 23:28:54 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail-40133.protonmail.ch (mail-40133.protonmail.ch [185.70.40.133]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 1740D8A8; Mon, 30 Sep 2019 23:28:54 +0000 (UTC) Date: Mon, 30 Sep 2019 23:28:43 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=default; t=1569886132; bh=pB1AFURZ0ImvEnI+0/WeVI0Q5z6cA+dhKaWdlF34Tek=; h=Date:To:From:Cc:Reply-To:Subject:In-Reply-To:References: Feedback-ID:From; b=NAEupCgxiGVcwGil2vqvFeIfLO7qyypE5/PQ3970O/97Cm7lHQIOI8nb1ryetPmlz 4TCzfy7XSGhWfTBpyywP1OZFI+xGLoYGspaIajV8yz9eTFf+UBpD6Y5KSLZwGyfaFv wH8zLIgBq8Uqtbw8CZXI50xFboqgzqonpkRTPz10= To: ZmnSCPxj , Bitcoin Protocol Discussion From: ZmnSCPxj Reply-To: ZmnSCPxj Message-ID: In-Reply-To: <-5H29F71ID9UFqUGMaegQxPjKZSrF1mvdgfaaYtt_lwI7l1OTmN_8OgcooyoMt2_XuyZ5aDljL6gEup9C7skF8iuP_NbMW_81h0tJIGbJno=@protonmail.com> References: <87wodp7w9f.fsf@gmail.com> <-5H29F71ID9UFqUGMaegQxPjKZSrF1mvdgfaaYtt_lwI7l1OTmN_8OgcooyoMt2_XuyZ5aDljL6gEup9C7skF8iuP_NbMW_81h0tJIGbJno=@protonmail.com> Feedback-ID: el4j0RWPRERue64lIQeq9Y2FP-mdB86tFqjmrJyEPR9VAtMovPEo9tvgA0CrTsSHJeeyPXqnoAu6DN-R04uJUg==:Ext:ProtonMail MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, FROM_LOCAL_NOVOWEL, RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: "lightning-dev@lists.linuxfoundation.org" Subject: Re: [bitcoin-dev] Continuing the discussion about noinput / anyprevout 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: Mon, 30 Sep 2019 23:28:55 -0000 Good morning list, To elucidate further --- Suppose rather than `SIGHASH_NOINPUT`, we created a new opcode, `OP_CHECKSI= G_WITHOUT_INPUT`. This new opcode ignores any `SIGHASH` flags, if present, on a signature, bu= t instead hashes the current transaction without the input references, then= checks that hash to the signature. This is equivalent to `SIGHASH_NOINPUT`. Yet as an opcode, it would be possible to embed in a Taproot script. For example, a Decker-Russell-Osuntokun would have an internal Taproot poin= t be a 2-of-2, then have a script `OP_1 OP_CHECKSIG_WITHOUT_INPUT`. Unilateral closes would expose the hidden script, but cooperative closes wo= uld use the 2-of-2 directly. Of note, is that any special SCRIPT would already be supportable by Taproot= . This includes SCRIPTs that may potentially lose funds for the user. Yet such SCRIPTs are already targetable by a Taproot address. If we are so concerned about `SIGHASH_NOINPUT` abuse, why are we not so con= cerned about Taproot abuse? Regards, ZmnSCPxj