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 32811723 for ; Sun, 2 Oct 2016 22:37:11 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-qk0-f174.google.com (mail-qk0-f174.google.com [209.85.220.174]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id A94D687 for ; Sun, 2 Oct 2016 22:37:10 +0000 (UTC) Received: by mail-qk0-f174.google.com with SMTP id j129so141846314qkd.1 for ; Sun, 02 Oct 2016 15:37:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=zFU8TVjj4w5MIlnzpJFp7ACNC5uKJXXM1/BvqSt1lDc=; b=Stq/UVxa5rxH5ssk17KzB6veYeY7WOSbsbUmAQuW4+2GM7NcfcOZCLQNtR9uo1QcuS 2LPj6/Wyu4Tt8vSRgz8I0Z9KFyzRBDx82ywfWeaeZgmE7Gbhk/DYMKM/wqM2hMqnLLmV +QKlM8EtC9GgcVMJoP/SyjARRXIf7o/PP5lkrpdc8q8I506XuDldfYEjN7en6X9kC0aa d+qr20sDZGxWLRiKJkX1SJI4rcU/HSEE123JQ1vf/zOiViHdgtasw2vB6dzwQTVysOhB 135FDeeyAVVFxmHR5RSBB0DR4wG5a93G3e3LLq2eYTcxMnfO2fdyrI/fLlnJU85CKyH4 s89A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=zFU8TVjj4w5MIlnzpJFp7ACNC5uKJXXM1/BvqSt1lDc=; b=HH8L3+eZP/Tj6wxmCwyqBljZXjwUDwR4QSJ0embCO9jdXom/0GZjQksi3muRBe7pcy Z1y0nwVjCifou9dWgOtJQMulu2gTdmRObmskL1H/L9hpvDbDvc6XQz6NWfI5WX3DGMmf EJzU5s813ulbTDa0gT29q3deR4szsZOa8lVVXOJWvYYc27JgXOGVSYESxsnKmzXx6t+5 8/GETJ/YaI2xCHrcZ6pYWKc+Xb1aXDUkSqNWl1FlEC4eMZOKbc/HSkODzVF6o9K+HlZz EtGl73Vhl0KoM35cEFnwS+Tk3nJVG3IyOTRtJYdLr0b6ONLnc3FtLR4iE+K5PDknANSn FP8g== X-Gm-Message-State: AA6/9RkhkOVFI34S5dn70hyD8Xn70d/ogGLbK9z2j9ny+kV7yZyajLsnMDuuNh8d2LMIylYIHm/FSSRUD1Cu7w== X-Received: by 10.55.128.129 with SMTP id b123mr16989384qkd.322.1475447829997; Sun, 02 Oct 2016 15:37:09 -0700 (PDT) MIME-Version: 1.0 Received: by 10.237.35.7 with HTTP; Sun, 2 Oct 2016 15:36:29 -0700 (PDT) In-Reply-To: References: <20161002171137.GA18452@fedora-21-dvm> <201610022128.52401.luke@dashjr.org> From: Sergio Demian Lerner Date: Sun, 2 Oct 2016 19:36:29 -0300 Message-ID: To: "Russell O'Connor" , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary=94eb2c06652ecaacaa053de977c7 X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HTML_MESSAGE, RCVD_IN_DNSWL_LOW, RCVD_IN_SORBS_SPAM 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] Drivechain proposal using OP_COUNT_ACKS 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: Sun, 02 Oct 2016 22:37:11 -0000 --94eb2c06652ecaacaa053de977c7 Content-Type: text/plain; charset=UTF-8 On Sun, Oct 2, 2016 at 6:46 PM, Russell O'Connor via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > > But I would argue that in this scenario, the only way it >> would become invalid is the equivalent of a double-spend... and therefore >> it >> may be acceptable in relation to this argument. >> > > The values returned by OP_COUNT_ACKS vary in their exact value depending > on which block this transaction ends up in. While the proposed use of this > operation is somewhat less objectionable (although still objectionable to > me), nothing stops users from using OP_EQUALVERIFY and and causing their > transaction fluctuate between acceptable and unacceptable, with no party > doing anything like a double spend. This is a major problem with the > proposal. > Transactions that redeem an output containing (or referencing by means of P2WSH) an OP_COUNT_ACKS are not broadcast by the network. That means that the network cannot be DoS attacked by flooding with a transaction that will not verify due to being too late. The only parties that can include the redeem transaction are the miners themselves. Therefore I see no problem that an OP_COUNT_ACKS scriptSig transaction is invalidated after the liveness times expires. If there is no expiration, then polls can last forever and the system fails to provide DoS protection for block validation since active polls can accumulate forever. --94eb2c06652ecaacaa053de977c7 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Sun, Oct 2, 2016 at 6:46 PM, Russell O'Connor via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wr= ote:

But I would argue that in this scenario, t= he only way it
would become invalid is the equivalent of a double-spend... and therefore i= t
may be acceptable in relation to this argument.

The values returned by OP_COUNT_ACKS vary in their exact value depending on which block= this transaction ends up in.=C2=A0 While the proposed use of this operatio= n is somewhat less objectionable (although still objectionable to me), noth= ing stops users from using OP_EQUALVERIFY and and causing their transaction= fluctuate between acceptable and unacceptable, with no party doing anythin= g like a double spend.=C2=A0 This is a major problem with the proposal.
=

Transaction= s that redeem an output containing (or referencing by means of P2WSH) an OP= _COUNT_ACKS are not broadcast by the network. That means that the network c= annot be DoS attacked by flooding with a transaction that will not verify d= ue to being too late.
The only parties that can include the r= edeem transaction are the miners themselves.
Therefore I see = no problem that an OP_COUNT_ACKS scriptSig transaction is invalidated after= the liveness times expires.
If there is no expiration, then = polls can last forever and the system fails to provide DoS protection for b= lock validation since active polls can accumulate forever.



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