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 D351914EB for ; Mon, 27 May 2019 07:26:34 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-lj1-f174.google.com (mail-lj1-f174.google.com [209.85.208.174]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 24D0BA9 for ; Mon, 27 May 2019 07:26:34 +0000 (UTC) Received: by mail-lj1-f174.google.com with SMTP id 188so13739383ljf.9 for ; Mon, 27 May 2019 00:26:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=UddGfSPsL242711cQeI15/TyDyU59R4JOjCPrdHMDpY=; b=q1oIJdMLEWn7YeZDSN9OA/9oJr8d4OCoAIyDdsAl9j/q2cAbYbza/Wem1YysgyOxAi n9X+OVGn8FLFVPPgARRTsV8Qe+6S6jDT0jzppXIghOTi2NSTIY0luUBUYjFh9DM6mb35 nQmdlLBUMVX6zkapPwOBRWaD7kB+BRemmL5owOU1CjmWSrcD+cw8Gez49O8GWD7n++OZ p2Chx/SvRndCy7Q6tXOtPacHmNVmQhRavk66QtbBiUarxsa+OJNqGvDtXdHaJlWrRzEZ mlnWQsKWWKUUZ9DQB16S0raMxOTUBDPf4nr6Sf1afDwp/4rDdBDOG/sJbAmfIWlDsU2G Xl7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=UddGfSPsL242711cQeI15/TyDyU59R4JOjCPrdHMDpY=; b=oZnvyiwLnbdxE3Hk89+ptst3e4oFCi3Ukb9/zke3xtdMSlQ3vnFEI1dhWCers0baIP obqZQ6HMkBuzMp0D4EHQ+0X4GjSX37ozhowVxSvWfWHRgkk21baX27AwFE/rDBARWoCv ypagZmEJWiyLDFsH2PjwAlR+wCpZ/GQCSxHtfIF6uCOBAgy255x5u5iV47SIicskzg9F +ew8jELm7ttgW+B048Wmrs3H1MmocH41Gm9xa5NR0PylWR1yOxtgCETeY0ppYEbEEe2C s/o3uqlTv2RP8f/+7bJSndbeRG6otkqXi1tDyukAb7IgMNBVVwRTOuBlVLZ+8/51Fbdg EaAw== X-Gm-Message-State: APjAAAXqQ3YCb5hxwzJhGopO4m1hCW+t37Quo1s8w6iDC0Q1alQyzt/P XW1e8Mfl6sJy221q1MANM8YWZ9JJic6R//t9Sy8= X-Google-Smtp-Source: APXvYqzXOAw+dHzlvthXXva9mDrXKK1si5+TImPn208rp6b9vrg2ACz1ugEr+zlW1+O98DeTW5qJVIaNdGSksLX89bI= X-Received: by 2002:a2e:8796:: with SMTP id n22mr2225475lji.75.1558941992532; Mon, 27 May 2019 00:26:32 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Kostas Karasavvas Date: Mon, 27 May 2019 10:26:21 +0300 Message-ID: To: Aymeric Vitte , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary="000000000000b0bd630589d9771d" X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HTML_MESSAGE, 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: Mon, 27 May 2019 14:29:09 +0000 Subject: Re: [bitcoin-dev] Two questions about segwit implementation 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, 27 May 2019 07:26:34 -0000 --000000000000b0bd630589d9771d Content-Type: text/plain; charset="UTF-8" On Sun, May 26, 2019 at 5:07 PM Aymeric Vitte via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > I realized recently that my segwit implementation was not correct, > basically some time ago, wrongly reading the specs (and misleaded by > what follows), I thought that scriptsig would go into witness data as it > was, but that's not the case, op_pushdata is replaced by varlen > > Now reading correctly the specs, they seem to be not totally correct, > then the first question is: why OP_0 is 00 in witness data and not 0100? > Does this apply to other op_codes? This does not look logical at all > > op_pushdata allows for unsigned integers and thus it uses the extra byte to specify that. A varint (varlen) is unsigned. 0 and anything <= 252 is one byte length, so 00. > The second question is: why for non segwit inputs there is a 00 length > in segwit data, what is the rational for that? It should just be nothing > since you don't need this to reconciliate things > > Because you don't have the number of witnesses as you have for inputs/outputs. The witness data length is assumed to be the same as the inputs length. And then for non-segwit inputs you need the 00 to specify that it is empty. Hope that helps. --000000000000b0bd630589d9771d Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


=
On Sun, May 26, 2019 at 5:07 PM Aymer= ic Vitte via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
I realized recently that my= segwit implementation was not correct,
basically some time ago, wrongly reading the specs (and misleaded by
what follows), I thought that scriptsig would go into witness data as it was, but that's not the case, op_pushdata is replaced by varlen

Now reading correctly the specs, they seem to be not totally correct,
then the first question is: why OP_0 is 00 in witness data and not 0100? Does this apply to other op_codes? This does not look logical at all


op_pushdata allows for unsigned intege= rs and thus it uses the extra byte to specify that.

A varint (varlen) is unsigned.=C2=A0 0 and anything <=3D 252 is one by= te length, so 00.=C2=A0
=C2=A0
The second question is: why for non segwit inputs there is a 00 length
in segwit data, what is the rational for that? It should just be nothing since you don't need this to reconciliate things


Because you don't have the number = of witnesses as you have for inputs/outputs. The witness data length is ass= umed to be the same as the inputs length. And then for non-segwit inputs yo= u need the 00 to specify that it is empty.
=C2=A0
Hope that helps.

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