path: root/e6/71ffc71e3b5236b40651082dd62fc9a9aa756b

Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194]
	helo=mx.sourceforge.net)
	by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76)
	(envelope-from <mark@friedenbach.org>) id 1Yzdcw-0000yG-9w
	for bitcoin-development@lists.sourceforge.net;
	Tue, 02 Jun 2015 04:16:34 +0000
X-ACL-Warn: 
Received: from mail-ig0-f178.google.com ([209.85.213.178])
	by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128)
	(Exim 4.76) id 1Yzdcr-0000KN-Ie
	for bitcoin-development@lists.sourceforge.net;
	Tue, 02 Jun 2015 04:16:34 +0000
Received: by igblz2 with SMTP id lz2so1192276igb.1
	for <bitcoin-development@lists.sourceforge.net>;
	Mon, 01 Jun 2015 21:16:24 -0700 (PDT)
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:content-type;
	bh=Ti+ojCxfZtPumSqaerOV86ApScUaXBjTp+am9KHpILg=;
	b=I4qJkaHbqfEAvCCz9ieXxqwjJ3oehsLD2lQLMRrHVTvo94gYGXqDUSjCWTpbXFH/P/
	uyohjHhF24E6PO13h8dr1iokbWtM33JuF3dsxjaG6trTKQILp2i7ii3A7XAiGhD3+ieH
	x+2DHVS/TGRg501cVH2bGJ2bqha+ab1QJ4rFMAELKnErS+rjkOhmJ6WSjAF48EMk2nTZ
	qqV55Cw5Dg3q5l5Aj7KJRQSYt4vlpvl8S0x1+waYYk88GP/exmkUYPXPKiyM0wlvyGqN
	NIhV6sn9LRwa2OANiko0OCI0PSu+lwmZ2nPw4nCmP5ASMr2nHmcisBdVkNd5zuG4MWTM
	77UA==
X-Gm-Message-State: ALoCoQmSASFdGEzUqdY0h1COVm9RHRxYMoBEsAIPTzZc2dCGpCgfC2vt6H5FYYFn0Y0mD1gcZHJY
X-Received: by 10.43.40.130 with SMTP id tq2mr32884118icb.46.1433218583924;
	Mon, 01 Jun 2015 21:16:23 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.107.10.197 with HTTP; Mon, 1 Jun 2015 21:16:03 -0700 (PDT)
X-Originating-IP: [50.0.37.37]
In-Reply-To: <CABHVRKQD4YPt0NA8VnXW4VYx0fmCgSHUYq-73F2esHZqX-FUxw@mail.gmail.com>
References: <CAOG=w-uufDPkQSEi1K_L82j4OXObGmESnfYyxi1z99fcBCotcg@mail.gmail.com>
	<CABHVRKQD4YPt0NA8VnXW4VYx0fmCgSHUYq-73F2esHZqX-FUxw@mail.gmail.com>
From: Mark Friedenbach <mark@friedenbach.org>
Date: Mon, 1 Jun 2015 21:16:03 -0700
Message-ID: <CAOG=w-tDdJTkkqGaEEpDZ6pX0kXT7f2wvoN_cEpd6+MVnu1CdQ@mail.gmail.com>
To: Stephen Morse <stephencalebmorse@gmail.com>
Content-Type: multipart/alternative; boundary=bcaec51dd84994c8610517813468
X-Spam-Score: 2.0 (++)
X-Spam-Report: Spam Filtering performed by mx.sourceforge.net.
	See http://spamassassin.org/tag/ for more details.
	1.0 HTML_MESSAGE           BODY: HTML included in message
	1.0 UC_GIBBERISH_OBFU Multiple instances of "word VERYLONGGIBBERISH
	word"
X-Headers-End: 1Yzdcr-0000KN-Ie
Cc: Bitcoin Development <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] [BIP draft] Consensus-enforced
 transaction replacement signalled via sequence numbers
X-BeenThere: bitcoin-development@lists.sourceforge.net
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: <bitcoin-development.lists.sourceforge.net>
List-Unsubscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
	<mailto:bitcoin-development-request@lists.sourceforge.net?subject=unsubscribe>
List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum_name=bitcoin-development>
List-Post: <mailto:bitcoin-development@lists.sourceforge.net>
List-Help: <mailto:bitcoin-development-request@lists.sourceforge.net?subject=help>
List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
	<mailto:bitcoin-development-request@lists.sourceforge.net?subject=subscribe>
X-List-Received-Date: Tue, 02 Jun 2015 04:16:34 -0000

--bcaec51dd84994c8610517813468
Content-Type: text/plain; charset=UTF-8

You are correct! I am maintaining a 'checksequenceverify' branch in my git
repository as well, an OP_RCLTV using sequence numbers:

https://github.com/maaku/bitcoin/tree/checksequenceverify

Most of the interesting use cases for relative lock-time require an RCLTV
opcode. What is interesting about this architecture is that it possible to
cleanly separate the relative lock-time (sequence numbers) from the RCLTV
opcode (OP_CHECKSEQUENCEVERIFY) both in concept and in implementation. Like
CLTV, the CSV opcode only checks transaction data and requires no
contextual knowledge about block headers, a weakness of the other RCLTV
proposals that violate the clean separation between libscript and
libconsensus. In a similar way, this BIP proposal only touches the
transaction validation logic without any impact to script.

I would like to propose an additional BIP covering the CHECKSEQUENCEVERIFY
opcode and its enabling applications. But, well, one thing at a time.

On Mon, Jun 1, 2015 at 8:45 PM, Stephen Morse <stephencalebmorse@gmail.com>
wrote:

> Hi Mark,
>
> Overall, I like this idea in every way except for one: unless I am missing
> something, we may still need an OP_RCLTV even with this being
> implemented.
>
> In use cases such as micropayment channels where the funds are locked up
> by multiple parties, the enforcement of the relative locktime can be done
> by the first-signing party. So, while your solution would probably work in
> cases like this, where multiple signing parties are involved, there may be
> other, seen or unforeseen, use cases that require putting the relative
> locktime right into the spending contract (the scriptPubKey itself). When
> there is only one signer, there's nothing that enforces using an nSequence
> and nVersion=2 that would prevent spending the output until a certain time.
>
> I hope this is received as constructive criticism, I do think this is an
> innovative idea. In my view, though, it seems to be less fully-featured
> than just repurposing an OP_NOP to create OP_RCLTV. The benefits are
> obviously that it saves transaction space by repurposing unused space, and
> would likely work for most cases where an OP_RCLTV would be needed.
>
> Best,
> Stephen
>
> On Mon, Jun 1, 2015 at 9:49 PM, Mark Friedenbach <mark@friedenbach.org>
> wrote:
>
>> I have written a reference implementation and BIP draft for a soft-fork
>> change to the consensus-enforced behaviour of sequence numbers for the
>> purpose of supporting transaction replacement via per-input relative
>> lock-times. This proposal was previously discussed on the mailing list in
>> the following thread:
>>
>> http://sourceforge.net/p/bitcoin/mailman/message/34146752/
>>
>> In short summary, this proposal seeks to enable safe transaction
>> replacement by re-purposing the nSequence field of a transaction input to
>> be a consensus-enforced relative lock-time.
>>
>> The advantages of this approach is that it makes use of the full range of
>> the 32-bit sequence number which until now has rarely been used for
>> anything other than a boolean control over absolute nLockTime, and it does
>> so in a way that is semantically compatible with the originally envisioned
>> use of sequence numbers for fast mempool transaction replacement.
>>
>> The disadvantages are that external constraints often prevent the full
>> range of sequence numbers from being used when interpreted as a relative
>> lock-time, and re-purposing nSequence as a relative lock-time precludes its
>> use in other contexts. The latter point has been partially addressed by
>> having the relative lock-time semantics be enforced only if the
>> most-significant bit of nSequence is set. This preserves 31 bits for
>> alternative use when relative lock-times are not required.
>>
>> The BIP draft can be found at the following gist:
>>
>> https://gist.github.com/maaku/be15629fe64618b14f5a
>>
>> The reference implementation is available at the following git repository:
>>
>> https://github.com/maaku/bitcoin/tree/sequencenumbers
>>
>> I request that the BIP editor please assign a BIP number for this work.
>>
>> Sincerely,
>> Mark Friedenbach
>>
>>
>> ------------------------------------------------------------------------------
>>
>> _______________________________________________
>> Bitcoin-development mailing list
>> Bitcoin-development@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>>
>>
>

--bcaec51dd84994c8610517813468
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div><div>You are correct! I am maintaining a &#39;checkse=
quenceverify&#39; branch in my git repository as well, an OP_RCLTV using se=
quence numbers:<br><br><a href=3D"https://github.com/maaku/bitcoin/tree/che=
cksequenceverify">https://github.com/maaku/bitcoin/tree/checksequenceverify=
</a><br><br></div>Most of the interesting use cases for relative lock-time =
require an RCLTV opcode. What is interesting about this architecture is tha=
t it possible to cleanly separate the relative lock-time (sequence numbers)=
 from the RCLTV opcode (OP_CHECKSEQUENCEVERIFY) both in concept and in impl=
ementation. Like CLTV, the CSV opcode only checks transaction data and requ=
ires no contextual knowledge about block headers, a weakness of the other R=
CLTV proposals that violate the clean separation between libscript and libc=
onsensus. In a similar way, this BIP proposal only touches the transaction =
validation logic without any impact to script.<br><br></div>I would like to=
 propose an additional BIP covering the CHECKSEQUENCEVERIFY opcode and its =
enabling applications. But, well, one thing at a time.<br></div><div class=
=3D"gmail_extra"><br><div class=3D"gmail_quote">On Mon, Jun 1, 2015 at 8:45=
 PM, Stephen Morse <span dir=3D"ltr">&lt;<a href=3D"mailto:stephencalebmors=
e@gmail.com" target=3D"_blank">stephencalebmorse@gmail.com</a>&gt;</span> w=
rote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;borde=
r-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr">Hi Mark,<br><br>Ov=
erall, I like this idea in every way except for one: unless I am missing so=
mething, we may still need an <font face=3D"monospace, monospace">OP_RCLTV<=
/font> even with this being implemented.=C2=A0<div><br></div><div>In use ca=
ses such as micropayment channels where the funds are locked up by multiple=
 parties, the enforcement of the relative locktime can be done by the first=
-signing party. So, while your solution would probably work in cases like t=
his, where multiple signing parties are involved, there may be other, seen =
or unforeseen, use cases that require putting the relative locktime right i=
nto the spending contract (the <font face=3D"monospace, monospace">scriptPu=
bKey</font> itself). When there is only one signer, there&#39;s nothing tha=
t enforces using an nSequence and nVersion=3D2 that would prevent spending =
the output until a certain time.=C2=A0</div><div><br></div><div>I hope this=
 is received as constructive criticism, I do think this is an innovative id=
ea. In my view, though, it seems to be less fully-featured than just repurp=
osing an <font face=3D"monospace, monospace">OP_NOP</font> to create <font =
face=3D"monospace, monospace">OP_RCLTV</font>. The benefits are obviously t=
hat it saves transaction space by repurposing unused space, and would likel=
y work for most cases where an <font face=3D"monospace, monospace">OP_RCLTV=
</font> would be needed.</div><div><br></div><div>Best,<br>Stephen</div></d=
iv><div class=3D"gmail_extra"><br><div class=3D"gmail_quote"><div><div clas=
s=3D"h5">On Mon, Jun 1, 2015 at 9:49 PM, Mark Friedenbach <span dir=3D"ltr"=
>&lt;<a href=3D"mailto:mark@friedenbach.org" target=3D"_blank">mark@frieden=
bach.org</a>&gt;</span> wrote:<br></div></div><blockquote class=3D"gmail_qu=
ote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex=
"><div><div class=3D"h5"><div dir=3D"ltr"><div>I have written a reference i=
mplementation and BIP draft for a soft-fork change to the consensus-enforce=
d behaviour of sequence numbers for the purpose of supporting transaction r=
eplacement via per-input relative lock-times. This proposal was previously =
discussed on the mailing list in the following thread:<br><br><a href=3D"ht=
tp://sourceforge.net/p/bitcoin/mailman/message/34146752/" target=3D"_blank"=
>http://sourceforge.net/p/bitcoin/mailman/message/34146752/</a><br><br></di=
v><div>In short summary, this proposal seeks to enable safe transaction rep=
lacement by re-purposing the nSequence field of a transaction input to be a=
 consensus-enforced relative lock-time.<br><br>The advantages of this appro=
ach is that it makes use of the full range of the 32-bit sequence number wh=
ich until now has rarely been used for anything other than a boolean contro=
l over absolute nLockTime, and it does so in a way that is semantically com=
patible with the originally envisioned use of sequence numbers for fast mem=
pool transaction replacement.<br><br></div><div>The disadvantages are that =
external constraints often prevent the full range of sequence numbers from =
being used when interpreted as a relative lock-time, and re-purposing nSequ=
ence as a relative lock-time precludes its use in other contexts. The latte=
r point has been partially addressed by having the relative lock-time seman=
tics be enforced only if the most-significant bit of nSequence is set. This=
 preserves 31 bits for alternative use when relative lock-times are not req=
uired.<br></div><div><br></div><div>The BIP draft can be found at the follo=
wing gist:<br><br><a href=3D"https://gist.github.com/maaku/be15629fe64618b1=
4f5a" target=3D"_blank">https://gist.github.com/maaku/be15629fe64618b14f5a<=
/a><br><br></div><div>The reference implementation is available at the foll=
owing git repository:<br></div><div><br><a href=3D"https://github.com/maaku=
/bitcoin/tree/sequencenumbers" target=3D"_blank">https://github.com/maaku/b=
itcoin/tree/sequencenumbers</a><br><br></div><div>I request that the BIP ed=
itor please assign a BIP number for this work.<br><br></div><div>Sincerely,=
<br></div><div>Mark Friedenbach<br></div></div>
<br></div></div>-----------------------------------------------------------=
-------------------<br>
<br>_______________________________________________<br>
Bitcoin-development mailing list<br>
<a href=3D"mailto:Bitcoin-development@lists.sourceforge.net" target=3D"_bla=
nk">Bitcoin-development@lists.sourceforge.net</a><br>
<a href=3D"https://lists.sourceforge.net/lists/listinfo/bitcoin-development=
" target=3D"_blank">https://lists.sourceforge.net/lists/listinfo/bitcoin-de=
velopment</a><br>
<br></blockquote></div><br></div>
</blockquote></div><br></div>

--bcaec51dd84994c8610517813468--