Message-ID: <55998AA3.4060801@thinlink.com>
Date: Sun, 05 Jul 2015 12:50:59 -0700
From: Tom Harding <tomh@thinlink.com>
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To: Mark Friedenbach <mark@friedenbach.org>
References: <55994696.1090705@thinlink.com>
	<CAOG=w-t+VCk66mM1N1Pc4PN2T9=X94hhyg_Pc+2_ULT51JfxCA@mail.gmail.com>
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Cc: bitcoin-dev@lists.linuxfoundation.org
Subject: Re: [bitcoin-dev] BIP 68 (Relative Locktime) bug
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Or you could flip the definition of your activation bit.  That would
avoid the inversion and put relative locktimes outside the realm of both
the MAX_INT and MAX_INT - 1 values.

It would also allow an explicit relative locktime of 0, which would help
applications avoid accidentally finalizing the whole transaction when
they only meant to not impose a relative locktime on one input.


On 7/5/2015 10:07 AM, Mark Friedenbach wrote:
> Note that you can put 0 in the sequence number field and it would work
> just as expected under the old rules. I will perhaps suggest instead
> that Bitcoin Core post-0.11 switch to doing this instead for that case.
>
> On Sun, Jul 5, 2015 at 8:00 AM, Tom Harding <tomh@thinlink.com
> <mailto:tomh@thinlink.com>> wrote:
>
>     BIP 68 uses nSequence to specify relative locktime, but nSequence also
>     continues to condition the transaction-level locktime.
>
>     This dual effect will prevent a transaction from having an effective
>     nLocktime without also requiring at least one of its inputs to be
>     mined
>     at least one block (or one second) ahead of its parent.
>
>     The fix is to shift the semantics so that nSequence = MAX_INT - 1
>     specifies 0 relative locktime, rather than 1.  This change will also
>     preserve the semantics of transactions that have already been created
>     with the specific nSequence value MAX_INT - 1 (for example all
>     transactions created by the bitcoin core wallet starting in 0.11).
>
>
>     _______________________________________________
>     bitcoin-dev mailing list
>     bitcoin-dev@lists.linuxfoundation.org
>     <mailto:bitcoin-dev@lists.linuxfoundation.org>
>     https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>


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    Or you could flip the definition of your activation bit.  That would
    avoid the inversion and put relative locktimes outside the realm of
    both the MAX_INT and MAX_INT - 1 values.<br>
    <br>
    It would also allow an explicit relative locktime of 0, which would
    help applications avoid accidentally finalizing the whole
    transaction when they only meant to not impose a relative locktime
    on one input.<br>
    <br>
    <br>
    <div class="moz-cite-prefix">On 7/5/2015 10:07 AM, Mark Friedenbach
      wrote:<br>
    </div>
    <blockquote
cite="mid:CAOG=w-t+VCk66mM1N1Pc4PN2T9=X94hhyg_Pc+2_ULT51JfxCA@mail.gmail.com"
      type="cite">
      <div dir="ltr">Note that you can put 0 in the sequence number
        field and it would work just as expected under the old rules. I
        will perhaps suggest instead that Bitcoin Core post-0.11 switch
        to doing this instead for that case.<br>
      </div>
      <div class="gmail_extra"><br>
        <div class="gmail_quote">On Sun, Jul 5, 2015 at 8:00 AM, Tom
          Harding <span dir="ltr">&lt;<a moz-do-not-send="true"
              href="mailto:tomh@thinlink.com" target="_blank">tomh@thinlink.com</a>&gt;</span>
          wrote:<br>
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">BIP 68
            uses nSequence to specify relative locktime, but nSequence
            also<br>
            continues to condition the transaction-level locktime.<br>
            <br>
            This dual effect will prevent a transaction from having an
            effective<br>
            nLocktime without also requiring at least one of its inputs
            to be mined<br>
            at least one block (or one second) ahead of its parent.<br>
            <br>
            The fix is to shift the semantics so that nSequence =
            MAX_INT - 1<br>
            specifies 0 relative locktime, rather than 1.  This change
            will also<br>
            preserve the semantics of transactions that have already
            been created<br>
            with the specific nSequence value MAX_INT - 1 (for example
            all<br>
            transactions created by the bitcoin core wallet starting in
            0.11).<br>
            <br>
            <br>
            _______________________________________________<br>
            bitcoin-dev mailing list<br>
            <a moz-do-not-send="true"
              href="mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.linuxfoundation.org</a><br>
            <a moz-do-not-send="true"
              href="https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev"
              rel="noreferrer" target="_blank">https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev</a><br>
          </blockquote>
        </div>
        <br>
      </div>
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