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Date: Thu, 18 Jul 2013 07:13:53 -0400
From: Peter Todd <pete@petertodd.org>
To: Jeremy Spilman <jeremy.spilman@gmail.com>
Message-ID: <20130718111353.GA11385@savin>
References: <CA+CODZEQX_xiaJE7WtFZC2qfVfDqZAgg-ydU5Q73O-QTkXJpPw@mail.gmail.com>
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Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] Anti DoS for tx replacement
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On Fri, Apr 19, 2013 at 06:48:11PM -0700, Jeremy Spilman wrote:
>  0. User and AP negotiate how much to escrow, who pays the fees, and how
> far in the future nLockTime will be set (how long user=E2=80=99s funds wi=
ll be tied
> if AP doesn=E2=80=99t close the channel)
>=20
>  1. User creates an unsigned TX1 with 1 or more inputs from user=E2=80=99s
> =E2=80=98listunspent=E2=80=99, change going back to user (if any), and a =
single output of
> =E2=80=98FundAmount=E2=80=99 with scriptPubKey of =E2=80=982 PK1 OP_0 CHE=
CKMULTISIG=E2=80=99, and sends to
> the AP

Note that with OP_DEPTH we can remove the small chance of the payee
vanishing and putting the funds in limbo:

    <height + n> OP_DEPTH OP_LESSTHAN
    IF 2 PK1 PK2 CHECKMULTISIG
    ELSE PK1 CHECKSIG
    ENDIF

Though that shows how to implement OP_DEPTH as a true soft-fork we're
probably best off doing it as part of a script v2 using the soft-fork
mechanism I outlined before when talking about fidelity-bonded ledgers.
(best to do MAST (merklized abstract syntax tree) support at the same
time)

--=20
'peter'[:-1]@petertodd.org

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