From bitcoin-dev at rgrant.org  Sun Sep 11 03:16:02 2016
From: bitcoin-dev at rgrant.org (Ryan Grant)
Date: Sat, 10 Sep 2016 22:16:02 -0500
Subject: [Lightning-dev] Payment presentation strawmen.
In-Reply-To: <20160910213612.GA15435@nex>
References: <87shtd7syz.fsf@rustcorp.com.au>
	<CAMnpzfoeJnFYQHgGUgH2Eg+8bDYqz-CCo=CoR0UCEqmf_SMLRQ@mail.gmail.com>
	<20160910213612.GA15435@nex>
Message-ID: <CAMnpzfr3P0PSaFRL=J543ExDGNvZH9FHhhWkFMm_f1pjHurFPA@mail.gmail.com>

On Sat, Sep 10, 2016 at 4:36 PM, Christian Decker
<decker.christian at gmail.com> wrote:
> At least for the implementation using the r-hash to condition the
> release of funds there is nothing special about splitting a
> payment. As long as the recipient knows the total amount it should be
> receiving it can delay the release of the secret until it is
> guaranteed all funds. Collating the partial payments is done with the
> r-hash. I'm pretty sure that the private key release would also work
> the same way.

I understand how to collect partial payments on one channel this way, but
my reading was that the same r-hash cannot be used safely across
multiple channels.  Once one channel completes, exposure of the r-hash
to a colluding intermediary in the other channel could allow pulling
funds before sending them onward.