From rusty at rustcorp.com.au  Wed Aug 17 10:23:03 2016
From: rusty at rustcorp.com.au (Rusty Russell)
Date: Wed, 17 Aug 2016 19:53:03 +0930
Subject: [Lightning-dev] [BOLT Draft] Onion Routing Spec
In-Reply-To: <20160815120647.GA2595@nex>
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Message-ID: <87h9ajae48.fsf@rustcorp.com.au>

Christian Decker <decker.christian at gmail.com> writes:
> I agree that the realm byte is a sensible addition. To trigger this we
> would need to have multiple channels, on different chains, using the
> same identifiers between two nodes. Only in this case we'd have an
> ambiguity where to transfer the funds. Assuming we have the route A ->
> B => C, where => indicates two channels, one in litecoin and one in
> bitcoin, and both channels use the same identity for C. Then the
> instruction to forward 0.01 units to C is ambiguous, as it could be
> denominated in either litecoin or bitcoin.
>
> While not dangerous it is rather unfortunate as it results in
> guesswork. It is not dangerous because if A transferred litecoin to B
> then B will (hopefully) never forward a higher value to C using
> bitcoin, and if it were bitcoin then the final recipient would not
> sign off an inferior amount than what he expected.

Worse case: C is a charity, accepting donations.  A's software screwed
up and didn't realize C was litecoin, not bitcoin.  B collects a huge
fee, C gets tiny donation.

Cheers,
Rusty.