[Lightning-dev] Question: Invoice

[Rusty Russell]

Cezary Dziemian <cezary.dziemian at gmail.com> writes:
> Thank you very much for answers. It is honor that you answered and it is
> also very important for us in Poland. My friend is building Bitcoin ATMs
> and off-course plan to use LN. BTW: In Poland a lot of people believe that
> LN is the next big thing. We have huge pro-LN community and even have LN
> whitepaper translated to polish.
>
> So for 1.1 such scenario will not be possible?:
>
> We have such network with such payment channel opened:
>
>            Hub A
>           /           \
> Payer              Merchant
>           \           /
>            Hub B
>
> Hub A and Hub B belong to the same person, who will try to cheat us. Now
> Payer try to send payment through Hub A to Merchant. Hub A updates HTLC
> contract with Payer for this payment but never updates HTLC contract to
> Merchant so payment cannot be processed and is "pending". Because payer see
> that payment is pending, tries to make payment using Hub B based on the
> same invoice. After Marchant reveals secret number to Hub B, Hub A also can
> use it to steal funds from first pending payment.

Exactly.  This is why the payer's wallet will *refuse* to make two
payments to the same payment_hash (until one has failed).

You need to ask the merchant for another invoice for now.

Thanks!
Rusty.