[Lightning-dev] AMP: Atomic Multi-Path Payments over Lightning

[Christian Decker]

CJP <cjp at ultimatestunts.nl> writes:
> Can you give a use case for this?
>
> Usually, especially in the common case that a payment is done in
> exchange for some non-cryptographic asset (e.g. physical goods), there
> already is some kind of trust between payer and payee. So, if a payment
> is split non-atomically into smaller transactions, and only a part
> succeeds, presumably they can cooperatively figure out some way to
> settle the situation.

The scenario that is commonly used in these cases is a merchant that
provides a signed invoice "if you pay me X with payment_hash Y I will
deliver Z". Now the user performs the payment, learns the payment_key
matching the payment_hash, but the merchant refuses to deliver, claiming
it didn't get the payment. Now the user can go to a court, present the
invoice signed by the merchant, and the proof-of-payment, and force the
merchant to honor its commitment.