From decker.christian at gmail.com Mon Feb 12 09:23:22 2018 From: decker.christian at gmail.com (Christian Decker) Date: Mon, 12 Feb 2018 10:23:22 +0100 Subject: [Lightning-dev] AMP: Atomic Multi-Path Payments over Lightning In-Reply-To: <1518171320.5145.0.camel@ultimatestunts.nl> References: <1518171320.5145.0.camel@ultimatestunts.nl> Message-ID: <87h8qmwohh.fsf@gmail.com> CJP 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.