Also covering AMP
Atomic Multipath Payments (AMPs), sometimes called Original AMP or OG AMP, allow a spender to pay multiple hashes all derived from the same preimage—a preimage the receiver can only reconstruct if they receive a sufficient number of shares.
Unlike Simplified Multipath Payments (SMP), this only allows the receiver to accept a payment if they receive all of the individual parts. Each share using a different hash adds privacy by preventing the separate payments from being automatically correlated with each other by a third party. The proposal’s downside is that the spender selects all the preimages, so knowledge of the preimage doesn’t provide cryptographic proof that they actually paid the receiver.
Both AMP and SMP allow splitting higher value HTLCs into multiple lower value HTLCs that are more likely to individually succeed, so a spender with sufficient liquidity can use almost all of their funds at once no matter how many channels those funds are split across.
Primary code and documentation
Optech newsletter and website mentions
- 2021 year-in-review: atomic multipath payments
- LND 0.14.0-beta allows multiple spontaneous payments to the same AMP invoice
- LND #5803 allows multiple spontaneous payments to the same AMP invoice
- LND 0.13.0-beta allows receiving and sending payments using AMP
- LND #5336 adds the ability for users to reuse AMP invoices non-interactively
- LND #5253 adds support for Atomic Multipath Payment (AMP) invoices
- LND #5159 adds support for making spontaneous AMPs
- LND #5108 adds support for spontaneous multipath payments using AMP