Definition
Atomic Multipath Payments (AMP) extend the idea of splitting a Lightning payment across many routes, but add a cryptographic guarantee that either every shard settles or none does. Where ordinary Multipath Payments reuse one payment hash across all shards, AMP derives a distinct hash for each shard from a shared secret, so the receiver can only reconstruct the final preimage once enough shards have arrived. This closes the partial-settlement gap that plain multipath leaves open.
How atomicity is enforced
The sender splits a base secret into shares, one per shard, and commits to each share inside its own conditional contract. The receiver cannot redeem any single shard in isolation; it must combine the shares to compute the preimage that unlocks the whole payment. Because each shard uses a different hash, the shards are also harder to correlate on the network, giving a modest privacy improvement over reused-hash multipath.
Spontaneous and reusable payments
AMP also enables spontaneous payments without a pre-issued invoice and supports paying the same static identifier more than once, which classic single-use invoices forbid. This makes AMP useful for donations, recurring transfers, and pooled payouts where the sender should not need a fresh invoice each time.
For sovereign node operators, AMP delivers the resilience of multipath routing with stronger settlement safety, building on the conditional-payment logic in our HTLC entry and the invoice format described under BOLT11.
In Simple Terms
Atomic Multipath Payments (AMP) extend the idea of splitting a Lightning payment across many routes, but add a cryptographic guarantee that either every shard settles…