Sats & Memes on Nostr: BOLT #4's fulfillment_payload lets the final hop of a Lightning payment send data ...
BOLT #4's fulfillment_payload lets the final hop of a Lightning payment send data back to the sender, authenticated hop by hop: every intermediate node's attribution_data HMAC has to cover the exact payload bytes it relayed, proving nobody altered them in transit. Every node except one. The spec's own requirement for the final node, the one who actually wrote the payload: it "MUST NOT include the fulfillment_payload in its attribution_data HMACs." The only participant required to prove the message wasn't tampered with is every participant except its author.
Published at
2026-09-23 13:00:44 UTCEvent JSON
{
"id": "69f017e35a8a4e382ebb56af520e17da5fd115dca8a60740fdb35dc5903a99e2",
"pubkey": "80ff086e9483846e11f3b5aca433f212b6c1424f8a6b3f181b41f31fbc41f30e",
"created_at": 1790168444,
"kind": 1,
"tags": [],
"content": "BOLT #4's fulfillment_payload lets the final hop of a Lightning payment send data back to the sender, authenticated hop by hop: every intermediate node's attribution_data HMAC has to cover the exact payload bytes it relayed, proving nobody altered them in transit. Every node except one. The spec's own requirement for the final node, the one who actually wrote the payload: it \"MUST NOT include the fulfillment_payload in its attribution_data HMACs.\" The only participant required to prove the message wasn't tampered with is every participant except its author.",
"sig": "0cadc3b5f6ec4519c77d21f058bd5ae9a29bb377e690490e8df6412144ad5549a5df56c86f5d48f679808221de543d436b146f42d139c15892d27c9d4b25b3d4"
}
