50735d1718
A trade proof of ['proof','zap','<receiptId>'] is now checked by verifyZapReceipt (kind-9735 signature + p = seller + decodable bolt11 amount + embedded 9734 request) and counted as paymentVerified, shown on TradeReputationCard as 'payment-verified (zap receipt)' - a real tier above the self-reported claim. Honest ceiling: proves the seller's LNURL provider acknowledged a payment, not that goods changed hands. NIP.md documents the zap proof variant.
66 lines
2.7 KiB
TypeScript
66 lines
2.7 KiB
TypeScript
/**
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* Verifying a payment claim that CAN be checked: a **NIP-57 zap receipt**.
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*
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* A `31871` may carry `["proof","zap","<receiptId>"]`. A zap receipt (kind 9735)
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* is signed by the recipient's **LNURL server** after it received the payment,
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* so — unlike a hand-typed invoice hash — it is independently checkable by
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* anyone: we fetch the receipt, verify its signature, that it pays the expected
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* seller, and what it paid.
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*
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* ⚠️ Honest ceiling: the receipt is only as trustworthy as the seller's own
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* LNURL provider. It proves *that provider* acknowledged a payment to that
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* seller — not that goods changed hands. Still, it is a real cryptographic
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* signal, a tier above a free-text claim.
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*/
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import { verifyEvent } from 'nostr-tools';
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import type { NostrEvent } from '@nostrify/nostrify';
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import { getSatoshisFromBolt11 } from '@/lib/bolt11';
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export interface ZapReceiptCheck {
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valid: boolean;
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sats: number;
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reason?: string;
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}
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/**
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* Verify a kind-9735 zap receipt pays `expectedRecipient`.
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* Never throws — returns `{ valid: false, reason }` on any problem.
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*/
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export function verifyZapReceipt(receipt: NostrEvent, expectedRecipient: string): ZapReceiptCheck {
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if (receipt.kind !== 9735) return { valid: false, sats: 0, reason: 'not a zap receipt' };
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if (!verifyEvent(receipt)) return { valid: false, sats: 0, reason: 'bad receipt signature' };
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const recipient = receipt.tags.find(([n]) => n === 'p')?.[1];
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if (recipient !== expectedRecipient) return { valid: false, sats: 0, reason: 'recipient mismatch' };
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const bolt11 = receipt.tags.find(([n]) => n === 'bolt11')?.[1];
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if (!bolt11) return { valid: false, sats: 0, reason: 'missing invoice' };
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let sats = 0;
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try {
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sats = getSatoshisFromBolt11(bolt11);
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} catch {
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return { valid: false, sats: 0, reason: 'undecodable invoice' };
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}
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if (!Number.isFinite(sats) || sats <= 0) return { valid: false, sats: 0, reason: 'no amount' };
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// The embedded `description` is the original zap request (kind 9734); when
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// present it must also name the same recipient.
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const description = receipt.tags.find(([n]) => n === 'description')?.[1];
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if (description) {
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try {
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const request = JSON.parse(description) as NostrEvent;
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if (request.kind && request.kind !== 9734) {
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return { valid: false, sats, reason: 'description is not a zap request' };
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}
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const requestRecipient = request.tags?.find(([n]) => n === 'p')?.[1];
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if (requestRecipient && requestRecipient !== expectedRecipient) {
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return { valid: false, sats, reason: 'zap request recipient mismatch' };
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}
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} catch {
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return { valid: false, sats, reason: 'unparsable description' };
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}
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}
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return { valid: true, sats };
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}
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