fix(p2sp): Function signature and output fixes

Some outputs wernt matching what we expected them to be.

Author: jvgelder

src/esm/payments/p2sp.js

@@ -71,10 +71,9 @@ export const findSmallestOutpoint = inputs =>
  */
 export const serOutpointLE = (txidHexBE, vout) => {
   const out = new Uint8Array(36);
-  const txidLE = tools.fromHex(txidHexBE);
-  if (txidLE.length !== 32) throw new Error('txid must be 32 bytes');
-  txidLE.reverse(); // BE -> LE
-  out.set(txidLE, 0);
+  if (txidHexBE.length !== 32) throw new Error('txid must be 32 bytes');
+  txidHexBE.reverse(); // BE -> LE
+  out.set(txidHexBE, 0);
   writeUInt32(out, 32, vout >>> 0, 'le');
   return out;
 };
@@ -273,8 +272,7 @@ export function calculateSharedSecret(
     throw new Error('summedSenderPrivkey was not provided?');
   const Si = ecc.pointMultiply(scanPubkey, inputHash, true);
   if (!Si) throw new Error('pointMultiply(B_scan, ih) failed');
-  let S;
-  S = ecc.pointMultiply(Si, summedSenderPrivkey, true);
+  const S = ecc.pointMultiply(Si, summedSenderPrivkey, true);
   if (!S) throw new Error('pointMultiply(Si, summedSenderPrivkey) failed');
   else return S;
 }
@@ -287,8 +285,7 @@ export function calculateSharedSecret(
  * @returns input_hash tweak
  */
 export function calculateT_k(S, k) {
-  if (!S) return null;
-  let t_k = taggedHash('BIP0352/SharedSecret', tools.concat([S, ser32BE(k)]));
+  const t_k = taggedHash('BIP0352/SharedSecret', tools.concat([S, ser32BE(k)]));
   return hashToTweak(t_k);
 }
 /**
@@ -313,6 +310,7 @@ export function calculateP_k(spendPubKey, t_k) {
 export function deriveOutput(S, spendPubkey, k) {
   // t_k = H_tag(SharedSecret, ser_P(S) || ser32BE(k))  -> reduce mod n
   const t_k = calculateT_k(S, k);
+  if (!t_k) throw new Error('t_k: failed');
   // P_k = B_spend + t_k·G (compressed) -> x-only for P2TR
   const P_k = calculateP_k(spendPubkey, t_k);
   const P_xOnly = toXOnly(P_k);
@@ -355,7 +353,6 @@ export function generateLabelAndAddress(B_scan, B_spend, label) {
  * Scans a transaction's inputs and outputs to find any silent payments for the receiver.
  * @param receiverScanPrivkey - b_scan
  * @param receiverSpendPrivkey - b_spend
- * @param smallestOutpoint
  * @param inputHashTweak
  * @param summedSenderPubkey - A_sum
  * @param outputsToCheck - array of hex xOnly encoded outputs to check
@@ -364,7 +361,6 @@ export function generateLabelAndAddress(B_scan, B_spend, label) {
 export function scanForSilentPayments(
   receiverScanPrivkey,
   receiverSpendPrivkey,
-  smallestOutpoint,
   inputHashTweak,
   summedSenderPubkey,
   outputsToCheck,

test/integration/silentpayment.spec.ts

@@ -14,7 +14,6 @@ import {
   encodeSilentPaymentAddress,
   findSmallestOutpoint,
   modN32,
-  generateLabelAndAddress,
   scanForSilentPayments,
 } from '../../ts_src/payments/p2sp.js';
 import { Input } from '../../ts_src/transaction.js';
@@ -35,7 +34,7 @@ interface TestInput {
   txinwitness: string;
   prevout: {
     scriptPubKey: {
-      hex: String;
+      hex: string;
     };
   };
   private_key?: string;
@@ -82,7 +81,7 @@ interface Recipient {
 interface RecipientOutput {
   priv_key_tweak: string;
   pub_key: string;
-  signature: String;
+  signature: string;
 }
 
 // ================================================================
@@ -315,7 +314,7 @@ function runSenderCase(tc: Sender) {
 
   // -------- 2) a_sum with Taproot-only odd-Y conditional negation --------
   // 2) a_sum = Σ negated (mod n) via tiny-secp
-  let aSum: Uint8Array = calculateSumA(inputPrivKeyTuples);
+  const aSum: Uint8Array = calculateSumA(inputPrivKeyTuples);
 
   // (optional) fixture check stays the same
   if (expected.input_private_key_sum) {
@@ -446,7 +445,6 @@ function runReceiverCase(tc: Recipient) {
   const foundScanned = scanForSilentPayments(
     b_scan,
     b_spend,
-    outpointL,
     inputHashTweak,
     A_sum_point,
     outputsToCheck,

ts_src/payments/p2sp.ts

@@ -8,7 +8,6 @@ import { bech32m } from 'bech32';
 // Explicitly import the Payment type for clarity
 import { Payment, PaymentOpts } from './index';
 import * as lazy from './lazy';
-import * as payments from './index.ts';
 import { taggedHash } from '../crypto';
 import { Input } from '../transaction';
 
@@ -90,12 +89,11 @@ export const findSmallestOutpoint = (inputs: Array<Input>) =>
  * @param vout - output index
  * @returns the serialized little endian encoded output
  */
-export const serOutpointLE = (txidHexBE: string, vout: number) => {
+export const serOutpointLE = (txidHexBE: Uint8Array, vout: number) => {
   const out = new Uint8Array(36);
-  const txidLE = tools.fromHex(txidHexBE);
-  if (txidLE.length !== 32) throw new Error('txid must be 32 bytes');
-  txidLE.reverse(); // BE -> LE
-  out.set(txidLE, 0);
+  if (txidHexBE.length !== 32) throw new Error('txid must be 32 bytes');
+  txidHexBE.reverse(); // BE -> LE
+  out.set(txidHexBE, 0);
   writeUInt32(out, 32, vout >>> 0, 'le');
   return out;
 };
@@ -395,9 +393,10 @@ export function deriveOutput(
   S: Uint8Array,
   spendPubkey: Uint8Array,
   k: number,
-): { pub_key: Uint8Array; tweak_key } {
+): { pub_key: Uint8Array; tweak_key: Uint8Array } {
   // t_k = H_tag(SharedSecret, ser_P(S) || ser32BE(k))  -> reduce mod n
   const t_k: Uint8Array<ArrayBufferLike> | null = calculateT_k(S, k);
+  if (!t_k) throw new Error('t_k: failed');
 
   // P_k = B_spend + t_k·G (compressed) -> x-only for P2TR
   const P_k: Uint8Array<ArrayBufferLike> = calculateP_k(spendPubkey, t_k);
@@ -453,7 +452,6 @@ export function generateLabelAndAddress(
  * Scans a transaction's inputs and outputs to find any silent payments for the receiver.
  * @param receiverScanPrivkey - b_scan
  * @param receiverSpendPrivkey - b_spend
- * @param smallestOutpoint
  * @param inputHashTweak
  * @param summedSenderPubkey - A_sum
  * @param outputsToCheck - array of hex xOnly encoded outputs to check
@@ -462,20 +460,19 @@ export function generateLabelAndAddress(
 export function scanForSilentPayments(
   receiverScanPrivkey: Uint8Array,
   receiverSpendPrivkey: Uint8Array,
-  smallestOutpoint: Uint8Array,
   inputHashTweak: Uint8Array,
   summedSenderPubkey: Uint8Array,
   outputsToCheck: Set<string>,
-  labelNonces: Array<Uint8Array> = Array.from([]),
+  labelNonces: Array<number> = Array.from([]),
 ): {
   priv_key_tweak: Uint8Array;
   pub_key: Uint8Array;
-  labelNonce?: Uint8Array;
+  labelNonce?: number;
 }[] {
   let foundPayments: {
     priv_key_tweak: Uint8Array;
     pub_key: Uint8Array;
-    labelNonce?: Uint8Array;
+    labelNonce?: number;
   }[] = [];
 
   // G
@@ -529,7 +526,7 @@ function performScan(
   outputsToCheck: Set<string>,
   labelScalar: Uint8Array | null, // L (or null for base)
 ): { priv_key_tweak: Uint8Array; pub_key: Uint8Array }[] {
-  const found: { payment: Payment; t: Uint8Array; P_xonly: Uint8Array }[] = [];
+  const found: { priv_key_tweak: Uint8Array; pub_key: Uint8Array }[] = [];
 
   for (let k = 0; k < outputsToCheck.size; k++) {
     const derivedOutput = deriveOutput(S, receiverSpendPubkey, k);