feat: remove hashOutpoint and update createOutput method to match BIP352

Signed-off-by: Anmol Sharma <anmolsharma0234@gmail.com>
Bitshala-Incubator · Mar 3, 2024 · 291c291 · 291c291
1 parent 04af65e
commit 291c291
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Showing 7 changed files with 382 additions and 361 deletions.
diff --git a/packages/core/src/outputs.ts b/packages/core/src/outputs.ts
@@ -1,24 +1,27 @@
 import { Outpoint, Output, PrivateKey, RecipientAddress } from './interface.ts';
 import {
     calculateSumOfPrivateKeys,
-    hashOutpoints,
+    createInputHash,
+    createTaggedHash,
     serialiseUint32,
 } from './utility.ts';
 import { decodeSilentPaymentAddress } from './encoding.ts';
 import secp256k1 from 'secp256k1';
-import createHash from 'create-hash';
 import { Buffer } from 'buffer';
 import { bitcoin } from 'bitcoinjs-lib/src/networks';
 import { Network } from 'bitcoinjs-lib';
 
 export const createOutputs = (
     inputPrivateKeys: PrivateKey[],
-    outpoints: Outpoint[],
+    smallestOutpoint: Outpoint,
     recipientAddresses: RecipientAddress[],
     network: Network = bitcoin,
 ): Output[] => {
     const sumOfPrivateKeys = calculateSumOfPrivateKeys(inputPrivateKeys);
-    const outpointHash = hashOutpoints(outpoints);
+    const inputHash = createInputHash(
+        Buffer.from(secp256k1.publicKeyCreate(sumOfPrivateKeys)),
+        smallestOutpoint,
+    );
 
     const paymentGroups = new Map<
         string,
@@ -43,15 +46,16 @@ export const createOutputs = (
     for (const [scanKeyHex, paymentGroup] of paymentGroups.entries()) {
         const scanKey = Buffer.from(scanKeyHex, 'hex');
         const ecdhSecret = secp256k1.publicKeyTweakMul(
-            secp256k1.publicKeyTweakMul(scanKey, outpointHash, true),
+            secp256k1.publicKeyTweakMul(scanKey, inputHash, true),
             sumOfPrivateKeys,
         );
 
         let n = 0;
         for (const { spendKey, amount } of paymentGroup) {
-            const tweak = createHash('sha256')
-                .update(Buffer.concat([ecdhSecret, serialiseUint32(n)]))
-                .digest();
+            const tweak = createTaggedHash(
+                'BIP0352/SharedSecret',
+                Buffer.concat([Buffer.from(ecdhSecret), serialiseUint32(n)]),
+            );
 
             const publicKey = secp256k1.publicKeyTweakAdd(
                 spendKey,

diff --git a/packages/core/src/utility.ts b/packages/core/src/utility.ts
@@ -3,21 +3,6 @@ import secp256k1 from 'secp256k1';
 import createHash from 'create-hash';
 import { Buffer } from 'buffer';
 
-export const hashOutpoints = (outpoints: Outpoint[]): Buffer => {
-    const outpointBuffer = Buffer.concat(
-        outpoints
-            .map((outpoint) =>
-                Buffer.concat([
-                    Buffer.from(outpoint.txid, 'hex').reverse(),
-                    serialiseUint32LE(outpoint.vout),
-                ]),
-            )
-            .sort((a, b) => a.compare(b)),
-    );
-
-    return createHash('sha256').update(outpointBuffer).digest();
-};
-
 export const createInputHash = (
     sumOfInputPublicKeys: Buffer,
     outpoint: Outpoint,