feat: export default tapscript version

Issue: BG-54756

Author: reardencode

src/taproot.d.ts

@@ -5,6 +5,7 @@ import { TinySecp256k1Interface, XOnlyPointAddTweakResult } from './types';
  * on all 32 byte x-only pub keys as defined in BIP340.
  */
 export declare const EVEN_Y_COORD_PREFIX: Buffer;
+export declare const INITIAL_TAPSCRIPT_VERSION = 192;
 /**
  * Aggregates a list of public keys into a single MuSig2* public key
  * according to the MuSig2 paper.
@@ -24,7 +25,7 @@ export declare function serializeScriptSize(script: Buffer): Buffer;
  * @param script
  * @returns
  */
-export declare function hashTapLeaf(script: Buffer): Buffer;
+export declare function hashTapLeaf(script: Buffer, leafVersion?: number): Buffer;
 /**
  * Creates a lexicographically sorted tapbranch from two child taptree nodes
  * and returns its tagged hash.
@@ -62,7 +63,7 @@ export interface Taptree {
  * @returns {Taptree} the tree, represented by its root hash, and the paths to that root from each of the input scripts
  */
 export declare function getHuffmanTaptree(scripts: Buffer[], weights: Array<number | undefined>): Taptree;
-export declare function getControlBlock(parity: 0 | 1, pubkey: Uint8Array, path: Buffer[]): Buffer;
+export declare function getControlBlock(parity: 0 | 1, pubkey: Uint8Array, path: Buffer[], leafVersion?: number): Buffer;
 export interface KeyPathWitness {
     spendType: 'Key';
     signature: Buffer;

src/taproot.js

@@ -3,7 +3,7 @@
 // https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki
 // https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki
 Object.defineProperty(exports, '__esModule', { value: true });
-exports.getTaptreeRoot = exports.getTapleafHash = exports.parseControlBlock = exports.parseTaprootWitness = exports.getControlBlock = exports.getHuffmanTaptree = exports.tapTweakPubkey = exports.tapTweakPrivkey = exports.hashTapBranch = exports.hashTapLeaf = exports.serializeScriptSize = exports.aggregateMuSigPubkeys = exports.EVEN_Y_COORD_PREFIX = void 0;
+exports.getTaptreeRoot = exports.getTapleafHash = exports.parseControlBlock = exports.parseTaprootWitness = exports.getControlBlock = exports.getHuffmanTaptree = exports.tapTweakPubkey = exports.tapTweakPrivkey = exports.hashTapBranch = exports.hashTapLeaf = exports.serializeScriptSize = exports.aggregateMuSigPubkeys = exports.INITIAL_TAPSCRIPT_VERSION = exports.EVEN_Y_COORD_PREFIX = void 0;
 const assert = require('assert');
 const FastPriorityQueue = require('fastpriorityqueue');
 const bcrypto = require('./crypto');
@@ -14,7 +14,7 @@ const varuint = require('varuint-bitcoin');
  * on all 32 byte x-only pub keys as defined in BIP340.
  */
 exports.EVEN_Y_COORD_PREFIX = Buffer.of(0x02);
-const INITIAL_TAPSCRIPT_VERSION = Buffer.of(0xc0);
+exports.INITIAL_TAPSCRIPT_VERSION = 0xc0;
 /**
  * Aggregates a list of public keys into a single MuSig2* public key
  * according to the MuSig2 paper.
@@ -82,11 +82,11 @@ exports.serializeScriptSize = serializeScriptSize;
  * @param script
  * @returns
  */
-function hashTapLeaf(script) {
+function hashTapLeaf(script, leafVersion = exports.INITIAL_TAPSCRIPT_VERSION) {
   const size = serializeScriptSize(script);
   return bcrypto.taggedHash(
     'TapLeaf',
-    Buffer.concat([INITIAL_TAPSCRIPT_VERSION, size, script]),
+    Buffer.concat([Buffer.of(leafVersion), size, script]),
   );
 }
 exports.hashTapLeaf = hashTapLeaf;
@@ -217,8 +217,13 @@ function getHuffmanTaptree(scripts, weights) {
   return { root: rootNode.taggedHash, paths };
 }
 exports.getHuffmanTaptree = getHuffmanTaptree;
-function getControlBlock(parity, pubkey, path) {
-  const parityVersion = INITIAL_TAPSCRIPT_VERSION[0] + parity;
+function getControlBlock(
+  parity,
+  pubkey,
+  path,
+  leafVersion = exports.INITIAL_TAPSCRIPT_VERSION,
+) {
+  const parityVersion = leafVersion + parity;
   return Buffer.concat([Buffer.of(parityVersion), pubkey, ...path]);
 }
 exports.getControlBlock = getControlBlock;

ts_src/taproot.ts

@@ -14,7 +14,7 @@ const varuint = require('varuint-bitcoin');
  * on all 32 byte x-only pub keys as defined in BIP340.
  */
 export const EVEN_Y_COORD_PREFIX = Buffer.of(0x02);
-const INITIAL_TAPSCRIPT_VERSION = Buffer.of(0xc0);
+export const INITIAL_TAPSCRIPT_VERSION = 0xc0;
 
 /**
  * Aggregates a list of public keys into a single MuSig2* public key
@@ -95,11 +95,11 @@ export function serializeScriptSize(script: Buffer): Buffer {
  * @param script
  * @returns
  */
-export function hashTapLeaf(script: Buffer): Buffer {
+export function hashTapLeaf(script: Buffer, leafVersion = INITIAL_TAPSCRIPT_VERSION): Buffer {
   const size = serializeScriptSize(script);
   return bcrypto.taggedHash(
     'TapLeaf',
-    Buffer.concat([INITIAL_TAPSCRIPT_VERSION, size, script]),
+    Buffer.concat([Buffer.of(leafVersion), size, script]),
   );
 }
 
@@ -275,8 +275,9 @@ export function getControlBlock(
   parity: 0 | 1,
   pubkey: Uint8Array,
   path: Buffer[],
+  leafVersion = INITIAL_TAPSCRIPT_VERSION,
 ): Buffer {
-  const parityVersion = INITIAL_TAPSCRIPT_VERSION[0] + parity;
+  const parityVersion = leafVersion + parity;
 
   return Buffer.concat([Buffer.of(parityVersion), pubkey, ...path]);
 }