refactor: compare GROUP_ORDER as buffer (instead of using BN.js)

Author: motorina0

src/taproot.js

@@ -13,12 +13,6 @@ const LEAF_VERSION_TAPSCRIPT = 0xc0;
 const TAP_LEAF_TAG = buffer_1.Buffer.from('TapLeaf', 'utf8');
 const TAP_BRANCH_TAG = buffer_1.Buffer.from('TapBranch', 'utf8');
 const TAP_TWEAK_TAG = buffer_1.Buffer.from('TapTweak', 'utf8');
-// todo: compare buffers dirrectly
-const GROUP_ORDER = buffer_1.Buffer.from(
-  'fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141',
-  'hex',
-);
-const GROUP_ORDER_BN = new BN(GROUP_ORDER);
 const EC_P_BN = new BN(types_1.EC_P);
 const EC_P_REDUCTION = BN.red(EC_P_BN);
 const EC_P_QUADRATIC_RESIDUE = EC_P_BN.addn(1).divn(4);
@@ -56,8 +50,7 @@ function tweakKey(pubKey, h) {
     TAP_TWEAK_TAG,
     buffer_1.Buffer.concat(h ? [pubKey, h] : [pubKey]),
   );
-  const t = new BN(tweakHash);
-  if (t.gte(GROUP_ORDER_BN)) {
+  if (tweakHash.compare(types_1.GROUP_ORDER) >= 0) {
     // todo: add test for this case
     throw new Error('Tweak value over the SECP256K1 Order');
   }

src/types.d.ts

@@ -3,6 +3,7 @@ import { Buffer as NBuffer } from 'buffer';
 export declare const typeforce: any;
 export declare const ZERO32: NBuffer;
 export declare const EC_P: NBuffer;
+export declare const GROUP_ORDER: NBuffer;
 export declare function isPoint(p: Buffer | number | undefined | null): boolean;
 export declare function UInt31(value: number): boolean;
 export declare function BIP32Path(value: string): boolean;

src/types.js

@@ -1,13 +1,17 @@
 'use strict';
 Object.defineProperty(exports, '__esModule', { value: true });
-exports.oneOf = exports.Null = exports.BufferN = exports.Function = exports.UInt32 = exports.UInt8 = exports.tuple = exports.maybe = exports.Hex = exports.Buffer = exports.String = exports.Boolean = exports.Array = exports.Number = exports.Hash256bit = exports.Hash160bit = exports.Buffer256bit = exports.TaprootNode = exports.TaprootLeaf = exports.Network = exports.ECPoint = exports.Satoshi = exports.Signer = exports.BIP32Path = exports.UInt31 = exports.isPoint = exports.EC_P = exports.ZERO32 = exports.typeforce = void 0;
+exports.oneOf = exports.Null = exports.BufferN = exports.Function = exports.UInt32 = exports.UInt8 = exports.tuple = exports.maybe = exports.Hex = exports.Buffer = exports.String = exports.Boolean = exports.Array = exports.Number = exports.Hash256bit = exports.Hash160bit = exports.Buffer256bit = exports.TaprootNode = exports.TaprootLeaf = exports.Network = exports.ECPoint = exports.Satoshi = exports.Signer = exports.BIP32Path = exports.UInt31 = exports.isPoint = exports.GROUP_ORDER = exports.EC_P = exports.ZERO32 = exports.typeforce = void 0;
 const buffer_1 = require('buffer');
 exports.typeforce = require('typeforce');
 exports.ZERO32 = buffer_1.Buffer.alloc(32, 0);
 exports.EC_P = buffer_1.Buffer.from(
   'fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f',
   'hex',
 );
+exports.GROUP_ORDER = buffer_1.Buffer.from(
+  'fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141',
+  'hex',
+);
 function isPoint(p) {
   if (!buffer_1.Buffer.isBuffer(p)) return false;
   if (p.length < 33) return false;

ts_src/taproot.ts

@@ -4,7 +4,7 @@ const BN = require('bn.js');
 import * as bcrypto from './crypto';
 // todo: use varuint-bitcoin??
 import * as varuint from 'bip174/src/lib/converter/varint';
-import { TweakedPublicKey, ZERO32, EC_P } from './types';
+import { TweakedPublicKey, ZERO32, EC_P, GROUP_ORDER } from './types';
 
 // todo: !!!Temp, to be replaced. Only works because bip32 has it as dependecy. Linting will fail.
 const ecc = require('tiny-secp256k1');
@@ -14,13 +14,6 @@ const TAP_LEAF_TAG = NBuffer.from('TapLeaf', 'utf8');
 const TAP_BRANCH_TAG = NBuffer.from('TapBranch', 'utf8');
 const TAP_TWEAK_TAG = NBuffer.from('TapTweak', 'utf8');
 
-// todo: compare buffers dirrectly
-const GROUP_ORDER = NBuffer.from(
-  'fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141',
-  'hex',
-);
-const GROUP_ORDER_BN = new BN(GROUP_ORDER);
-
 const EC_P_BN = new BN(EC_P);
 const EC_P_REDUCTION = BN.red(EC_P_BN);
 const EC_P_QUADRATIC_RESIDUE = EC_P_BN.addn(1).divn(4);
@@ -69,8 +62,8 @@ export function tweakKey(
     TAP_TWEAK_TAG,
     NBuffer.concat(h ? [pubKey, h] : [pubKey]),
   );
-  const t = new BN(tweakHash);
-  if (t.gte(GROUP_ORDER_BN)) {
+
+  if (tweakHash.compare(GROUP_ORDER) >= 0) {
     // todo: add test for this case
     throw new Error('Tweak value over the SECP256K1 Order');
   }

ts_src/types.ts

@@ -7,6 +7,10 @@ export const EC_P = NBuffer.from(
   'fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f',
   'hex',
 );
+export const GROUP_ORDER = NBuffer.from(
+  'fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141',
+  'hex',
+);
 
 export function isPoint(p: Buffer | number | undefined | null): boolean {
   if (!NBuffer.isBuffer(p)) return false;