From 5175e9813f3875436236bcf45fdf27ad5cd09740 Mon Sep 17 00:00:00 2001
From: Paul Miller <paul@paulmillr.com>
Date: Wed, 15 Jun 2022 14:31:45 +0400
Subject: [PATCH 1/2] Small refactor: compat, scrypt

---
 src/scrypt.ts           |  8 ++++----
 src/secp256k1-compat.ts | 34 +++++++++++++++-------------------
 2 files changed, 19 insertions(+), 23 deletions(-)

diff --git a/src/scrypt.ts b/src/scrypt.ts
index 9049fbb..484797d 100644
--- a/src/scrypt.ts
+++ b/src/scrypt.ts
@@ -10,11 +10,11 @@ export async function scrypt(
   n: number,
   p: number,
   r: number,
-  dklen: number
+  dkLen: number
 ): Promise<Uint8Array> {
   assertBytes(password);
   assertBytes(salt);
-  return _scryptAsync(password, salt, { N: n, r, p, dkLen: dklen });
+  return _scryptAsync(password, salt, { N: n, r, p, dkLen });
 }
 
 export function scryptSync(
@@ -23,9 +23,9 @@ export function scryptSync(
   n: number,
   p: number,
   r: number,
-  dklen: number
+  dkLen: number
 ): Uint8Array {
   assertBytes(password);
   assertBytes(salt);
-  return _scrypt(password, salt, { N: n, r, p, dkLen: dklen });
+  return _scrypt(password, salt, { N: n, r, p, dkLen });
 }
diff --git a/src/secp256k1-compat.ts b/src/secp256k1-compat.ts
index d01bd34..8704bbf 100644
--- a/src/secp256k1-compat.ts
+++ b/src/secp256k1-compat.ts
@@ -5,12 +5,6 @@ import { assertBool, assertBytes, hexToBytes, toHex } from "./utils";
 // Use `secp256k1` module directly.
 // This is a legacy compatibility layer for the npm package `secp256k1` via noble-secp256k1
 
-// Copy-paste from secp256k1, maybe export it?
-const bytesToNumber = (bytes: Uint8Array) => hexToNumber(toHex(bytes));
-const numberToHex = (num: number | bigint) =>
-  num.toString(16).padStart(64, "0");
-const numberToBytes = (num: number | bigint) => hexToBytes(numberToHex(num));
-
 function hexToNumber(hex: string): bigint {
   if (typeof hex !== "string") {
     throw new TypeError("hexToNumber: expected string, got " + typeof hex);
@@ -18,11 +12,13 @@ function hexToNumber(hex: string): bigint {
   return BigInt(`0x${hex}`);
 }
 
-// Calculates a modulo b
-function mod(a: bigint, b: bigint = secp.CURVE.P): bigint {
-  const result = a % b;
-  return result >= 0 ? result : b + result;
-}
+// Copy-paste from secp256k1, maybe export it?
+const bytesToNumber = (bytes: Uint8Array) => hexToNumber(toHex(bytes));
+const numberToHex = (num: number | bigint) =>
+  num.toString(16).padStart(64, "0");
+const numberToBytes = (num: number | bigint) => hexToBytes(numberToHex(num));
+const { mod } = secp.utils;
+
 const ORDER = secp.CURVE.n;
 
 type Output = Uint8Array | ((len: number) => Uint8Array);
@@ -165,23 +161,23 @@ export function privateKeyTweakAdd(
 ): Uint8Array {
   assertBytes(privateKey, 32);
   assertBytes(tweak, 32);
-  let bn = bytesToNumber(tweak);
-  if (bn === 0n) {
+  let t = bytesToNumber(tweak);
+  if (t === 0n) {
     throw new Error("Tweak must not be zero");
   }
-  if (bn >= ORDER) {
+  if (t >= ORDER) {
     throw new Error("Tweak bigger than curve order");
   }
-  bn += bytesToNumber(privateKey);
-  if (bn >= ORDER) {
-    bn -= ORDER;
+  t += bytesToNumber(privateKey);
+  if (t >= ORDER) {
+    t -= ORDER;
   }
-  if (bn === 0n) {
+  if (t === 0n) {
     throw new Error(
       "The tweak was out of range or the resulted private key is invalid"
     );
   }
-  privateKey.set(hexToBytes(numberToHex(bn)));
+  privateKey.set(hexToBytes(numberToHex(t)));
   return privateKey;
 }
 

From 66bf7086a931e75a6f516e58b6230bc270b705ab Mon Sep 17 00:00:00 2001
From: Paul Miller <paul@paulmillr.com>
Date: Wed, 15 Jun 2022 14:34:02 +0400
Subject: [PATCH 2/2] Remove 0x prefix in hexToBytes.

---
 src/utils.ts | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/utils.ts b/src/utils.ts
index e5328b4..7ba16a5 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,5 +1,6 @@
 // buf.toString('hex') -> toHex(buf)
 import assert from "@noble/hashes/_assert";
+import { hexToBytes as _hexToBytes } from "@noble/hashes/utils";
 const assertBool = assert.bool;
 const assertBytes = assert.bytes;
 export { assertBool, assertBytes };
@@ -7,7 +8,6 @@ export {
   bytesToHex,
   bytesToHex as toHex,
   concatBytes,
-  hexToBytes,
   createView,
   utf8ToBytes
 } from "@noble/hashes/utils";
@@ -20,6 +20,11 @@ export function bytesToUtf8(data: Uint8Array): string {
   return new TextDecoder().decode(data);
 }
 
+export function hexToBytes(data: string): Uint8Array {
+  const sliced = data.startsWith("0x") ? data.substring(2) : data;
+  return _hexToBytes(sliced);
+}
+
 // buf.equals(buf2) -> equalsBytes(buf, buf2)
 export function equalsBytes(a: Uint8Array, b: Uint8Array): boolean {
   if (a.length !== b.length) {