feat: add Uint8Array compare function

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `areUint8ArraysEqual` function to compare two `Uint8Array` types ([#268](https://github.com/MetaMask/utils/pull/268))
+
 ## [11.7.0]
 
 ### Added

src/bytes.test.ts

@@ -7,6 +7,7 @@ import {
   UTF_8_BYTES_FIXTURES,
 } from './__fixtures__';
 import {
+  areUint8ArraysEqual,
   assertIsBytes,
   base64ToBytes,
   bigIntToBytes,
@@ -536,4 +537,33 @@ describe('createDataView', () => {
       expect(dataView.getUint8(2)).toBe(4);
     });
   });
+
+  describe('areUint8ArraysEqual', () => {
+    it('returns true if the Uint8Arrays are equal', () => {
+      expect(
+        areUint8ArraysEqual(
+          new Uint8Array(32).fill(1),
+          new Uint8Array(32).fill(1),
+        ),
+      ).toBe(true);
+    });
+
+    it('returns false if the Uint8Arrays are not equal', () => {
+      expect(
+        areUint8ArraysEqual(
+          new Uint8Array(32).fill(1),
+          new Uint8Array(32).fill(2),
+        ),
+      ).toBe(false);
+    });
+
+    it('returns false if the Uint8Arrays length is different', () => {
+      expect(
+        areUint8ArraysEqual(
+          new Uint8Array(32).fill(1),
+          new Uint8Array(31).fill(1),
+        ),
+      ).toBe(false);
+    });
+  });
 });

src/bytes.ts

@@ -459,3 +459,27 @@ export function createDataView(bytes: Uint8Array): DataView {
 
   return new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
 }
+
+/**
+ * Compares two Uint8Arrays in a timing-safe manner.
+ *
+ * @param a - The first Uint8Array to compare.
+ * @param b - The second Uint8Array to compare.
+ * @returns Whether the Uint8Arrays are equal.
+ */
+export function areUint8ArraysEqual(a: Uint8Array, b: Uint8Array): boolean {
+  if (a.byteLength !== b.byteLength) {
+    return false;
+  }
+
+  const viewA = new DataView(a.buffer, a.byteOffset, a.byteLength);
+  const viewB = new DataView(b.buffer, b.byteOffset, b.byteLength);
+
+  let diff = 0;
+
+  for (let i = 0; i < a.byteLength; i++) {
+    diff += viewA.getUint8(i) === viewB.getUint8(i) ? 0 : 1;
+  }
+
+  return diff === 0;
+}

src/index.test.ts

@@ -52,6 +52,7 @@ describe('index', () => {
         "VersionRangeStruct",
         "VersionStruct",
         "add0x",
+        "areUint8ArraysEqual",
         "assert",
         "assertExhaustive",
         "assertIsBytes",

src/node.test.ts

@@ -52,6 +52,7 @@ describe('node', () => {
         "VersionRangeStruct",
         "VersionStruct",
         "add0x",
+        "areUint8ArraysEqual",
         "assert",
         "assertExhaustive",
         "assertIsBytes",