fix: unhandled rejections for invalid base64

crypto/hmac-buffer.test.ts

@@ -31,7 +31,7 @@ test('bufferFromBase64 - converts base64 strings to Buffer correctly', () => {
 	}
 })
 
-test('bufferFromBase64 - validates base64 strings correctly', () => {
+test('bufferFromBase64 - validates valid base64 strings correctly', () => {
 	// Valid base64 strings should work
 	const validBase64 = [
 		'aGVsbG8=', // normal case
@@ -46,10 +46,12 @@ test('bufferFromBase64 - validates base64 strings correctly', () => {
 		assertEquals(
 			typeof bufferFromBase64(base64),
 			'object',
-			`bufferFromBase64 should accept valid base64 string "${base64}"`,
+			`bufferFromBase64 should accept valid base64 string "${base64}".`,
 		)
 	}
+})
 
+test('bufferFromBase64 - validates invalid base64 strings correctly', () => {
 	// Invalid base64 strings should throw
 	const invalidBase64 = [
 		'!@#$', // invalid characters
@@ -62,7 +64,7 @@ test('bufferFromBase64 - validates base64 strings correctly', () => {
 			() => bufferFromBase64(base64),
 			Error,
 			'base64', // error message should include
-			`bufferFromBase64 should reject invalid base64 string "${base64}"`,
+			`bufferFromBase64 should reject invalid base64 string "${base64}".`,
 		)
 	}
 })

crypto/hmac.ts

@@ -11,10 +11,9 @@
  */
 
 // load packages
-import { Buffer } from 'node:buffer'
+import { Buffer, atob } from 'node:buffer'
 import { createHmac } from 'node:crypto'
 
-const BASE64_ENCODING = 'base64'
 const BASE64_REGEX = /^[0-9a-zA-Z+/=]*$/
 const HEX_ENCODING = 'hex'
 const HEX_REGEX = /^[0-9a-fA-F]*$/
@@ -67,11 +66,18 @@ export const hmacSha512 = (str: string | Buffer, key: string | Buffer): string =
  * hmacSha512('hello world', bufferFromBase64('MDEyMzQ1Njc4OWFiY2RlZg=='))
  * ```
  */
-export const bufferFromBase64 = (base64: string): Buffer => {
+export const bufferFromBase64 = (base64: string, preferNativeError = false): Buffer => {
 	// check if base64 string is valid
-	if (!BASE64_REGEX.test(base64)) throw new Error('Invalid base64 string')
+	if (!BASE64_REGEX.test(base64)) throw new Error('Invalid base64 characters')
 
-	return Buffer.from(base64, BASE64_ENCODING)
+	try {
+		// we're using atob because Buffer.from(base64, 'base64') throws unhandled rejections on some systems
+		return Buffer.from(atob(base64))
+	} catch (error) {
+		// the native error varies between runtimes, so the default is to throw our own error
+		if (preferNativeError) throw error
+		throw new Error('Invalid base64 string')
+	}
 }
 
 /**