2 files changed, 16 insertions, 1 deletions
diff --git a/packages/server/src/registration/generateRegistrationOptions.test.ts b/packages/server/src/registration/generateRegistrationOptions.test.ts
index 3b7f62b..fded674 100644
--- a/packages/server/src/registration/generateRegistrationOptions.test.ts
+++ b/packages/server/src/registration/generateRegistrationOptions.test.ts
@@ -192,6 +192,21 @@ Deno.test('should generate a challenge if one is not provided', async () => {
   mockGenerateChallenge.restore();
 });
 
+Deno.test('should treat string challenges as UTF-8 strings', async () => {
+  const options = await generateRegistrationOptions({
+    rpID: 'not.real',
+    rpName: 'SimpleWebAuthn',
+    userID: '1234',
+    userName: 'usernameHere',
+    challenge: 'こんにちは',
+  });
+
+  assertEquals(
+    options.challenge,
+    '44GT44KT44Gr44Gh44Gv',
+  );
+});
+
 Deno.test('should use custom supported algorithm IDs as-is when provided', async () => {
   const options = await generateRegistrationOptions({
     rpID: 'not.real',
diff --git a/packages/server/src/registration/generateRegistrationOptions.ts b/packages/server/src/registration/generateRegistrationOptions.ts
index 54bdaa5..c894abb 100644
--- a/packages/server/src/registration/generateRegistrationOptions.ts
+++ b/packages/server/src/registration/generateRegistrationOptions.ts
@@ -157,7 +157,7 @@ export async function generateRegistrationOptions(
    */
   let _challenge = challenge;
   if (typeof _challenge === 'string') {
-    _challenge = isoUint8Array.fromASCIIString(_challenge);
+    _challenge = isoUint8Array.fromUTF8String(_challenge);
   }
 
   return {