No error message on wrong password

packages/kdbx/src/crypto.ts

@@ -82,9 +82,18 @@ export async function aesCbcDecrypt(
 ): Promise<Uint8Array> {
   const subtle = kx_getCrypto().subtle;
   const cryptoKey = await subtle.importKey('raw', kx_buf(key), 'AES-CBC', false, ['decrypt']);
-  return new Uint8Array(
-    await subtle.decrypt({ name: 'AES-CBC', iv: kx_buf(iv) }, cryptoKey, kx_buf(data)),
-  );
+  try {
+    return new Uint8Array(
+      await subtle.decrypt({ name: 'AES-CBC', iv: kx_buf(iv) }, cryptoKey, kx_buf(data)),
+    );
+  } catch {
+    // WebCrypto throws a DOMException with an empty message on a PKCS#7
+    // padding failure (deliberately, to avoid a padding-oracle side
+    // channel) — and a wrong key almost always produces invalid padding, so
+    // this is the ordinary "wrong password" case for KDBX 3.1 files, not a
+    // rare corruption edge case. Give callers something to show the user.
+    throw new Error('AES-CBC decryption failed (wrong credentials or corrupt file)');
+  }
 }
 
 /**

packages/kdbx/tests/kdbx.test.ts

@@ -103,16 +103,26 @@ for (const config of CONFIGS) {
   });
 }
 
-test('wrong credentials are rejected', async () => {
+test('wrong credentials are rejected, with a message the UI can show', async () => {
   const kdbx = await Kdbx.create(Credentials.fromPassword('right'), options({ version: 4 }));
   const saved = await kdbx.save();
-  await assert.rejects(() => Kdbx.load(saved, Credentials.fromPassword('wrong')));
+  await assert.rejects(
+    () => Kdbx.load(saved, Credentials.fromPassword('wrong')),
+    (err: Error) => err.message.length > 0,
+  );
 });
 
-test('wrong credentials are rejected (KDBX 3.1)', async () => {
+test('wrong credentials are rejected, with a message the UI can show (KDBX 3.1)', async () => {
+  // Regression test: KDBX 3.1 decrypts the outer AES-CBC payload before any
+  // "wrong credentials" check runs, and WebCrypto throws an empty-message
+  // DOMException on the resulting padding failure — page.ts's unlock screen
+  // was rendering that empty message as a blank error bar.
   const kdbx = await Kdbx.create(Credentials.fromPassword('right'), options({ version: 3 }));
   const saved = await kdbx.save();
-  await assert.rejects(() => Kdbx.load(saved, Credentials.fromPassword('wrong')));
+  await assert.rejects(
+    () => Kdbx.load(saved, Credentials.fromPassword('wrong')),
+    (err: Error) => err.message.length > 0,
+  );
 });
 
 test('multiple protected fields decrypt in document order', async () => {