fix: reset position before demanding new data for frame decryption

src/lib.rs

@@ -513,8 +513,6 @@ impl BackupDecryptor {
                 Err(e) => return Err(e),
             };
 
-            // if we got to an attachment, but there we demand more data, it will be faulty, because we try to decrypt the frame although we would need
-            // to decrypt the attachment
             match decrypt_frame(
                 &mut self.reader,
                 hmac,
@@ -524,6 +522,8 @@ impl BackupDecryptor {
                 frame_length,
             ) {
                 Ok(None) => {
+                    // here we have to reset as well because the hmac depends on the length decryption which should therefore happen next time on the correct bits
+                    self.reader.set_position(initial_reader_position);
                     return Ok(true);
                 }
                 Ok(Some(backup_frame)) => {

test/src/App.tsx

@@ -133,6 +133,7 @@ const App: Component = () => {
       <input
         type="file"
         id="backup-input"
+        accept=".backup"
         onChange={(event) => {
           setBackupFile(event.currentTarget.files?.[0]);
         }}