diff --git a/um_cli/src/cmd/qtfm.rs b/um_cli/src/cmd/qtfm.rs
index bcbc763..21d2ca2 100644
--- a/um_cli/src/cmd/qtfm.rs
+++ b/um_cli/src/cmd/qtfm.rs
@@ -45,7 +45,12 @@ impl ArgsQingTingFM {
         };
 
         let device_key = self.make_device_key()?;
-        let iv = make_decipher_iv(file_name)?;
+        let iv = make_decipher_iv(&file_name)?;
+        if cli.verbose {
+            eprintln!(" file_name: {}", file_name);
+            eprintln!("device_key: {}", hex::encode(&device_key));
+            eprintln!("   file_iv: {}", hex::encode(&iv));
+        }
 
         let decipher = Decipher::new(&device_key, &iv);
 
diff --git a/um_wasm/src/exports/qtfm.rs b/um_wasm/src/exports/qtfm.rs
index e69de29..f5388a3 100644
--- a/um_wasm/src/exports/qtfm.rs
+++ b/um_wasm/src/exports/qtfm.rs
@@ -0,0 +1,40 @@
+use std::convert::TryInto;
+use umc_qtfm::{nonce, secret, Decipher};
+use wasm_bindgen::prelude::wasm_bindgen;
+use wasm_bindgen::JsError;
+
+/// QingTingFM QTA file decipher.
+#[wasm_bindgen(js_name=QingTingFM)]
+pub struct JsQingTingFM(Decipher);
+
+#[wasm_bindgen(js_class = QingTingFM)]
+impl JsQingTingFM {
+    #[wasm_bindgen(js_name=getDeviceKey)]
+    pub fn get_device_key(
+        product: &str,
+        device: &str,
+        manufacturer: &str,
+        brand: &str,
+        board: &str,
+        model: &str,
+    ) -> Vec<u8> {
+        secret::make_device_secret(product, device, manufacturer, brand, board, model).to_vec()
+    }
+
+    #[wasm_bindgen(js_name=getFileIV)]
+    pub fn get_file_iv(file_name: &str) -> Result<Vec<u8>, JsError> {
+        let iv = nonce::make_decipher_iv(file_name)?;
+        Ok(iv.to_vec())
+    }
+
+    #[wasm_bindgen(constructor)]
+    pub fn new(device_key: &[u8], file_iv: &[u8]) -> Result<JsQingTingFM, JsError> {
+        let decipher = Decipher::new(device_key.try_into()?, file_iv.try_into()?);
+        Ok(JsQingTingFM(decipher))
+    }
+
+    /// Decrypt encrypted buffer part.
+    pub fn decrypt(&self, buffer: &mut [u8], offset: usize) {
+        self.0.decrypt(buffer, offset)
+    }
+}
diff --git a/um_wasm_loader/src/loader.mjs b/um_wasm_loader/src/loader.mjs
index 38ab160..1a0bf97 100644
--- a/um_wasm_loader/src/loader.mjs
+++ b/um_wasm_loader/src/loader.mjs
@@ -1,11 +1,12 @@
 import umWasm from '../pkg/um_wasm_bg.wasm';
-import { __wbg_init, initSync } from '../pkg/um_wasm.js';
+import { __wbg_init, initPanicHook, initSync } from '../pkg/um_wasm.js';
 
 export * from '../pkg/um_wasm.js';
 
 function loader() {
   if (process.env.UMC_INLINE_BUILD === '1') {
     initSync({ module: umWasm() });
+    initPanicHook();
     return Promise.resolve(true);
   } else {
     const url = new URL('um_wasm_bg.wasm', import.meta.url);
@@ -17,7 +18,7 @@ function loader() {
               console.log('read wasm failed', err);
             })
         : undefined;
-    return __wbg_init({ module_or_path: wasm }).then(() => true);
+    return __wbg_init({ module_or_path: wasm }).then(() => (initPanicHook(), true));
   }
 }