[wasm] fix: decode ekey before decryption

um_wasm/src/exports/qmc.rs

@@ -19,7 +19,8 @@ impl JsQMC2 {
     /// Create a new QMC2 (mgg/mflac) cipher instance.
     #[wasm_bindgen(constructor)]
     pub fn new(ekey: &str) -> Result<JsQMC2, JsError> {
-        let cipher = QMCv2Cipher::new(ekey.as_bytes()).map_err(map_js_error)?;
+        let key = umc_qmc::ekey::decrypt(ekey).map_err(map_js_error)?;
+        let cipher = QMCv2Cipher::new(key).map_err(map_js_error)?;
         Ok(JsQMC2(cipher))
     }