diff --git a/unipay/providers/alipay.py b/unipay/providers/alipay.py
index d52569f..e638e33 100644
--- a/unipay/providers/alipay.py
+++ b/unipay/providers/alipay.py
@@ -31,10 +31,10 @@ class AlipayGateway(Gateway):
 
         # -------- load keys -------
         self._private_key = serialization.load_pem_private_key(
-            app_private_key_pem.encode(), password=None
+            app_private_key_pem, password=None
         )
         self._alipay_public_key = serialization.load_pem_public_key(
-            alipay_public_key_pem.encode()
+            alipay_public_key_pem
         )
 
         self.session = aiohttp.ClientSession(timeout=aiohttp.ClientTimeout(total=20))