diff --git a/paas2/login/bkauth/forms.py b/paas2/login/bkauth/forms.py
index a309c4282..d214d369b 100644
--- a/paas2/login/bkauth/forms.py
+++ b/paas2/login/bkauth/forms.py
@@ -25,10 +25,9 @@ def clean(self):
         username = self.cleaned_data.get("username")
         password = self.cleaned_data.get("password")
 
-        if settings.ENABLE_PASSWORD_RSA_ENCRYPTED:
-            password = rsa_decrypt_password(password, settings.PASSWORD_RSA_PRIVATE_KEY)
-
         if username and password:
+            if settings.ENABLE_PASSWORD_RSA_ENCRYPTED:
+                password = rsa_decrypt_password(password, settings.PASSWORD_RSA_PRIVATE_KEY)
             self.user_cache = authenticate(
                 username=username,
                 password=password,