diff --git a/rhodecode/lib/encrypt.py b/rhodecode/lib/encrypt.py
--- a/rhodecode/lib/encrypt.py
+++ b/rhodecode/lib/encrypt.py
@@ -29,7 +29,7 @@ from Crypto.Cipher import AES
 from Crypto import Random
 from Crypto.Hash import HMAC, SHA256
 
-from rhodecode.lib.utils2 import safe_str
+from rhodecode.lib.str_utils import safe_bytes
 
 
 class SignatureVerificationError(Exception):
@@ -57,7 +57,7 @@ class AESCipher(object):
         self.hmac_size = 32
         self.hmac = hmac
 
-        self.key = SHA256.new(safe_str(key)).digest()
+        self.key = SHA256.new(safe_bytes(key)).digest()
         self.hmac_key = SHA256.new(self.key).digest()
 
     def verify_hmac_signature(self, raw_data):