  
  import pyghmi.exceptions as exc
  from pyghmi.ipmi.private import constants
-@@ -309,10 +309,6 @@ class Session(object):
+@@ -309,10 +309,6 @@
      # can do something like reassign our threading and select modules
      socketchecking = None
  

diff --git a/lower-constraints.txt b/lower-constraints.txt
index a02749a..1741a51 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -1,5 +1,4 @@
 coverage===4.0
-cryptography===2.1
 fixtures===3.0.0
 openstackdocstheme==1.18.1
 oslotest===3.2.0
diff --git a/pyghmi/ipmi/private/session.py b/pyghmi/ipmi/private/session.py
index 0cd2043..c31020d 100644
--- a/pyghmi/ipmi/private/session.py
+++ b/pyghmi/ipmi/private/session.py
@@ -28,8 +28,8 @@ import struct
 import threading
 
 

     @classmethod
     def _cleanup(cls):
         for sesskey in list(cls.bmc_handlers):
@@ -872,14 +868,9 @@
                 iv = os.urandom(16)
                 message += iv
                 payloadtocrypt = bytes(payload + _aespad(payload))
