error in running it

[sumitdadhich]

first of all thanks and i appreciate your efforts , i was trying your npv script but its showing

Traceback (most recent call last):
File "nsw.py", line 630, in
crypter = Crypter_pure()
File "nsw.py", line 595, in init
self.m = AESModeOfOperation()
NameError: global name 'AESModeOfOperation' is not defined

how to remove this error