1diff --git i/pysimplesoap/c14n.py w/pysimplesoap/c14n.py
2index 5749e49..297592e 100644
3--- i/pysimplesoap/c14n.py
4+++ w/pysimplesoap/c14n.py
5@@ -55,11 +55,8 @@ except:
6 class XMLNS:
7 BASE = "http://www.w3.org/2000/xmlns/"
8 XML = "http://www.w3.org/XML/1998/namespace"
9-try:
10- import cStringIO
11- StringIO = cStringIO
12-except ImportError:
13- import StringIO
14+
15+from io import StringIO
16
17 _attrs = lambda E: (E.attributes and E.attributes.values()) or []
18 _children = lambda E: E.childNodes or []
19diff --git i/pysimplesoap/xmlsec.py w/pysimplesoap/xmlsec.py
20index 2f96df7..053149f 100644
21--- i/pysimplesoap/xmlsec.py
22+++ w/pysimplesoap/xmlsec.py
23@@ -15,7 +15,7 @@ from __future__ import print_function
24 import base64
25 import hashlib
26 import os
27-from cStringIO import StringIO
28+from io import StringIO
29 from M2Crypto import BIO, EVP, RSA, X509, m2
30
31 # if lxml is not installed, use c14n.py native implementation