diff --git a/implementation.py b/implementation.py
new file mode 100644
index 0000000..b7dce2d
--- /dev/null
+++ b/implementation.py
@@ -0,0 +1,40 @@
+import pyaes
+from time import time
+
+# A 256 bit (32 byte) key
+key = "123456789012345ef890123456789012"
+
+# For some modes of operation we need a random initialization vector
+# of 16 bytes
+iv = "9988776655443310"
+
+
+# Each block into the mode of operation must be a multiple of the segment
+# size. For this example we choose 8 bytes.
+s = time()
+aes = pyaes.AESModeOfOperationCFB(key, iv = iv, segment_size = 4)
+plaintext =  "baf9dffc8b690539"
+ciphertext = aes.encrypt(plaintext)
+
+# '''v\xa9\xc1w"\x8aL\x93\xcb\xdf\xa0/\xf8Y\x0b\x8d\x88i\xcb\x85rmp
+#    \x85\xfe\xafM\x0c)\xd5\xeb\xaf'''
+#print repr(ciphertext)
+
+p = time()
+m = time() - s
+print m
+# The cipher-block chaining mode of operation maintains state, so 
+# decryption requires a new instance be created
+aes = pyaes.AESModeOfOperationCFB(key, iv = iv, segment_size = 4)
+decrypted = aes.decrypt(ciphertext)
+
+print time() - p
+#print decrypted
+# True
+#print decrypted == plaintext
+
+print "CFB Mode"
+print "Unencrypted data: ", plaintext
+print "Encrypted data  : ", ciphertext
+print "Decrypted data  : ", decrypted
+print "Enc == Dec      : ", decrypted == plaintext
diff --git a/setup.py b/setup.py
old mode 100644
new mode 100755
index 884701d..f2d5235
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/python
 
 from distutils.core import setup