ImportError: No module named cryptography.fernet

Question

I have the following script, crypto.py in Python 2:

import hashlib
from cryptography.fernet import Fernet

def make_hash(password):
    return hashlib.sha224(password).hexdigest()

def check_hash(password, hash):
    """Check a password against an existing hash."""
    return hashlib.sha224(password).hexdigest() == hash

def start():
    key = Fernet.generate_key()
    print key
    cipher_suite = Fernet(key)
    print cipher_suite
    return cipher_suite

def crypt(message):
    global cipher_suite
    cipher_suite=start()
    cipher_text = cipher_suite.encrypt(message)
    return cipher_text
print "123"

def decrypt(cipher_text):
    plain_text = cipher_suite.decrypt(cipher_text)
    return plain_text
print "456"

message = "Hello!"
print crypt(message)
print decrypt(crypt(message))

When I run this script I get the following output:

123
456
Hgir1BHvlLLMUH-Xi-aDrtNFcT3XU86XQsWtrvn6S2s=
<cryptography.fernet.Fernet object at 0x01661A10>
gAAAAABYRAxpvX9ksY5HVNiVa__S9zfBtV0XvVjUS9RpOOJhLp0fVZPbnk1hNMk9xB9x_s88WDRNF14GhY7DJG7B7g0ngIrENA==
cUKBKF-dsP-sQ5_BN1H6yuq_t1h-kBbBgf6N-LCrynM=
<cryptography.fernet.Fernet object at 0x01BDB5D0>
Hello!

In the same folder I have server and client scripts and I want to use the crypt() and decrypt() in the client scrypt client.py, in line 6:

import threading, socket, crypto

When I run the client.py script I get this ImportError:

Traceback (most recent call last):
  File "K:/A/Project/client.py", line 6, in <module>
    import threading, socket, crypto
  File "K:\A\Project\crypto.py", line 2, in <module>
    from cryptography.fernet import Fernet
ImportError: No module named cryptography.fernet

Solution

Version 2.5 is a work around:

pip install cryptography==2.5

(See https://github.com/oracle/oci-python-sdk/issues/108)

Then to avoid "ImportError: No module named enum" errors, use python3.

You might need to install enum34, but I didn't need to. (See ImportError: No module named enum)