inconsistent results in Python2 - Python3

When I run the following command below. I receive inconsistent results.

Expected Result

The same token should be returned. There is one noticeable difference in the second token which is the b (byte) prefixed to the string.

Actual Result

two different strings

Reproduction Steps

# Python 2.7.15
# Name: PyJWT
# Version: 1.6.4

>>> import jwt
>>> jwt.encode({'transaction': '6fa459ea-ee8a-4ca4-894e-db77e160355e', 'exp': 1497965640}, 'a') 
'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ0cmFuc2FjdGlvbiI6IjZmYTQ1OWVhLWVlOGEtNGNhNC04OTRlLWRiNzdlMTYwMzU1ZSIsImV4cCI6MTQ5Nzk2NTY0MH0.-bpx5A3DfSe3-HO6aH_glS8adcCxUn8lSK1-RPxohhI'

# Python 3.7.0
# Name: PyJWT
# Version: 1.6.4
>>> import jwt
>>> jwt.encode({'transaction': '6fa459ea-ee8a-4ca4-894e-db77e160355e', 'exp': 1497965640}, 'a')
b'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ0cmFuc2FjdGlvbiI6IjZmYTQ1OWVhLWVlOGEtNGNhNC04OTRlLWRiNzdlMTYwMzU1ZSIsImV4cCI6MTQ5Nzk2NTY0MH0.NuqwXlHt27nRxg5W2hHoP5ugnLmw-7QYBumO7lRa1i0'

System Information

$ python -m jwt.help

Tested on Mac OS

{
  "cryptography": {
    "version": "2.2.2"
  },
  "implementation": {
    "name": "CPython",
    "version": "3.7.0"
  },
  "platform": {
    "release": "17.7.0",
    "system": "Darwin"
  },
  "pyjwt": {
    "version": "1.6.4"
  }
}

Tested on Ubuntu 16.04

{
  "cryptography": {
    "version": ""
  },
  "implementation": {
    "name": "CPython",
    "version": "3.5.2"
  },
  "platform": {
    "release": "4.15.13-x86_64-node584",
    "system": "Linux"
  },
  "pyjwt": {
    "version": "1.6.4"
  }
}

This command is only available on PyJWT v1.6.3 and greater. Otherwise, please provide some basic information about your system.

[justmobilize]

The other thing to note is that your data is the same:

eyJ0cmFuc2FjdGlvbiI6IjZmYTQ1OWVhLWVlOGEtNGNhNC04OTRlLWRiNzdlMTYwMzU1ZSIsImV4cCI6MTQ5Nzk2NTY0MH0

It’s the first part, which is the header. eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9 >> b'{"alg":"HS256","typ":"JWT"}' or eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9 >> b'{"typ":"JWT","alg":"HS256"}'

When testing you can use base64.b64decode on the first part (before the first .) and make sure the header is correct

[macmichael01]

@jadhavmanoj I don’t think this will be a common bug that most developers will run into.

I would recommend identifying in your code where PyJWT is being called and run some tests on those specific parts of code both in py2 and py3 and verify that you are receiving expected results.

If you have already developed an app using Flask + PyJWT, I wouldn’t recommend converting to another 3rd party library which wraps PyJWT unless there is a valued added for doing so. Perhaps the value added for the above libraries recommended would help to mitigate the issues that I ran into but then again maybe it wouldn’t. If it doesn’t, converting might cost you more time than it’s worth. The decision is up to you to decide.