Tutorial : Python JSON Web Tokens

What is JWT?

JWT or JSON Web Tokens is a compact, URL-safe means of representing claims between two parties. The claim between the parties is often encoded as a payload onto the JWT and which is further signed using a SECRET_KEY.

JWT for Web Developers

The most interesting usage of JWT is in the field of Web Development.
I have been developing Web Applications for quite a long time now. Recently I was supposed to build an API for an Open Source Project which required me to handle User sessions. The stack I am using is:

Python
Flask Blueprint
PostgreSQL
JSON Web Tokens

Installing PyJWT

gabru-md ~ $ pip install pyjwt

Using JWT

Implementing or using JSON web tokens is very easy. All we need to understand is how it works.
A JWT consists of a payload which is protected using a SECRET_KEY. A JWT has tow main functions

jwt.encode
jwt.decode

Let us begin by encoding some stuff into our JSON Web Token

Fire up your terminal & open Python

gabru-md ~ $ python

Import jwt library into python shell

import jwt
import datetime

Create your payload
For our use case we want to generate a JWT for a logged in user into our system. So we will embedd the user details as well as an expiration time into our JSON Web Token.

payload = {
"user": user.username,
"exp": datetime.datetime.utcnow() + datetime.timedelta(seconds=900)
}

Now we will create a SECRET_KEY for our JWT
The secret key in our case will be out Flask's SECRET_KEY. To create one, just follow the steps below.

from flask import Flask

app = Flask(__name__)

app.config['SECRET_KEY'] = 'somesuperrandomsecretkeynoonecancrack'

Encode your JWT with the SECRET_KEY

token = jwt.encode(payload, app.config.get('SECRET_KEY')

View your token generated

print(token.decode('UTF-8'))

Output will be something like

u'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjoibWFuaXNoIn0.JX4_nxeJAY8lOSrTiyzU43eKt-qEWXtNhkPwfLWanUY'

Congratulations , Now you have your very own JSON Web Token for your User, which will expire in exactly 900 seconds or 15 minutes :)

I hope to write another blog on Authentication using JWT very soon. Please let me know If you like this post .
Thank you for reading :)
My Github : github@gabru-md
Link to my PR : here