Generate Jwt Secret Key Python
Often in Flask applications we want to add login/logout functionality. Depending on the type of application you're creating, you could use sessions or tokens.
- Sessions are best suited to applications where you're serving web pages with Flask—i.e. making extensive use of
render_template. - Tokens are best suited to APIs, where your Flask application accepts and returns data to another application (such as mobile apps or web apps).
After making a connection with MongoDB the next step is to create a Flask App and do some configuration on it. Use the Following Code. App = Flask(name) jwt = JWTManager(app) # JWT Config app.config'JWTSECRETKEY' = 'this-is-secret-key' #change it. As you can see in the above code. Rather than using the JWT for authorization on REST requests, you'll exchange it for an access token, which you'll then include with a Bearer authorization header (if you're constructing your REST requests manually). I use JWT in Python in one of my projects and have a Gist available showing how to use it with simplesalesforce. And copy the output to the variable SECRETKEY (don't use the one in the example). Create a variable ALGORITHM with the algorithm used to sign the JWT token and set it to 'HS256'. Create a variable for the expiration of the token. Define a Pydantic Model that will be used in the token endpoint for the response. Secretkey: Backend server secret key. Use the method above to generate it. Firstsuperuser: The first superuser generated, with it you will be able to create more users, etc. By default, based on the domain. Firstsuperuserpassword: First superuser password. Use the method above to generate it.
In this post we'll learn how to add token-based authentication to your Flask apps. But first...
What is a JWT?
JWT stands for JSON Web Token, and it is a piece of text with some information encoded into it.
Generate Jwt Secret Key Python Online
The information stored when doing authentication in a Flask app is usually something that we can use to identify the user for whom we generated the JWT.
The flow goes like this:
- User provides their username and password
- We verify they are correct inside our Flask app
- We generate a JWT which contains the user's ID.
- We send that to the user.
- Whenever the user makes a request to our application, they must send us the JWT we generated earlier. By doing this, we can verify the JWT is valid—and then we'll know the user who sent us the JWT is the user for whom we generated it.
That last point is important. When we receive a JWT we know to be valid, we know we generated it for a specific user. We can check this using the information stored inside the JWT.
Since we know the user sent us the JWT that we generated when they logged in, we can treat this used as a 'logged in user'.
Any user that does not send us a valid JWT, we will treat as a 'logged out' user.
Authentication with Flask-JWT
There are two main libraries for authentication with Flask: Flask-JWT and Flask-JWT-Extended.
Flask-JWT is slightly simpler, while Flask-JWT-Extended is a bit more powerful. Learning one will make learning the other very straightforward.
In this post we'll use Flask-JWT.
Installing and linking with our app
To install Flask-JWT, activate your virtual environment and then do:
Then, in the file where your app is defined, you'll need to import Flask-JWT and create the JWT object. You also need to define app.secret_key as that is used to sign the JWT so you know it is your app that created it, and not anyone else:
We also have an import for authenticate and identity. These two functions are required for Flask-JWT to know how to handle an incoming JWT, and also what data we want to store in an outgoing JWT.
As soon as we create the JWT object, Flask-JWT registers an endpoint with our application, /auth.
That means that the simple app in that code already has an endpoint that users can access. By default, users should be able to send POST requests to the /auth endpoint with some JSON payload:
What is authenticate?
The authenticate function is used to authenticate a user. That means, when a user gives us their username and password, what data we want to put into the JWT. Remember, the data we put into the JWT will come back to us when the user sends it with each request.
The flow goes like this:
- User makes a POST request to the new
/authendpoint with their username and password as the JSON payload. - The
authenticatefunction is called with that username and password. Flask-JWT set this up when we created theJWTobject.
Usually in the authenticate function I check the validity of a user's username and password, and then tell Flask-JWT to store the user's id inside the JWT.
Something like this:
My authenticate function accepts a username and password. It then goes into the database and finds a user matching that username, and checks the password is correct.
If it is, it returns the user.
Does that mean the user is stored in the JWT?
No. Flask-JWT will take the id property of the user object and store that in the JWT.
If your user object does not have an id property, you'll get an error.
You can change which property gets stored in the JWT by setting an app configuration property. Learn more in our Flask-JWT Configuration blog post.
What is identity?
The identity function is used when we receive a JWT.
In any of our endpoints (except the /auth endpoint) the user can send us a JWT alongside their data. They will do this by adding a header to their request:
When that happens, Flask-JWT will take the JWT and get the data out of it. Data stored inside a JWT is called a 'payload', so our identity function accepts that payload as a parameter:
The payload['identity'] contains the user's id property that we saved into the JWT when we created it. The payload also contains other things, such as when the token was created, when it expires, and more. For more information, read the 'Payload' section of this post.
Since payload['identity'] is the user's id—we use that to find the user in the database and return it.
Important: the identity function is not called unless we decorate our endpoints with the @jwt_required() decorator, like so:
Inside any endpoint that is decorated with @jwt_required(), we can access the current_identity proxy—it will give us whatever the identity function returns for the JWT we received in this specific request.
Testing and error messages
Here's a simple app, taken from the official documentation, that you can use to test your Flask-JWT requests.
I would recommend testing different scenarios with Flask-JWT to check what it can return you. For example, what happens if:
- You send an invalid username or password;
- You send an invalid or incomplete JWT;
- Your user isn't found in the database with the id in the payload;
Jwt Secret Key Generator Python
Flask-JWT-Extended
Flask-JWT-Extended is very similar to Flask-JWT, but has more configuration options and some more functionality. For example, it allows for token refreshing.
After you're comfortable with Flask-JWT—and if you need those advanced features—read our blog post on Flask-JWT-Extended for more!
I hope you've found this post useful, and you've learned something!
If you want an even better and more digestible set of video tutorials guiding you through creating Flask applications and REST APIs, check out our REST APIs with Flask and Python course. It contains everything you need to develop simple, professional REST APIs easily.
If you sign up to our mailing list below, that's the best way to get access to a discount code—we share them every month with our subscribers!
2018-02-16T22:25:45Z
When working with web applications, it is often necessary to generate passwords, tokens or API keys, to be assigned to clients to use as authentication. While there are many sophisticated ways to generate these, in many cases it is perfectly adequate to use sufficiently long and random sequences of characters. The problem is that if you are doing this in Python, there is more than one way to generate random strings, and it isn't always clear which way is the best and most secure.
You would think that adding yet one more method to generate random strings would confuse things even more, but unlike all the other options, the new secrets module introduced in Python 3.6 is actually designed for this specific use case, so from my part it is a welcome addition to the Python standard library. In this short article I'm going to give you an overview of this new module.
Generating Tokens
The secrets module is part of the Python standard library in Python 3.6 and newer. You can import this module into your application or into a Python shell as follows:
At the core of this module there are three functions that generate random tokens using the best random number generator provided by your system. The first function generates binary sequences of random bytes:
Invoking the token_bytes() function without any arguments returns a token with a default length that is determined to be sufficiently safe and secure. You can also pass the desired length as an argument, as you can see in the second example above.
The token_hex() function works in a similar way, but returns a string with the bytes rendered in hexadecimal notation instead of a raw binary string:
With this function, each byte in the sequence is rendered as two hexadecimal digits, so in the second example above, where I request a token with 20 characters, the resulting string is going to be 40 characters long.
The third function in this group is token_urlsafe(), which returns the random string encoded in base64 format:
The base64 encoding is more efficient than hexadecimal. In the example above you can see that when I requested a token of 20 characters, the resulting base64 encoded string is 27 characters long.
How to know when to use each of these functions? For most cases, the token_urlsafe() function is probably the best option, so start from that one. If you prefer random strings encoded in hexadecimal notation (which will give you only characters in the 0-9 and a-f ranges) then use token_hex(). Finally, if you prefer a raw binary string, without any encodings, then use token_bytes().
There are many use cases that benefit from have a simple and secure way to generate tokens. Here are a few examples:
- API keys that are given to clients after they authenticate with username and password
- Password reset tokens to be sent to the user by email
- Initial passwords for new accounts (you will likely want users to change their password after the first login)
- IDs for background tasks or other asynchronous operations
- Passwords to assign to other services such as databases, message queues, etc.
- Dynamically created unique URLs
Generating Random Numbers
While the token generation functions I described in the previous section are the most useful, the secrets module also provides a few functions that deal with random numbers.
The choice() function returns a randomly selected item from the list provided as an argument:
This function can be combined with a list comprehension to generate random strings that only use a specific set of characters. For example, if you want to generate a random string of 20 characters that only uses the letters abcd you can do so as follows:
The randbelow() function generates a random integer number between 0 and the number given as an argument (not including this number):
Finally, the randbits() function returns an random integer number that has the specified number of bits:
Conclusion
I hope you found this little article useful. I find the token generation functions, and in particular token_urlsafe(), very convenient and keep discovering new uses for it. Are you using these functions for an original purpose I have not described in this article? Let me know below in the comments!
Hello, and thank you for visiting my blog! If you enjoyed this article, please consider supporting my work on this blog on Patreon!
9 comments
#1Eddy van den Aker said 2018-04-20T10:12:29Z
#2Miguel Grinberg said 2018-04-22T06:49:12Z
#3Chinmay Prabhudesai said 2019-01-08T00:06:52Z
#4Miguel Grinberg said 2019-01-08T10:32:19Z
#5Abhi said 2019-02-12T18:29:07Z
#6Fergus said 2020-04-12T10:21:43Z
#7Miguel Grinberg said 2020-04-12T10:27:49Z
#8Rafael Ribeiro said 2020-05-11T03:08:36Z
#9Firas Fatnassi said 2020-05-24T10:44:46Z