How to Install SSL Certificate in Python?

Beginner’s Guide to Setup an SSL Certificate in Python

Python is a popular programming language used for a wide variety of applications, including web development. There are a few simple steps that need to be followed to install an SSL Certificate in Python. SSL certificates allow websites to establish an encrypted link and enable data to be transmitted securely.

This tutorial will walk through obtaining an SSL certificate, installing it on your Python server, and configuring your application to use HTTPS. By the end, you’ll have an SSL certificate installed and enabled in Python to make your web traffic and data more secure.

Key Takeaways

Installing SSL/TLS Certificate in Python

Let’s now examine the steps to install an SSL/TLS certificate and configure the Python web server for the HTTPS protocol.

Prerequisites for Installing an SSL Certificate in Python

To follow this guide and run the code examples, you need:

Generating a Self-Signed SSL/TLS Certificate

For testing purposes, we will generate a self-signed certificate using the OpenSSL toolkit. It involves 3 steps:

Step 1: Creating a Private Key

The private key forms the basis for securing the certificate. We generate a 4096-bit RSA private key:

openssl genrsa -out private.key 4096

You can add a passphrase to encrypt the private key file for extra security:

openssl genrsa -des3 -out private.key 4096

Step 2: Generating a Certificate Signing Request (CSR)

The CSR contains information about your organization and domain. Use below OpenSSL command to generate the certificate:

openssl req -new -key private.key -out csr.pem

Enter the requested domain and organization details when prompted.

Step 3: Signing the CSR to create the SSL Certificate

The final step is to self-sign the CSR using our private key to generate the SSL certificate (cert.pem):

openssl x509 -req -days 365 -in csr.pem -signkey private.key -out cert.pem

This creates a valid SSL certificate file that we can use for local testing in Python.

Using the Self-Signed Certificate in a Python HTTPS Server

We will now write a simple Python script to start an HTTPS server using our self-signed SSL certificate:

import http.server
import ssl
httpd = http.server.HTTPServer(('localhost', 4443), http.server.SimpleHTTPRequestHandler)
httpd.socket = ssl.wrap_socket (httpd.socket,
        keyfile="private.key", 
        certfile='cert.pem', server_side=True)
httpd.serve_forever()

Import the http.server and ssl modules. The ssl.wrap_socket() method takes the server socket and wraps SSL encryption over it using our private key and certificate files.

We can make a sample GET request to test the HTTPS server:

import requests
response = requests.get("https://localhost:4443")
print(response.status_code)  
# Should print 200 status OK response

How to Verify SSL/TLS Certificate Validity

Before trusting a website, we should verify if it has a valid SSL certificate installed. Python’s requests module provides an easy way to do this.

Here is a simple script to check a website’s SSL certificate:

import requests
try:
  response = requests.get("https://expired.badssl.com/")
except requests.exceptions.SSLError as err:  
  print(err)
else:
  print("SSL Certificate is valid")

For an invalid certificate, it will raise requests.exceptions.SSLError. This shows how to gracefully handle SSL verification errors in Python.

The main aspects to verify are:

You can also use Python’s ssl module to get certificate details and validation status programmatically.

Overall, handling SSL certificate issues properly is important for security and end-user experience.

How to Deploy SSL/TLS Certificate for Production

Self-signed SSL certificates on public production websites will cause browser warnings. Visitors may only use the site if they encounter TLS security errors.

It is recommended to purchase an SSL certificate from a trusted CA like:

Many web hosting providers and cloud platforms also make it easy to install SSL certificates for the domains and sites hosted with them.

Once you have the SSL certificate files from the CA, install them on the production server by providing the paths in Python:

httpd.socket = ssl.wrap_socket (httpd.socket,
        keyfile="/etc/letsencrypt/live/yourdomain/privkey.pem", 
        certfile='/etc/letsencrypt/live/yourdomain/fullchain.pem', server_side=True) 

The certificate procurement and setup process varies based on your hosting environment. Your domain registrar or hosting provider will have specific instructions to follow.

Proper SSL configuration in production is crucial to securing your Python web applications.

Troubleshooting and Best Practices

Let us look at some common issues faced and best practices around SSL/TLS certificate installation:

Addressing Common SSL/TLS Issues

Maintaining SSL/TLS Certificate Lifecycle

Incorporating SSL/TLS in CI/CD Pipelines

Automating SSL certificate management through CI/CD improves reliability and reduces the chances of errors in production.

Final Thoughts

Installing an SSL certificate in Python allows your application to use HTTPS for secure connections. The process involves obtaining a certificate file, converting it to PEM format if needed, and configuring your Python code to use the certificate.

Proper SSL certificate installation is important for encrypting sensitive data in transit and authenticating your server. While the setup takes a few steps, the benefits of enabling HTTPS for your Python app are significant.

Using certificates and HTTPS adds an important layer of security and trust for your users. With the certificate installed, your Python app can securely send and receive sensitive data over the internet.

FAQs About Installing SSL Certificates on Python

Here are answers to some frequently asked questions site owners have about installing SSL certificates on Python:

How do I generate a CSR for an SSL certificate in Python?

Use the openssl req command and specify your private key, organization details, domain name, etc., to generate the Certificate Signing Request (CSR) required for purchasing an SSL certificate.

What is the process to install an SSL certificate purchased from a CA?

Get the certificate files from the CA. Place the files on your server. Configure the path to these files using the ssl.wrap_socket() method while starting the Python HTTPS server.

How can I check SSL certificate details programmatically in Python?

Import the ssl module and use ssl.get_server_certificate() to fetch the certificate and ssl.PEM_cert_to_DER_cert() is used to convert and decode it into an object containing the issuer, validity date, domain, etc.

Why am I getting an SSL certificate verification failed error in Python?

This error occurs when the SSL certificate on the server side is invalid, expired, self-signed, has a domain name mismatch, is signed by an untrusted CA, etc. Fix the certificate issue or disable certificate verification in requests by setting verify=False.

How do I renew an SSL certificate that is about to expire?

Follow your CA’s renewal process before the expiration date. For auto-renewal, use APIs provided by the CA. Place the renewed certificate and update the path configured in your Python code.

What is the best way to manage SSL certificates used by my Python apps?

Automate SSL certificate renewal and provisioning by integrating it with your CI/CD pipelines. Let the pipeline handle domain validation, procurement, deployment to servers, and renewal reminders.

Priya Mervana

Verified Web Security Experts

Priya Mervana is working at SSLInsights.com as a web security expert with over 10 years of experience writing about encryption, SSL certificates, and online privacy. She aims to make complex security topics easily understandable for everyday internet users.