What is an SSL certificate? Why is it important for websites?

This article is about basic concepts to help explain SSL certificates, and show the ways to get a free SSL certificate for supporting the study or business.


What is an SSL certificate?

An SSL certificate is a data file that verifies the identity and encryption of a website. It allows a website to use HTTPS, which is a secure version of HTTP. HTTPS protects the data that is exchanged between a web server and a web browser. An SSL certificate contains the following information:

  • The domain name that the certificate was issued for
  • The person, organisation, or device that owns the certificate
  • The certificate authority that issued the certificate
  • The digital signature of the certificate authority
  • The issue date and expiration date of the certificate
  • The public key that is used to encrypt and decrypt data

To get an SSL certificate, a website owner must create a request file on their server and send it to a certificate authority. The certificate authority will check the request file and the identity of the website owner, and then issue an SSL certificate if everything is valid. The website owner must install the SSL certificate on their server and also an intermediate certificate that links their SSL certificate to the root certificate of the certificate authority. This creates a chain of trust that browsers can verify.

Why is it important for websites?

An SSL certificate is important for websites because it:

  • Encrypts the data that is sent and received by the website, such as passwords, credit card numbers, personal information, etc.
  • Authenticates the identity of the website and prevents attackers from creating fake versions of the website
  • Increases the trust and confidence of the users who visit the website
  • Improves the ranking and visibility of the website on search engines

How does it work?

An SSL certificate works by using a combination of asymmetric and symmetric cryptography to establish and secure a communication session between a client and a server. Here is a simplified explanation of how an SSL certificate works:

  • A client (such as a web browser) requests a connection to a website that has an SSL certificate installed on its web server.
  • The web server sends the client a copy of its SSL certificate, which contains its public key and other information, such as the domain name, the issuer, the validity period, etc.
  • The client verifies the SSL certificate by checking its signature, its expiration date, and its issuer. The issuer is a trusted entity called a certificate authority (CA) that validates the identity of the website owner and issues the SSL certificate.
  • If the client trusts the SSL certificate, it generates a random session key and encrypts it with the public key of the web server. The session key is used for symmetric encryption, which means that both parties use the same key to encrypt and decrypt data.
  • The client sends the encrypted session key to the web server, which decrypts it with its private key. The private key is kept secret and only known by the web server. The private key is mathematically related to the public key, but it is impossible to derive one from the other.
  • The client and the web server now have a shared session key that they can use to securely exchange data using symmetric encryption. This means that any data that is sent or received by either party is encrypted with the session key and can only be decrypted by the other party with the same session key.
  • The client and the web server also use message authentication codes (MACs) to ensure that the data has not been altered or tampered with during transmission. A MAC is a code that is generated from the data and the session key, and it is sent along with the data. The recipient can verify the MAC by using the same session key and comparing it with the received MAC.

By using an SSL certificate, a website can provide security, privacy, and trust for its visitors. An SSL certificate can also improve the ranking and visibility of a website on search engines, as they prefer websites that use HTTPS over HTTP. 

How to get a free SSL certificate?

There are several ways to get a free SSL certificate for your website, which is a data file that verifies the identity and encryption of your website.

  • One way to get a free SSL certificate is to use Let's Encrypt, which is a free, automated, and open certificate authority brought to you by the nonprofit Internet Security Research Group (ISRG). Let's Encrypt provides TLS certificates to 300 million websites and has a simple process to request and renew certificates. You can use various tools and plugins to integrate Let's Encrypt with your web server and website platform. 
  • Another way to get a free SSL certificate is to use Cloudflare, which is a cloud-based service that provides security, performance, and reliability for websites. Cloudflare offers free SSL/TLS certificates for all its customers, regardless of their plan. Cloudflare also handles the issuance and renewal of certificates for you. You can use Cloudflare to enable HTTPS on your website by changing your DNS settings and configuring your SSL/TLS mode. 
  • A third way to get a free SSL certificate is to use HubSpot, which is a software platform that helps you grow your business with marketing, sales, and service tools. HubSpot offers free SSL/TLS certificates for all its customers who host their websites on HubSpot's CMS Hub. HubSpot also manages the issuance and renewal of certificates for you. You can use HubSpot to create and publish secure websites with HTTPS by connecting your domain name and enabling SSL in your domain manager.

These are some of the ways to get a free SSL certificate for your website. There are also other sources that offer free SSL certificates, such as ZeroSSL, SSL For Free, GoDaddy, etc. You can find more information about them on the web or by watching some of the videos in the results. I hope this helps you secure your website with HTTPS

Duoc Le, DevOps @UnDigital®

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