Knowledge Base

What is an SSL Certificate and How Does it Work?

SSL (Secure Sockets Layer) is a security protocol that encrypts data communication over the internet, making it secure. Today, it has been replaced by TLS (Transport Layer Security), but it is still commonly referred to as SSL. An SSL certificate verifies the identity of a web server and encrypts the communication between the browser and the server. This ensures that users' sensitive information (e.g., credit card information, passwords, personal data) is transmitted securely without falling into the hands of third parties. For more information, you can visit our SSL Certificate page.

The basic working principle of SSL is as follows:

1. The user's browser requests access to a secure website (e.g., https://www.example.com).
2. The web server sends the SSL certificate to the browser.
3. The browser verifies the certificate. This verification process involves checking whether the certificate is signed by a valid certificate authority (CA).
4. If the verification is successful, the browser and server agree on encryption keys to establish a secure connection.
5. Using these keys, all data communication between the browser and the server is encrypted.

This process is called the "SSL Handshake" and takes place in seconds without the user being aware of it.

Why Do I Need an SSL Certificate?

An SSL certificate provides many important benefits for a website:

• Security: The most important benefit is that it encrypts data communication, protecting users' sensitive information. This is critical, especially for e-commerce sites, banking sites, and other websites that collect personal data.
• Trustworthiness: An SSL certificate verifies the identity of your website and allows users to trust you. Browsers mark websites without an SSL certificate as "not secure," which may cause users to leave the site.
• SEO (Search Engine Optimization): Search engines like Google list websites with SSL certificates higher in search results. This increases your website's visibility and helps you attract more traffic.
• Compliance: Some industry standards, such as PCI DSS (Payment Card Industry Data Security Standard), require websites that process credit card information to use SSL.
• Data Integrity: SSL ensures that the transmitted data reaches the recipient without being altered. This provides protection against man-in-the-middle attacks.

What are the Different Types of SSL Certificates?

SSL certificates are divided into different types according to their validation levels and the number of domain names they cover:

SSL Certificates by Validation Level

• Domain Validated (DV) SSL: This is the most basic type of SSL certificate. It only verifies the ownership of the domain name. It is generally fast and inexpensive.
• Organization Validated (OV) SSL: In addition to verifying the ownership of the domain name, it also verifies the organization's (company's) information. It is a more reliable option.
• Extended Validation (EV) SSL: This is the SSL certificate with the highest level of validation. It comprehensively verifies the domain name and the organization's information. A green padlock icon and the company name are displayed in the browser address bar.

SSL Certificates by Number of Domain Names Covered

• Single Domain SSL: Protects only one domain name (e.g., www.example.com).
• Wildcard SSL: Secures a domain name and all its subdomains (e.g., *.example.com).
• Multi-Domain (SAN) SSL: Protects multiple different domain names and subdomains (e.g., www.example.com, www.example.net, blog.example.com).

The following table shows a comparison of different types of SSL certificates:

How to Install an SSL Certificate?

SSL certificate installation generally involves the following steps:

1. Purchasing an SSL Certificate: Purchase an SSL certificate from a trusted certificate authority (CA) or your hosting provider.
2. Creating a CSR (Certificate Signing Request): Create a CSR on your web server. The CSR is a text file that will be sent to the certificate authority and contains your certificate request.
3. Sending the CSR to the Certificate Authority: Send the CSR to the certificate authority for the SSL certificate you purchased.
4. Domain Name Verification: The certificate authority will ask you to verify ownership of the domain name. This is usually done via email or DNS records.
5. Downloading the Certificate: After the verification process is complete, the certificate authority will send you the SSL certificate files (usually with .crt or .pem extensions).
6. Uploading the Certificate to the Server: Upload the SSL certificate files and your private key (which you created when creating the CSR) to your web server.
7. Configuring the Web Server: Configure your web server (e.g., Apache, Nginx) to use the SSL certificate.
8. Testing the Website: Visit your website with https:// to check that the SSL certificate is installed correctly. You should see a lock icon in the browser address bar.

An example SSL configuration file for Apache:

&ltVirtualHost *:443>
    ServerName www.example.com
    DocumentRoot /var/www/example.com

    SSLEngine on
    SSLCertificateFile /etc/ssl/certs/example.com.crt
    SSLCertificateKeyFile /etc/ssl/private/example.com.key
    SSLCertificateChainFile /etc/ssl/certs/example.com.ca-bundle

    &ltDirectory /var/www/example.com>
        Options Indexes FollowSymLinks MultiViews
        AllowOverride All
        Require all granted
    &lt/Directory>

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
&lt/VirtualHost>

How Long is an SSL Certificate Valid?

The validity period of SSL certificates is usually 1 to 2 years. The certificate authority may also issue certificates for shorter periods. An expired SSL certificate is marked as "not secure" by browsers and can cause problems for users accessing the site. Therefore, it is important to regularly check the validity period of the SSL certificate and renew it before it expires.

Important Note: An expired certificate damages your site's reputation and can cause you to lose users' trust. Therefore, it may be helpful to consider automatic renewal options.

What is the Difference Between SSL Certificate and TLS?

SSL and TLS are security protocols that essentially perform the same function: securing data communication by encrypting it. TLS is a more advanced and secure version of SSL. It was developed by addressing the security vulnerabilities in SSL and adding new features. Today, most web servers and browsers use the TLS protocol, but it is still commonly referred to as SSL. Technically, if a website uses an "SSL certificate," it may actually be using the TLS protocol.

The following table shows the main differences between SSL and TLS:

Can an SSL Certificate Be Obtained for Free?

Yes, some certificate authorities, such as Let's Encrypt, offer free SSL certificates. Let's Encrypt is an open-source project that makes it easy to obtain and install SSL certificates through an automated process. However, free SSL certificates may have some limitations. For example, they only offer DV (Domain Validated) certificates and do not provide commercial support. If you need a higher level of validation (OV or EV) or commercial support, you may need to purchase a paid SSL certificate. If you are considering obtaining an SSL Certificate, it is important to determine your needs and choose the correct certificate type.

Important Note: While free SSL certificates may be sufficient for small websites and blogs, paid SSL certificates, which are a more reliable and comprehensive solution, should be preferred for e-commerce sites and corporate websites.

Common Problems and Solutions Encountered During SSL Certificate Installation

Some common problems may be encountered during SSL certificate installation. Here are some of these problems and suggested solutions:

• "Not Secure" Warning: This warning indicates that the SSL certificate is not properly installed or is invalid. Make sure the certificate files are uploaded correctly and the web server is configured correctly. Also, check that the certificate has not expired.
• Mixed Content Error: This error indicates that the web page uses both secure (HTTPS) and insecure (HTTP) resources (e.g., images, style sheets). Make sure all resources are loaded over HTTPS.
• Certificate Chain Error: This error indicates that the certificate chain is incomplete. You also need to install the intermediate certificates you received from the certificate authority on your web server.
• Domain Name Mismatch: This error indicates that the domain name covered by the SSL certificate does not match the domain name of the website. Make sure the certificate was obtained for the correct domain name.

Real-Life Examples and Case Studies

Case Study 1: E-commerce Site Security Breach

An e-commerce site experienced a security breach resulting in the theft of customer credit card information because it did not use an SSL certificate. This incident damaged the company's reputation and caused significant financial losses. After the incident, the company installed an SSL certificate and increased security measures.

Case Study 2: Small Business SEO Success

A small business experienced a significant increase in search engine rankings after installing an SSL certificate on its website. This helped the website attract more traffic and increase the number of customers.

Example: A banking website has increased user trust and is better protected against phishing attacks by using an EV SSL certificate. The EV SSL certificate shows the company name in the browser address bar, ensuring that users are on the correct website.