SSL certificates are a core technology for ensuring the security of network communications. They act like a “digital key,” establishing an encrypted connection between the client (such as a browser) and the server, thereby guaranteeing the confidentiality, integrity, and authenticity of data transmission. In today’s web environment, where HTTPS is the standard, correctly deploying SSL certificates has become a fundamental and critical task, whether it’s for search engine rankings, user trust, or compliance with regulatory requirements.
The core types and differences of SSL certificates
Understanding the different types of SSL certificates is the first step in making the right choice. Certificates are mainly classified based on the verification method and the scope of domain names they cover.
Domain Validation Certificate
Domain Name Validation (DV) certificates are the type of certificate with the lowest acquisition cost and the fastest issuance process. The certificate authority only verifies the applicant’s control over the domain name, typically by sending an email to the registered email address for that domain, setting up DNS resolution records, or uploading a specified file to the website’s root directory. DV certificates are suitable for personal websites, blogs, testing environments, or internal services. They provide encryption for communications, but the company name is not displayed in the browser’s address bar, resulting in relatively basic security levels.
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Organizational validation type certificate
Organizational Validation (OV) certificates have a higher security level than Domain Validation (DV) certificates. In addition to verifying the ownership of a domain name, the Certificate Authority (CA) also confirms the actual existence of the applying organization by checking, for example, its registration information with the relevant authorities. This ensures that OV certificates can prove to users that the website is associated with a real, legitimate entity. OV certificates are commonly used for corporate websites, e-commerce platforms, and other formal business websites that require user trust. Information about the organization can be found in the details of the OV certificate.
Extended Validation Certificate
Extended Validation (EV) certificates represent the highest level of security and undergo the most stringent verification processes. The Certificate Authority (CA) conducts a comprehensive review of the applying organization, including legal, physical, and operational aspects. Websites that use EV certificates display the most recognizable signs of trust in major browsers: a green address bar or the direct display of the company’s name. This provides the strongest form of identity verification for websites in industries with high trust requirements, such as finance, payments, and large e-commerce platforms, effectively protecting them from phishing attacks.
Classification based on coverage: Single domain name, wildcard, multiple domain names
In addition to the verification level, certificates are also classified based on the number of domains they cover. A single-domain certificate only protects one fully qualified domain name (for example: www.example.comWildcard certificates can protect a primary domain name and all its subdomains at the same level (for example, …) *.example.comThis is suitable for platforms that have multiple subdomains. A multi-domain certificate allows you to include multiple different fully qualified domain names in a single certificate, which facilitates the management of multiple independent domains for organizations.
How to apply for and obtain an SSL certificate
The process of applying for an SSL certificate typically involves several standard steps: selecting the type of certificate, generating a CSR (Certificate Signing Request), undergoing verification, and then downloading and installing the certificate.
Select a certificate provider and generate a CSR (Certificate Signing Request).
First, select the appropriate CA (Certificate Authority) or its agent based on the website's requirements (such as the level of validation required and the number of domains to be certified). Next, generate a Certificate Signing Request (CSR) on your web server. The CSR contains your public key as well as the organization information that will be included in the certificate (country, province, city, organization name, domain name, etc.). When the CSR is generated, a private key is also created automatically; this private key must be securely stored on the server and must not be disclosed under any circumstances.
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Complete the verification required by CA.
After submitting the CSR (Certificate Signing Request), you need to complete the validation process with the CA (Certificate Authority) based on the type of certificate you have applied for. For DV (Domain Validation) certificates, the validation is usually completed within a few minutes through DNS or file verification. For OV (Organizational Validation) and EV (Extended Validation) certificates, the CA may contact the organization phone number you provided or request the submission of legal documents such as a business license; this process may take several days.
Download and back up the certificate file.
After the verification is successful, the CA will issue the certificate. You will need to download the certificate file from the CA’s console (it is usually in a specific format, such as .crt or .pem)..crtOr.pem(The format) as well as any possible intermediate certificate chain files. Make sure to back up the certificate files and the locally generated private key files for use in case of server migration or reset.
Mainstream Web Server Deployment Guidelines
After obtaining the certificate file, it needs to be deployed on the web server. The configuration process varies depending on the server software used.
Configure it on the Nginx server
For Nginx, you need to edit the website's configuration file (which is usually located in…) /etc/nginx/sites-available/The core aspect is the configuration. ssl_certificate and ssl_certificate_key Instructions.ssl_certificate Point to the merged file that contains your server certificate and the intermediate certificate chain (or specify them separately).ssl_certificate_key This is the path to your private key file. Once the configuration is complete, use it accordingly. nginx -t Test the configuration syntax; once it is confirmed to be correct, systemctl reload nginx Reload the service.
Configure on the Apache server
In Apache, you need to enable… ssl The module should be used in the configuration file of the virtual host. SSLCertificateFile The instruction specifies the path to your server certificate file. Please use it accordingly. SSLCertificateKeyFile The instruction specifies the path to the private key file. SSLCertificateChainFile The command specifies the intermediate certificate chain file (if it has not been merged already). After saving the configuration, restart the Apache service to apply the changes.
Configure on the IIS server.
In a Windows server and IIS environment, graphical operations are typically performed using the IIS Manager. You need to transfer the certificate file (such as…) .pfx Import the certificate (including the private key) into the “Computer Accounts” certificate store on the server. Then, in IIS Manager, select your website, go to the “Bindings” settings, and add a new binding with the following type: https Bind the certificate, and then select the certificate you imported from the SSL certificate dropdown menu.
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After all the deployments are completed, it is highly recommended to use online SSL inspection tools (such as SSL Labs’ SSL Test) to conduct a comprehensive scan of your configuration. This will ensure that there are no configuration errors, that strong encryption suites are being used, and that you receive a high security rating.
The maintenance and management of SSL certificates
Deploying certificates is not a one-time task; effective lifecycle management is crucial for maintaining ongoing security.
Monitoring certificate validity and timely renewal
SSL certificates have a clear expiration date (currently up to 13 months). Once a certificate expires, a security warning will appear on the website, causing service interruptions. It is essential to establish an effective monitoring system to initiate the renewal process 30–45 days before the certificate expires. Many Certificate Authorities (CAs) or certificate management platforms offer automatic expiration alerts, and some even support automated renewal.
Processing of certificate revocations
If the private key is accidentally leaked, or if the website domain name or organization information changes, you need to immediately revoke the existing certificate and request a new one from the CA (Certificate Authority). Once revoked, the certificate will be added to the certificate revocation list, and browsers will no longer trust it. This is an important security emergency procedure.
Forcing HTTPS and HTTP redirection
After deploying an SSL certificate, the best practice is to enforce the use of HTTPS for all traffic. This can be achieved by permanently redirecting all HTTP requests (on port 80) to the corresponding HTTPS address (on port 443) in the web server configuration using a 301 redirect. This ensures that users are always connected via an encrypted connection, which also benefits search engine optimization (SEO).
summarize
SSL certificates are the foundation for implementing HTTPS encryption and establishing the credibility of a website. Understanding the differences in security levels between DV, OV, and EV certificates is essential, as is selecting the right type of certificate (single-domain, wildcard, or multi-domain) based on the specific needs of your website. The process of applying for and verifying the certificate, as well as correctly deploying it on servers such as Nginx, Apache, or IIS, is also critical. Once the certificate is deployed, ongoing maintenance and management—particularly monitoring its validity period and enforcing the use of HTTPS—are key to maintaining long-term security and credibility. By following this guide, you will be able to establish a strong security barrier for your website.
FAQ Frequently Asked Questions
What are the differences in the display of DV, OV, and EV certificates in browsers?
DV certificates only enable HTTPS and display a lock icon; they do not show the organization’s name. OV certificates include organizational information in their details. EV certificates, on the other hand, display the company’s name in green directly in the address bar of certain browsers, providing the highest level of visual trust indication.
If I renew a certificate after it has expired, do I need to generate a new CSR (Certificate Signing Request) and a new private key?
For best security practices, it is recommended to generate a new CSR (Certificate Signing Request) and private key pair with each renewal. This helps to reduce the risks associated with the long-term use of old private keys. Of course, in some cases, it is possible to reuse the old CSR, but the security level will be lower as a result.
Can an SSL certificate be used on multiple servers?
Sure, as long as these servers host the same domain name (or the set of domain names covered by the same certificate). You will need to securely deploy the same certificate file and private key to each server that needs to provide HTTPS services.
Will deploying an SSL certificate affect the speed of a website?
The initial SSL/TLS handshake process when establishing an HTTPS connection consumes very little additional CPU resources and causes a slight increase in latency (referred to as “TLS latency”). However, due to the high performance of modern computers, as well as optimizations in protocols like TLS 1.3, the impact is minimal for the vast majority of websites. The benefits in terms of security and trust far outweigh the minor performance costs.
What's next, what's next?
Extended reading and practical knowledge
The following are related to the topic of this article and are suitable for further in-depth reading. Prioritize starting with the article that is closest to your current problem, and gradually expanding to surrounding topics usually works better.
- What is an SSL certificate? A comprehensive explanation from its principles to the process of applying for and using it.
- What is an SSL certificate? A comprehensive guide to understanding the principles, types, and installation procedures of digital certificates.
- In-depth Analysis of SSL Certificates: From Beginner to Expert – Comprehensive Protection for Website Security
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