If you're concerned about the security of your data when connecting to the internet from Windows, it's normal to get confused by concepts like TLS, SSL, VPN, OpenVPN, and IPsec . At first glance, they seem the same (they all "encrypt" something), but in reality, they solve different problems and are used at different layers of the communication.
Before you rush to install a VPN app or mess with your browser's advanced settings, it's a good idea to understand exactly what TLS is, what a VPN is, what protocols like SSL or IPsec are for , and, above all, in what situations you should use each one on your Windows PC. Let's take a look at it calmly, but without unnecessary technical jargon.
What is TLS and how does it differ from SSL?
When you hear about "SSL certificate," "secure website," or see the padlock icon in your browser, what's actually being used today is TLS (Transport Layer Security) , the standard protocol that encrypts data between your device and a server on the internet. SSL was its predecessor, but it's now considered insecure and has been phased out of modern systems.
We can say that TLS is a transport layer encryption protocol , which ensures that data traveling between client and server cannot be easily read or manipulated by third parties. It does two key things: it protects the confidentiality of the data and guarantees that it has not been modified along the way.
SSL and TLS had different versions over the years. However, SSL became obsolete long ago. In fact, it has been disabled in reputable browsers and services. Some providers still refer to "SSL certificates" out of habit, even though in practice they are TLS certificates and use only modern versions of the protocol.
How TLS works: encryption, handshake, and certificates
For a TLS connection to work (for example, when accessing a website with HTTPS), an automatic process called a TLS handshake takes place between your browser and the server . It's transparent to you, but it's the foundation of all security.
During this handshake, the client and server exchange information to choose encryption algorithms, authenticate each other, and generate temporary keys that will be used only in that session. This negotiation is based on public-key cryptography and digital certificates issued by certificate authorities (CAs).
Certificates allow your browser to verify the server's identity. They include the domain name, public key, certificate issuer, owner, validity dates, and other information such as subdomains and permitted uses. Without a valid certificate, your browser will display security warnings.
In terms of security, TLS covers three basic pillars:
- Authentication (know who you're talking to).
- Confidentiality (that no one reads the data).
- Integrity (ensuring that the content has not been modified). This is achieved with combinations of symmetric encryption algorithms, hash functions, and message authentication codes (MAC or HMAC).
TLS versions: from 1.0 to 1.3
Over time, TLS has evolved to patch vulnerabilities and improve performance. TLS versions 1.0 and 1.1 were released in 1999 and 2006 respectively, and are now considered obsolete and vulnerable. Therefore, modern browsers no longer support them.
The most widespread version currently is TLS 1.2 , released in 2008. It remains very robust and is installed on most servers and services. Even so, it is already recommended to switch to TLS 1.3 in new environments or when updating a service.
With TLS 1.3 , released in 2018, the protocol was simplified and weak algorithms were eliminated. Performance was also improved by reducing the number of handshake steps, and security requirements were strengthened. Furthermore, modern ciphers such as AES-GCM and ChaCha20-Poly1305 are supported, and future integration of post-quantum algorithms is facilitated.
An important point is that TLS 1.3 is no longer backward compatible with SSL , which prevents downgrade attacks where an attacker forces the use of older, insecure versions, as happened with POODLE-type vulnerabilities.
Key differences between SSL and TLS
Although conceptually SSL and TLS do the same thing, there are technical nuances that make all the difference. TLS improves upon the older SSL in several areas, both in terms of security and performance , and that's why it has become the current standard.
- Handshake processTLS introduces faster and more efficient methods, reducing latency compared to SSL handshakes, which were less optimized and penalized the loading time of web pages more.
- Authentication and integritySSL relied heavily on algorithms that are now broken or weak, such as MD5, while TLS uses HMAC with stronger hash functions and modern cipher suites. This greatly reduces the risk of man-in-the-middle attacks.
- Error alertsIn older versions, many alerts were sent in plain text, something that TLS 1.3 corrects by encrypting all alert messages once the connection is established, so that an attacker cannot extract information about the session's behavior.
- Cipher suitesTLS selects and enforces stronger encryption, discarding weaker options inherited from SSL. This minimizes the margin of error when misconfiguring a server and maintains a more consistent level of security.
Does HTTPS actually use SSL or TLS?
For years HTTPS was referred to as "HTTP over SSL," but by 2026 virtually no serious website maintains SSL support . What is now widely used is HTTPS over TLS 1.2 and, increasingly, over TLS 1.3.
Less than 1% of websites still support SSL in some form, while almost all work with TLS 1.2 and a large majority also support TLS 1.3. At the user level, you only see the padlock and the “https://”, but behind the scenes this security protocol is at work.
When you enter a website and type your card number, credentials, or personal data, TLS encrypts those communications so that, even if someone intercepts the traffic on the network, they will only see unintelligible data.
In addition to encryption, the browser performs a series of comprehensive checks on the website's certificate: signature integrity, expiration date, possible revocation (via OCSP), issuer legitimacy, correspondence with the domain, permitted uses and policy restrictions, among others. Any critical failure in this chain results in a warning or connection block.
Thanks to this validation process, the browser only establishes a secure HTTPS connection if all the conditions are met. If something seems off, you'll see messages like "site not secure," expired certificates, or similar warnings that shouldn't be ignored.
SSL/TLS certificates: what they are and what types there are
Certificates that enable HTTPS and other secure communications are based on public key infrastructure (PKI) . A certificate authority (CA) issues a certificate after verifying certain applicant data and signing it with its private key.
The certificate includes elements such as the Common Name (CN) and often Subject Alternative Name (SAN) extensions to protect multiple domains or subdomains with a single certificate. It also specifies the validation type, validity period, and associated public key.
There are several levels of validation:
- DV (Domain Validation) certificates. They only verify that the applicant controls the domain.
- OV (Organization Validation) CertificatesThey also verify the existence of the company.
- EV (Extended Validation) certificates. They apply a stricter verification process to the entity, although their visual indicator is being used less and less in browsers.
There are also special certificates such as wildcard certificates , which protect a domain and all its top-level subdomains, or SAN certificates, designed to cover multiple different names (ideal in complex corporate environments).
When generating a certificate, a Certificate Signing Request (CSR) is first created , containing the server's public key and identity data. This request is sent to the Certificate Authority (CA), which, after validating the information, issues the signed certificate for installation on the server.
What is a VPN and what does it solve that TLS doesn't cover?
While TLS protects specific connections (for example, between your browser and a website), a VPN protects all network traffic from your device or a part of the network . In other words, it works like an "encrypted tunnel" that all your traffic passes through before reaching the internet.
Technically, a VPN is a virtual private network that runs over a public network (the Internet). It encapsulates and encrypts data packets so that, from the outside, it appears that everything is flowing between your computer and the VPN server, even though it's actually being routed to many different services.
This allows for several interesting uses: hiding your real IP address behind the VPN server's IP, remotely accessing internal resources of a company or home network, bypassing geo-restrictions, and strengthening security when connecting to unreliable public WiFi networks.
Unlike TLS, which is associated with specific protocols like HTTPS or FTPS, a VPN operates at lower layers of the network stack (at the IP or even link level), so it "wraps" virtually everything your computer does without the applications needing to know.
On Windows, you can use built-in VPN clients (for IPsec, for example) or third-party applications that implement protocols like OpenVPN, WireGuard, or other proprietary ones . Each has its advantages, but they all share the idea of creating an encrypted tunnel to a remote server.
Differences between SSL/TLS VPN and IPsec VPN
Within the world of VPNs, there are two main families that should be distinguished: SSL/TLS VPNs and IPsec-based VPNs . Both provide an encrypted tunnel, but they do so in layers and with different technologies.
SSL/TLS VPNs (often simply called “SSL VPN”) are built on top of TLS, the same protocol used for HTTPS. Popular protocols like OpenVPN work this way: they create an encrypted tunnel that typically uses TCP or UDP port 443, making it easier to bypass firewalls and proxies.
In this type of VPN, authentication and encryption rely on X.509 certificates, public and private keys, and parameters such as Diffie-Hellman for secure key exchange. It is a highly flexible solution, especially useful for remote access by individual users from Windows, macOS, or mobile devices.
On the other hand, IPsec VPNs use the IPsec (Internet Protocol Security) protocol , which operates directly at the network level (layer 3). IPsec provides authentication, integrity, and encryption to IP packets through various modes and algorithms.
IPsec VPNs are very common in corporate environments to connect entire networks (Net-to-Net) or to implement remote access solutions integrated into the operating system, since Windows has included support for IPsec for years.
Regulations and standards that support the use of VPN and TLS
Both TLS and VPNs are not just a technical recommendation; in many cases, they are a requirement for complying with data protection regulations and security standards. In fact, many regulatory frameworks mention them explicitly or implicitly.
In the European Union, the GDPR insists that personal data must be protected with appropriate technical measures, including encryption. The use of TLS for web communications and VPNs for remote access to systems containing sensitive data fits perfectly within this approach.
In the healthcare sector, regulations such as HIPAA (in the United States) require the protection of the confidentiality of medical information, which in practice means encrypting data in transit using TLS and often encapsulating internal access through VPN.
Other standards such as PCI-DSS, which is geared towards the management of credit card data, clearly require the use of strong encryption in communications and administrative remote access, which usually translates into secure HTTPS and properly configured VPNs.
Many technical specifications for public or private contracts explicitly require the use of TLS 1.2 or higher and IPsec or SSL/TLS VPN to guarantee the security of connections between sites and users , which shows that these technologies are already a de facto standard.
When to use TLS and when to use VPN on Windows?
On a Windows PC, TLS and VPNs don't compete; rather, they complement each other. The choice depends on the problem you want to solve, so it's important to understand what each technology offers in everyday use.
If you simply want to browse the internet securely, enter passwords, or pay by card on a website, your browser needs to establish HTTPS connections based on TLS . You don't need a VPN just to view a secure website, as long as the site is properly configured.
On the other hand, if you need to connect from home to your company's internal network, access shared folders, or use office printers, then we're talking about a typical VPN usage scenario in Windows . The VPN tunnel will give you an internal IP address and routes to those resources.
Another reason to consider a VPN is when you frequently connect to public Wi-Fi (cafes, hotels, airports). Although many websites use HTTPS, some services and applications still don't encrypt all their traffic, and a VPN can offer an additional layer of protection for the rest of your connections.
Finally, if your goal is to change your apparent location (for example, to access country-restricted content), TLS won't help you at all. In that case, you need a commercial VPN with servers in the region you're interested in, because the VPN hides your real IP address behind the IP address of the remote server.
How to set up SSL/TLS VPNs with OpenVPN (overview)
OpenVPN is one of the best-known and most widely used VPN protocols, especially in Linux environments, and is also integrated into many Windows clients. It relies on OpenSSL and X.509 certificates to implement SSL/TLS encryption.
In this model, a small internal certificate authority (CA) is typically set up first using tools like easy-RSA. From there, certificates are generated for the VPN server and for each client, as well as the Diffie-Hellman parameters necessary for key exchange.
Typical files include the CA certificate (e.g., ca.crt ), the server certificate and its private key (server.crt, server.key), the DH parameters (dh.pem), and, for each user, their own certificate and key pair (client.crt, client.key).
On the server side, OpenVPN is configured to create a virtual interface (tun or tap), define the VPN network, specify the path to each certificate file, and enable or disable routing between networks . The configuration changes slightly depending on whether routed (IP tunnel) or bridged mode is used.
On the Windows client, the OpenVPN software is installed, the necessary certificates are copied to the appropriate locations, and a configuration file is used that specifies the server's IP address or domain, the port, the interface type (tun/tap), and the certificate location . When the connection is established, if everything is correct, a virtual network interface is created, and traffic is routed through the tunnel.
Understanding what each piece (TLS, legacy SSL, SSL/TLS VPN, IPsec) does and how they fit into your Windows connection style allows you to make much better decisions: when to rely on the browser's padlock , when to set up a VPN tunnel, and how to configure both to balance security, performance, and regulatory compliance without overcomplicating things.