TLS (Transport Layer Security) Explained: Why TLS 1.3 is the New Standard

Transport Layer Security (TLS) is the backbone of secure online communications. From securing a bank transaction, sending an encrypted email via S/MIME, or protecting an authentication attempt into a corporate VPN remotely, to connecting to a secure Wi-Fi network using RADIUS, TLS ensures that your data remains private and unaltered. In short, every organization relies on TLS to keep the sensitive data safe from interception, tampering, and replay attacks during transit.

With its roots in Secure Socket Layer (SSL), TLS has evolved over time and has undergone several iterations to address weaknesses and adapt to evolving threats.

The latest version, TLS 1.3, allows organizations to have access to more secure and more resilient encryption, with faster handshakes, removal of outdated cipher suites, and enforced forward secrecy against modern attacks like protocol downgrades and passive decryption, without sacrificing performance.

In this blog, we’ll explore what TLS is, how it works, and why TLS 1.3 is the version enterprises should use to combat modern threats.

The Transition from SSL to TLS

While performing a network connection and communication without encryption is possible, it’s risky. The connection would be open to eavesdropping or even theft. If you’re communicating an email login with an unsecured website, that login could potentially be viewed and used for unauthorized access.

SSL was created in 1995 to combat theft and secure network connections. The first generation was updated in 1999 and renamed to TLS with security and communication protection improvements. While SSL is not supported today by modern processes, the acronym has become synonymous with TLS and is still used.

It ensures three key principles of communication security:

• Encryption – Keeps your data private by preventing eavesdropping.
• Authentication – Confirms that you’re talking to the server you intended (and not an imposter).
• Integrity – Guarantees that your data hasn’t been tampered with during transmission.

SSL and TLS are protocols to establish authenticated and encrypted links between computers, websites, servers, and more. To establish this link, they use an encryption protocol that ensures no outsiders can read the messages transferred between the two parties. To establish this link, they bind identities to cryptographic key pairs via certificates.

Two main encryption types are used to authenticate with keys: asymmetric and symmetric. With symmetric encryption, both parties use a single shared key to encrypt and decrypt communications. This highly efficient method can be quickly processed because it involves only one key. However, using one key is less secure than asymmetric encryption.

Asymmetric encryption occurs when both parties hold one key in a key pair. In this situation, the server securely holds the private key, while clients freely receive the public key. When authenticating, the public key encrypts a message sent to the server and can only be decrypted by the private key. Without the private key, the message is unreadable. This method is more secure than symmetric encryption but is more resource-intensive.

Each key is bound to a TLS certificate that contains identifying information about the holder. A Certificate Authority (CA) signs TLS certificates, adds identifying information, and distributes them to user devices, servers, or other tech. As a result, when a certificate is sent to be authenticated, the receiver can quickly see that a trusted CA signs the certificate and move forward with the authentication. The subsequent process that establishes trust is known as the TLS handshake.

The TLS Handshake

The TLS handshake is a series of communications between two entities that establishes trust before allowing regular network communication. This process occurs when opening an HTTPS website or authenticating to a RADIUS server. This exchange makes sure that both parties can communicate privately and that the server’s identity can be verified before any sensitive data is shared.

Here’s a simplified breakdown of how a TLS 1.3 handshake works:

1. ClientHello – The client initiates the connection by sending the supported TLS version (1.3) and a key share.
2. ServerHello – The server selects the TLS version (typically TLS 1.3) and key share, then provides its digital certificate.
3. Key Exchange and Authentication – Using ECDHE (Elliptic Curve Diffie-Hellman Ephemeral), both sides derive a shared key and verify each other’s identities.
4. Encrypted Communication – Both client and server confirm that the handshake was successful, and encrypted communication begins.

The entire process is speedy in real-time and establishes a secure connection between the parties. This process is vitally important and should be the benchmark before communicating sensitive information. For example, you should be sure that any website you’re using has undergone a TLS handshake before gaining access.

Session Resumption

There are scenarios in enterprise environments where clients often reconnect to the same server multiple times, such as VPN tunnels or Wi-Fi authentication. TLS 1.3 addresses this with session resumption, which allows a returning client to skip the full cryptographic handshake. By reusing previously negotiated keying material, the client and server can quickly re-establish a secure session while reducing latency and ensuring strong security.

The Evolution of TLS Versions

TLS has evolved significantly over the last two decades, with each version addressing vulnerabilities and adapting to the demands of modern cryptography.

TLS 1.0 and 1.1

Introduced in 1999 and 2006, these early versions laid the groundwork for encrypted communications but relied heavily on outdated cipher suites such as RC4 and CBC. Modern compliance frameworks prohibit their use, and both protocols are now formally deprecated and blocked by all major browsers and operating systems due to well-documented security flaws.

TLS 1.2

Released in 2008, this version became the backbone of secure communications. It introduced support for modern ciphers (like AES) and stronger hash functions (SHA-256), significantly improving resilience against attacks. While still in widespread use, regulatory standards such as PCI DSS and HIPAA now mandate TLS 1.2 or higher, pushing organizations towards migration.

TLS 1.3

Published in 2018, TLS 1.3 represents a significant protocol redesign and is the most secure and efficient version. It addresses long-standing attack vectors like replay attacks, mitigated by carefully handling 0-RTT data. Built-in downgrade protection blocks adversaries from forcing clients and servers to fall back to weaker protocol versions. The protocol simplifies cipher suite negotiation, removing legacy options and padding mechanisms that attackers often used for downgrade and negotiation attacks.

Beyond stronger cryptography, TLS 1.3 also introduces meaningful privacy enhancements. Features such as Encrypted Server Name Indication (ESNI) and its successor Encrypted ClientHello (ECH) conceal the hostname a client is connecting to, preventing ISPs, middleboxes, or attackers on the wire from easily tracking user activity even when traffic is encrypted. This shift acknowledges that metadata can be just as valuable to attackers as the data itself.

These enhancements make TLS 1.3 significantly more resilient against common attack classes that affected earlier versions. The result is stronger security and lower latency, making it the preferred standard for modern, high-performance applications.

TLS 1.3: What’s New and Why It Matters

TLS 1.3 is more than just an update. It brings major security and performance improvements over earlier versions:

Faster Handshake with 0-RTT

Unlike TLS 1.2, which required multiple round-trips to establish a session, TLS 1.3 provides faster performance by streamlining the handshake to a single round trip (1-RTT). It also supports 0-RTT session resumption, allowing returning clients to reconnect almost instantly, aiding faster HTTPS connections, reducing latency, and improving user experience. That speed, however, comes with a certain tradeoff. Because 0-RTT data is sent before the handshake is fully validated, it is susceptible to replay attacks. An attacker who captures 0-RTT traffic could attempt to resend it, making it unsuitable for sensitive operations like financial transactions. In practice, many enterprises either disable 0-RTT or restrict its use to low-risk scenarios where performance is more important than replay protection.

Removal of Legacy Cryptography

The major vulnerabilities in TLS 1.2 stemmed from its continued support of legacy cryptographic algorithms. TLS 1.3 eliminates these outdated ciphers, reducing the attack surface and significantly improving resistance to modern cryptographic attacks. Ciphers such as RC4, SHA-1, and CBC-based modes are no longer supported. It mandates the use of modern AEAD (Authenticated Encryption with Associated Data) ciphers, like AES-GCM and ChaCha20-Poly1305, ensuring both confidentiality and integrity.

Mandatory Forward Secrecy

Unlike TLS 1.2, where forward secrecy was optional, all TLS 1.3 sessions rely on ECDHE (ephemeral Diffie-Hellman key exchange), which ensures forward secrecy. This means that even if a server’s private key is compromised in the future, past communications will remain secure.

Real-World Adoption of TLS 1.3

Modern operating systems, browsers, and application platforms widely support TLS 1.3. However, adoption requires thoughtful configuration to balance security, compliance, and backward compatibility.

Web Servers and Infrastructure

Modern web servers such as Apache (2.4.36+), Nginx (1.13+), and Microsoft IIS (Windows Server 2022) all provide TLS 1.3 support with minimal configuration. Cloud services like AWS ELB, Azure Front Door, and Cloudflare enable TLS 1.3 by default. Administrators enable both TLS 1.2 and 1.3 so newer clients can use the stronger protocol while older systems can still connect.

Compliance

Compliance frameworks such as PCI DSS 4.0, HIPAA, and NIST SP 800-52r2 guidelines require TLS 1.2 or higher, so TLS 1.3 checks the box and goes beyond it. Because it enforces forward secrecy and removes outdated cryptographic options, TLS 1.3 exceeds the minimum compliance requirements, strengthening an organization’s security posture.

Compatibility

All major browsers (Chrome, Firefox, Safari, Edge) and operating systems (Windows 10/11, macOS, iOS, Android, Linux distributions with OpenSSL 1.1.1+) fully support TLS 1.3. The primary compatibility challenge is with legacy applications and embedded/IoT devices that still rely on TLS 1.0 or 1.1. That’s why most organizations often use a dual-stack approach or a progressive deployment strategy, i.e., keeping TLS 1.2 around during the transition to TLS 1.3, ensuring interoperability, and eventually phasing out the older versions once the impact is minimal. This staged approach ensures a smooth transition while maximizing the security and performance benefits of the new protocol.

A Modern Approach to Network Security with TLS and SecureW2

TLS 1.3 represents the future of secure communication. It addresses the shortcomings of older versions, brings in stronger cryptography, and delivers faster performance. For organizations, TLS 1.3 has become essential for staying compliant and ensuring top-level security. If you haven’t already updated, now is the time.

However, upgrading to TLS 1.3 is only part of the equation. You need a modern certificate management strategy to take advantage of its security benefits. That’s where SecureW2 comes in.

SecureW2’s JoinNow Connector, a Cloud PKI solution, opens up new possibilities for SSL setup and ensures the highest level of security for network authentication. It provides a single certificate production and maintenance platform, streamlining SSL management. This implies that organizations may eliminate the need for costly infrastructure and the hassle of managing or maintaining their SSL operations. No extra fees are associated with storing all of the keys in an HSM.

The JoinNow onboarding solution is the most efficient certificate provisioning experience for the end user. All the user must do is enter their IDP credentials, and they are quickly configured for EAP-TLS and issued a certificate. Our live enforcement within our defense-in-depth framework continuously monitors and adapts trust decisions in real-time, ensuring that certificates respond to changing device posture and risk. Meanwhile, our management portal delivers full visibility and tracking, to give you an accurate picture of who is on the network and what device they use.

If your organization isn’t utilizing TLS, it could be at greater risk for outside attacks and accidental exposure.