Key differences Between TLS 1.2 and TLS 1.3

Transport Layer Security (TLS) is a foundational technology for online privacy. As a cryptographic protocol, Transport Layer Security encrypts data and authenticates connections when moving data over the internet via HTTP—an extension of the protocol known as HTTPS (Hyper Text Transfer Protocol Secure). When a user visits a website, their browser checks for a TLS certificate on the site. If one is present, their browser performs a TLS handshake to check its validity and authenticate the server. Once a link has been established between the two servers, TLS encryption and SSL decryption enable secure data transport

Since its initial definition in January 1999, Transport Layer Security has gone through a series of updates. The most recent, TLS 1.3, was released in August 2018. The differences between TLS 1.2 and 1.3 are extensive and significant, offering improvements in both performance and security. At the same time, TLS 1.2 remains in widespread use given its absence of known vulnerabilities and its continued suitability for enterprise use. The decision of whether or when to upgrade to TLS 1.3 is an open question for many organizations.

How do Secure Sockets Layer (SSL) and Transport Layer Security (TLS) Differ?

Like its successor Transport Layer Security, Secure Sockets Layer (SSL) is a cryptographic protocol that extends HTTP to authenticate internet connections and enable encryption and SSL decryption for data communication over a network. In fact, TLS is a direct evolution of SSL and introduced to address security vulnerabilities in the earlier protocol. The differences between the two are relatively minor, such as the stronger encryption algorithms and ability to work on different ports offered by TLS. The terms are used somewhat interchangeably, and the same certificates can be used with both TLS and SSL. Still, all releases of SSL have been deprecated, and most modern browsers no longer support the protocol.

TLS 1.2 vs TLS 1.3: What are the Main Differences?

TLS 1.3 offers several improvements over earlier versions, most notably a faster TLS handshake and simpler, more secure cipher suites. Zero Round-Trip Time (0-RTT) key exchanges further streamline the TLS handshake. Together, these changes provide better performance and stronger security.

Differences between TLS 1.2 and TLS 1.3 Full Handshake
TLS 1.3 is faster than its predecessors

A Faster TLS Handshake

TLS encryption and SSL decryption require CPU time and add latency to network communications, somewhat degrading performance. Under TLS 1.2, the initial handshake was carried out in clear text, meaning that even it needed to be encrypted and decrypted. Given that a typical handshake involved 5 – 7 packets exchanged between the client and server, this added considerable overhead to the connection. Under version 1.3, server certificate encryption was adopted by default, making it possible for a TLS handshake to be performed with 0 – 3 packets, reducing or eliminating this overhead and allowing faster, more responsive connections.

Simpler, Stronger Cipher Suites

In addition to reducing the number of packets to be exchanged during the TLS handshake, version 1.3 has also shrunk the size of the cipher suites used for encryption. In TLS 1.2 and earlier versions, the use of ciphers with cryptographic weaknesses had posed potential security vulnerabilities. TLS 1.3 includes support only for algorithms that currently have no known vulnerabilities, including any that do not support Perfect Forward Secrecy (PFS). The update has also removed the ability to perform “renegotiation,” in which a client and server that already have a TLS connection can negotiate new parameters and generate new keys, a function that can increase risk.

Zero Round-Trip Time (0-RTT)

As with SSL, TLS relies on key exchanges to establish a secure session. In earlier versions, keys could be exchanged during the handshake using one of two mechanisms: a static RSA key, or a Diffie-Hellman key. In TLS 1.3, RSA has been removed, along with all static (non-PFS) key exchanges, while retaining ephemeral Diffie-Hellman keys. In addition to eliminating the security risk posed by a static key, which can compromise security if accessed illicitly, relying exclusively on the Diffie-Hellman family allows the client to send the requisite randoms and inputs needed for key generation during its “hello.” By eliminating an entire round-trip on the handshake, this saves time and improves overall site performance. In addition, when accessing a site that has been visited previously, a client can send data on the first message to the server by leveraging pre-shared keys (PSK) from the prior session—thus “zero round-trip time” (0-RTT).

How A10 Networks Supports TLS Encryption and SSL Decryption

Encrypted traffic can create a security blind spot, making it possible for threat actors to hide malware, ransomware, and other cyberattacks targeting an organization. A10 Networks Thunder® SSL Insight (SSLi®) eliminates the blind spot introduced by TLS encryption by providing an efficient way to decrypt and inspect incoming traffic without impacting performance. Instead of having each security device in the network environment decrypt, inspect, and re-encrypt data in turn, which can have significant negative impacts on performance, scalability, and cost, the A10 Networks solution enables data to be decrypted once, inspected by each element of the security stack, and then re-encrypted once. Operating as a full proxy, which enables adjusting of cipher suite selection for encryption, the solution supports both TLS 1.2 and TLS 1.3, and will support future versions as well. In this way, SSL Insight addresses the challenges introduced by TLS 1.3, while making the network more resilient and future-proof.


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August 3, 2020

About Babur Khan

Babur Nawaz Khan is a Technical Marketing Engineer at A10 Networks. He primarily focuses on A10's Enterprise Security and DDoS Protection solutions. Prior to this, he was a member of A10's Corporate Systems Engineering team, focusing on Application Delivery Controllers. Babur holds a master's degree in Computer Science from the University of Maryland, Baltimore County. READ MORE