TLS 1.2 vs TLS 1.3
TLS 1.2 and TLS 1.3 in brief
TLS 1.2 vs 1.3 compares two versions of Transport Layer Security (TLS), the protocol that encrypts HTTPS connections. Both are widely supported, but TLS 1.3 is the newer design, published in 2018, that makes connections faster and removes options that had become weak.
Each version defines how a client and server agree on keys and ciphers, verify each other and then exchange encrypted data. Most of the differences sit in the handshake, the opening exchange that sets up the connection.
How the handshake differs
In TLS 1.2, the handshake usually takes two round trips between client and server before application data can flow. Each round trip adds network latency, which matters most on mobile connections or when the server is far away.
TLS 1.3 reduces this to one round trip in the common case. The client sends its key share in the first message, so the server can answer with its own share and its certificate in one go. TLS 1.3 also encrypts more of the handshake, which exposes less information to observers on the network.
TLS 1.3 offers a faster path for returning visitors as well. Resumption with 0-RTT lets a client send data in its first message, but that data can be replayed by an attacker. Servers therefore accept it only for requests that are safe to repeat, such as simple page loads.
What TLS 1.3 removed and why
TLS 1.2 supports many options, and some of them are weak or hard to configure safely. TLS 1.3 removes older building blocks, including RSA key exchange, which does not provide forward secrecy, and many older cipher suites.
In TLS 1.3, every connection uses forward secrecy, and the list of allowed ciphers is short. The choices are limited to modern authenticated encryption, which reduces the chance that a site accidentally enables a weak option.
The trade-off is compatibility. A few old clients and devices support only TLS 1.2, so a server that still serves them needs TLS 1.2 enabled. Most current browsers and operating systems support both versions, so a server that offers both reaches the widest audience.
An online shop with mixed visitors
An online shop with customers around the world sees a mix of visitors. Most use recent browsers that negotiate TLS 1.3, which means faster page starts. A small share uses older devices, such as legacy point-of-sale terminals, that speak only TLS 1.2.
Keeping TLS 1.2 enabled lets those customers still connect, while TLS 1.3 gives everyone else the faster handshake. The shop does not need to choose one version for all visitors, because the client and server agree on the best version they both support.
Frequently asked questions
Is TLS 1.3 faster than TLS 1.2?
Usually yes. TLS 1.3 needs one fewer round trip for a new connection, which reduces the delay before the first data arrives. The real difference depends on latency, the content and whether the connection can be resumed. The gain is noticeable on distant or mobile connections and small on a fast local network.
Should a website turn off TLS 1.2?
Usually not. Disabling TLS 1.2 would block visitors whose devices or software support only that version. Most sites offer TLS 1.3 alongside TLS 1.2 and let the client pick the best version that both sides support. The older version is used only when the newer one is not available. The retired versions are covered in the deprecated protocols article.