Differences Between TLS 1.2 and 1.3 – What Sets Them Apart?

You’re in the middle of setting up a secure connection for a new web server and need to choose between two protocols: TLS 1.2 vs. TLS 1.3. While they may seem interchangeable, their distinct features could significantly affect your server’s performance and security.

For instance, TLS 1.3 has an improved handshake process that speeds up secure connections. But that’s just the tip of the iceberg. Let’s dive a little deeper into the technical nuances of these two protocols so you understand the differences between TLS 1.2 and 1.3.

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Table of Contents

1. What Is the TLS 1.2 Handshake?
2. What Is the TLS 1.3 Handshake?
3. What Is the Difference Between TLS 1.2 and 1.3?

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What Is the TLS 1.2 Handshake?

To better grasp the TLS 1.2 handshake, let’s see how a client and server establish a secure connection. The first step is the initiation, where the client sends a ‘Client Hello’ message to the server. This message includes the client’s TLS (Transport Layer Security) version, cipher suites, and a random byte string known as a Client Random.

In response, the server sends a ‘Server Hello’ message. This message contains the server’s chosen protocol version, cipher suite, and a Server Random byte string. After this, the server sends its Certificate and Server Key Exchange messages.

Next, the client verifies the server’s certificate with the Certificate Authority (CA). If the verification is successful, the client sends a Client Key Exchange message, which includes a pre-master secret encrypted with the server’s public key.

Both client and server then use the pre-master secret and their respective random byte strings to generate the same symmetric session key. The client then sends a ‘Change Cipher Spec’ message, indicating that it will encrypt all further communication with the session key.

To wrap up the TLS handshake, the client sends an ‘Encrypted Handshake Message’ to confirm the successful establishment of the session key. The server will also send a similar message to the client.

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What Is the TLS 1.3 Handshake?

TLS 1.3 eliminates several steps, reducing the round trips between client and server from two to just one by combining the client and server hello messages. The client sends a ‘Client Hello’ with its supported cipher suites and a random number. Instead of waiting for a server hello, the client sends its key share and predicted cipher and server certificate straight away.

This streamlined process, known as ‘Zero Round Trip Time’ or 0-RTT, not only speeds up the handshake but also significantly improves overall connection time. TLS 1.3 also introduces a concept called ‘Early Data,’ allowing some data to be sent by the client in the first round trip, further improving performance.

Security-wise, the TLS 1.3 handshake enhances privacy by encrypting more of the process. In contrast, TLS 1.2 reveals some details about the server and client in plaintext, posing potential security risks.

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What Is the Difference Between TLS 1.2 and 1.3?

The key difference between TLS 1.2 and 1.3 lies in the handshake process itself. In later versions, such as TLS 1.3, the handshake is simplified and faster due to the reduction of round-trip times – just one of the upgrades that improved performance and security. Understanding the key differences between TLS 1.3 vs. 1.2 will help you transition to the latest 1.3 release.

Round Trip Time (RTT)

Round Trip Time (RTT) is the time it takes for a signal to travel from the sender to the receiver and back. In protocols like TLS, RTT is crucial because it directly affects how quickly a user’s browser and a website’s server establish a secure connection.

In TLS 1.2, when your browser connects to a secure website, the handshake process requires two round trips between the client (your browser) and the server before they can start exchanging data securely.

The two-step handshake in TLS 1.2 introduces a delay, especially noticeable in situations where the distance between the client and server is far, causing higher latency.

On the other hand, TLS 1.3 requires only one round trip between the client and the server to establish a secure connection. By eliminating one round of back-and-forth communication, TLS 1.3 reduces the time to set up a secure connection, resulting in faster and more efficient data transmission.

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Faster TLS Handshake

In TLS 1.2, the initial handshake process occurs in clear text, requiring additional encryption and decryption steps. This process, involving 5-7 exchanged packets between your device and the server, creates a slowdown.

However, TLS 1.3 introduces a change by default. It encrypts the server certificate during the handshake, allowing the TLS handshake to happen with only 0-3 packets, drastically reducing or even eliminating the previous overhead.

As a result, connections are faster and more responsive because there’s less back-and-forth communication between your device and the server during the handshake.

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Cipher Suites

TLS 1.2 supports numerous cipher suites, providing various combinations of encryption, authentication, and hashing algorithms. However, the abundance of options increases the risk of selecting less secure cipher suites, potentially exposing the communication to vulnerabilities.

TLS 1.3 narrows the supported cipher suites to five, all based on the Authenticated Encryption with Associated Data (AEAD) principle. This simplification aims to improve both security and efficiency.

The restricted but secure cipher suite options in TLS 1.3 reduce the complexity of negotiations and mitigate the potential for unintentional use of weak cryptographic algorithms.

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Perfect Forward Secrecy

TLS 1.3 enables Perfect Forward Secrecy (PFS) by default. It means that even if someone manages to steal the secret key used for your secure communication, they can’t decrypt the messages from the past. It’s like changing the locks on your door regularly.

Now, in TLS 1.2, using this extra security feature was optional. So, if you didn’t specifically choose it, there was a chance that if someone got hold of your secret key, they could decrypt and read your previous messages.

In essence, TLS 1.3 ensures that your past data transmission stays locked up, no matter what, providing a higher level of security compared to TLS 1.2.

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Key Exchange Mechanism

TLS 1.2 uses various key exchange methods, including RSA (Rivest-Shamir-Adleman) and Diffie-Hellman. RSA involves the server sending an encrypted pre-master secret to the client, while Diffie-Hellman allows the client and server to establish a shared secret over an open channel. However, TLS 1.2 often defaults to using RSA for key exchange.

Now, in TLS 1.3, there’s a notable shift in the default key exchange mechanism. The protocol mandates the Diffie-Hellman key exchange, specifically the elliptic curve variant (ECDHE). This method ensures a more efficient and secure negotiation of the encryption keys.

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FAQ

Is TLS 1.2 Still Recommended?

TLS 1.2 remains secure if configured to exclude weak ciphers and algorithms; however, the newer TLS 1.3 is preferred due to its support for contemporary encryption, absence of known vulnerabilities, and performance enhancements.

Is TLS 1.3 Enabled by Default?

The default status of TLS 1.3 depends on the specific software or service. However, many modern implementations enable TLS 1.3 by default for improved security and performance. Consult your OS or server documentation for more information.

Is TLS 1.3 More Secure Than 1.2?

Yes, TLS 1.3 is more secure than TLS 1.2. It features enhanced cryptographic algorithms, improved resistance against attacks, and a simplified handshake process. Upgrading to TLS 1.3 is recommended for better security.

Is TLS 1.3 Backwards Compatible With 1.2?

Yes, TLS 1.3 is designed to be backward compatible with TLS 1.2, allowing systems that support TLS 1.3 to communicate with those that only support TLS 1.2.

Why Is TLS 1.3 Handshake Faster Than TLS 1.2?

TLS 1.3 handshake is faster than TLS 1.2 because it reduces the number of round trips required for the handshake process, incorporates more efficient cryptographic algorithms, and minimizes unnecessary data exchanges.

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Bottom Line

You’ve learned that the TLS 1.2 handshake is a complex, multi-step process, while TLS 1.3 simplifies this to a quicker, more secure exchange.

The main differences between TLS 1.2 and 1.3 are efficiency and security. With improved encryption and faster connections, TLS 1.3 is a clear upgrade. So, if you haven’t enabled TLS 1.3 on your server yet, now is the best time to do it.

Upgrading to TLS 1.3 not only boosts performance but also proactively defends against evolving security threats. It’s a move that maintains the integrity and confidentiality of online interactions.