Securing communication between devices is critical. For business owners managing IoT devices or handling sensitive data, understanding security protocols like TLS (Transport Layer Security) is essential. TLS is a protocol that ensures data exchanged over the internet remains private and secure, making it a cornerstone of online security.
A key component of TLS is the TLS handshake—the process by which secure communication is established between devices. In this guide, you’ll learn what is a TLS handshake, how it works, and why it’s vital for maintaining secure connections.
What is a TLS handshake?
The TLS handshake is the process that starts secure communication on the internet. It creates a safe connection between a client, like a web browser, and a server, such as a website. During this process, the client and server agree on how to encrypt data, verify each other’s identity, and share the keys needed to keep the data safe.
Understanding the TLS handshake can help you secure your organisation from a cyber-attack. Ensuring every communication starts with a proper handshake helps prevent unauthorised access and keeps your data secure. This handshake is a key part of the SSL/TLS protocol, which protects data sent over the internet.
The TLS handshake is essential for making sure that any data shared online stays private and unaltered. It’s the step that begins a secure session between a client and server, ensuring your online interactions are safe. If you’ve ever wondered how TLS handshake works or what it means, it’s essentially the procedure that kicks off a secure session between a client and server.
How does a TLS handshake work?
To understand how a TLS handshake works, it helps to break the process into simple steps. The handshake involves several exchanges between the client and server, but despite being complex, it all happens in just a few seconds. This quick process ensures that users don’t experience noticeable delays in their online activities.
The main purpose of the TLS handshake is to create a secure session between the client and server. This session is encrypted, meaning any data shared during the communication is protected. During the handshake, the client and server verify each other’s identity, agree on how to encrypt data, and generate the keys needed for encryption.
Whether you’re securing IoT devices or need to encrypt email communication, knowing how the TLS handshake works is key to improving your risk profile. Understanding this process helps you ensure that your business communications remain safe from potential threats and unauthorised access. By mastering the TLS handshake, you can enhance the overall security of your digital infrastructure.
When does a TLS handshake occur?
A TLS handshake happens at the very beginning of a communication session between a client and a server, before any data is exchanged. For example, when you visit a website that uses HTTPS, your browser starts a TLS handshake with the website’s server to set up a secure connection. This handshake is essential whenever secure communication is needed.
When workplace devices connect to a central server, the handshake ensures the connection is secure and protected from eavesdropping or tampering. During this process, the client and server agree on how to encrypt the data for the session. This step is crucial in preventing cyber-attacks, ensuring that unauthorised parties cannot intercept or alter the data being exchanged.
What happens during a TLS handshake?
During a TLS handshake, several important steps occur to create a secure connection. First, the client sends a “ClientHello” message to the server, listing its supported encryption methods and including a random value called a “nonce.” This message starts the process of establishing a secure link between the client and server.
The server then responds with a “ServerHello” message, choosing an encryption method from the options provided by the client. Along with this, the server sends its digital certificate, which includes its public key. This certificate allows the client to verify that the server is legitimate and trustworthy.
After verifying the server’s certificate, the client generates a “pre-master secret,” which it encrypts using the server’s public key before sending it back. This pre-master secret is crucial, as both the client and server use it to generate session keys. These session keys are then used to encrypt the data exchanged during the secure communication session.
What are the steps of a TLS handshake?
The TLS handshake consists of several key steps, each essential for creating a secure connection. These steps ensure that both the client and server agree on encryption methods and verify each other’s identity before any data is exchanged. This process is designed to protect the communication from unauthorised access.
First, the client sends the “ClientHello” message to the server, which includes information about the client’s supported encryption methods, a random nonce, and other necessary details. This step is the client’s way of saying, “Here’s what I can support; let’s agree on how to communicate securely.” It’s the first move in agreeing on how to protect the data being shared.
Next, the server responds with a “ServerHello” message, selecting an encryption method from the client’s list. This message also includes the server’s own random nonce and its digital certificate, which contains the server’s public key. The digital certificate is crucial, as it allows the client to verify that the server is authentic and trustworthy.
Once the client verifies the server’s certificate, it generates a “pre-master secret,” encrypts it with the server’s public key, and sends it back to the server. Both the client and server use this pre-master secret to generate session keys, which will be used to encrypt and decrypt the data during the session. This ensures that the communication remains secure and private.
Finally, both the client and server send “Finished” messages to each other, confirming that the handshake is complete. At this point, the secure communication session begins, with all data being encrypted using the session keys. This marks the start of a protected exchange of information between the client and server.
What is different about a handshake in TLS 1.3?
TLS 1.3 introduces several changes to the traditional handshake process, making it faster and more secure than earlier versions. These improvements make the protocol more efficient and safer for modern communications. Understanding these differences can help you decide if upgrading to the latest version is right for your business.
One of the biggest changes in TLS 1.3 is the reduction in the number of handshake steps. By combining several steps from previous versions, TLS 1.3 completes the handshake more quickly. This speed boost is especially helpful for IoT devices, which often need fast and efficient communication.
Another important change in TLS 1.3 is the removal of weaker cryptographic algorithms. The protocol no longer supports outdated encryption methods, ensuring that all communications are protected with the strongest encryption available. This improvement greatly reduces the risk of cyber-attacks, making TLS 1.3 a critical update for businesses focused on security.
FAQs about TLS handshakes
Is TLS 1.1 better than 1.2 handshake?
TLS 1.2 is generally considered better than TLS 1.1 because it offers stronger security features. It supports more advanced encryption algorithms and provides better protection against certain types of attacks. Upgrading to TLS 1.2 or higher is recommended for the best security in your communications.
Why does a TLS handshake take so long?
A TLS handshake might take longer due to factors like network delays, high server load, or the need to negotiate multiple parameters between the client and server. Even with these factors, the handshake usually completes in just a fraction of a second. Upgrading to TLS 1.3 can help reduce handshake time because of its more efficient process.
Is TLS handshake symmetric or asymmetric?
The TLS handshake uses both asymmetric and symmetric encryption. Asymmetric encryption is used at the beginning of the handshake to securely exchange keys between the client and server. Once the keys are exchanged, symmetric encryption is used to protect the data during the session, ensuring both security and efficiency.