What is Transport Layer Security?

Define Transport Layer Security: What is it?

Communication online is more widespread now than ever before - among individuals, organisations and governments alike. Besides heightened awareness through awareness training, there is a huge need to secure this communication with encryption technologies. Transport Layer Security (TLS) is one of such encryption technologies.

In short, TLS is a security protocol that ensures that communications between two devices are transformed into encrypted traffic. TLS thus prevents data and communications from being intercepted and manipulated. The same applies to Secure Sockets Layer (SSL), which can be considered as the predecessor of TLS.

Introduction to Transport Layer Security

Transport Layer Security (TLS) is a widely deployed security protocol that provides secure communication between web browsers and web servers over the internet. Developed by the Internet Engineering Task Force (IETF), TLS is designed to ensure data integrity, confidentiality, and authenticity between two communicating applications. As a successor to the Secure Sockets Layer (SSL) protocol, TLS has become the de facto standard for secure online communication. By encrypting data transmitted over the internet, TLS protects sensitive information from being intercepted or tampered with, making it a cornerstone of modern internet security.

How Transport Layer Security works

TLS is mainly used for secure web browsing. For example, when you see a padlock icon in your browser, HTTPS is used, which means that your connection is encrypted with TLS.

In addition, TLS protects email, file transfers, video services and Internet Service Providers (ISPs).

A TLS certificate (often called an SSL certificate) contains both a public and a private key that authenticate the server and allow it to encrypt and decrypt data. When you then visit a website, your web browser searches for the website’s TLS certificate and then performs a kind of handshake to check its validity.

The TLS record protocol plays a crucial role in securing application data through the keys established during the TLS handshake. It ensures the integrity and authenticity of the data, providing connection security alongside the handshake protocol which facilitates authentication and key negotiation.

TLS is established in the following way:

1. The user connects to a website that has HTTPS enabled.

2. The user’s browser requests the server’s public key against its own. A key exchange thus takes place, allowing both parties to encrypt messages through the private and public keys. In this way, only the other party can read and decrypt with its private key.

3. A set of unique keys specific to the user is generated when sending a message encrypted through the server’s private key previously shared with the user.

So when you establish a secure connection online, TLS provides the framework for two endpoints (server computer and client computer) to communicate. Thanks to encryption, TLS ensures that the two parties speak the same language, which a third party can in no way read or manipulate.

When the connection is not secure, users are typically greeted with the warning “Your connection is not private.” This means that the TLS certificate is not valid.

In addition to securing web browsing, TLS also plays a crucial role in protecting file transfers, ensuring that data remains encrypted during transmission. Learn more about File Transfer Protocol (FTP) in our blog post or dive into our guide on HTTPS to understand how it protects your online activity.

Symmetric and asymmetric encryption

TLS is a set of protocols consisting of one for the transport layer and one for securing web pages.

Using these cryptographic protocols, TLS employs both symmetric and asymmetric cryptography, supporting newer and more secure algorithms to increase the security of data transmission.

Symmetric encryption

Secure data transmission contributes to the efficient encryption and decryption of messages via secret keys known to both parties.

However, it can be difficult to share these secret keys securely, especially if you are trying to send the information over an insecure connection.

Asymmetric encryption

Asymmetric encryption does not require the two parties to share a secure channel. Instead, the process is typically much simpler than symmetric encryption. For example, one party sends a public key to the other party in an email and the other party downloads it onto their device.

However, larger keys are required to increase security. This means that they are more computationally intensive and therefore in some cases very slow.

TLS validates the ownership of the server's public key. All connections go through a so-called X.509 certificate, which confirms the authenticity for them to be considered secure. An X.509 certificate is a digital certificate that associates cryptographic key pairs with an identity such as a website, an individual or an organisation.

TLS handshake protocol

The TLS handshake protocol is a critical component of the TLS protocol, responsible for establishing a secure connection between a client and a server. This process involves a series of steps, including negotiating the TLS version, selecting a cipher suite, and exchanging cryptographic parameters. During the handshake, the client and server agree on the security parameters, such as the encryption algorithm and keys, before any data is transmitted. This ensures that both parties have a mutual understanding of the security measures in place, creating a secure and trusted connection. The TLS handshake is essential for initiating a secure session and protecting data integrity and confidentiality.

Digital certificates and TLS

Digital certificates play a crucial role in the TLS protocol, providing authentication and encryption for online transactions. Issued by a trusted third-party certificate authority (CA), digital certificates contain information such as the identity of the certificate holder and the public key. When a client connects to a server, the server presents its digital certificate, which the client verifies to ensure the server’s identity and authenticity. This verification process is vital for establishing trust between the client and server, enabling secure and trusted communication over the internet. The use of digital certificates is a key component of the TLS protocol, ensuring that data is transmitted securely and that the parties involved are who they claim to be.

What is the difference between TLS and Secure Sockets Layer?

As mentioned, TLS is a newer version of SSL (Secure Sockets Layer). In this way, TLS addresses certain security vulnerabilities in SSL.

SSL 1.0 was never published due to security flaws. Therefore SSL 2.0 was first released in 1995, but was already replaced by SSL 3.0 in 1996 due to security flaws.

In 1999, the first version of TLS was then released as an upgrade to SSL. Since then, there have been further upgrades to TLS, which is thus the most secure protocol today. It is both more secure and has higher performance. However, TLS can often be referred to as SSL.

Why you should use TLS handshake protocol

There's no doubt that it's always a good idea to use secure, encrypted connections - especially when dealing with sensitive information. TLS ensures privacy when you send emails and buy things online, for example.

While it's possible to set up encryption without the TLS certificate, it's the only way to make sure you're communicating with the right server. That's why it's also important to use TLS. We recommend that you keep an eye on the padlock icon in your browser, as it indicates that HTTPS is used and that the connection is thus encrypted with Transport Layer Security.

Challenges of TLS

While TLS is a widely deployed and effective security protocol, it is not without its challenges. One of the primary challenges is the complexity of implementing and managing TLS, particularly for organizations with multiple web servers and applications. Ensuring that all systems are properly configured and up-to-date with the latest security standards can be a daunting task. Additionally, the TLS protocol requires ongoing maintenance and updates to remain compatible with evolving security standards and protocols. Another challenge is the potential impact on web application performance, as the encryption and decryption processes can be resource-intensive if not implemented correctly. Despite these challenges, the benefits of TLS far outweigh the drawbacks, making it an essential component of secure online communication. By providing robust encryption and authentication, TLS helps protect sensitive data and maintain the integrity of online transactions.