Transport Layer Security (TLS) is the latest version of the Secure Socket Layer (SSL) protocol. Both protocols ensure data privacy and authenticity over the internet. These widely used protocols provide end-to-end security by applying encryption for web-based communication. However, despite the similarities of TLS and SSL, they have significant differences, too.

This article explains how the TLS and SSL encryption protocols work, their importance, how they differ, and why it's the right time to switch to TLS protocol.

The Historical Background of TLS and SSL

The Internet Engineering Task Force (IETF), the organization responsible for developing internet standards, published Request for Comments (RFC-1984), recognizing the importance of personal data protection in the growing internet. The Netscape Communication Corporation introduced SSL to secure web communication which underwent multiple upgrades.

The SSL 1.0 version was never released due to security flaws, and SSL 2.0 was the first public release by Netscape in 1995. However, due to security vulnerabilities and drawbacks, it was replaced by another SSL version 3.0 in November 1996. The latest SSL version is also not in use due to its insecurity against the POODLE attack in October 2014 and was officially deprecated in June 2015.

TLS was released in 1999 as an application-independent protocol: an upgrade to SSL version 3.0 made by Internet Engineering Task Force (IETF). The idea was to implement TLS over TCP to encrypt applications using FTP, IMAP, SMTP, and HTTP protocols. For instance, HTTPS is a secure version of HTTP as it implements TLS to ensure safe data delivery by avoiding content alterations and eavesdropping.

Basic Working of TLS/SSL Protocols

Communication between parties (e.g., your computer browser and a website) initiates by identifying if it will incorporate TLS/SSL protocol or not, such that the client can specify the use of TLS encryption either by:

• Specifying a port that supports SSL communication encryption, or
• By making TLS protocol-specific requests

In the meantime, a website requires a TLS/SSL certificate installed on its hosting server to use the protocol. A trusted third party issues the certificate that binds the public key to the domain that owns the private key and enables it to encrypt/decrypt the communication.

After agreeing on using TLS/SSL for client-server communication, it proceeds to perform the handshake. The handshake establishes the specifications required to exchange messages. The following section summarizes the series of information exchanges to enable TLS/SSL connection:

1. The parties agree on the version of the protocol they will use, then
2. Decides on the cryptographic algorithms or the cipher suite to use, then
3. Authenticates communicating parties with their public key and digital signatures of the issuing certificate authority, then
4. Exchanges session keys to use during communication. Both TLS and SSL protocols use asymmetric cryptography to generate shared (public) and private keys.

If the browser can not validate theTLS/SSL certificate, it returns an error of "Connection is not Private."

After establishing the decryption method during the handshake, the record protocol uses symmetric encryption for communication for the entire session. Besides, the record protocol also appends the message with the HMAC for TLS and MAC for SSL to ensure data integrity.

Hence, the protocols accomplish three fundamental goals of security:

• Confidentiality: Encrypts data to hide it from third parties such that only an intended recipient can view the content.
• Integrity: Applies message authentication code to verify encrypted message content.
• Authentication: Authenticates the website/client/server's identity with the help of a certificate to ensure parties exchanging information cannot back off from their identity.

What's the Difference Between TLS and SSL?

As mentioned earlier, the main difference you notice between both protocols is how they establish connections. TLS handshake uses an implicit way of establishing a connection via a protocol, while SSL makes explicit connections with a port.

Irrespective of all other differences, the fundamental feature that differentiates both TLS/SSL connections is the use of a cipher suite that decides the overall security of the connection.

The essential part of a TLS/SSL connection is to agree on a cipher suite that defines a set of algorithms for key exchange, authentication, bulk encryption, and a hash-based message authentication code (HMAC) or message authentication code algorithms, etc. for a particular session. Each TLS/SSL version supports a different set of cipher suites for the communication session. Hence, each cipher suite supports its own set of algorithms that improves security and overall connection performance.

Why Did TLS Replace SSL?

TLS encryption is now a standard practice to secure web applications or in-transit data from eavesdropping and tampering. It's unrealistic to assume TLS as the most secure protocol as it has been prone to breaches such as Crime and Heartbleed in 2012 and 2014, but it has shown a lot of improvements in terms of performance and security.

TLS is replacing SSL, and almost all of the SSL versions are now deprecated due to its known vulnerabilities. Google Chrome is one such example that stopped using the SSL 3.0 version back in 2014, and most modern web browsers do not support SSL at all.

Use TLS For Encrypted Communication

TLS helps secure sensitive on-transit information such as credit card details, emails, voice over IP (VOIP), file transfer, and passwords. Even though both certificates perform the task of in-transit data encryption, they differ in functionality and are not interoperable.

It is important to note that TLS is referred to as SSL only because SSL is the most commonly used terminology, and the presence of a certificate does not guarantee the use of the TLS protocol. Besides, you do not need to worry about changing SSL to TLS certificates as all you need to do is install the certificate on the server as it supports both protocols and decides which one to use.