What function does SSL/TLS serve in network security?

SSL/TLS is a protocol that provides essential security functions for data transmitted over a network, specifically focusing on confidentiality, integrity, and authentication.

Confidentiality is achieved through encryption, which secures data such that it can only be read by the intended recipient. This is critical for protecting sensitive information during transmission.

Integrity ensures that the data has not been altered or tampered with during transit, guaranteeing that the receiver receives the information exactly as it was sent. This is often achieved through the use of message authentication codes (MACs) that verify the integrity of the message.

Authentication allows parties to verify each other's identities, ensuring that the communication is happening between legitimate entities and not malicious actors.

By providing these three core security functions above the transport layer, SSL/TLS plays a vital role in securing communications over the Internet and other networks. This makes it highly suitable for applications like web browsing, email, and any scenario where secure data transmission is critical.

The other options do not accurately represent the function of SSL/TLS. For instance, availability, non-repudiation, encryption, and firewalls pertain to different aspects of cybersecurity and network protection that are outside the specific capabilities of SSL/TLS.