What is an SSH authentication key used for?

An SSH authentication key is primarily used as a secure way to access a computer, particularly for remote login and command execution. SSH, or Secure Shell, is a protocol that provides a secure channel over an unsecured network in a client-server architecture. By utilizing authentication keys, users can establish a secure connection without the need for a password, which enhances security by reducing the risk of password theft.

The SSH authentication process usually involves a public-private key pair. The public key is placed on the server, while the private key remains confidential with the user. When the user attempts to connect to the server, the server uses the public key to create a challenge for the client, who can then prove possession of the private key without transmitting it over the network. This method ensures a strong layer of security, protecting data and maintaining confidentiality.

In contrast, the other options describe different functions that do not relate to SSH authentication. Data compression is focused on reducing file sizes, backing up data involves creating copies for recovery, and network troubleshooting is about diagnosing and resolving connectivity issues. Each of these tasks serves different purposes, distinct from the primary function of SSH keys in providing secure remote access.