What should Alice never do regarding her password?

The recommendation for Alice to never send a plaintext password stems from security best practices that aim to protect sensitive information from interception and unauthorized access. Sending a password in plaintext means that it is transmitted without any encryption, making it easily readable by anyone who may be monitoring the network traffic. This includes potential eavesdroppers or cyber attackers who can use various techniques to capture data being transmitted over the internet or even on local networks.

By ensuring that passwords are never sent in plaintext, Alice is taking a critical step to secure her accounts and reduce the risk of unauthorized access. Instead, passwords should be transmitted using secure methods, such as HTTPS, which encrypts the data in transit, protecting it from being intercepted.

In contrast, the other options suggest behaviors that either carry a risk of exposing passwords or advocate for unsafe practices. For instance, sending passwords in plaintext, even to well-known companies, remains risky as any breach in the communications could expose her credentials. Similarly, sending them over a local network in plaintext poses a risk of internal threats or malware. Storing passwords in a public document not only makes them accessible to anyone but also violates the principles of confidentiality and data protection. Therefore, never sending a plaintext password is a fundamental security practice Alice should adhere to.