Where are user passwords for encryption stored in a Linux system?

In a Linux system, user passwords for encryption are stored in the /etc/shadow file. This file contains the hashed passwords of the users along with additional information related to password management, such as password expiration and account status.

Storing the hashed passwords in /etc/shadow instead of /etc/passwd significantly enhances security. While /etc/passwd is accessible by all users and contains user account details such as usernames and user IDs, it does not contain password hashes. Instead, it contains a placeholder character (usually an 'x') in the password field for users that have their password stored in /etc/shadow, which is only accessible by the root user. This separation helps protect sensitive password information from unauthorized access.

The other options provided do not serve this purpose: /var/log/auth.log is a logfile that records authentication attempts and security events, while /usr/local/etc is typically used for configuration files and does not store user passwords.