Which control best strengthens the use of reusable passwords?

• A. System uses a database of known strong passwords to validate new passwords
• B. Software automatically scans password files and notifies users that their passwords have expired and need to be changed
• C. Microprocessor programmed with an algorithm generates a new and unique password every 60 seconds
• D. Internal algorithm generates a response to a network authentication software-issued challenge

Answer: (B)

Regularly forcing users to change their passwords limits how long a single credential can be used. When passwords are reused across systems, an attacker who gains one password can potentially access multiple accounts. Automatic checks that remind users when a password has expired and prompt a change enforce up-to-date credentials and reduce the window of opportunity for misuse. This directly strengthens the security of reusable passwords by ensuring they are not kept in place indefinitely.

The other options don’t address this as effectively. A system that validates against a database of strong passwords helps at creation time but doesn’t control how long a password is used or prevent reuse across sites. Generating a new password every 60 seconds would break usability and means there’s no true reuse at all, not strengthening it. A mechanism that responds to a challenge changes how authentication is performed, rather than reinforcing the habit of changing reusable passwords.