Which of the following tools is primarily used for password protection in networks?

The most appropriate tool for password protection in networks is hashing and salting. This method involves transforming the original password into a fixed-size string of characters, which is a representation of the data that isn’t reversible (hashing). Salting adds an additional unique value to each password before it is hashed, thereby strengthening security by preventing the use of precomputed hash tables (rainbow tables) to crack passwords.

When passwords are stored using hashing and salting, even if attackers gain access to the stored data, they cannot easily retrieve the original passwords. This makes hashing and salting a critical practice for ensuring the confidentiality of user credentials in network security.

The other tools listed serve different purposes: firewalls primarily manage and filter network traffic to protect against unauthorized access, encryption secures data in transit or at rest but does not focus exclusively on password protection, and certificates are used primarily for authentication and secure communications, such as in SSL/TLS connections, rather than for the direct protection of passwords.