Which security measure is designed to verify the authenticity of users or devices?

Password authentication is a critical security measure used to verify the authenticity of users or devices. It operates by requiring users to provide a secret word or phrase known only to them, which is then compared against stored credentials to confirm their identity. This process ensures that only those who know the correct password are granted access to systems or data, thereby helping to protect against unauthorized access.

Other security measures such as firewalls, encryption, and salting serve different purposes. While firewalls protect networks by controlling incoming and outgoing traffic, they do not specifically authenticate users. Encryption protects data by converting it into a secure format that is unreadable without a key but does not verify who the user or device is. Salting, meanwhile, is a technique used in password storage to enhance security by adding random data to passwords before hashing them, but it does not itself verify identity.