How do shadow passwords improve the password security in comparison to standard passwd passwords?

Shadow passwords are not stored in plain text; they are stored as one-way cryptographic hashes, which is a fundamental aspect of their security.

Password validity periods are configurable policy settings managed by tools like `chage` and are not an inherent mechanism by which shadow passwords improve security over standard `passwd` entries.

Shadow passwords utilize cryptographic hashing algorithms to create one-way hashes; they are not encrypted with the system's host key.

Shadow passwords deal with password hashes for traditional authentication and are not directly combined with public/private key pairs, which are used for other authentication methods like SSH.

Shadow passwords improve security because the password hashes are moved from the world-readable `/etc/passwd` file to `/etc/shadow`, which has restricted permissions allowing only the root user to read it. This crucial change prevents unprivileged users from accessing and potentially cracking other users' password hashes, significantly bolstering system security against offline brute-force or dictionary attacks.