Which of the following protocols uses public-key cryptography to authenticate the remote computer?

Question

Options

• ASSH
• BTelnet
• CSCP
• DSSL

• A
  74% (17)
• B
  9% (2)
• C
  4% (1)
• D
  13% (3)

Explanation

SSH (Secure Shell) uses public-key cryptography to authenticate the remote computer through a host key exchange - the server presents its public key, and the client verifies it against known hosts, establishing mutual trust before any data is exchanged.

Telnet (B) transmits everything in plaintext with no encryption or authentication mechanism whatsoever, making it the insecure predecessor SSH was designed to replace. SCP (C) is a file transfer protocol that runs on top of SSH and inherits its encryption, but SCP itself is not the protocol performing the authentication - SSH is. SSL (D) does use public-key cryptography, but it authenticates via certificates (PKI/CA chain), not host keys in the SSH sense; it's the foundation of HTTPS, not remote shell access.

Memory tip: Think "SSH = Secure Shell = keys" - SSH is the go-to answer for any question about secure remote login with public-key authentication. If you see Telnet, it's always the insecure option by design.

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