ISC2 Systems Security Certified Practitioner (SSCP) Practice Question

The Secure File Transfer Protocol (SFTP) runs inside an SSH session, which provides strong confidentiality through encryption, integrity protection via message authentication codes, and mutual authentication when key pairs are exchanged by both client and server. Key-based authentication enables unattended batch jobs, and only TCP port 22 has to be opened on the firewall.

Explicit FTPS uses TLS but still negotiates separate data ports and usually authenticates only the server unless mutual TLS is added, complicating firewall and credential management. HTTPS with just a server certificate and an API token does not enforce client authentication at the transport layer. SMTP with STARTTLS and DKIM secures email delivery and message authenticity but is not intended for reliable bulk file integrity verification or efficient batch transfers. Therefore, SFTP over SSH with mutual key authentication best satisfies all stated requirements.