IPA IP 2021 Question 68
A question IPA Japan published in 令和3年度 ITパスポート試験 公開問題 問68, translated into English. ITPEC is based on the same exams.
In a communication environment where there is a risk of eavesdropping in all communication sections, which of the following is the most appropriate method of sending a file whose content should not be known by anyone other than the recipient as an attachment to an e-mail?
Explanation
Encrypt the e-mail with S/MIME — only end-to-end encryption of the message itself protects it on every section of the route.
S/MIME encrypts the e-mail body and its attachments with public key cryptography: the sender encrypts with the recipient's public key, and only the recipient's private key can decrypt. The message stays encrypted from the sender's terminal, through every mail server and network, to the recipient's terminal, so eavesdropping on any section reveals nothing.
Answer (a)
Why not others:
- •(b) — SSL/TLS protects only the section between the sender and the provider's mail server; the e-mail is plain on the server and on the later sections to the recipient
- •(c) — WPA2 encrypts only the wireless LAN section between the terminal and the access point
- •(d) — the second e-mail travels over the same eavesdropped route, so whoever intercepts the file also intercepts its password
Key rule: When every section may be tapped, encrypt the content itself end to end (S/MIME); protocols that encrypt one link protect only that link.
Security · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.