IPA IP 2023 Question 65
A question IPA Japan published in 令和5年度 ITパスポート試験 公開問題 問65, translated into English. ITPEC is based on the same exams.
Which of the following is an appropriate description of the PSK that is set when a PC is connected to a wireless LAN router by using WPA2, a security standard for Wi-Fi?
Explanation
A passphrase that authenticates the connection, from which each PC's encryption key is generated — PSK (Pre-Shared Key) is the secret shared in advance by the access point and its users in WPA2-Personal.
The same passphrase is set on the wireless LAN router and on each PC. When a PC connects, the two sides prove to each other that they know it without sending it over the air, and from it they derive a key for that PC's session. So every connecting PC encrypts its traffic with its own key, even though all of them were given the same passphrase.
Answer (a)
Why not others:
- •(b) — private IP addresses are handed out by DHCP, not derived from the PSK
- •(c) and (d) — a name that identifies the access point is the SSID (ESSID); it is broadcast openly and is not a secret. In (d) the IP address is again DHCP's job
Key rule: On a wireless LAN, the SSID names the network, the PSK (passphrase) authenticates and seeds the encryption keys, and DHCP assigns the IP addresses.
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.