問76
頻出度★★★
無線LANの暗号化方式はどれか。
平成26年度 秋期 ITパスポート試験 問76
テクノロジ系ネットワーク › ネットワーク方式
This question's explanation and your answers so far.
解説
問 76
Incorrectア
ESSID is the network identification name assigned to a wireless LAN access point (up to 32 characters), used to distinguish which wireless LAN to connect to. It is merely a name indicating that devices belong to the same wireless LAN, and it has no function to encrypt the content of communication. There is a setting to hide the ESSID (stealth mode), but that only makes the connection target harder to see; it is not an encryption method.
Incorrectイ
HTTPS is a mechanism that encrypts HTTP communication with SSL/TLS; it is an application-layer protocol that protects the exchange between a web browser and a web server. It can be used over both wired and wireless connections and is not a standard that encrypts the wireless section itself. If the wireless LAN is not encrypted, communication other than HTTPS (unencrypted communication) can still be intercepted.
Incorrectウ
POP3 is a protocol for receiving e-mail from a mail server; it is not an encryption mechanism. POP3 originally exchanges IDs, passwords, and message bodies in plain text, so to protect them you must separately combine it with SSL/TLS, using POP3S or similar. In any case, it is not an encryption method for wireless LAN.
- エ
正解 The correct answer is エ (WPA2). WPA2 (Wi-Fi Protected Access 2) is an encryption and authentication standard created to protect wireless LAN (Wi-Fi) communication. It is based on IEEE 802.11i and adopts CCMP, a strong encryption method that uses AES. Because a wireless LAN uses radio waves, a third party can intercept those waves without plugging into a cable, unlike a wired LAN; without encryption, the content of the communication and passwords can be read directly. A mechanism that encrypts the wireless section itself is therefore needed. The early WEP standard was quickly compromised once cracking methods were found, so its successor WPA, and then the further strengthened WPA2, came into wide use (today there is also the newer WPA3). Since the question asks for an encryption method for wireless LAN, WPA2 — an encryption standard designed specifically for wireless LAN — is the only one that fits.
ここがポイント
- Wireless LAN encryption has been strengthened in the order WEP → WPA → WPA2 → WPA3. WEP should not be used because cracking methods are already known, while WPA2, which uses AES (CCMP), is the current standard method. Since wireless LAN radio waves are easy to intercept, treat encryption settings as mandatory.
- ESSID is the name that identifies the wireless LAN you connect to, HTTPS is a protocol that protects web communication with SSL/TLS, and POP3 is a protocol for receiving e-mail. Sort out which layer and which purpose each term belongs to, so you can tell whether a question is asking about encryption of the wireless section or encryption of application-level communication.
用語