正解The correct answer is ア. When an address, a name, a credit card number and similar data are exchanged over the Internet, there is a risk of being eavesdropped on or tampered with along the communication path. The standard mechanism for preventing this is encrypting the communication with SSL/TLS, and as its foundation the server obtains in advance a digital certificate (an electronic certificate, that is, what is called a server certificate) issued by a third-party organization known as a certificate authority (CA). When the user's browser connects to the site, it verifies this certificate, achieving two things at the same time. The first is confirming that the site being connected to really is Company N's site. Because the certificate is issued only after the third-party organization has verified that the company actually exists, a closely resembling fake site (spoofing, a phishing site) can be told apart from it. The second is using the public key contained in the certificate to share an encryption key safely and to encrypt the data sent and received from then on. As a result, the personal information and the card number entered on the purchase procedure screen travel over the network in encrypted form, so even if they are intercepted on the way, the contents cannot be read. An address bar that begins with https:// and shows a padlock mark indicates that this protection is working. From the user's point of view, their own important information is protected and they can confirm that the other party is genuine, so they can make a purchase with peace of mind. Therefore ア is the appropriate measure for a shopping site operator to implement.
×Incorrectイ
Information about the system configuration, such as the server model, the name of the OS, the software in use and the IP address, becomes material for an attack exactly as it is. If the names and versions of the OS and the software are known, an attacker can narrow down which of the already published vulnerabilities is likely to work against that site, and if the IP address is known, the attacker can directly pin down the target for things such as port scanning. In other words, far from demonstrating reliability, this is an act that raises the risk of being attacked by one's own hand. There is no need to release information about the system configuration to the outside, and disclosing only the minimum necessary is a basic principle of information security, so this does not lead to peace of mind.
×Incorrectウ
Unless special measures are taken, the body of an email flows along the path as plaintext and is stored as it passes through any number of mail servers, so there is a risk that it will be eavesdropped on, or delivered to a third party because the address was mistyped. Putting an address, a name and a credit card number into such a message as they are and sending it back is an act of placing the information that most needs protecting in a dangerous location by one's own hand, and it is not permissible even when the purpose is to have the user check the contents. Checking what was entered can simply be done on an encrypted web confirmation screen. In addition, even when a card number is displayed for confirmation, the usual practice is to show only the last 4 digits and hide the rest (masking).
×Incorrectエ
The Personal Information Protection Act requires businesses that handle personal information to specify the purpose of use as clearly as possible and then to notify the person concerned or make it public, and also to make clear a contact point that accepts complaints and requests for disclosure. Stating the purpose of use and the method of inquiry in a privacy policy or similar document is an obligation, and failing to state it violates the law. Moreover, from the user's standpoint, they are left not knowing what their own information will be used for or where to get in touch when they run into trouble, so this enlarges anxiety rather than removing it. The reasoning that one does not state these things in order to avoid causing anxiety has cause and effect reversed, and is wrong.
ここがポイント
The role of SSL/TLS and of a digital certificate (electronic certificate). By using a server certificate issued by a third-party organization called a certificate authority (CA), a site achieves at the same time confirmation that the other party in the communication is genuine (a countermeasure against spoofing and phishing) and encryption of the communication contents (a countermeasure against eavesdropping and tampering). It is an essential measure on screens where personal information and credit card numbers are entered, and on the user's side it can be checked by https:// and the padlock mark.
The criterion for judging whether a measure gains peace of mind and trust. Measures in the direction of protecting (encrypting the communication, not publishing system configuration information, properly stating the purpose of use of personal information and the contact point) are correct, while measures in the direction of exposing (sending a card number back in a plaintext email, publishing the server model and the IP address) or in the direction of abandoning accountability (not stating the purpose of use) may be judged wrong.