Using the check digit only to check accuracy of an identity card number inputted via a web page

Q: We are a government department providing our services on a web-site. For certain on-line applications, we require the applicants to fill in their ID card numbers. In this connection, in order to increase user-friendliness, we intend to use only the check digit of a HKID number to check the accuracy of the ID number inputted via our web-page. The question is whether this arrangement contravenes the Code of Practice on the Identity Card Number and Other Personal Identifiers ("the Code").

A: Regarding your proposed on-line collection of the ID card number from the applicants, we notice that none of the means of verification as provided by paragraphs 2.4.1, 2.4.2 or 2.4.3 of the Code is to be adopted. Instead, you intend to rely solely on the check digit in the ID card number to check the validity of such number. So far as we understand, however, this may not be a foolproof way to check the validity of a HKID card number inputted on a web page. In any event, such means of checking is not consistent with paragraph 2.4 of the Code, which has already prescribed the proper means of verification.