That is an excellent question.
As I always say, it is important, when you have situations like this, to review and rethink certain things.
As far as the social insurance number is concerned, as I said, it is one of several identifiers. At the federal level—and, of course, in many places— people are invited to add secret questions that only they can answer. It is not a PIN, but it is an additional way to ensure security and identify the right person.