Be sure to read these articles as well as the lecture text. William Dwyer found out the hard way how unprivate databases can be. Someone at a Florida Honda dealership downloaded his credit report and, using his Social Security number and other data, applied for credit cards in his name. It took him a year to clear his name, and, along the way, his bank turned down an application for a loan to pay his son's college tuition.
Credit bureaus maintain information on practically every American adult.
It is fairly easy for anyone with access to that information to assume the identity of another individual. It is a delicate balancing act to reconcile the need of citizens to keep their records private with the need of others to access credit information. A Social Security number is widely used as a means of identification , especially for financial transactions over the phone. The problem is that it is used as a key in so many databases that by giving it out, you provide access not only to the information that is requested, but also to a lot of other information as well. This means that you should be careful about giving out your SSN, but it also means that if you are designing a database, you should look for other ways to assign unique keys.