https://motherboard.vice.com/en_us/article/pakwnb/replacing-social-security-numbers-is-harder-than-you-think

Steven M. Bellovin is a professor of computer science at Columbia University. He focuses on security, privacy, and related legal and policy questions.

In the wake of the massive Equifax system compromise, in which the personal information of at least 145 million people may have been stolen, many people have questioned the ubiquitous use of social security numbers (SSNs) for authentication. This is only the latest of many data breaches; why have we not learned better? Using SSNs like this seems like an obviously bad idea—even the White House is considering a proposal to replace them—but solving the problem is a lot harder than it seems. Furthermore, alternatives are often worse in other respects.