"For years, government officials have urged consumers to protect their social security numbers by giving out the nine-digit codes only when absolutely necessary. Now it turns out that all the caution in the world may not be enough: New research shows that social security numbers can be predicted from publicly available birth information with a surprising degree of accuracy.

By analyzing a public data set called the “Death Master File,” which contains SSNs and birth information for people who have died, computer scientists from Carnegie Mellon University discovered distinct patterns in how the numbers are assigned. In many cases, knowing the date and state of an individual’s birth was enough to predict a person’s SSN.

“We didn’t break any secret code or hack into undisclosed data set,” said privacy expert Alessandro Acquisti, co-author of the study published Monday in the journal Proceedings of the National Academy of Sciences. “We used only publicly available information, and that’s why our result is of value. It shows that you can take personal information that’s not sensitive, like birth date, and combine it with other publicly available data to come up with something very sensitive and confidential.”

With just two attempts, the researchers correctly guessed the first five digits of SSNs for 60 percent of deceased Americans born between 1989 and 2003. With fewer than 1,000 attempts, they could identify the entire nine digits for 8.5 percent of the group."

Read more: http://www.wired.com/wiredscience/2009/07/predictingssn/