This year we started accepting doodles from kids even if their school hadn't registered for the contest. To help us keep entries distinct and remove duplicate entries from any particular student, we asked parents for limited information, including the last 4 digits of a student's social security number. We later updated our forms when we recognized that we could sufficiently separate legitimate contest entries while requesting less information. To be clear, these last 4 digits were not entered into our records and will be safely discarded.
As for the city of birth:
The city of birth helps us identify whether contestants are eligible for the contest, as winners must be either U.S. citizens or permanent legal residents of the U.S. The information isn't used for any other purpose.
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.So handing out the last four and the DOB, it's a lot easier to figure out the first five and get a good starting point to test out online. Intriguing.
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.
...
“A botnet can be programmed to try variations of a Social Security number to apply for an instant credit card,” Acquisti said. “In 60 seconds, these services tell you whether you are approved or not, so they can be abused to tell whether you’ve hit the right social security number.”
.... last 4 is important beccaaauuuussseee?Well, first of all as others mentioned the last four digits have the most entropy, but there's another issue.
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posted by jeffamaphone at 7:27 AM on February 23, 2011 [3 favorites]