Inferring Social Security Numbers from Birth Data

Posted by plektix in Uncategorized on September 4th, 2009 | View Comments

An article in July’s PNAS investigates the possibility of predicting a person’s Social Security number from their birth date and place.  Exploiting patterns in how SSN’s are assigned, authors Alessandro Acquisti and Ralph Gross developed an algorithm which could correctly predict the first 5 digits of a social security number 44% of the time, for people born after 1988 (older SSNs are significantly harder to predict).  The accuracy varied from state to state; for smaller states and recent birthdays, the algorithm could sometimes predict an entire SSN on the first try.

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  • plektix
    Unsafe in that if someone wants to know your social security number, an algorithm such as the one described could get it within a few hundred or a thousand tries (possibly much less). If combined with a way of checking whether the number is correct, this would pose little challenge to a determined hacker with a computer.

    In addition, the last four numbers of a social security number are often used as a kind of security code, and are therefore more likely to be revealed than the last five. If someone knew your last four digits, they could get your entire number within the first couple tries.
  • Chris
    Unsafe exactly how?
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