For people born after 1988 - when the government began issuing numbers at birth - the researchers were able to identify, in a single attempt, the first five Social Security digits for 44 percent of individuals. And they got all nine digits for 8.5 percent of those people in fewer than 1,000 attempts.
For smaller states their accuracy was considerably higher than in larger ones.
Acquisti said in a telephone interview that he has sent the findings to the Social Security Administration and other government agencies with a suggestion they adopt a more random system for assigning numbers.
Social Security spokesman Mark Lassiter said the public should not be alarmed by the report “because there is no foolproof method for predicting a person’s Social Security number.’’
“The suggestion that Mr. Acquisti has cracked a code for predicting an SSN is a dramatic exaggeration,’’ Lassiter said via e-mail.
However, he added: “For reasons unrelated to this report, the agency has been developing a system to randomly assign SSNs. This system will be in place next year.’’
The researchers say their report omits some details to make sure they aren’t providing criminals a blueprint for obtaining the numbers.
The predictability of the numbers increases the risk of identity theft, which cost Americans almost $50 billion in 2007 alone, Acquisti said.
A problem in the battle against identity thieves is that many businesses use Social Security numbers as passwords or for other forms of authentication, something that was not anticipated when Social Security was devised in the 1930s.
The Social Security Administration has long cautioned educational, financial, and healthcare institutions against using the numbers as personal identifiers.
“In a world of wired consumers, it is possible to combine information from multiple sources to infer data that is more personal and sensitive than any single piece of original information alone,’’ Acquisti said, warning against providing too much data on social networking sites.
