WashingtonPost.com wrote:Researchers: Social Security Numbers Can Be Guessed
Researchers have found that it is possible to guess many -- if not all -- of the nine digits in an individual's Social Security number using publicly available information, a finding they say compromises the security of one of the most widely used consumer identifiers in the United States.
Many numbers could be guessed at by simply knowing a person's birth data, the researchers from Carnegie Mellon University said.
The researchers at Carnegie Mellon set out to see if they could discover people's numbers by first exploiting what is publicly known about how the numbers are derived.
The Social Security number's first three digits -- called the "area number" -- is issued according to the Zip code of the mailing address provided in the application form. The fourth and fifth digits -- known as the "group number" -- transition slowly, and often remain constant over several years for a given region. The last four digits are assigned sequentially.
As a result, SSNs assigned in the same state to applicants born on consecutive days are likely to contain the same first four or five digits, particularly in states with smaller populations and rates of birth.