Abstract: A computer based method of authentication including the steps of displaying a field operatively arranged for entry of data representative of a mathematical function of digits in a person's Social Security Number and displaying instructions to the person indicating a specific mathematical function to be performed by the person to arrive at the representative data, performing the specific mathematical function of digits in the person's Social Security Number, and comparing a result of the performing the specific mathematical function of digits in the person's Social Security Number with the received data representative of the mathematical function of digits in the person's Social Security Number to authenticate the person's identity.