US Patent 7162456 Method for private personal identification number management

A method for private personal identification number (PIN) management comprises ascertaining a first delay period of a preceding PIN. The first delay period is greater than zero if the preceding PIN does not match a validated PIN and the first delay period equals zero if the preceding PIN matches the validated PIN. The method also includes receiving a current PIN after at least the first delay period and delaying for a second delay period if the current PIN does not match the validated PIN. The second delay period is greater than the first delay period.