Personal identification number code verifying method for authorizing transaction between e.g. chip card and payment terminal, involves verifying whether control value is identical to random number corresponding to selected order number

摘要

The method involves recuperating a code referred by a user, when a remainder real number is different from zero. A control value is calculated, from a result corresponding to a selected order number, through inverse function of a bijective function e.g. data encryption standard (DES) function by using the code as an inverse function specifying parameter. The calculated value is stored, and the real number is decremented. The decremented number is stored as remainder theoretical number. Verification is made whether the value is identical to random number corresponding to the selected number.