Abstract: Security equipment protects the relaying of account numbers and personal identification numbers (PIN) by telephonic or other communication link. The equipment includes a host computer an a remote portable transaction device that interact. A credit granting institution generates an account number and a series of unique personal identification numbers for each account number. This information is stored in the host computer's memory and is assigned as a reference series to an individual customer account number. An identical series of numbers in the same sequence is stored in the memory of the remote device. In operation, the customer account on the host computer is activated and the host computer's memory is indexed sequentially to the first number in the reference series. During the use of the remote device, a unique personal identification number is added to the customer account number and transmitted to the host computer.

Abstract: A secure credit card 10 has a body member to which is attached a microprocessor controller 14 electrically coupled a Programmable Read Only Memory (PROM) device 18 programmed with a series of random numbers in a predetermined sequence. The random numbers are identical to random numbers in a host computer and in the identical sequence as the random numbers in the host computer. This computer is accessible upon each use of the credit card 10. The Programmable Read Only Memory (PROM) accesses the next random number in sequence with each use of the credit card 10 to permit verification by comparing the random number with each use of the credit card 10 with the next random number in sequence as indicated by the computer. A switch 20 actuated with each use of the credit card 10 provides a pulse signal that activates the microprocessor controller 14 to turn on the Programmable Read Only Memory (PROM) to access the next random number in the sequence.