Abstract: A portable Personal Identification Card allows a cardholder to enter a PIN code into his card at a location remote from an authorization terminal. In an alternate embodiment, a PIN code may be enterd at the authorization terminal. The authorization terminal reads the cardholder's account number from the PIN card. The account number is transmitted to a central computer which uses this number to index into memory to find a personal identification number and encryption parameters. The centerl computer transmits a pseudo-random number to the PIN Card. Both the PIN Card and the central computer perform an encryption of a function of the corresponding personal indentification number and pseudo-random number to derive a CGIPIN (Computer Generated Image of the PIN). If the CGIPIN transmitted from the PIN card matches the CGIPIN of the central computer, access is authorized.