Abstract: A computer network system includes a first computer of a first corporation having a plurality of member shops and a second computer of a second corporation which is the member shop of the first corporation and runs a virtual shop on a network. The first computer includes a memory for storing display information indicating that a corresponding shop is the member shop of the first corporation, a memory for storing encryption information for encrypting the display information, and an output section for encrypting the display information by the encryption information and outputting the encrypted display information. The second computer includes a reception section for receiving the encrypted display information through the communication line, and a memory for storing the received encrypted display information.

Abstract: A card transaction system and method which includes the card medium, an accepting apparatus for the card medium, and a host computer of a card medium issuer connected to the accepting apparatus via a communication line, comprises, an approving function for causing the host computer to answer one credit inquiry from the issuer so that the host computer approves right of use for the card medium within a predetermined amount of money without a necessity of performing a credit inquiry, a supply function for causing the accepting apparatus to supply information of the right of use to the card medium when the approving function approves the right of use, and a function for causing information of the right of use to be stored in a storage region of the card medium so as to realize a plurality of transactions with the card medium within the predetermined range of the amount of money without the necessity of performing the credit inquiry.

Abstract: When fixed data common to IC cards is written in an unpersonalized IC card, a key card and a fixed data card holding fixed data common to the IC cards are used. When data read/write access is performed among the key and fixed data cards and the unpersonalized IC card, the fixed data is written in the unpersonalized IC card. The data read/write access among the key and fixed data cards and the unpersonalized IC card is performed by a microprocessor and a read/write controller. The data read/write access among the key and fixed data cards and the unpersonalized IC card can be performed without going through a host processor.

Abstract: According to a portable medium (IC card) of this invention, a memory area is divided into a system program area and a user program area. A text transmitted between the IC card and a host system connected thereto includes a command text and a response text. The command or response text includes a flag indicating that the text is written in the user program area or the system program area. The memory area has a conversion table for a function code and the start address of a program corresponding to the function code. The conversion table is looked up using the given function code as a parameter, thereby obtaining the start address of the corresponding program. The memory area has a correspondence table between a newly added function code and the start address of an added function program. The added function program is selectively executed.

Abstract: An IC card, as a portable medium, has an oscillator for generating a low-frequency clock signal for time-piece. A display clock for display is provided for counting the clock signal. The time based on a count carried out by the display clock is displayed on the IC card a display section. In this case, the count of the display clock can be changed, as appropriate, by using keys on the keyboard provided on the IC card. The IC card also incorporates a transaction clock for counting the clock signal. The count carried out by this transaction clock is used to indicate the standard time. A count carried out by the transaction clock cannot be altered by use of the keys of the keyboard. The clock for time display may be the transaction clock allowing an access of the keyboard. The time for setting a term of validity and the key for encoding may be provided by the transaction clock rejecting an access by the keyboard and providing the time equal to that of other cards.

Abstract: A memory card has a card medium and a laser memory for storing data. A data processing section for storing encryption and/or decryption key data, an encryption and/or decryption program and a password is arranged in the card medium. When the same password as prestored in the data processing section is input, the input data is encrypted and/or decrypted in accordance with the encryption and/or decryption key data and the encryption and/or decryption program. The encrypted and/or decrypted data is stored in the laser memory.