Electronic bankbook, and processing system for financial transaction information using electronic bankbook

An IC card for functioning as a book of electronic checks in the form of electronic data, comprising:

• an IC chip for storing a set money amount and an usable money amount which must be lower than or equal to said set money amount stored in said IC chip, said usable money amount for defining an upper limit for a face value of a single electronic check which can be issued;
• wherein said IC chip imposes a rewrite restriction with respect to said set money amount stored in said IC chip, and maintain said rewrite restriction unless a rewrite authority key which only a payer knows is used;
• and
• said IC chip has a processor for comparing a payment amount with said usable money amount stored in said IC chip, for issuing an electronic check having the face value of said payment amount only if said payment amount does not exceed said usable money amount stored in said IC chip, and for updating said usable money amount stored in said IC chip by subtracting from said usable money amount said face value of said electronic check which has been issued.

A method for issuing an electronic check of the form of electronic data, comprising the steps of:

• preparing an IC card that functions as a book of electronic checks, having an IC chip in which are stored a set money amount on which a rewrite restriction is imposed by said IC chip and an usable money amount for defining the upper limit for a face value of a single electronic check which can be issued;
• comparing a payment money amount with said usable money amount stored in said IC chip;
• issuing an electronic check having the face value of said payment money amount, only is said payment money amount does not exceed said usable money amount stored in said IC chip;
• and
• updating said usable money amount stored in said IC chip by subtracting from said usable money amount said face value of said electronic check which has been issued.