Registers – Systems controlled by data bearing records – Banking systems
Reexamination Certificate
1998-11-04
2001-10-09
Frech, Karl D. (Department: 2876)
Registers
Systems controlled by data bearing records
Banking systems
C705S044000, C380S030000
Reexamination Certificate
active
06299062
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an off-line electronic transaction system which is secured in respect of cryptographics using a telecommunication system or a smart card and an electronic commercial transaction method using the same.
As information-based society has been constructed, the world much depends on network communication. Thus, computer-based technology has greatly affected the access, the storing and the distribution of the information. An electronic commercial transaction is a representative example of such a computer-based technology, which performs a financial transaction by exchanging the electronic informations on communication network.
However, the electronic commercial transaction has problems in that the transmitted information can be illegally captured or transformed by others in open type network such as the Internet, thereby infringing the privacy of the transaction-related parties or causing them to be economically damaged. These problems make a role of hinderance in implementing the electronic commercial transaction. In addition, for the sake of making the electronic commercial transaction popular, the cost for using the electronic commercial transaction should be reduced to be much smaller than the money to be transacted. That is it should be economical. Therefore, in order for activating the electronic commercial transaction, a safe and high efficient electronic transaction system is required.
This electronic transaction system has been implemented an electronic check, a debit-card, a credit card, a stored value card, an electronic cash or the like. The present invention is addressed to the electronic cash, which is able to be electronically implemented by modelling the real cash currently passing in the real world. The real cash has characteristics that it is easy to be carried, easily authenticated, transferable, divisible into small changes, untraceable and anonymous. Thus, it is necessary that the electronic cash should be designed to have the above characteristics. In particular, the untraceability for payment and anonymity among the above characteristics have been much focused on by electronic cash designers.
For providing the untraceability for payment and the anonymity of payer so that a bank apparatus can not find out who have paid to whom, it is necessary that the bank apparatus can not relate a specific withdrawal transaction to a specific account. This can be accomplished by using a special kind of electronic signature called as “blind signature”, which has been disclosed in “Blind signatures for untraceable payments”, the Proceedings of Crypto'88, pp.199-203, 1983, by D. Chaum.
Also, since the electronic cash is digital data, it may be easily copied to be illegally used in twice or more times. For preventing the multiple use of an electronic cash, in an on-line transaction system, the bank apparatus intervenes the payment so double-spending can be prevented. However, in an off-line transaction system, since the bank does not intervene when a user pays an electronic cash to a shop, it is more difficult to prevent in advance the multiple use (that is, double-spending) of the electronic cash in comparison with that in an on-line transaction system. Only after the electronic cash having been paid by a user is deposited from a shop to a bank, the electronic cash may be examined with a database stored in the bank so as to find out whether the electronic cash has been illegally double-spent. That is to say, in off-line system the electronic cash can be only traced after the fact.
To compensate for this shortage, there has been recently proposed a tamper-resistant device called as “observer”, which is issued from a bank and inserted into a payment apparatus of user, so as,to prevent the multiple use of the electronic cash. In this method, the payment of the electronic cash is successfully made with the cooperation of the observer.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide an electronic cash system, more specifically an off-line electronic transaction system, an electronic transaction method using the same, and an electronic cash transaction method, in which the electronic cash used in the electronic transaction is untraceable due to the anonymity of payer, transferable to another user, divisible into small changes and preventive of illegally double-spending.
To accomplish the above object, according to one aspect of the present invention, there is provided an off-line electronic transaction system for performing an electronic transaction using an electronic cash, comprising: at least one user apparatus each capable of using the electronic cash; an authentication center apparatus, for receiving a user identity information, a corresponding public key along with a certificate issue request from one of the user apparatus and for issuing a certificate for the user apparatus's public key after confirming the identity of the corresponding user; at least one shop apparatus for confirming the identification of the user based on the user apparatus's public key, the corresponding certificate, for producing a challenge value unique to respective transaction using an electronic cash received from the user apparatus and then for confirming the validity of the electronic cash based on a response value from the user apparatus in response to the challenge value, so as to perform an electronic cash transaction with the user apparatus; and at least one bank apparatus for opening an anonymous account to one of the user apparatus and issuing an electronic cash according to the user apparatus's request after confirming the identification of the user based on the user apparatus's public key and the corresponding certificate, and for confirming the validity of an electronic cash received from one of the shop apparatus or the user apparatus so as to credit a corresponding account.
According to another aspect of the present invention, there is provided an electronic commercial transaction method using an off-line electronic transaction system including at least one user apparatus, an authentication center apparatus, at least one shop apparatus, and a bank apparatus, the method comprising: a first step wherein one of the user apparatus transmits it's identity information along with it's public key, and wherein the authentication center apparatus confirms the identity of the user apparatus, and if valid, then issues a certificate for the user apparatus public key; a second step wherein the user apparatus transmits it's public key and the certificate along with a request of opening an anonymous account to the bank apparatus, and wherein the bank apparatus confirms the validity of the user apparatus public key, and if valid, then opens an anonymous account for the user apparatus; a third step wherein one of the user apparatus withdraws an electronic cash from his account at the bank apparatus and then confirms the validity of the electronic cash; a fourth step wherein the user apparatus transmits it's public key, the certificate and the electronic cash to one of the shop apparatus along with a transaction request, and wherein the shop apparatus confirms the validity of user apparatus, and if valid, then performs the requested transaction with the user apparatus; and a fifth step wherein the shop apparatus transmits a transaction-related record including the electronic cash, the user apparatus public key and the user apparatus public key related to the electronic cash, to the bank apparatus along with a deposit request, and wherein the bank apparatus confirms the validity of the user apparatus public key and the electronic cash and verifies that there is no double-spending of the electronic cash, and if all valid, then credits an account of the shop apparatus by the value of the electronic cash.
According to still anther aspect of the present invention, there is provided an electronic cash transaction method comprising: a certificate issue step wherein an aut
Antonelli Terry Stout & Kraus LLP
Electronics and Telecommunications Research Institute
Frech Karl D.
Taylor Larry D
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