Off-line compatible electronic cash method and system
First Claim
1. In an off-line electronic cash system having an electronic coin, a bank B, a user U having an account at said bank B and a payee S, a method for performing an electronic cash transfer independently of public key cryptography, comprising the steps of:
- (a) withdrawing said electronic coin from said bank B by said user U;
(b) storing an electronic record of said electronic coin by said bank B;
(c) paying said electronic coin to said payee S by said user U;
(d) depositing said electronic coin with said bank B by said payee S;
(e) determining that said electronic coin is spent in accordance with the depositing of step (d);
(f) deleting said record by said bank B in response to the determining of step (e);
(g) determining a further deposit of said electronic coin after said deleting of said record; and
(h) determining said user U in accordance with said determining of said further deposit.
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Accused Products
Abstract
An off-line electronic cash system having an electronic coin, a bank B, a payee S, and a user U with an account at the bank B as well as a user password zu,i, has a method for performing an electronic cash transfer. An electronic coin is withdrawn from the bank B by the user U and an electronic record of the electronic coin is stored by the bank B. The coin is paid to the payee S by the user U. The payee S deposits the coin with the bank B. A determination is made that the coin is spent and the record of the coin is deleted by the bank B. A further deposit of the same coin after the record is deleted is determined. Additionally, a determination is made which user U originally withdrew the coin after deleting the record. To perform these operations a key pair is generated by the user, including public and secret signature keys. The public signature key along with a user password zu,i and a withdrawal amount are sent to the bank B by the user U. In response, the bank B sends a coin to the user U signed by the secret key of the bankindicating the value of the coin and the public key of the user U. The payee S transmits a challenge counter to the user U prior to receiving the coin.
175 Citations
24 Claims
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1. In an off-line electronic cash system having an electronic coin, a bank B, a user U having an account at said bank B and a payee S, a method for performing an electronic cash transfer independently of public key cryptography, comprising the steps of:
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(a) withdrawing said electronic coin from said bank B by said user U; (b) storing an electronic record of said electronic coin by said bank B; (c) paying said electronic coin to said payee S by said user U; (d) depositing said electronic coin with said bank B by said payee S; (e) determining that said electronic coin is spent in accordance with the depositing of step (d); (f) deleting said record by said bank B in response to the determining of step (e); (g) determining a further deposit of said electronic coin after said deleting of said record; and (h) determining said user U in accordance with said determining of said further deposit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. In an off-line electronic cash system having an electronic coin with a value withdrawal-- value, a bank B, a user U having a user password and an account at said bank B and a payee S, a method for performing an electronic cash transfer independently of public key cryptography, comprising the steps of:
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(a) withdrawing said electronic coin from said bank B by said user U; (b) storing an electronic record of said electronic coin by said bank B; (c) paying said electronic coin to said payee S by said user U; (d) depositing said electronic coin with said bank B by said payee S; (e) determining that said electronic coin is spent in accordance with the depositing of step (d); (f) generating by said user U a key pair (coin-- signP,coin-- signs) wherein said coin-- signP is a public signing key and said coin-- signs is a secret signing key; (g) transmitting (zu,i,coin-- signP,withdrawal-- value) by said user U to said bank B; (h) verifying the transmission of step (g) by bank B; (i) deducting withdrawal-- value from said account of said user U; and (j) transmitting (coin-- signP,withdrawal-- value) to said user U by said bank B.
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Specification