Multi-purpose transaction card system

• US 6,434,238 B1
• Filed: 08/11/1997
• Issued: 08/13/2002
• Est. Priority Date: 01/11/1994
• Status: Expired due to Term

• Current Assignee: Van Detsan Networks LLC (Intellectual Ventures LLC)
• Original Assignee: InfoSpace, Inc. (Blucora Incorporated)
• Inventors: Chaum, David, Ferguson, Niels, Van Der Hoek, Jelte
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US08/909,480
• Time in Patent Office: 1,828 Days
• Field of Search: 380/30, 380/45-47, 235/380, 705/67-69, 713/169-172
• US Class Current: 380/45
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/367 involving electronic purses or money safes
• CPC Class Codes: G06Q 20/3674 involving authentication
• CPC Class Codes: G06Q 20/382 insuring higher security of transaction
• CPC Class Codes: G06Q 20/401 Transaction verification
• CPC Class Codes: G06Q 20/40975 using encryption therefor
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: H04L 2209/30 Compression, e.g. Merkle-Damgard construction
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 9/3257 using blind signatures
• CPC Class Codes: H04L 9/50 using hash chains, e.g. blockchains or hash trees

Abstract

Disclosed is a multi-purpose transaction card system comprising an issuer, one or more cards, one or more terminals, and optionally one or more acquires, communicating using a variety of cryptographic confidentiality and authentication methods. Cards authenticate messages using public key based cryptographic without themselves performing the extensive computations usually associated with such cryptography. Integrity of complex transaction sequences and plural card storage updates are maintained, even under intentionally generated interruptions and/or modifications of data transmitted between card and terminal. Cards do not reveal any information to the terminal which is not directly necessary for the transaction or any information to which the terminal should not have access, though externally measurable aspects of its behavior. Transaction types supported include those suitable for off-line credit cards, in which the “open to buy” is maintained on the card.

Claims

1. A method for conducting financial transactions using a card, a terminal, and an issuer substantially according to EMV specification, the method comprising:

generating variable transaction data;

constructing a message block having a value dependent on at least some of said variable transaction data;

generating, by the card, an authentication of the message block;

sending said authentication to the terminal; and

verifying, by said terminal, the authentication.

2. The method of claim 1, wherein the message block includes a transaction certificate.

3. The method of claim 1, wherein said generating comprises using public key cryptography on the message block.

4. An apparatus for conducting financial transactions using a card, a terminal, and an issuer substantially according to EMV specification, the method comprising:

means for generating variable transaction data;

means for constructing a message block having a value dependent on at least some of said variable transaction data;

means for generating, by the card, an authentication of the message block;

means for sending said authentication to the terminal; and

means for verifying, by said terminal, the authentication.

5. The method of claim 4, wherein the message block includes a transaction certificate.

6. The method of claim 5, wherein said means for generating comprises means for using public key cryptography on the message block.

7. A method for conducting financial transactions using a card, a terminal, and an issuer substantially according to EMV specification, the method comprising:

maintaining a balance value in the card for financial transaction applications;

changing the balance value by an amount of each transaction; and

refusing to carry out an off-line transaction if the amount of the transaction exceeds the balance value.

8. The method of claim 7, said changing comprising the issuer using a script feature of the EMV to change the balance value maintained on the card.

9. The method of claim 7, further comprising:

the issuer storing information relating to the card and on-line transactions performed by the card;

the issuer detecting a failure to execute a first script, as issued by the issuer, during an on-line transaction;

creating a second script;

sending the second script to the terminal; and

the terminal executing the second script with the card.

10. The method of claim 9, further comprising:

the issuer detecting, after a predetermined period of time, off-line transactions performed with said card but not presented to the issuer for clearing;

estimating a total amount of said off-line transactions; and

adding substantially the total amount to the balance value using a script.