Polymorphic data structures for secure operation of a virtual cash system

• US 6,023,508 A
• Filed: 05/22/1997
• Issued: 02/08/2000
• Est. Priority Date: 05/22/1997
• Status: Expired due to Fees

• Current Assignee: Currency Scientific Incorporated
• Original Assignee: Currency Scientific Incorporated
• Inventors: Bombard, Thomas J., Hassett, John J.
• Primary Examiner(s): Swann, Tod R
• Assistant Examiner(s): JACK, TODD M
• Application Number:
  US08/861,628
• Time in Patent Office: 992 Days
• Field of Search: 380/3, 380/4, 380/25, 705/68, 705/69, 713/200, 235/379, 364/408
• US Class Current: 705/69
• CPC Class Codes: G06Q 20/06 Private payment circuits, e.g. involving electronic currency used among participants of a common payment scheme
• CPC Class Codes: G06Q 20/105 involving programming of a portable memory device, e.g. IC cards, "electronic purses"
• CPC Class Codes: G06Q 20/367 involving electronic purses or money safes
• CPC Class Codes: G06Q 20/3678 e-cash details, e.g. blinded, divisible or detecting double spending
• CPC Class Codes: G06Q 20/3827 Use of message hashing

Abstract

A system for transferring value carrying data packets representative of cash between transferor and transferee terminals without the intervention of a centralized database provides for data packets convertible between an inspected state and an uninspected state. Data packets in an inspected state can be negotiated between terminals once, whereupon they become uninspected and hence, non-negotiable. Uninspected data packets are restored to inspected state by having a central bank compare a hash code generated by a transferor terminal against a corresponding hash code generated by the central bank.

Claims

1. A data packet created by an issuing module at the request of a requesting module, said data packet being representative of a cash note and comprising

encrypted identifying means for uniquely identifying said data packet, said encrypted identifying means including a representation of an original face value;

cleartext identifying means including a representation of a current face value less than or equal to said original face value and specifying an inspection state of said data packet, said inspection state being switchable between an inspected state having a transfer authorization key and an uninspected state having a hash code derived from said transfer authorization key.

2. A data packet representative of a cash note and adapted for secure transfer from a transferor terminal having a signature to a transferee terminal, said data packet comprising

encrypted identifying means permanently identifying said data packet;

cleartext identifying means specifying an inspection state switchable between an uninspected state in which said transfer from said transferor terminal to said transferee terminal is restricted and an inspected state in which said transfer from said transferor terminal to said transferee terminal is unrestricted.

3. The data packet of claim 2 wherein said cleartext identifying means includes a field in which said transferor terminal can affix said signature.

4. The data packet of claim 3 wherein said signature comprises a hash code derived from said cleartext identifying means in its inspected state.

5. A method for inspecting a data packet in possession of a holder upon transmission of a request from said holder to an inspector having an associated inspection database containing records of valid data packets, said data packet representative of a cash note and having

a first encrypted identification means permanently identifying said data packet, said encrypted identification means including a representation of an original face value;

a first cleartext identification means specifying an inspection state switchable between an inspected state and an uninspected state, said cleartext identification means indicating that said data packet is in an uninspected state;

a corresponding data packet in said inspection database, said corresponding data packet having a second encrypted identification means identical to said first encrypted identification means and having a second cleartext identification means indicating that said corresponding data packet is in an inspected state, said second cleartext identification means having means to independently generate said first cleartext identification means;

said method comprising the steps of;

transferring said data packet from said holder to said inspector,

verifying that said data packet has a corresponding data packet in said inspection database,

verifying that said data packet is in an uninspected state,

verifying that said current face value of said data packet is less than or equal to said original face value of said data packet,

independently generating said first cleartext record from said second cleartext record,

verifying that said first cleartext record and said independently generated first cleartext record are identical,

altering said first cleartext record to indicate that said data packet is in an inspected state, and

replacing said second cleartext record with said altered first cleartext record,

transmitting said data packet from said inspector to said holder,

such that said data packet in possession of said holder includes a cleartext record identifying said data packet as an inspected data packet.

6. The method of claim 5 wherein said step of independently generating said first cleartext record from said second cleartext record comprises the steps of:

reading an identifying field from said first cleartext record,

reading a transfer authorization key from said second cleartext record, and

applying a hash coding function to said identifying field and said transfer authorization key to generate a hash code, said hash code being identical to a corresponding hash code on said first cleartext record.

7. The method of claim 6 wherein said step of altering said first cleartext record to indicate that said data packet is in an inspected state comprises the steps of:

deleting said corresponding hash code from said first cleartext record,

deleting said identifying field from said first cleartext record,

generating a transfer authorization key, and

adding said transfer authorization key to said first cleartext record.

8. A method for negotiating a data packet in the possession of a transferor module having data processing means to a transferee module, said data packet representative of a cash note having

an inspection state switchable between an uninspected state and an inspected state and set to the inspected state;

an encrypted record uniquely identifying said data packet; and

a cleartext record specifying said inspection state of said data packet, said cleartext record including a transfer authorization key;

method comprising the steps of;

reading said transfer authorization key, with said data processing means, from said cleartext record,

writing with said data processing means, an identifying field to said cleartext record,

generating with said data processing means, a signature based on said transfer authorization key and said identifying field,

writing, with said data processing means, said signature to said cleartext record, thereby indicating that said data packet is in an uninspected state,

transmitting said data packet to said transferor module such that said inspected data packet in possession of said transferor module becomes an uninspected data packet in possession of said transferor module.

9. A system for the secure transfer of a data packet representative of a cash note having

an encrypted record uniquely identifying said data packet,

a cleartext record specifying an inspection state switchable between an inspected state and an uninspected state, and a circulation state switchable between a circulating state and a non-circulating state,

said system comprising:

a central bank terminal for issuing said data packet, said central bank terminal maintaining a record for said data packet and having means to authenticate said data packet and means to alter said inspection state of said data packet from being in an uninspected state to being in an inspected state;

an account custodian terminal for receiving said data packet issued by said first database system, said account custodian terminal having means to alter said circulation state of said data packet from being in a circulating state to being in a non-circulating state;

a personal terminal for receiving said data packet from said account custodian system, said personal terminal having means to alter said inspection state of said data packet from being in an inspected state to being in an uninspected state

such that said data packet issued by said central bank terminal is placed into circulation by said account custodian terminal upon being transferred by said account custodian terminal to said personal terminal.

10. A method for negotiating a data packet from a transferor module to a transferee module, said data packet representative of a cash note and having:

an inspection state switchable between an inspected state and an uninspected state and set to an inspected state,

an encrypted record uniquely identifying said data packet, and

a cleartext record specifying said inspection state,

said method comprising the steps of;

generating a signature based on said cleartext record;

changing said inspection state of said data packet by writing said signature to said cleartext record;

transmitting said data packet to said transferee module.

11. A method for circulating a data packet representative of a cash note, said data packet being switchable from an inspected state to an uninspected state, said method comprising the steps of:

transferring said data packet, in an inspected state, from a central bank to an account custodian,

transferring said data packet from said account custodian to a first terminal,

changing said data packet at said first terminal from an inspected state to an uninspected state,

transferring said uninspected data packet to a second terminal,

changing said uninspected data packet at said second terminal into an inspected data packet,

transferring said inspected data packet from said second terminal to said account custodian,

transferring said inspected data packet from said account custodian to said central bank, and

removing said data packet from circulation.

12. A method for inspecting a data packet in possession of a holder, said data packet representative of a cash note and having

an inspection state switchable between an inspected state and an uninspected state and

a signature generated by said holder, said signature being based on said inspected state of said data packet,

said method comprising the step of

verifying that said signature is consistent with said inspected state of said data packet,

altering said data packet to indicate that said data packet is in an inspected state so that said data packet in possession of said holder is in an inspected state.

13. A system for the secure transfer of a data packet representative of a cash note, said data packet having

an encrypted record uniquely identifying said data packet,

a cleartext record specifying an inspection state switchable between an inspected state and an uninspected state,

said system comprising:

a central bank system for issuing said data packet, said central bank system maintaining a record for said data packet and having means to authenticate said data packet and means to alter said inspection state of said data packet from being in an uninspected state to being in an inspected state,

a terminal for receiving said data packet from said central bank system, said terminal having means to alter said inspection state of said data packet from being in an inspected state to being in an uninspected state.