Application US20050171903

System and method for flexible micropayment of low value electronic assets
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US20050171903

1. A computer readable medium having computer-executable instructions for performing steps comprising: (7) (3)

minting a stick of electronic assets by digitally signing with an issuer's signature a composite of user-provided data items including a user identity, a bottom asset from a bottom of the stick, and a length of the stick;

spending one or more assets from the stick at one or more vendors, wherein each expenditure with a particular vendor involves digitally signing with a user's signature a first asset from the stick to be spent and passing the user-signed first asset along with the issuer-signed composite to the particular vendor for verification and subsequently passing any additional assets to be spent without user signature to the particular vendor; and

depositing one or more assets collected by the particular vendor by digitally signing with the particular vendor's signature a composite of data items including the user-signed first asset and a last asset spent by the user from the stick and passing the vendor-signed composite along with the issuer-signed composite to the issuer.

2. The computer-readable medium of claim 1, further comprising steps of storing the stick of electronic assets in a tamper-resistant electronic wallet. (0)

3. The computer-readable medium of claim 1, further comprising steps of storing the stick of electronic assets in an electronic wallet constructed with a secure-processor architecture. (0)

4. The computer-readable medium of claim 1, wherein the minting comprises minting the stick of assets using a blind signature protocol. (0)

5. The computer-readable medium of claim 1, wherein the spending comprises: (0) (5)

concatenating a vendor identity with the first asset from the stick to form a payment request;

signing the payment request with a signature of the user:

submitting the user-signed payment request along with the issuer-signed withdrawal request to the vendor;

accepting the first asset as payment in an event that the user and the issuer are verified; and

subsequently passing any additional assets from the stick as payment to the vendor without digitally signing them with the user's signature;

6. The computer-readable medium of claim 1, further comprising steps of auditing the assets deposited by the vendor. (0)

7. The computer-readable medium of claim 1, further comprising steps of auditing a sample of the assets paid by the user to the vendor. (0)

8. The computer-readable medium of claim 1, further comprising steps of selecting, at the vendor, a subset of less than all of the assets paid by the user to the vendor and submitting the subset of assets to an auditor for fraud evaluation. (0)

9. A computer comprising a: (7) (2)

a memory that stores an operating system; and

a central processing unit running the operating system and configured to perform the steps of: forming a stick of L electronic assets C_i(for i=1, . . . , L) where each asset can be derived from a preceding asset in the stick;

signing the stick with a signature of a party issuing the assets;

spending a first run of one or more assets from the stick at a first vendor; and

spending a second run of one or more assets from the stick at a second vendor.

10. The computer of claim 9 wherein the central processing unit further performs the step of storing the stick of electronic assets in a tamper-resistant electronic wallet. (0)

11. The computer of claim 9 wherein the central processing unit further performs the step of storing the stick of electronic assets in an electronic wallet constructed with a secure-processor architecture. (0)

12. The computer of claim 9 wherein the step of forming comprises anonymously issuing the stick of assets using a blind signature protocol. (0)

13. The computer of claim 9 wherein the step of spending comprises: (0) (3)

14. The computer of claim 9 wherein the central processing unit further performs the step of auditing the assets from the first and second runs of assets for fraud. (0)

15. The computer of claim 9 wherein the central processing unit further performs the step of auditing a sample of assets from the first and second runs of assets for fraud. (0)

16. The computer of claim 9 wherein the central processing unit further performs the step of depositing the first and second runs of assets. (0)

17. A computer readable medium having computer-executable instructions for performing steps comprising: (3) (6)

creating, at a user, a stick of L electronic assets by computing:

C_i=hⁱ(x) (for i=1, . . . , L)

where h(x) is a hashing function of a value x;

submitting a withdrawal request from the user to an issuer, the withdrawal request having a user identity U, a last asset value C_Ltaken from a bottom of the stick, and the value L, while omitting any vendor identity;

signing, at the issuer, the withdrawal request; and

returning the signed withdrawal request to the user.

18. The computer-readable medium of claim 17, further comprising steps of storing the stick of electronic assets and signed withdrawal request in a tamper-resistant electronic wallet. (0)

19. The computer-readable medium of claim 17, further comprising steps of storing the stick of electronic assets and signed withdrawal request in an electronic wallet constructed with a secure-processor architecture. (0)

20. The computer-readable medium of claim 17 wherein the withdrawal request further has a user secret K, a denomination d indicating a value for the assets in the stick, and an expiration t. (0)

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Application US20050171903

System and method for flexible micropayment of low value electronic assets

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