Anonymous certified delivery

• US 6,076,078 A
• Filed: 02/14/1997
• Issued: 06/13/2000
• Est. Priority Date: 02/14/1996
• Status: Expired due to Fees

• Current Assignee: Carnegie Mellon University
• Original Assignee: Carnegie Mellon University
• Inventors: Harkavy, Michael R., Tygar, Justin D., Camp, Linda Jean
• Primary Examiner(s): Swann, Tod R.
• Assistant Examiner(s): Callahan, Paul E.
• Application Number:
  US08/800,504
• Time in Patent Office: 1,215 Days
• Field of Search: 380/21, 380/23, 380/24, 380/30, 380/54, 380/59, 364/478.04, 364/478.03, 364/478.09, 364/400, 364/478.13, 364/478.14, 364/478.15, 364/479.02, 364/479.07, 902/2, 902/4, 902/5, 902/25, 902/41, 705/65-68
• US Class Current: 705/65
• CPC Class Codes: G06Q 20/045 using payment protocols involving tickets
• CPC Class Codes: G06Q 20/085 involving remote charge determination or related payment systems
• CPC Class Codes: G06Q 20/0855 involving a third party
• CPC Class Codes: G06Q 20/12 specially adapted for electronic shopping systems
• CPC Class Codes: G06Q 20/367 involving electronic purses or money safes
• CPC Class Codes: G06Q 20/3672 initialising or reloading thereof
• CPC Class Codes: G06Q 20/3674 involving authentication
• CPC Class Codes: G06Q 20/3676 Balancing accounts
• CPC Class Codes: G06Q 20/3678 e-cash details, e.g. blinded, divisible or detecting double spending
• CPC Class Codes: G06Q 20/3821 Electronic credentials
• CPC Class Codes: G06Q 20/3823 combining multiple encryption tools for a transaction
• CPC Class Codes: G06Q 20/3827 Use of message hashing
• CPC Class Codes: G06Q 20/3829 involving key management
• CPC Class Codes: G06Q 20/389 Keeping log of transactions for guaranteeing non-repudiation of a transaction
• CPC Class Codes: G06Q 20/401 Transaction verification
• CPC Class Codes: G06Q 30/06 Buying, selling or leasing transactions
• CPC Class Codes: H04L 2209/42 Anonymization, e.g. involving pseudonyms
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 9/3213 using tickets or tokens, e.g. Kerberos network architectures or network communication protocols for entities authentication using tickets in a packet data network H04L63/0807
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3247 : involving digital signatures

Abstract

A number of fault-tolerant methods for purchasing digital goods with a digital token over a network in which the token'"'"'s value resides either with a customer or a merchant are disclosed. One version of the method comprises the steps of establishing a price with a merchant for a digital good. A merchant-signed invoice and the digital good in encrypted form are then sent from the merchant to the customer. The invoice is signed with the customer'"'"'s signature to produce a countersigned invoice. The countersigned invoice, a token (which can be an anonymous token), and identifying information for the token are sent from the customer to the merchant. The countersigned invoice, the token, and the identifying information are sent from the merchant for verification. The token is verified with the identifying information and the other information in the countersigned purchase order is checked. The transaction is committed when the token and other information in the countersigned purchase order are verified such that the value of the token is transferred from the customer to the merchant. The transaction is then completed by providing the customer with the key for decrypting the encrypted goods.

Claims

1. A fault-tolerant method of purchasing digital goods with a digital token in which the token'"'"'s value resides either with a customer or with a merchant, comprising the steps of:

initiating a transaction with a merchant for a digital good;

sending a merchant-signed invoice and the digital good in encrypted form from the merchant to a customer;

signing the invoice with the customer'"'"'s signature to produce a countersigned invoice;

sending the countersigned invoice, a token, and identifying information for the token from the customer to the merchant;

sending the countersigned invoice, the token, and the identifying information for verification;

verifying the token with the identifying information and verifying the other information in the countersigned purchase order;

committing the transaction when the token and other information in the countersigned purchase order are verified such that the value of the token is transferred from the customer to the merchant;

completing the transaction by making a key for decrypting the digital good available to the customer; and

retaining records of the transaction.

2. The method of claim 1 wherein said step of sending identifying information for the token includes the step of sending a hash of the token.

3. The method of claim 2 wherein said step of sending the countersigned invoice for verification includes the step of sending the countersigned invoice to an archive for verification.

4. The method of claim 1 wherein said step of verifying the other information in the countersigned invoice includes the step of determining if the price of the goods and the value of the token are the same.

5. The method of claim 1 additionally comprising the step of communicating to the merchant'"'"'s bank the transfer of the token'"'"'s value to the merchant.

6. The method of claim 1 wherein said step of retaining records includes the step of storing the identifying information and the token.

7. The method of claim 1 additionally comprising the steps of:

sending verification information for the encrypted digital good with the merchant-signed invoice from the merchant to the customer;

calculating corresponding verification information for the received encrypted digital good;

comparing the calculated verification information to the received verification information; and

one of terminating the purchase or resending the encrypted digital good if the verification information is not the same.

8. The method of claim 1 wherein said token is an anonymous token and wherein said identifying information includes registration information.

9. A method of purchasing digital goods with a digital token belonging to a customer in which the value of the token resides with only one party at a time, comprising:

initiating a transaction with a merchant for a digital good;

transferring the digital good in an encrypted form from the merchant to a customer;

locking at least a portion of the value of the token to the transaction;

sending a digital token and transactional information to the merchant;

verifying the transactional information and the value of the token;

providing a decryption key to the customer;

unlocking said locked value of the token and transferring said value to the merchant; and

retaining a record of the transaction.

10. The method of claim 9 wherein said step of verifying the value of the token includes the step of verifying if the value of the token has been previously spent.

11. The method of claim 9 wherein said step of providing the decryption key to the customer includes the step of sending the key to the customer.

12. The method of claim 9 additionally comprising the step of reusing the token until the entire value of the token is transferred.

13. The method of claim 9 wherein said step of sending the digital token includes the step of sending an anonymous token and identifying information.

14. The method of claim 9 wherein the token has a key associated therewith, said method including the step of generating a customer signature with the key associated with the token, and wherein said step of sending transactional information includes the step of sending the customer signature.

15. The method of claim 9 wherein said step of sending a token includes the step of sending multiple tokens.

16. The method of claim 15 wherein each token has a key associated therewith, said method including the step of generating customer signatures with the keys associated with the tokens, and wherein said step of sending transactional information includes sending the generated signatures.

17. The method of claim 9 wherein said step of verifying the transactional information includes the step of determining if the price of the goods and the value of the token are the same.

18. The method of claim 9 additionally comprising the step of communicating to the merchant'"'"'s bank the transfer of the token'"'"'s value to the merchant.

19. The method of claim 9 wherein said step of sending transactional information includes the step of sending a public half of a customer chosen asymmetric key pair.

20. The method of claim 9 wherein said step of verifying the value of the token is performed by one of a bank, the merchant, or an archive.

21. A method of purchasing digital goods with a digital token belonging to a customer in which the value of the token resides with only one party at a time, comprising:

initiating a transaction with a merchant for a digital good;

locking at least a portion of the value of the token to the transaction;

sending an entity signed purchase approval including a digital token and transactional information to the merchant;

transferring the digital good in an encrypted form from the merchant to a customer after the value of the token is locked to the transaction;

providing a decryption key to the customer;

unlocking said locked value of the token and transferring said value to the merchant; and

retaining a record of the transaction.

22. The method of claim 21 wherein said step of initiating a transaction includes the step of sending a merchant signed invoice from the merchant to the customer.

23. The method of claim 21 wherein said step of locking at least a portion of the value of the token includes the step of sending a customer signed purchase authorization from the customer to an entity for verification.

24. The method of claim 21 wherein said entity performs the step of sending the entity signed purchase approval.

25. The method of claim 24 additionally comprising the step of verifying the entity signed purchase approval.

26. The method of claim 25 wherein said step of verifying the entity signed purchase approval is performed by one of the merchant or an archive.

27. The method of claim 26 wherein the merchant forces the transaction to commit by sending a copy of the message transferring the digital good and a copy of the message verifying the entity signed purchase approval to an archive.

28. The method of claim 27 wherein the decryption key is encoded.

29. The method of claim 21 wherein said step of transferring the encrypted digital good includes the step of transferring a merchant signature with the encrypted good.

30. The method of claim 29 additionally comprising the steps of adding a customer signature to the merchant signature and sending the encrypted good and the signatures from the customer to the merchant.

31. A method for purchasing digital goods with a digital token belonging to a customer in which the value of the token resides with only one party at a time, comprising:

initiating a transaction with a merchant for a digital good;

transferring the digital good in an encrypted form from the merchant to a customer;

sending a digital token and transactional information to an entity for verification;

locking at least a portion of the value of the token to the transaction;

verifying the transactional information and the value of the token;

providing a decryption key to the entity;

unlocking said locked value of the token and transferring said value to the merchant;

completing the transaction by making the key available to the customer; and

retaining a record of the transaction.

32. The method of claim 31 wherein said step of transferring the digital good includes the step of sending a merchant signed invoice and the encrypted digital good from the merchant to the customer.

33. The method of claim 31 wherein said step of sending transactional information includes the step of sending a customer-signed authorization from the customer to an entity for verification.

34. The method of claim 31 wherein said step of providing a decryption key to the entity includes the step of sending a merchant-signed key from the merchant to the entity.

35. The method of claim 31 wherein said step of completing the transaction includes the step of sending an entity-signed key from the entity to the customer and wherein said step of unlocking said locked value of the token includes the step of sending an entity-signed unlocked value of the token from the entity to the merchant.

36. The method of claim 31 wherein said step of verifying the value of the token includes the step of verifying if the value of the token has been previously spent.

37. The method of claim 31 wherein said step of providing the decryption key to the entity includes the step of storing the key at an archive which both the entity and the merchant can access.

38. The method of claim 37 additionally comprising the step of verifying that an expiration time for the transaction has not passed before the decryption key is stored at the archive.

39. The method of claim 37 additionally comprising the step of the archive countersigning the decryption key and wherein said step of retaining records includes the step of retaining the countersigned decryption key.

40. The method of claim 39 additionally comprising the step of the merchant demonstrating that the value of the token has been transferred by providing a copy of the archive countersigned decryption key.

41. The method of claim 31 wherein the value of the token remains locked until the transaction is one of aborted or completed by providing the decryption key to the customer.

42. The method of claim 31 wherein said step of providing the decryption key to the entity includes the step of sending the key to the entity.

43. The method of claim 31 additionally comprising the step of reusing the token until the entire value of the token is transferred.

44. The method of claim 31 wherein said step of sending the digital token includes the step of sending an anonymous token and identifying information.

45. The method of claim 31 wherein the token has a key associated therewith, said method including the step of generating a customer signature with the key associated with the token, and wherein said step of sending transactional information includes the step of sending the customer signature.

46. The method of claim 31 wherein said step of sending a token includes the step of sending multiple tokens.

47. The method of claim 46 wherein each token has a key associated therewith, said method including the step of generating customer signatures with the keys associated with the tokens, and wherein said step of sending transactional information includes sending the generated signatures.

48. The method of claim 31 wherein said step of verifying the transactional information includes the step of determining if the price of the goods and the value of the token are the same.

49. The method of claim 31 additionally comprising the step of communicating to the merchant'"'"'s bank the transfer of the token'"'"'s value to the merchant.

50. The method of claim 31 wherein said step of sending transactional information includes the step of sending a public half of a customer chosen asymmetric key pair.

51. The method of claim 31 wherein said step of verifying the value of the token is performed by one of a bank, the merchant, or an archive.

52. A method of purchasing digital goods with a digital token belonging to a customer in which the value of the token resides with only one party at a time, comprising:

initiating a transaction with a merchant for a digital good;

transferring the digital good in an encrypted form from the merchant to a customer;

sending a digital token and transactional information to an entity for verification;

locking at least a portion of the value of the token to the transaction;

verifying the transactional information and the value of the token;

providing a decryption key to the customer;

unlocking said locked value of the token and transferring said value to the merchant;

retaining a record of the transaction; and

repeating the foregoing steps until a sequence of transactions is completed.

53. A fault-tolerant method of purchasing digital goods with a digital token in which the delivery of goods is atomic, comprising the steps of:

establishing a price with a merchant for a digital good;

sending a merchant-signed invoice and the digital good in encrypted form from the merchant to a customer;

sending a customer-signed purchase authorization including the token from the customer to a bank for verification;

verifying the customer-signed purchase authorization;

sending a bank-signed purchase approval from the bank to the merchant for verification;

verifying the bank-signed purchase approval;

completing the transaction by making the key for decrypting the digital good available to the customer; and

retaining records of the transaction.

54. A fault-tolerant method of purchasing digital goods with a digital token in which the token'"'"'s value resides either with a customer or with a merchant, comprising the steps of:

initiating a transaction with a merchant for a digital good;

sending a merchant-signed invoice and the digital good in encrypted form from the merchant to a customer;

signing the invoice with the customer'"'"'s signature to produce a countersigned invoice;

sending the countersigned invoice, a token, and identifying information for the token, including a hash of the token, from the customer to the merchant;

sending the countersigned invoice to an archive for verification, wherein said archive stores the hash of the token in conjunction with a key for the token;

sending the token and the identifying information for verification;

verifying the token with the identifying information by using the key stored in conjunction with the hash of the token, and verifying the other information in the countersigned purchase order;

committing the transaction when the token and other information in the countersigned purchase order are verified such that the value of the token is transferred from the customer to the merchant;

completing the transaction by making a key for decrypting the digital good available to the customer; and

retaining records of the transaction.

55. A fault-tolerant method of purchasing digital goods with a digital token in which the token'"'"'s value resides either with a customer or with a merchant, comprising the steps of:

initiating a transaction with a merchant for a digital good;

sending a merchant-signed invoice and the digital good in encrypted form from the merchant to a customer;

signing the invoice with the customer'"'"'s signature to produce a countersigned invoice;

sending the countersigned invoice, a token, and identifying information for the token from the customer to the merchant;

sending the countersigned invoice, the token, and the identifying information for verification;

verifying the token with the identifying information and verifying the other information in the countersigned purchase order;

committing the transaction when the token and other information in the countersigned purchase order are verified such that the value of the token is transferred from the customer to the merchant;

completing the transaction by making a key for decrypting the digital good available to the customer; and

storing the identifying information, the token, and the countersigned invoice.

56. A method of purchasing digital goods with a digital token belonging to a customer in which the value of the token resides with only one party at a time, comprising:

initiating a transaction with a merchant for a digital good;

transferring the digital good in an encrypted form from the merchant to a customer;

locking at least a portion of the value of the token to the transaction;

sending a digital token and transactional information to the merchant;

verifying the transactional information and the value of the token;

storing a decryption key at an archive which both the customer and the merchant can access;

unlocking said locked value of the token and transferring said value to the merchant; and

retaining a record of the transaction.

57. The method of claim 56 additionally comprising the step of verifying that an expiration time for the transaction has not passed before the decryption key is stored at the archive.

58. The method of claim 56 additionally comprising the step of the archive countersigning the decryption key and wherein said step of retaining records includes the step of retaining the countersigned decryption key.

59. The method of claim 58 additionally comprising the step of the merchant demonstrating that the value of the token has been transferred by providing a copy of the archive countersigned decryption key.

60. A method of purchasing digital goods with a digital token belonging to a customer in which the value of the token resides with only one party at a time, comprising:

initiating a transaction with a merchant for a digital good;

transferring the digital good in an encrypted form from the merchant to a customer;

locking at least a portion of the value of the token to the transaction;

sending a digital token and transactional information to the merchant;

verifying the transactional information and the value of the token;

providing a decryption key to the customer;

unlocking said locked value of the token and transferring said value to the merchant; and

retaining a record of the transaction, wherein the portion of the value of the token remains locked until the transaction is one of aborted or completed by providing the decryption key to the customer.

61. A method of purchasing digital goods with a digital token belonging to a customer in which the value of the token resides with only one party at a time, comprising:

initiating a transaction with a merchant for a digital good;

transferring the digital good in an encrypted form from the merchant to a customer;

locking at least a portion of the value of the token to the transaction;

sending a digital token and transactional information to the merchant;

verifying the transactional information and the value of the token;

providing a decryption key to the customer;

sending a hash of the encrypted digital good to the customer;

calculating a hash of the received encrypted digital good;

comparing the calculated hash to the received hash;

one of aborting the transaction or resending the encrypted digital good if the hashes are not equal;

unlocking said locked value of the token and transferring said value to the merchant; and

retaining a record of the transaction.

62. A method of purchasing digital goods with a digital token belonging to a customer in which the value of the token resides with only one party at a time, comprising:

initiating a transaction with a merchant for a digital good;

locking at least a portion of the value of the token to the transaction;

the entity sending an entity-signed purchase approval including a digital token and transactional information to the merchant;

one of the merchant and an archive verifying that the entity signed the purchase approval;

transferring the digital good in an encrypted form from the merchant to a customer after the value of the token is locked to the transaction;

the merchant forcing the transaction to commit by sending a copy of a message transferring the digital good and a copy of a message verifying that the entity signed the purchase approval to the archive;

providing a decryption key to the customer, wherein the decryption key is encoded using a one-time pad;

unlocking said locked value of the token and transferring said value to the merchant; and

retaining a record of the transaction.

63. A method of purchasing digital goods with a digital token belonging to a customer in which the value of the token resides with only one party at a time, comprising:

initiating a transaction with a merchant for a digital good;

locking at least a portion of the value of the token to the transaction;

sending an entity-signed purchase approval including a digital token and transactional information to the merchant;

transferring the digital good in an encrypted form from the merchant to a customer after the value of the token is locked to the transaction;

storing a decryption key at an archive which both the customer and the merchant can access;

unlocking said locked value of the token and transferring said value to the merchant; and

retaining a record of the transaction.

64. A method for purchasing digital goods with a digital token belonging to a customer in which the value of the token resides with only one party at a time, comprising:

initiating a transaction with a merchant for a digital good;

transferring the digital good in an encrypted form from the merchant to a customer;

sending a digital token and transactional information to an entity for verification;

locking at least a portion of the value of the token to the transaction;

verifying the transactional information and the value of the token;

sending a hash of the encrypted digital good to the customer;

calculating a hash of the received encrypted digital good;

comparing the calculated hash to the received hash;

one of aborting the transaction or resending the encrypted digital good if the hashes are not equal;

providing a decryption key to the entity;

unlocking said locked value of the token and transferring said value to the merchant;

completing the transaction by making the key available to the customer; and

retaining a record of the transaction.