Document transfer systems

• US 20020091640A1
• Filed: 01/18/2002
• Published: 07/11/2002
• Est. Priority Date: 02/12/1998
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Gupta, Dipankar
• Granted Patent: US 7,058,605 B2
• Time in Patent Office: Days
• US Class Current: 705/51
• CPC Class Codes: G06Q 20/382 insuring higher security of transaction
• CPC Class Codes: G06Q 20/3829 involving key management
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 2209/605 Copy protection
• CPC Class Codes: H04L 9/085 Secret sharing or secret splitting, e.g. threshold schemes
• CPC Class Codes: H04N 1/32771 in response to a request, e.g. for a particular document
• CPC Class Codes: H04N 1/34 for coin-freed systems ; Pay systems
• CPC Class Codes: H04N 1/44 Secrecy systems
• CPC Class Codes: H04N 1/4406 Restricting access, e.g. according to user identity mechanisms actuated y cards, PIN or the like in apparatus for dispensing G07F7/08
• CPC Class Codes: H04N 1/444 to a particular document or image or part thereof
• CPC Class Codes: H04N 1/4486 using digital data encryption

Abstract

A document transfer system enabling a consumer to obtain a document from an owner upon payment uses a cryptographic protocol involving the consumer, the owner, a document source, such as a printer, and a mediator, the protocol comprising the following steps:

(a) the consumer requests a document;

(b) the owner provides the source with first and third portions of the key and provides the mediator with a fourth portion of the key, which can combine with said first portion to generate the complete key;

(c) the consumer provides the owner with the payment; and

(d) the owner provides the source with a second portion of the key, which can combine with said first portion to generate the complete key.

A printer 1 for use in the above system comprises a document memory 2 for storing a received encrypted document, a key memory 3 for storing a first cryptographic key portion, a processor 4 for receiving a second cryptographic key portion and combining it with the first key portion to form a complete cryptographic key which is supplied to a decrypting module 5. The encrypted document is supplied to the decrypting module 5 whereupon the document is decrypted and supplied to the consumer.

Claims

1. A cryptographic method of enabling a consumer to obtain a document from an owner upon a payment, the method comprising the use of a protocol involving the consumer, the owner and a document source, wherein the source requires knowledge of a key in which a said document is encrypted in order to provide the said document, the protocol comprising the following sequential steps:

(a) the consumer requests a specified document;

(b) the owner provides the source with a first portion of the key;

(c) the consumer provides the owner with the payment; and

(d) the owner provides the source with a second portion of the key, which can combine with said first portion to generate the complete key.

6. A cryptographic method as claimed in any preceding claim, wherein the document source comprises a printer.

7. A document source for use in a method as claimed in any preceding claim, the source comprising a memory for storing a said first key portion, means for receiving a said second key portion and means for decrypting an encrypted document transmitted thereto in accordance with the encryption key defined by said first and said second key portions.

9. A document source as claimed in claim 7 or claim 8 comprising a printer.

10. A document source as claimed in claim 9, arranged to print a number of copies of a said document in each of a plurality of formats.

11. A document source as claimed in claim 10, arranged to print only one copy of a said document in a first format and an unlimited number of copies of said document in a second format.

12. A document source as claimed in claim 10 or claim 11, wherein said formats comprise different resolutions.

13. A document source as claimed in any one of claims 10 to 12, wherein said formats comprise monochrome and colour images.

2. A cryptographic method of enabling a consumer to obtain a document from an owner upon a payment, the method comprising the use of a protocol involving the consumer, the owner, a document source and a mediator, wherein the source requires knowledge of a key in which a said document is encrypted in order to provide the said document, the protocol comprising the following sequential steps:

(a) the consumer requests a specified document;

(b) the owner provides the source with first and third portions of the key and provides the mediator with a fourth portion of the key, which can combine with said third portion to generate the complete key;

(c) the consumer provides the owner with the payment; and

(d) the owner provides the source with a second portion of the key, which can combine with said first portion to generate the complete key.

3. A cryptographic method as claimed in claim 2, wherein said first and said third portions of the key are different.

4. A cryptographic method as claimed in claim 2 or claim 3, and arranged for enabling a said consumer to receive a plurality of such documents, wherein said first and second portions are different for each document.

5. A cryptographic method as claimed in any one of claims 2 to 4, wherein the mediator is involved in the protocol only in the event of a dispute between the owner and the consumer.

8. A document source comprising a memory for storing a first cryptographic key portion, means for receiving a second cryptographic key portion and means for decrypting an encrypted document transmitted thereto in accordance with the encryption key defined by said first and said second key portions.

14. A fair exchange method of enabling a consumer to obtain a document from an owner upon a payment, the method comprising the use of a protocol involving the consumer, the owner and a printer, wherein the owner transfers a document to the printer and the consumer transfers a payment to the owner, the printer interacting with the owner and the consumer to ensure that the consumer receives the document only when the payment has been made.

15. A cryptographic method of enabling a first party to obtain an item of value from a second party upon receipt by said second party of a second item of value, the method comprising the use of a protocol involving the first party, the second party and a source of said first item of value, wherein the source requires knowledge of a key in order to provide the said first item of value, the protocol comprising the following sequential steps:

(a) the first party requests a specified first item of value;

(b) the second party provides the source with a first portion of the key;

(c) the first party provides the second party with the second item of value; and

(d) the second party provides the source with a second portion of the key, which can combine with said first portion to generate the complete key.

16. A fair exchange method of enabling a contract between a buyer and a seller of a commodity comprising the use of a cryptographic protocol involving the buyer, the seller and a source of said commodity, the source interacting with the buyer and the seller to ensure that the buyer receives the commodity only when a payment has been made by the buyer to the seller.