Secure pre-caching through local superdistribution and key exchange

• US 20090327729A1
• Filed: 03/30/2007
• Published: 12/31/2009
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Rhodes, Bradley J., Savitzky, Stephen R., Piersol, Kurt
• Granted Patent: US 8,046,328 B2
• Time in Patent Office: Days
• US Class Current: 713/171
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: G06F 21/6218 to a system of files or objects, e.g. local or distributed file system or database

Abstract

A distributed peer-to-peer document archival system provides the version-control, security, access control, linking among stored documents and remote access to documents usually associated with centralized storage systems while still providing the simplicity, personalization and robustness to network outages associated with personal and peer-to-peer storage systems.

Claims

1. A method in a first device for distributing documents among a plurality of second devices, the first device comprising a local data store, the method in the first device comprising:

receiving from a user of the first device a document retrieval request, the document retrieval request identifying a first document, contents of the first document being stored in encrypted form in a document object;

if the document object is stored in the local data store, then for each second device that does not have a copy of the document object stored thereat, sending the document object to said each second device; and

if the document object is not stored in the local data store, then retrieving the object from one of the second devices including;

sending a retrieve request to the second devices to retrieve a copy of the document object from one of the second devices; and

storing the retrieved copy of the document object on the local data store.

2. The method of claim 1 further comprising, subsequent to the step of storing the retrieved copy of the document object, for each second device that does not have a copy of the document object stored thereat, sending a copy of the retrieved copy of the document object to said each second device.

3. The method of claim 1 wherein the first device and a first plurality of the second devices constitute members of a neighborhood, wherein the steps of sending a retrieve request and sending the document object are performed only for members of the neighborhood,

wherein when a joining second device that is not already a member of the neighborhood becomes a member of the neighborhood, then subsequent thereto the steps of sending a retrieve request and sending the document object are also performed with the joining second device,

wherein when a leaving second device that is already a member of the neighborhood leaves the neighborhood, then subsequent thereto the steps of sending a retrieve request and sending the document object are no longer performed with the leaving second device.

4. The method of claim 1 wherein the first device and a first plurality of the second devices collectively define a neighborhood, wherein the steps of sending a retrieve request and sending the document object are performed only for the second devices that are members of the neighborhood, the method further comprising:

the first device learning of a second device joining the neighborhood; and

subsequent to learning of the newly joined second device, performing the steps of sending a retrieve request and sending the document object only with the newly joined second device and with the first plurality of second devices.

5. The method of claim 1 wherein the first device and a first plurality of the second devices collectively define a neighborhood, wherein the steps of sending a retrieve request and sending the document object are performed only for the second devices that are members of the neighborhood, the method further comprising:

the first device learning of one of the first plurality of second devices leaving the neighborhood; and

subsequent to learning that one of the first plurality of second devices has left the neighborhood, performing the steps of sending a retrieve request and sending the document object only to the remaining ones of the first plurality of second devices.

6. The method of claim 1 wherein storing the retrieved copy of the document object on the local data store comprises:

computing derived data based on contents of the retrieved copy of the document object;

comparing the derived data with document information contained in the document retrieval request; and

storing the retrieved copy of the document object on the local data store depending on a result of the comparison.

7. The method of claim 6 wherein the derived data is obtained by computing a hash of the contents of the retrieved copy of the document object.

8. The method of claim 1 further comprising obtaining a document key from the local data store, the document key including a decryption key for decrypting the document object.

9. The method of claim 1 wherein the cleartext content of the first document is a directory file, the directory file identifying a plurality of second document objects.

10. The method of claim 9 wherein, for a document object selected from among the second document objects, the method further comprises:

if the selected document object is not stored in the local data store, then retrieving the selected document object from one of the second devices including;

sending a retrieve request to the second devices to retrieve a copy of the selected document object from one of the second devices; and

storing the retrieved copy of the selected document object on the local data store; and

for each second device that does not have a copy of the selected document object stored thereat, sending the selected document object to said each second device.

11. The method of claim 10 further comprising decrypting the selected document object to obtain cleartext content of the selected document.

12. The method of claim 1 further comprising decrypting the document object to obtain cleartext content of the document object which constitutes the first document.

13. The method of claim 12 further comprising presenting the cleartext content on a display device.

14. The method of claim 12 further comprising printing or faxing the cleartext content.

15. A method for distributing documents from a first device to a plurality of second devices comprising:

receiving a first document key, wherein data comprising the first document key identifies a first document object;

if the first document object is stored on a local storage device of the first device, then for each second device that does not have a copy of the first document object stored thereat, sending the first document object to said each second device; and

if the first document object is not stored on the local storage device, then obtaining the first document object from one of the second devices and storing the obtained first document object on the local storage device.

16. The method of claim 15 further comprising, subsequent to the step of storing the obtained the first document object, for each second device that does not have a copy of the first document object stored thereat, sending a copy of the obtained first document object to said each second device.

17. The method of claim 15 wherein the first device and a first plurality of the second devices constitute members of a neighborhood, wherein the steps of sending a retrieve request and sending the document object are performed only for members of the neighborhood,

wherein when a joining second device that is not already a member of the neighborhood becomes a member of the neighborhood, then subsequent thereto the steps of sending the first document object, obtaining the first document object, and sending the obtained first document object are also performed with the joining second device,

wherein when a leaving second device that is already a member of the neighborhood leaves the neighborhood, then subsequent thereto the steps of sending the first document object, obtaining the first document object, and sending the obtained first document object are no longer performed with the leaving second device.

18. The method of claim 15 wherein the first device and a first plurality of the second devices collectively define a neighborhood, wherein the steps of sending a retrieve request and sending the document object are performed only for the second devices that are members of the neighborhood, the method further comprising:

the first device learning of a second device joining the neighborhood; and

subsequent to learning of the newly joined second device, performing thereto the steps of sending the first document object, obtaining the first document object, and sending the obtained first document object only with the newly joined second device and with the first plurality of second devices.

19. The method of claim 15 wherein the first device and a first plurality of the second devices collectively define a neighborhood, wherein the steps of sending a retrieve request and sending the document object are performed only for the second devices that are members of the neighborhood, the method further comprising:

the first device learning of one of the first plurality of second devices leaving the neighborhood; and

subsequent to learning that one of the first plurality of second devices has left the neighborhood, performing thereto the steps of sending the first document object, obtaining the first document object, and sending the obtained first document object only to the remaining ones of the first plurality of second devices.

20. The method of claim 15 wherein the first document key is provided by a user of the first device.

21. The method of claim 15 wherein the obtaining step includes:

generating first derived data based on data comprising the first document key;

sending a retrieve request to the second devices, the retrieve request including the first derived data, wherein the first derived data serves to identify the document object; and

receiving a copy of the first document object from one of the second devices.

22. The method of claim 21 wherein the retrieve request is sent to one second device at a time.

23. The method of claim 15 further comprising decrypting the first document using some of the data comprising the document key as a decryption key to produce cleartext content of the first document object.

24. A method in a first device for distributing documents among a plurality of second devices, the first device comprising a local data store, the method in the first device comprising:

receiving from a user of the first device a document retrieval request to access a first document, the first document being associated with a plurality of first document objects;

for each first document object that is stored in the local data store, then

for each second device that does not have a copy of said each first document object stored thereat, sending said each first document object to said each second device; and

for each first document object that is not stored in the local data store, retrieving said each first document object from one of the second devices including;

sending a retrieve request to the second devices to retrieve a copy of said each first document object from one of the second devices; and

storing the retrieved copy of said each first document object on the local data store.

25. The method of claim 24 further comprising, subsequent to the step of storing the retrieved copy of said each first document object, for each second device that does not have a copy of said each first document object stored thereat, sending a copy of the retrieved copy of said each first document object to said each second device.

26. The method of claim 24:

wherein the first device and a first plurality of the second devices constitute members of a neighborhood,

wherein the steps of sending a retrieve request and sending the document object are performed only for second devices that are members of the neighborhood,

wherein when a joining second device that is not already a member of the neighborhood becomes a member of the neighborhood, then subsequent thereto the steps of sending a retrieve request and sending said each first document object are performed with the joining second device,

wherein when a leaving second device that is already a member of the neighborhood leaves the neighborhood, then subsequent thereto the steps of sending a retrieve request and sending said each first document object are no longer performed with the leaving second device.

27. A method for distributing documents from a first device to a plurality of second devices comprising:

receiving a first document key, wherein data comprising the first document key identifies a first object, the first object having associated therewith a plurality of first document objects;

for each first document object;

if said each first document object is stored on a local storage device of the first device, then for each second device that does not have a copy of said each first document object stored thereat, sending said each first document object to said each second device; and

if said each first document object is not stored on the local storage device, then;

obtaining said each first document object from one of the second devices; and

storing said obtained first document object on the local storage device.

28. The method of claim 27 further comprising subsequent to the step of for each second device that does not have a copy of said each first document object stored thereat, sending the obtained first document object to said each second device.

29. The method of claim 27 wherein the first device and a first plurality of the second devices collectively define a neighborhood, wherein the steps of sending a retrieve request and sending the document object are performed only for the second devices that are members of the neighborhood, the method further comprising:

the first device learning of a second device joining the neighborhood; and

subsequent to learning of the newly joined second device, performing the steps of sending said each first document object, obtaining said each first document object, and sending the obtained said each first document object only with the newly joined second device and with the first plurality of second devices.

30. The method of claim 27 wherein the first device and a first plurality of the second devices collectively define a neighborhood, wherein the steps of sending a retrieve request and sending the document object are performed only for the second devices that are members of the neighborhood, the method further comprising:

the first device learning of one of the first plurality of second devices leaving the neighborhood; and

subsequent to learning that one of the first plurality of second devices has left the neighborhood, performing the steps of sending said each first document object, obtaining said each first document object, and sending the obtained said each first document object only with the remaining ones of the first plurality of second devices.