System and method for secure information sharing with untrusted recipients

• US 20120047103A1
• Filed: 08/19/2010
• Published: 02/23/2012
• Est. Priority Date: 08/19/2010
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Srivatsa, Mudhakar, Marecki, Janusz
• Granted Patent: US 8,793,211 B2
• Time in Patent Office: Days
• US Class Current: 706/52
• CPC Class Codes: G06Q 10/10 Office automation; Time management
• CPC Class Codes: G06Q 30/00 Commerce
• CPC Class Codes: H04L 2209/603 Digital right managament [DRM]
• CPC Class Codes: H04L 2209/606 Traitor tracing
• CPC Class Codes: H04L 2209/608 Watermarking
• CPC Class Codes: H04L 2463/101 applying security measures for digital rights management
• CPC Class Codes: H04L 63/104 Grouping of entities
• CPC Class Codes: H04L 63/1416 Event detection, e.g. attack signature detection

Abstract

System, method and computer program product for modelling information sharing domains as Partially Observable Markov Decision Processes (POMDP), and that provides solutions that view the information sharing as a sequential process where the trustworthiness of the information recipients is monitored using data leakage detection mechanisms. In one embodiment, the system, method and computer program product performs (i) formulating information sharing decisions using Partially Observable Markov Decision Processes combined with a digital watermarking leakage detection mechanism, and (ii) deriving optimal information sharing strategies for the sender and optimal information leakage strategies for a recipient as a function of the efficacy of the underlying monitoring mechanism. By employing POMDPs in information sharing domains, users (senders) can maximize the expected reward of their data/information sharing actions.

Claims

1. A method for optimally sharing information from a sender to one or more recipients comprising:

receiving, at a processor device, a parameter information including;

identifiers of one or more recipients to receive shared information sent by a sender entity, number of information sharing decision time intervals n where 0≦

n<

N, and, a reward value for successful sharing and a penalty value for detecting a leakage; and

building, at said processor device, a model of a dynamic trustworthiness of each said one or more recipients as a Partially Observable-Markov Decision Process (POMPD), said POMPD model including an initial sender belief state of trustworthiness of each of said recipients;

deriving based on said model, an optimal information sharing policy for sharing with said one or more recipients that maximizes an expected reward for said sender;

sharing said information with said one or more recipients, and,

updating, in each decision time interval n, said belief state of trustworthiness of each recipient in said POMPD model by;

a) monitoring a communications network, using a leakage detection device, for a leakage of said information shared with the one or more recipients;

b) observing or not any shared information leakage associated with a recipient;

c) computing, for the sender, based on the observing, a policy to share the information among the one or more recipients in a subsequent decision time interval; and

,

d) sharing, according to the policy, said information among the one or more recipients in the subsequent time interval.

2. The method as claimed in claim 1, wherein prior to sharing said information to said one or more recipients, applying a watermark key to an information object to transform said information object to be shared, said leakage detection device including a correlation device to determine if a watermark of a detected leaked information object correlates with the transformed watermarked information object;

determining a degree of correlation against a threshold; and

observing an information object leakage based on said determined degree.

3. The method as claimed in claim 2, wherein said information object comprises a digital media, multi-media, or data file.

4. The method as claimed in claim 2, wherein said POMDP models said sender belief state of trustworthiness for a recipient as a probability distribution.

5. The method as claimed in claim 4, wherein information is shared between a sender and a single deterministic recipient, said POMPD model modeling said single deterministic recipient as leaking information object according to one of:

a 0% probability or a 100% probability.

6. The method as claimed in claim 4, wherein information is shared between a sender and a single fuzzy recipient, said POMPD models said single fuzzy recipient as having an f % probability level of leaking information object in a time interval, wherein 0%<

f %<

100%, said sender maintaining a probability distribution over a finite set of chosen fuzziness levels for said fuzzy recipient, each said levels associated with a probability distribution with which said single fuzzy recipient can leak said packets.

7. The method as claimed in claim 6, wherein said parameter information further including an accuracy of the approximated probability level of said single fuzzy recipient.

8. The method as claimed in claim 4, wherein information is shared between a sender and multiple fuzzy recipients, said POMPD model modeling each said multiple fuzzy recipients as having an f % probability level of leaking information object in a time interval, wherein 0%<

f %<

100%, said sender maintaining a probability distribution over a finite amount of chosen fuzziness levels for each of said multiple recipients, each said levels associated with a probability with which said fuzzy recipient can leak said packets.

9. The method as claimed in claim 8, wherein said parameter information further including an accuracy of the approximated probability level of each said multiple recipients.

10. The method as claimed in claim 4, further comprising:

grouping a number of recipients and modeling said group as a single recipient in said POMDP model.

11. The method as claimed in claim 2, further comprising:

corrupting, by a recipient, a portion of a watermark applied to said shared information object, said removal performed according to a recipient strategy devised to alter a sender observing an information object leakage; and

,

leaking, by a recipient, said shared information object with said corrupted watermark.

18. The computer system as claimed in claim 1^-7, wherein said parameter information further including an accuracy of the approximation of the probability level of said single fuzzy recipient.

12. A computer system for optimally sharing information from a sender to one or more recipients comprising:

a memory;

a processor in communications with the memory, wherein the system performs a method comprising;

receiving, at a processor device, a parameter information including;

identifiers of one or more recipients to receive shared information sent by a sender entity, number of information sharing decision time intervals n where 0≦

n<

N, and, a reward value for successful sharing and a penalty value for detecting a leakage; and

building, at said processor device, a model of a dynamic trustworthiness of each said one or more recipients as a Partially Observable-Markov Decision Process (POMDP), said POMDP model including an initial sender belief state of trustworthiness of each of said recipients;

deriving based on said model, an optimal information sharing policy for sharing with said one or more recipients that maximizes an expected reward for said sender;

sharing said information with said one or more recipients, and,

updating, in each decision time interval n, said belief state of trustworthiness of each recipient in said POMPD model by;

a) monitoring a communications network, using a leakage detection device, for a leakage of said information shared with the one or more recipients;

b) observing or not any shared information leakage associated with a recipient;

c) computing, for the sender, based on the observing, a policy to share the information among the one or more recipients in a subsequent decision time interval; and

,

d) sharing, according to the policy, said information among the one or more recipients in the subsequent time interval.

13. The computer system as claimed in claim 12, wherein prior to sharing said information to said one or more recipients, said method includes:

applying a watermark key to an information object to transform said information object to be shared, said leakage detection device including a correlation device to determine if a watermark of a detected leaked information object correlates with the transformed watermarked information object;

determining a degree of correlation against a threshold; and

observing an information object leakage based on said determined degree.

14. The computer system as claimed in claim 13, wherein said information object comprises a digital media, multi-media, or data file.

15. The computer system as claimed in claim 13, wherein said POMDP models said sender belief state of trustworthiness for a recipient as a probability distribution.

16. The computer system as claimed in claim 15, wherein information is shared between a sender and a single deterministic recipient, said POMDP model modeling said single deterministic recipient as leaking information object according to one of:

a 0% probability or a 100% probability.

17. The computer system as claimed in claim 15, wherein information is shared between a sender and a single fuzzy recipient, said POMDP models said single fuzzy recipient as having an f % probability level of leaking information object in a time interval, wherein 0%<

f %<

100%, said sender maintaining a probability distribution over a finite set of chosen fuzziness levels for said fuzzy recipient, each said levels associated with a probability distribution with which said single fuzzy recipient can leak said packets.

19. The computer system as claimed in claim 15, wherein information is shared between a sender and multiple fuzzy recipients, said POMPD model modeling each said multiple fuzzy recipients as having an f % probability level of leaking information object in a time interval, wherein 0%<

f %<

100%, said sender maintaining a probability distribution over a finite amount of chosen fuzziness levels for each of said multiple recipients, each said levels associated with a probability with which said fuzzy recipient can leak said packets.

20. The computer system as claimed in claim 14, wherein said method further comprises:

corrupting, by a recipient, a portion of a watermark applied to said shared information object, said removal performed according to a recipient strategy devised to alter a sender observing an information object leakage; and

,

leaking, by a recipient, said shared information object with said corrupted watermark.

21. A computer program product for optimally sharing information from a sender to one or more recipients, the computer program product comprising:

a storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising;

receiving, at a processor device, a parameter information including;

identifiers of one or more recipients to receive shared information sent by a sender entity, number of information sharing decision time intervals n where 0≦

n<

N, and, a reward value for successful sharing and a penalty value for detecting a leakage; and

building, at said processor device, a model of a dynamic trustworthiness of each said one or more recipients as a Partially Observable-Markov Decision Process (POMDP), said POMDP model including an initial sender belief state of trustworthiness of each of said recipients;

deriving based on said model, an optimal information sharing policy for sharing with said one or more recipients that maximizes an expected reward for said sender;

sharing said information with said one or more recipients, and,

updating, in each decision time interval n, said belief state of trustworthiness of each recipient in said POMDP model by;

a) monitoring a communications network, using a leakage detection device, for a leakage of said information shared with the one or more recipients;

b) observing or not any shared information leakage associated with a recipient;

c) computing, for the sender, based on the observing, a policy to share the information among the one or more recipients in a subsequent decision time interval; and

,

d) sharing, according to the policy, said information among the one or more recipients in the subsequent time interval.

22. The computer program product as claimed in claim 21, wherein prior to sharing said information to said one or more recipients, applying a watermark key to an information object to transform said information object to be shared, said leakage detection device including a correlation device to determine if a watermark of a detected leaked information object correlates with the transformed watermarked information object;

determining a degree of correlation against a threshold; and

observing an information object leakage based on said determined degree.

23. The computer program product as claimed in claim 22, wherein said POMDP models said sender belief state of trustworthiness for a recipient as a probability distribution.

24. The computer program product as claimed in claim 23, wherein information is shared between a sender and a single deterministic recipient, said POMDP model modeling said single deterministic recipient as leaking information object according to one of:

a 0% probability or a 100% probability.

25. The computer program product as claimed in claim 23, wherein information is shared between a sender and a single fuzzy recipient, said POMDP models said single fuzzy recipient as having an f % probability level of leaking information object in a time interval, wherein 0%<

f %<

100%, said sender maintaining a probability distribution over a finite set of chosen fuzziness levels for said fuzzy recipient, each said levels associated with a probability distribution with which said single fuzzy recipient can leak said packets.

26. The computer program product as claimed in claim 23, wherein information is shared between a sender and multiple fuzzy recipients, said POMDP model modeling each said multiple fuzzy recipients as having an f % probability level of leaking information object in a time interval, wherein 0%<

f %<

100%, said sender maintaining a probability distribution over a finite amount of chosen fuzziness levels for each of said multiple recipients, each said levels associated with a probability with which said fuzzy recipient can leak said packets.