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1
GROUP CENTRIC INFORMATION SHARING USING HIERARCHICAL MODEL
By
Amit Mahale
Advisor: Dr Tim Finin
Co-Advisor: Dr Anupam Joshi
2
RISE OF INFORMATION SHARING
Need to Know v/s Need to share 9/11 commission US Federal Systems
Need to share: Uncover, respond and protect against threat
Collaborative systems examples University Environment
3
MOTIVATION
One of the central problems in information sharing is the ability to securely and differentially share information.
This issue has been addressed by Ravi Sandhu et al in their model Group Centric Information Sharing(gSIS).
Formal model for Group Centric Information sharing is available, but no practical implementation.
4
CONTRIBUTION
Develop a prototype for Group centric Information Sharing model using semantic web technologies
Modeled Hierarchical groups using OWL.
Leverage OWL’s capacity of automating group membership using Necessary and sufficient conditions
5
OUTLINE
Background : Group Centric Information Sharing
System Use-cases System Architecture System Implementation Results Algorithm Complexity Conclusion Future Work References
6
GROUP CENTRIC INFORMATION SHARING
Model developed by Ravi Sandhu et al
A first step towards a formal and systematic study of Group-Centric Secure Information Sharing Models
Brings users & objects together in a group Secure Meeting Room
7
PROPERTIES
Two types of properties
Core gSIS properties Must be enforced by all the systems modeling
gSIS.
gSIS Operations A subset of the operations may be used in the
system depending on designers discretion.
8
CORE GSIS PROPERTIES
The core properties must be satisfied by any g-SIS specificationo Persistence Properties
When a user u is authorized to access an object o, it remains the same until a group event involving u or o occurs.
o Authorization ProvenanceA user u will not be authorized to access an object o until both u and o are simultaneously group members
o Bounded AuthorizationAuthorizations do not increase during non-membership period.
G-SIS OPERATIONS
9
GROUPAuthz (u,o,r)?
Join Leave
Add Remove
Users
Objects
GROUPAuthz (u,o,r)?
Strict Join
Strict Leave
Liberal Add
Liberal Remove
LiberalJoin
LiberalLeave
StrictAdd Strict
Remove
Users
Objects
Figure courtesy Ram Krishnan et al[1]
MEMBERSHIP SEMANTICS Strict Vs Liberal Operations
User operations: <SJ, LJ> and <SL, LL> Object operations: <SA, LA> and <SR, LR>
10
SJ (u)
u not authorized to access objects added prior to join time
SA (o)
Users joining after add time not authorized to access o
LL (u)
u retains access to objects authorized at leave time
LR (o)
Users authorized to access o at remove time retain access
Figure courtesy Ram Krishnan et al[1]
11
STRICT JOIN V/S LIBERAL JOIN
During Join, If the second Join (u1; g) is an SJ.
u1 can access o4 and o5 but cannot access o2 and o3. If the Join was an LJ ,
u1 can also access o2 and o3.
During Leave SL : u1 loses access to all group objects (o1 and o2), LL: allows u1 to retain access to o2
12
STRICT ADD V/S LIBERAL ADD
During Add If (o2; g) is a SA,
Only u1 can access the object. Users u2 and u3, joining later, cannot access this object.
If (o2; g) is a LA, Current user u1 and future users u2 and u3 may access o2.
During Remove if Remove (o1; g) is an SR,
Every group user (including u1) loses access to o1. if Remove (o1; g) is an LR,
u1 can continue to access o1. However u2 and u3 will not have access to o1.
13
Operation Explaination
Strict Join(SJ) Only objects added after join time can be accessed
Liberal Join(LJ) Can access objects added before and after join time
Strict Leave(SL) Lose access to all objects on leave
Liberal Leave(LL) Retain access to objects authorized before leave time
Strict Add(SA) Only users who joined prior to add time can access
Liberal Add(LA)Users who joined before or after add time may access
Strict Remove(SR)All users lose access on remove
Liberal Remove(LR) Users who had access at remove time retain access
14
SYSTEM USE CASE
Graduate Student Admissions Promotion and Tenure Committee (P&T) Social Media Application
15
GRADUATE STUDENT ADMISSIONS
A process in which graduate student applications are scrutinized by a group of faculty members from the department.
Requirements Member should be able to access older
application. Member should not have access to documents
after leaving the groups.
16
Members join the group through ‘Liberal Join’. This will allow them to access previous
applications Applications are added with ‘Liberal Add’
Members joining the committee at a later point of time should have access to these applications.
Member leave the group using ‘Strict Leave’ Lose access to all the applications
Applications are removed from the group using ‘Liberal Remove’. Members who previously have access will still be
able to access the document.
GRADUATE STUDENT ADMISSIONS
17
PROMOTION AND TENURE COMMITTEE (P&T)
P & T committee consists of a group of full professors (tenured) who decide on the fate of an Associate professor under consideration for tenure.
Requirements Members should not have access to the P&T
documents of their senior members
18
Add the P&T documents with ‘Strict Add’ Members join the group though ‘Strict Join’/
‘Liberal Join’ If a tenured professor leaves the group, then
use ‘Strict Leave’, the documents are to be removed from the
group then use ‘Strict Remove’.
PROMOTION AND TENURE COMMITTEE (P&T)
19
SOCIAL MEDIA APPLICATION
20
SOCIAL MEDIA APPLICATION
Amit becomes a friend of Dr Finin Amit gets access to all the personal
information as well as the content (from Facebook Wall) that was shared previously
This might not be as per Dr Finin’s expectation
gSIS to the rescue
21
DR FININ, BEFORE ADDING AS A FRIEND
22
AFTER ADDING AS A FRIEND
23
WHAT GSIS CAN OFFER?
if Dr Finin adds a new friend Amit to his friend list through Strict Join: Amit will be able to access the data posted after his join time, overcoming the problem discussed in the previous slide
“Share From now” button?
Liberal Join: In addition to allowing access to new documents, Liberal
Join would allow Amit to access posts that Dr Finin shared prior to Amit’s join time through Liberal Add.
“Share Everything” button?
For Posts, Strict Add: Dr Finin should use this operation, if he wants to share the post with current set of friends and protect from his future friends.
Liberal Add: This post can be accessed by current friends as well as new friends who join at a later point of time through Liberal Add.
24
INCORPORATING GSIS INTO FACEBOOK: ADDING A FRIEND
SJLJ
25
INCORPORATING GSIS INTO FACEBOOK: ADDING A POST
Current
Current + Future
LA
SA
26
SR
LR
INCORPORATING GSIS INTO FACEBOOK: REMOVING A FRIEND
27
INCORPORATING GSIS INTO FACEBOOK: REMOVING A POST
28
COMPARISON TO CURRENT FACEBOOK MODEL
Liberal Join
Liberal Add
Strict Leave
Strict Remove
29
REVIEW
o Every user and document is associated with at least one group.
o Multiple groups may exist.o Groups may further be hierarchical.o A user may join and leave the group multiple
number of times.o A document may be added and removed from
the group multiple number of times.o The access decision of a user to a document
depends on multiple factors like Join type, Add type and the timestamps associated.
30
SYSTEM ARCHITECTURE
31
Hierarchy Ontology
Decision Engine
gSIS Rules
Inferred Data
Group data
Results
gSIS Ontolog
y
Access decisions
Reasoning
Reasoning
SYSTEM ARCHITECTURE
32
GROUP OPERATION DATA
Data about the group members/documents and their operations.
Group user can join and leave the group multiple numbers of times
<user_id>,<join_time>,<join_type>,<leave_time>,<leave_type>, <group_name>
<doc_id>,<Add_time>,<Add_type>,<Remove_time>,<Remove_type>, <group_name>
33
HIERARCHY ONTOLOGY
Used to represent the hierarchy of the system
Helps to infer the additional groups that the member belongs to
In a hierarchy of Professor, Asst Professor and Lab Instructor.
An user added to a Professor group should by default have access to the documents added to Asst Professor and Lab Instructor group.
34
CEO
CTO
Project Manager
Team Lead
Associate Engineer
CFO
Finances Team
HIERARCHY IN GROUPS
Disaster Management GroupFire
Fighters
Police Department
Ambulance
35
MOTIVATION FOR USING SEMANTIC WEB
System Understandable
Usage of Ontology makes the system flexible and extendable.
gSIS is modeled using temporal logic, thus developing the prototype using OWL(based on logic) helps to prove the correctness of the model.
36
INFERRED DATA
The RDFS reasoner is used to infer additional groups to which the user belongs to; using the hierarchy ontology.
The inferred data along with the Group data is then fed to the decision engine.
37
GSIS ONTOLOGY
38
DECISION ENGINE
Central system of the gSIS model
Every access decision depends on the combination of group operations and the timestamp’s associated with them.
The rules are modeled to cover all combinations of events that can occur in a group centric information sharing environment.
39
STRICT JOIN, STRICT ADD, STRICT LEAVE, STRICT REMOVE
Let Uj & UL be the User Join and Leave time and
DA & DR be the Document Add and Remove time
User Join (Uj)
Doc Add (DA)
Access time[DA – Min (UL, DR)]
User Leave (UL)
Doc Remove (DR)
40
LIBERAL JOIN, LIBERAL ADD, LIBERAL LEAVE, LIBERAL REMOVE
Let Uj & UL be the User Join and Leave time and
DA & DR be the Document Add and Remove time
User Join (Uj)
Doc Add (DA)
Access time[Max(UJ,DA) – Max (UL, DR)]
User Leave (UL)
Doc Remove (DR)
41
STRICT JOIN, LIBERAL ADD, STRICT LEAVE, LIBERAL REMOVE
Let Uj & UL be the User Join and Leave time and
DA & DR be the Document Add and Remove time
User Join (Uj)
Doc Add (DA)
Access time[DA –UL]
User Leave (UL)
Doc Remove (DR)
42
LIBERAL JOIN, STRICT ADD, LIBERAL LEAVE, STRICT REMOVE
Let Uj & UL be the User Join and Leave time and
DA & DR be the Document Add and Remove time
User Join (Uj)
Doc Add (DA)
Access time[DA –DR]
User Leave (UL)
Doc Remove (DR)
43
CONCLUDE DECISION ENGINE
Can observe a pattern Check for conformance with gSIS operations properties Compute access start time Compute access end time.
Constructing the rule becomes tedious and complex to handle in OWL. Our prototype uses an pragmatic approach, Semantic web + procedural method.
Semantic Web technology to represent and reason about the hierarchy; Procedural method to compute access decisions relying on the gSIS semantics.
44
AUTOMATING GROUP MEMBERSHIP
Automatically classifies users to relevant groups.
Leverages OWL feature of Necessary and Sufficient conditions.
Whenever a user satisfies the N&C, the user is added to the group.
45
EXAMPLE
A Professor is added to the UMBC CS Tenure committee if He/She is a Full Professor A Professor @ UMBC. Faculty in the CS DepartmentThe ontology is as follows
46
N & C
N & C
N & C
AUTOMATING GROUP MEMBERSHIP
47
AUTOMATED DOCUMENT CLASSIFICATION
Documents are classified as Top Secret, Secret, Confidential, Restricted, Unclassified.
Groups can be governed by policies on the type of documents added to each group.
Utilizes OWL Features and Hierarchy resolution
48
‘War room’ group contains all documents from level ‘ Top Secret’ and below.
‘Air Force’ group ‘Top Secret’ ‘ Air Force’ domain.
‘Air Force Research’ group ‘Air Force’ domain Unclassified
49
SYSTEM IMPLEMENTATION
50
SYSTEM IMPLEMENTATION
53
RESULTS
54
VALIDATION
We develop sample data set for the P & T use case
o To demonstrate hierarchical groups, we have two groups, ‘Tenure group’ and ‘Associate Professor Group’
o Data contains details about members and their documents.
o Rule : Tenure group members have access to the documents of ‘Associate Professor group’
55
QUERIES
56
QUERY 1: USER-DOCUMENT-TIME
Did Dr Finin have access to Dr Joshi’s Tenure file in 2005?
Access Granted
57
QUERY 2: USER ACCESS DETAILS
List all the documents that Dr Finin has access to
58
QUERY 3: DOCUMENT ACCESS
List all the users who have access to ‘Andrewdoc'[Andrew is an Assistant Prof and under consideration for tenure]
59
QUERY 4: TIME BASED ACCESS
List all the documents that were accessible to users in 1994
60
QUERY 5: USER-DOCUMENT
Did Dr Finin ever have access to Nicholasdoc?
61
ALGORITHMIC COMPLEXITY
n users m documents Computing Access intervals would take n*m O(nm) when m=n O(n2)
Whenever group membership changes User joins the group: (1 * m) O(m) Document is added to the group: (n * 1) O(n)
62
CONCLUSION
We have presented a agile framework for secure information sharing.
We have also modeled gSIS to support hierarchical groups and opened up opportunities to extend gSIS in several dimensions like automated group membership.
Finally we have demonstrated the usefulness of gSIS in real world applications.
63
FUTURE WORK
Develop the administrative model for gSIS.
Write policies to enforce the gSIS operation semantics.
64
65
66
REFERENCES[1]Ram Krishnan, Ravi Sandhu, Jianwei Niu and William Winsborough, Foundations for Group-Centric Secure Information Sharing Models. Proc. 14th ACM Symposium on Access Control Models and Technologies (SACMAT), Stresa, Italy, June 3-5, 2009, pages 115-124. [2] Ram Krishnan, Ravi Sandhu, Jianwei Niu and William Winsborough, Towards a Framework for Group-Centric Secure Collaboration. In Proc. 5th IEEE International Conference on Collaborative Computing: Networking, Applications and Worksharing (CollaborateCom), Crystal City, Virginia, November 11-14, 2009, pages 1-10. [3] Ravi Sandhu, Ram Krishnan, Jianwei Niu and William Winsborough, Group-Centric Models for Secure and Agile Information Sharing. In Proceedings 5th International Conference, on Mathematical Methods, Models, and Architectures for Computer Network Security, MMM-ACNS 2010, St. Petersburg, Russia, September 8-10, 2010, pages 55-69. Published as Springer Lecture Notes in Computer Science Vol. 6258, Computer Network Security (Igor Kotenko and Victor Skormin, editors), 2010. [4] T. Finin, A. Joshi, L. Kagal, J. Niu, R. Sandhu, W. Winsborough, and B. Thuraisingham, ROWLBAC - Representing Role Based Access Control in OWL, Proceedings of the 13th
ACM symposium on Access Control Models and Technologies, ACM Press New York, June 2008.
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[5] Anne Cregan, Malgorzata Mochol, Denny Vrandecic, Sean Bechhofer Pushing the limits of OWL, Rules and
Protégé. A simple example Workshop - OWL: Experiences and Directions (OWLED-2005), Galway, Ireland,
November 2005 [6] R. Sandhu et al, Role-Based Access Control Models, IEEE Computer, 29(2):38-47,Feb 1996,
Google Scholar Search [7] R. Sandhu and P. Samarati, Access Control: Principles and Practice, IEEE Communications, 32(9): 40-48, Sept. 1994, Google Scholar Search
[8] Semantic web: http://www.w3.org/2001/sw/ [9] Bechhofer, S.; van Harmelen, F.; Hendler, J.; Horrocks, I.; McGuinness, D.; Patel-Schneider, P.; and Stein, L. 2004. Owl web ontology language reference. w3crecommendation. [10] United States Intelligence community ‘INFORMATION SHARING STRATEGY’, OfficeOf the Director of National Intelligence, http://www.dni.gov/reports/IC_Information_Sharing_Strategy.pdf [11] Jones, H., and Soltren, J. 2005. Facebook: Threats to privacy.
REFERENCES