Multi-Agent Based Access Control Framework for Social Networking Systems Using Ontology Vipin Kumar1 1 Krishna Institute of Engineering & Technology, Ghaziabad, 201206, 1 Ph. D Scholar of Shri Venkateshwara University Gajraula, J. P. Nagar (UP) Dr. Sachin Kumar2 2 AKG Engineering College, 27th KM stone, Delhi Hapur Bypass Road, Ghaziabad, [email protected] [email protected] Abstract Online Social Networks (OSN) have been achieved tremendous growth in recent years and become a de facto standard for social gathering for hundreds of millions of Internet users. Social gathering web sites such as Facebook, Google+, and Twitter are naturally designed to enable people to share personal or public information and make social relations with friends, coworkers, colleagues, family and even with strangers. These OSN sites offer attractive means for digital social interactions and information sharing, but also raise a number of security and privacy issues. While OSN allow users to restrict access to shared data, they currently do not provide any mechanism or trusted access control framework to enforce privacy concerns over data associated with multiple users plus do not provide fast interaction among users. In this paper, we proposed multi-agent based access control framework for SNS using ontology web for Web 3.0 for providing maximum security assurance with fast interaction among OSN users during online interaction. In this paper, we also proposed ontology to satisfy or validate the need of this framework using Protégé ontology development tools designed by University of Stanford and used Java based Jena Semantic Web Framework for practical implementation of this framework. Keywords: SNS, CRACF, MABACF, MABOGM, MABDBU 1. Introduction Online Social Networks (OSN) is live representations of the relationships between individuals and groups in a community. In terms of abstract representation, these networks are just simple graphs with nodes for the people and groups and links for the relationships. In practice, the links can encode all kinds of relationships – familial and friendship. Online communities like Facebook are groups of people connected through the Internet. These communities have become an important part of modern society and contribute to life in many contexts – social, educational, political and business. The communication technologies and infrastructures used to support online communities have evolved with the Internet and include electronic mailing lists, bulletin boards, UseNet, IRC, Wikis, and blogs. Online communities built on social network structures began appearing from 2002 and have become most popular web-based applications now a day’s. Such sites allow individuals to publish personal information in a semi-structured form and to define links to other members with whom they have relationships of various kinds. Current examples include Facebook, Friendster, LinkedIn, Tribe.net, and Orkut. Other webbased online communities have successfully combined social networking with various interests, such as photography (www.Flickr. com), film (www.Netflix.com), personal blogging (www.Myspace.com) and dating (www.Thefacebook.com). The advent of emerging technologies such as online social networks, service-oriented architecture and cloud computing has enabled us to perform social networking and business services more efficiently and effectively. However, we still suffer from unwanted or unintended security leakages by unauthorized actions in social networking services and business services while providing more convenient services to users through such a cuttingedge technological growth. Access control is one of the most fundamental and pervasive mechanisms in use today to secure these services. There have been two parallel areas in access control research in recent years. On one hand, there are efforts to develop access control models to fulfill the authorization requirements from real-world application domains. These have turned out several successful and well-established access control models, such as the RBAC96 model [1], the NIST/ANSI standard RBAC model [2, 3], the RT model [4], and the Usage Control model [5]. On other hand, in parallel, and almost separately, many researchers have devoted to develop policy languages for access control to support policy-based computing, including applicationlevel policies (e.g., XACML [6], SAML [7], Ponder [8] and EPAL [9]), network-level policies (e.g., firewall policy [10] and IPSec policy [11]), and system level policies (e.g., SELinux policy [12] and AppArmor policy [13]). There is big gap between access control developing and implementing it on real life application like social networking system or cloud computing, because there is not any standard framework to implement these access control model in these application. In this paper, we have proposed a multi-agent based access control model for SNS using Ontology for Web 3.0. 2. Importance of Access Control Framework Over the past decade, online social networks have witnessed phenomenal growth in popularity to an extent that today two thirds of the world’s Internet population participates in some form of online social networking. This large audience spends a significant amount of time both viewing existing information and contributing new information to the social web. In regards with member communities such as Facebook, MySpace, Orkut, Twitter, and LinkedIn, the data generated is stored with the relevant social network service providers. This data, which is mainly a representation of real life of the members, includes pictures, videos, educational and work profiles, personal contact information, and list of friends and acquaintances. While networking online presents obvious benefits to users, the flaws of the current model of centralized online social networks is raising concerns. The two major issues with the centralized system are emergence of “information silos” which are closed to the outside web and even other social networks as well as lack of user control over dissemination of personal information; a major privacy concern. To solve above mentioned problems, proper access control model or framework is required, but so far, no such standard access control models are present according to the need of social networking system. Our approach in this paper is proposed multi-agent based access control framework for social networking system using ontology. 3. Related Work In recent years, many research efforts have been devoted to UML-based security model. Ahn et al. [14] showed how RBAC model and constraints can be expressed in UML using OCL. Jurjens et al. [15] proposed an extension to UML that defines several new stereotypes towards formal security verification of elements. Alghathbar et al. [16] defined an approach AuthUML that includes a process and a modeling language to express RBAC policies via use cases. Ray et al. specified reusable RBAC policies using UML diagram templates and showed how RBAC policies can be easily integrated with the application. Basin et al. defined a meta-model to generate security definition languages, an instance of which is SecureUML, a platformindependent language for RBAC. Mouheb et al. [17] presented an aspect-oriented modeling approach for specifying and integrating security concerns into UML design models. All of these approaches accommodated security requirements without considering the validation of security model and policy. One important aspect of access control model analysis is to formally check general properties of access control. In formal verification, a formal specification of a system is proven with a set of higher-level properties that the system should satisfy [18]. Currently, formal verification offers a rich toolbox containing a variety of techniques such as model checking, SAT solving [19] and theorem proving, for supporting automatic system verification. Schaad and Moffett [20] specified the access control policies under the RBAC96 and ARBAC97 model and a set of separation of duty constraints in Alloy. They attempted to check the constraint violations caused by administrative operations. In [21], Shafig et al. explored a Petri-Net based framework to verify the correctness of event-driven RBAC policies in real-time system. Toahchoodee et al. [22] demonstrated how the spatiotemporal aspects in RBAC model can be verified with Alloy. Our approach also adopts Alloy to analyze the formal specifications of an RBAC model and constraints, which are then used for access control system development. In addition, the verified specifications are used to automatically derive the test cases for conformance testing. In [23], Shor et al. demonstrated how the USE tool, a validation tool for OCL constraints, can be utilized to validate authorization constraints against RBAC configurations. The policy designers can employ the USEbased approach to detect certain conflicts between authorization constraints and to identify missing constraints. However, the USE tool mainly focuses on the analysis of OCL constraints and has limitations for specifying models and policies. Similarly, Basin et al. [24] showed security-design models represented with UML and OCL can be validated based on system scenarios, which represent possible run-time instances of systems. However, very few studies addressed how access control mechanisms could be tested. Recently, mutation analysis was applied to security policy testing. Masood et al. [25] used formal techniques to conceive a fault model and adopt mutation for RBAC models. Xie et al. [27] proposed a fault model for XACML policies. The mutation operators were introduced to implement the fault model. Pretschner et al. also used mutation analysis and defined security policy mutation operators in order to improve the security tests. However, no existing work could adopt formal verification technologies for test case generation for the purpose of checking the compliance of access control system design and implementation. In our proposed ACF, we are implementing ontology using well known ontology development tool Protégé. Protégé is developed by University of Stanford. 4. CRACF Working Architecture There are many ways to represent CRACF (Currently Running Access Control Framework) architecture, here figure 1 use to represent currently running access control framework architecture, in this architecture user is the actor that make request to SNS using Internet via Web Browser as shown in figure 1. Web Browser is the user interface that used by user or actor to interact with SNS. SNS represents social networking websites like Facebook, Orkut, and Twitter etc. that directly make connection with database managed by DBMS or RDBMS. This interaction between database layer and SNS may be implemented using Client/Server architecture or distributive DBMS architecture And at last Database layer represent the data or Meta data used in SNS. This data may be stored using any database management software like MSSQL, Oracle, and MySQL etc. transaction with the database. If load on server is high then it takes more time for transaction as compare to normal time taken. In this paper, we purposed a new innovative multi-agent based access control framework which is more suitable for next generation web or semantic web environments that will take less time for transaction as compare to currently running ACF. 5. Proposed Multi-Agent Based Access Control Framework (MABACF) Architecture This proposed access control framework is completely based on innovative idea that came in mind after studying related work in the area of OSN (Online Social Network) This framework is distributed into two sections, first section control or interacted by users or actors and second section is control or interacted by administration for the framework. User in the first section is the actor in this framework as same as CRACF that interacts with the other OSN users via web browser that may be friends, relatives or unknown users of same SNS (Social Network System) on Internet. Query Analyzer Interface gets request from user via Internet and send request to multi-agent based Ontology Manager in sentence skeleton form. On the base of sentence skeleton send by query analyzer, MABOM generate query using query generator and pattern heuristic and then send that query to SPARQL engine. SPARQL is a recursive acronym for the SPARQL Protocol and RDF Query Language. SPARQL is a structure query language for RDF as SQL is a structure query language for DBMS or RDBMS. SPARQL engine execute query send by MABOM from SNS Ontology and send result of that query to user that made request earlier for the specific query. Ontology is a data model that represents knowledge as a set of concepts within a domain and the relationships between these concepts. In short Ontology is simply data management that why, here SNS Ontology represent semantic web ontology that have relationship, rules, assertions and regulation among classes, object properties, data properties and individual. Figure 1: Currently Running ACF Model for SNS This approach is very simple or straight forward that have less flexibility or security which is more suitable for Web 2.0, but may not be suitable for Web 3.0 or Semantic Web (third generation web). In this type of architecture database access type is more or constant for each and every Administrator is the actor in second section in this framework that interacts with the SNS Database using MABOGM and MABDBU. MABDBU is Multi-Agent Based Database Updater that managed by administrator to update or modified SNS Database for time to time modification of this database. MABOGM is Multi-Agent Based Ontology Generator and Modifier that also managed by administrator to create or update SNS ontology time to time as per new rules inserted in SNS Database. SNS Database is RDBMS database that store data related to elements and relations, such as a set of roles, a set of users, a set of permissions, and relationships between users, roles, permissions and etc. Figure 2: Proposed MABAC Framework 6. SNS Ontology A. Introduction According to Thomas Gruber, Ontology is an explicit specification of conceptualization. It uses to represent knowledge, meta-data, rules and assertions. For creating SNS Ontology, we have used Protégé; Protégé is a free, open source ontology editor and knowledge-based framework that is supported by a strong community of developers and academic, government and corporate users, who are using Protégé for knowledge solutions in areas as diverse as biomedicine, intelligence gathering, and corporate modeling. B. SNS Ontology Classes Graphical Representation In this paper, we proposed Social Networking Systems Ontology (SNS Ontology) that models the key entities and their relationships that typically found in SNS; partly because we could not find an appropriate ontology representation in the literature that we studied. Based on this, we elaborate and discuss various scenarios regarding our proposed access control model. Note, however, that our access control model is not tied or limited to this specific ontology. It can be implements for any ontology. This is the version 2 of the SNS Ontology comprises of 18 classes and 42 object properties that is upgraded version of SNS ontology version 1[28]. Figure 3 shows graphical representation of relationship among classes in SNS Ontology. The Thing is the root class of all classes in SNS Ontology, with four immediate descendants classes are: DigitalObjects, Persons, Relations and Events. The DigitalObjects class models any object with digital properties. The Persons class models human users in the context of Social Networking and it is specialized by Woman and Man class. Man class represents male and Woman class represent female. The DigitalObjects class is specialized by sub-classes such as Notes, Photos, Wall, VideoClips and Annotation. The Notes class represents a textual content or data. The Wall class models the posting board on the homepage of a currently login person, such as the one Facebook or Orkut provides. The Annotation class represents special digital objects that instead of directly representing a content, annotate one object (e.g., a wall, a photo, etc.) using another object (e.g., a textual comment, a person, etc.). The two objects are related to an annotation object, using properties Annotates and AnnotatesWith, respectively. Annotation class itself is specialized by Comment, Tag, and WallPost. Comment class annotates an object with a note. Tag class itself is specialized by PersonTag. PersonTag class has two subclasses PhotoPersonTag and VideoPersonTag. PhotoPersonTag class is a specialized tag that annotates a photo with a person and VideoPersonTag class is specialized tag that annotates a video with a person. WallPost class annotates a wall with an object, e.g., a photo or video. We choose to represent annotation as a concept, rather than a relation, in order to be able to capture more semantics regarding it. For instance, it is usually important to know who has tagged a person in a photo; that might be different from the owner and the tagged person Figure 3: SNS Ontology Classes individuals like note1, note2, note3 & note4. Man class has 12 individuals like Amit, Ankit, Madurendra, Rajiv, Ravi, C. SNS Ontology Graphical Representation Robert, Vipin, Sachin, Santosh, Shashank, ssn_singh, & In this section, three figures are used to different tom. Woman class 7 individuals like Sita, Savatri, Preveen, perspective of this ontology. Figure 4 shows PG ETI Sova Preeti, Marry, Arti & Alice. Photos class has 5 individuals representation of proposed SNS ontology to show like photo1, photo2, photo3 photo4 & photo5 and at last relationships among classes and objects. Figure 5 shows the VideoClips class has 5 individuals like video1, video2, PG ETI Sova Radical Tree representation this ontology. video3 video4 & video5. Figure 4 also shows relationships and assertions among all classes and individuals used in All these figures show that in this ontology models, there SNS Ontology are 18 classes, 48 individuals. Comment class has 5 individuals like comment1, comment2, comment3 comment4 & comment5. Event class has 4 individuals like event1, event2, event3 & event4. Notes class has 4 Figure 4: SNS Ontology PG ETI Sova Representation Figure 5: SNS Ontology PG ETI Sova Radical Tree Representation B. Policy and Rule Enforcements 7. Implementation A. Framework Setup For testing authentication of this framework, we have developed a prototype implementation of an SNS knowledge-base that is protected based on the proposed MABACF for SNS using Ontology model. The implementation has been done in Java language based on the Jena Semantic Web framework. We leverage Jena’s TDB for persistent storage of SNS ontologies. In an initialization phase, based on the SNS knowledge captured in SNSO, SNSO is populated with the corresponding reified properties and permissions. Figure 2 illustrates the architecture of the prototype implementation. Access control policy rules are provided by users and system administrators, using separate interfaces, and are stored in the policy rule-base. Rules are expressed using SWRL. However, since SWRL is not directly supported in Jena, we programmatically convert rules to Jena’s own rule language in a policy compilation phase. Note that there is no loss of expressiveness in this process. At run time, the Query Analyzer accepts the requests from a user via web browser and passes it to the Matching Center module, where it is augmented with access control primitives. The modified query is then sent to the SPARQL Engine my MAB Ontology Manager. The SPARQL Engine interacts with the SNSO to retrieve the query results and pass it to web browser for user. Knowledge resources are needed to be captured or store using ontology. In SNS, access control policies need to be semantically express them using ontology concepts. Our approach is to capture the other components of policies for getting right decision using ontology. This way access control policies and protected knowledge resources can naturally be integrated to facilitate an efficient and semantic rich access control decision. For this purpose, we propose SNS ontology with access control framework. We consider relations main protection objects in an ontology-based knowledge base. However, current semantic web based languages like OWL do not support such kind of statement about the relation instances, which is necessary for specifying authorizations on them. In order to support this, we have modified some rules using Java language and tried to implement them on Jena Semantic Web Framework as much as possible to implement. There are so many approaches available for it like reified [29], permission authorizations, personal authorization, direct authorization, basic authority specification, dependent authorization, dependent authorization & multi-authority specification etc. but we do not consider all of them in our ontology policies, we have categories all of them in two types direct or indirect rules. Direct Rules: In this ontology we have asserted more than 100 direct rules as prototyped for running this access control framework model. Direct authorization rules allow the system to grant permissions to users without involvement of user authorities. Similar to a personal authorization rule [29], the antecedent specifies the protection resource. The formats of a direct authorization rule are shown in table 1 as follows: 4 5 6 7 8 9 S. No 1 2 3 4 5 6 7 8 9 10 11 12 Direct Rules sns:property(alice,robert) ⇒ sns:hasBrother(alice, robert) sns:property(alice,marry) ⇒ sns:isFriendOf(alice, marry) sns:property(amit,vipin) ⇒ sns:isFriendOf(amit, vipin) sns:property(arti,preveen) ⇒ sns:isSisterOf(arti, preveen) sns:property(comment4,photo1) ⇒ sns:postedOn(comment1, photo1) sns:property(note1,photo1) ⇒ sns:annotatesWith(note1, photo1) sns:property(shashank,ankit) ⇒ sns:hasFriend(shashank, ankit) sns:property(robert,video1) ⇒ sns:canView(robert, video1) sns:property(vipin,comment2) ⇒ sns:posted(vipin, comment2) sns:property(sachin,vipin) ⇒ sns:isBrotherOf(sachin, vipin) sns:property(marry,sita) ⇒ sns:isSiblingOf(marry, sita) sns:property(robert,tom) ⇒ sns:isFatherOf(robert, tom) 10 hasParent(?x, ?y) ^ hasSister(?y, ?z) -> hasAunt(?x, ?z) hasParent(?x, ?y) ^ man(?y) -> hasFather(?x, ?y) hasChild(?x, ?y) ^ man(?x) -> hasSon(?x, ?y) hasChild(?x, ?y) ^ woman(?x) -> hasDaughter(?x, ?y) Person(?x) ^ hasSibling(?x, ?y) ^ man(?y) >hasBrother(?x, ?s) hasParent(?x, ?y) ^ hasBrother(?y, ?z) -> hasUncle(?x, ?z) Person(?x) ^ has Age(?x, ?age) ^ swrlb:greaterthan(?age, 17)-> adult(?x) Table 2: Indirect Rules of SNS Ontology These variables ?x and ?p represent the object and subject represented in this ontology. These all rules are derived from one or more direct rules or metadata to make intelligence in this ontology. C. Query Analysis The Semantic Web, typically represented using the RDF data format, requires a specific query language to make it possible to send queries and receive results. This is provided by the SPARQL query language and the accompanying semantics and protocols. SPARQL queries are similar in syntax to SQL but are based on the RDF triple models and provide patterns against such relationships in which some resource references are variables. A SPARQL engine would return the resources that match these patterns for all triples. General formatting for SPARQL query is like this: Let (sub, Q) be a query access request, where Table 1: Direct Rules of SNS Ontology The above rules state that a subject can read a property instance of which it is either the subject or the object, respectively. Indirect Rules: In this ontology we have also asserted more than 100 direct rules as prototyped for running this access control framework model. In direct rules are rules that extract from combination of one or more direct rules and extract with the help of semantic based languages like SWRL etc. SWRL rule contains antecedent part and a consequent part. If all the atoms in the antecedent are true, then the consequent must be true. Some of the main indirect rules enforced in this ontology are follows in table 2 S. NO 1 2 3 Indirect Rules hasSibling(?x, ?y) ^ man(?y) -> hasBrother(?x, ?y) hasSibling(?x, ?y) ^ woman(?x) >hasSister(?x, ?y) hasParent(?x, ?y) ^ woman(?x) -> hasMother(?x, ?y) Represents a conjunctive WHERE clause. A retrieval engine automatically enforces the access control policy and retrieves the authorized result by evaluating In each query predicate is followed by two predicate for access control purpose: first predicate bounds the relation to a resource variable and second predicate checks if the subject has permission to access the resource. A SPARQL query that is augmented with access primitives can be directly processed by a SPARQL engine on ontology. The access control information is seamlessly captured in the ontology by using an ontology reasoned on authorization rules For example: Suppose Amit requests access to the list of Vipin friends who live in Ghaziabad. This is the complex query, syntax of this query in SPARQL format is: PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntaxns#> PREFIX owl: <http://www.w3.org/2002/07/owl#> PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX : <http://SNSOntology.owl#> SELECT ?x WHERE { {?x :isFriendOf :vipin} UNION {?x :liveIn :Ghaziabad} } Similarly we also executed many query in our proposed SNS ontology for result analysis to write this paper. Few examples from those executed query are: Example 1: This is the example to show name of person that hasBrother x and x is the brother of vipin. PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntaxns#> PREFIX owl: <http://www.w3.org/2002/07/owl#> PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX : <http://SNSOntology.owl#> SELECT ?name ?x WHERE { ?name :hasBrother ?x . ?x :isBrotherOf :vipin } Example 2: This is the example to show name of person who has sister x and posted photo1 PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntaxns#> PREFIX owl: <http://www.w3.org/2002/07/owl#> PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX : <http://SNSOntology.owl#> SELECT ?name ?x WHERE { ?name :isSisterOf ?x . ?name :posted :photo1 } 8. Result Analysis We have conducted this test on the access control engine by submitting SPARQL queries on Jena Semantic Web Framework. The engine successfully returns only the authorized information that is expected according to the sample access control policy rules. We also developed a data generator that randomly populates SNS ontology. Table 1 shows the performance results of the prototype access engine based on the following input parameters: the number of users, friendship links, photos, and maximum number of people had been tagged in a photo. Since the inference engine that Jena provides only works in memory, we were not able to run the experiment for very large ontologies. Our experiments show that the first access control inference is relatively expensive. However, subsequent access checks are performed almost instantaneously. This is because in the first round the inference model caches some of the inferred axioms, which enhances performance for subsequent inference. In fact, the first access check can be considered as part of the initialization phase, which can be triggered with a dummy access request. Table 3: Prototype Performance Results Data Generation Parameters Access Times (in second) User Pho to Tag/ Phot o isFrien dOf Initia l First Subsequ ent 10 50 80 110 130 200 6 30 60 70 80 90 6 10 20 20 30 50 50 150 180 210 500 600 2.1 4.8 6.2 12.4 18.3 20.5 0.3 36.0 176.2 2116.2 4321.8 5421.6 0.004 0.004 0.006 0.008 0.008 0.009 9. Conclusion And Future scope In this paper, we have proposed an innovative access control framework for SNS using ontology, an ontology based access control model based on Semantic Web standards that empowers the individual users of a social networking system to express fine-grained access control policies on their related information. We proposed prototype ontology for SNSs to further demonstrate our approach. The key idea in this model is to express the policies on the relations among concepts in the social network ontology. We have also implemented a framework prototype of the proposed model in order to show the applicability of our approach. Although this model provides powerful access control features to the users of the SNSs, even savvy users of such systems should not have to be able to compose access control policy rules manually. An SNS employing this framework may simply provide a user interface similar to the current practices, but with more flexible options to its user; then, provide the access control engine with policy rules corresponding to the user choices. In future research, it can be explore more to improve its aspect in implementation, and theoretically analyze the complexities introduced by ontological data and each policy component; we have tested this framework on Jena Semantic Web Framework, but it is not 100% compatible for purposed access control policies, in future it can be tested on real time framework environment or more semantic web compatible framework that may be developed in the future. 10. References [1] R.S. Sandhu, E.J. Coyne, H.L. Feinstein, and C.E. 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