Trustworthy Semantic Web Confidentiality, Privacy and Trust Prof. Bhavani Thuraisingham The...

Trustworthy Semantic Web Confidentiality, Privacy

and TrustProf. Bhavani Thuraisingham

The University of Texas at Dallas

February 2010

Outline of the Unit

What are logic and inference rules Why do we need rules? Example rules Logic programs Monotonic and Nonmonotoic rules Rule Markup Example Rule Markup in XML Policy Specification Relationship to the Inference and Privacy problems Summary and Directions Confidentiality, Privacy and Trust

Logic and Inference

First order predicate logic High level language to express knowledge Well understood semantics Logical consequence - inference Proof systems exist Sound and complete OWL is based on a subset of logic – descriptive logic

Why Rules?

RDF is built on XML and OWL is built on RDF We can express subclass relationships in RDF; additional

relationships can be expressed in OWL However reasoning power is still limited in OWL Therefore the need for rules and subsequently a markup language

for rules so that machines can understand

Example Rules

Studies(X,Y), Lives(X,Z), Loc(Y,U), Loc(Z,U) HomeStudent(X)

i.e. if John Studies at UTDallas and John is lives on Campbell Road and the location of Campbell Road and UTDallas are Richardson then John is a Home student

Note that

Person (X) Man(X) or Woman(X) is not a rule in predicate logic

That is if X is a person then X is either a man of a woman. This can be expressed in OWL

However we can have a rule of the form

Person(X) and Not Man(X) Woman(X)

Monotonic Rules

Mother(X,Y) Mother(X,Y) Parent(X,Y)

If Mary is the mother of John, then Mary is the parent of John

Syntax: Facts and Rules

Rule is of the form:

B1, B2, ---- Bn A

That is, if B1, B2, ---Bn hold then A holds

Logic Programming

Deductive logic programming is in general based on deduction

- i.e., Deduce data from existing data and rules

- e.g., Father of a father is a grandfather, John is the father of Peter and Peter is the father of James and therefore John is the grandfather of James

Inductive logic programming deduces rules from the data

- e.g., John is the father of Peter, Peter is the father of James, John is the grandfather of James, James is the father of Robert, Peter is the grandfather of Robert

- From the above data, deduce that the father of a father is a grandfather

Popular in Europe and Japan

Nonmonotonic Rules

If we have X and NOT X, we do not treat them as inconsistent as in the case of monotonic reasoning.

For example, consider the example of an apartment that is acceptable to John. That is, in general John is prepared to rent an apartment unless the apartment ahs less than two bedrooms, is does not allow pets etc. This can be expressed as follows:

Acceptable(X) Bedroom(X,Y), Y<2 NOT Acceptable(X) NOT Pets(X) NOT Acceptable(X)

Note that there could be a contradiction. But with nonmotonic reasoning this is allowed.

Rule Markup

The various components of logic are expressed in the Rule Markup Language – RuleML

Both monotonic and nonmonotnic rules can be represented

Example representation of Fact P(a) - a is a parent

<fact>

<atom>

<predicate>p</predicate>

<term>

<const>a</const>

<term>

<atom>

</fact>

Policies in RuleML

<fact><atom>

<predicate>p</predicate> <term> <const>a</const> <term> <atom>Level = L </fact>

Example Policies Temporal Access Control

- After 1/1/05, only doctors have access to medical records Role-based Access Control

- Manager has access to salary information

- Project leader has access to project budgets, but he does not have access to salary information

- What happens is the manager is also the project leader? Positive and Negative Authorizations

- John has write access to EMP

- John does not have read access to DEPT

- John does not have write access to Salary attribute in EMP

- How are conflicts resolved?

Privacy Policies

Privacy constraints processing

- Simple Constraint: an attribute of a document is private

- Content-based constraint: If document contains information about X, then it is private

- Association-based Constraint: Two or more documents taken together is private; individually each document is public

- Release constraint: After X is released Y becomes private Augment a database system with a privacy controller for constraint

processing

System Architecture for Access Control

UserPull/Query Push/result

RuleML DataDocuments

RuleML-Access

RuleMF-Admin Admin

Tools

Policybase

Credentialbase

RuleML Data Management

Data is presented as RuleML documents Query language – Logic programming based? Policies in RuleML Reasoning engine

- Use the one developed for RuleML

Inference/Privacy Control

Policies

Ontologies

Rules

Rule-based Data Management

Rules Data

Inference Engine/Rules Processor

Interface to the Semantic WebTechnologyBy UTD

Summary and Directions

Rules have expressive and reasoning power Handles some of the inadequacies of OWL Both monotonic and nonromantic reasoning Logic programming based Policies specified in RulesML Need to build an integrated system Other rules: SWRL (semantic web rules language)

CPT: Confidentiality, Privacy and Trust

Before I as a user of Organization A send data about me to organization B, I read the privacy policies enforced by organization B

- If I agree to the privacy policies of organization B, then I will send data about me to organization B

- If I do not agree with the policies of organization B, then I can negotiate with organization B

Even if the web site states that it will not share private information with others, do I trust the web site

Note: while confidentiality is enforced by the organization, privacy is determined by the user. Therefore for confidentiality, the organization will determine whether a user can have the data. If so, then the organization van further determine whether the user can be trusted

What is Privacy

Medical Community

- Privacy is about a patient determining what patient/medical information the doctor should be released about him/her

Financial community

- A bank customer determine what financial information the bank should release about him/her

Government community

- FBI would collect information about US citizens. However FBI determines what information about a US citizen it can release to say the CIA

Some Privacy concerns

Medical and Healthcare

- Employers, marketers, or others knowing of private medical concerns

Security

- Allowing access to individual’s travel and spending data

- Allowing access to web surfing behavior Marketing, Sales, and Finance

- Allowing access to individual’s purchases

Data Mining as a Threat to Privacy

Data mining gives us “facts” that are not obvious to human analysts of the data

Can general trends across individuals be determined without revealing information about individuals?

Possible threats:

- Combine collections of data and infer information that is private Disease information from prescription data Military Action from Pizza delivery to pentagon

Need to protect the associations and correlations between the data that are sensitive or private

Some Privacy Problems and Potential Solutions

Problem: Privacy violations that result due to data mining

- Potential solution: Privacy-preserving data mining Problem: Privacy violations that result due to the Inference problem

- Inference is the process of deducing sensitive information from the legitimate responses received to user queries

- Potential solution: Privacy Constraint Processing Problem: Privacy violations due to un-encrypted data

- Potential solution: Encryption at different levels Problem: Privacy violation due to poor system design

- Potential solution: Develop methodology for designing privacy-enhanced systems

Privacy Constraint /Policy Processing

Privacy constraints processing

- Based on prior research in security constraint processing

- Simple Constraint: an attribute of a document is private

- Content-based constraint: If document contains information about X, then it is private

- Association-based Constraint: Two or more documents taken together is private; individually each document is public

- Release constraint: After X is released Y becomes private Augment a database system with a privacy controller for constraint

processing

Inference/Privacy Control

Privacy Policies

Ontologies

Rules

OWL/RDF Data Management

OWL/RDFDocumentsWeb Pages, Databases

Inference Engine/Rules Processor(Reasoning in OWL?)

Interface to the Semantic WebTechnologyBy UTD

Semantic Model for Privacy Control

Patient John

CancerInfluenza

Has disease

Travels frequently

England

address

John’s address

Dark lines/boxes containprivate information

Privacy Preserving Data Mining Prevent useful results from mining

- Introduce “cover stories” to give “false” results

- Only make a sample of data available so that an adversary is unable to come up with useful rules and predictive functions

Randomization

- Introduce random values into the data and/or results

- Challenge is to introduce random values without significantly affecting the data mining results

- Give range of values for results instead of exact values Secure Multi-party Computation

- Each party knows its own inputs; encryption techniques used to compute final results

- Rules, predictive functions Approach: Only make a sample of data available

- Limits ability to learn good classifier

Platform for Privacy Preferences (P3P): What is it?

P3P is an emerging industry standard that enables web sites to express their privacy practices in a standard format

The format of the policies can be automatically retrieved and understood by user agents

It is a product of W3C; World wide web consortium

www.w3c.org When a user enters a web site, the privacy policies of the

web site is conveyed to the user; If the privacy policies are different from user preferences, the user is notified; User can then decide how to proceed

Several major corporations are working on P3P standards including

Platform for Privacy Preferences (P3P): Organizations

Several major corporations are working on P3P standards including:-Microsoft- IBM- HP- NEC- Nokia- NCR

Web sites have also implemented P3PSemantic web group has adopted P3P

Platform for Privacy Preferences (P3P): Specifications Initial version of P3P used RDF to specify policies; Recent version has

migrated to XML P3P Policies use XML with namespaces for encoding policies P3P has its own statements and data types expressed in XML; P3P

schemas utilize XML schemas P3P specification released in January 20005 uses catalog shopping

example to explain concepts; P3P is an International standard and is an ongoing project

Example: Catalog shopping

- Your name will not be given to a third party but your purchases will be given to a third party

- <POLICIES xmlns = http://www.w3.org/2002/01/P3Pv1>

<POLICY name = - - - -

</POLICY>

</POLICIES>

P3P and Legal Issues

P3P does not replace laws P3P work together with the law What happens if the web sites do no honor their P3P policies

- Then appropriate legal actions will have to be taken XML is the technology to specify P3P policies Policy experts will have to specify the policies Technologies will have to develop the specifications Legal experts will have to take actions if the policies are

violated

Privacy for Assured Information Sharing

ExportData/Policy

ComponentData/Policy for

Agency A

Data/Policy for Federation

ExportData/Policy


Agency C


Agency B

ExportData/Policy

Key Points

1. There is no universal definition for privacy, each organization must definite what it means by privacy and develop appropriate privacy policies

2. Technology alone is not sufficient for privacy We need technologists, Policy expert, Legal experts and Social scientists to work on Privacy

3. Some well known people have said ‘Forget about privacy” Therefore, should we pursue research on Privacy?

- Interesting research problems, there need to continue with research

- Something is better than nothing

- Try to prevent privacy violations and if violations occur then prosecute

4. We need to tackle privacy from all directions

Application Specific Privacy?

Examining privacy may make sense for healthcare and financial applications

Does privacy work for Defense and Intelligence applications? Is it meaningful to have privacy for surveillance and

geospatial applications

- Once the image of my house is on Google Earth, then how much privacy can I have?

- I may want my location to be private, but does it make sense if a camera can capture a picture of me?

- If there are sensors all over the place, is it meaningful to have privacy preserving surveillance?

This suggestion that we need application specific privacy It is not meaningful to examine PPDM for every data mining

algorithm and for every application

Data Mining and Privacy: Friends or Foes?

They are neither friends nor foes Need advances in both data mining and privacy Need to design flexible systems

- For some applications one may have to focus entirely on “pure” data mining while for some others there may be a need for “privacy-preserving” data mining

- Need flexible data mining techniques that can adapt to the changing environments

Technologists, legal specialists, social scientists, policy makers and privacy advocates MUST work together

Popular Social Networks

Face book - A social networking website. Initially the membership was restricted to

students of Harvard University. It was originally based on what first-year students were

given called the “face book” which was a way to get to know other students on campus.

As of July 2007, there over 34 million active members worldwide. From September 2006

to September 2007 it increased its ranking from 60 to 6th most visited web site, and was

the number one site for photos in the United States.

Twitter- A free social networking and micro-blogging service that allows users to send

“updates” (text-based posts, up to 140 characters long) via SMS, instant messaging,

email, to the Twitter website, or an application/ widget within a space of your choice, like

MySpace, Facebook, a blog, an RSS Aggregator/reader.

My Space - A popular social networking website offering an interactive, user-submitted

network of friends, personal profiles, blogs, groups, photos, music and videos

internationally. According to AlexaInternet, MySpace is currently the world’s sixth most

popular English-language website and the sixth most popular website in any language,

and the third most popular website in the United States, though it has topped the chart

on various weeks. As of September 7, 2007, there are over 200 million accounts.

Social Networks: More formal definition

A structural approach to understanding social interaction.

Networks consist of Actors and the Ties between them.

We represent social networks as graphs whose vertices are the actors and whose edges are the ties.

Edges are usually weighted to show the strength of the tie.

In the simplest networks, an Actor is an individual person.

A tie might be “is acquainted with”. Or it might represent the amount of email exchanged between persons A and B.

Social Network Examples

Effects of urbanization on individual well-being

World political and economic system

Community elite decision-making

Social support, Group problem solving

Diffusion and adoption of innovations

Belief systems, Social influence

Markets, Sociology of science

Exchange and power

Email, Instant messaging, Newsgroups

Co-authorship, Citation, Co-citation

SocNet software, Friendster

Blogs and diaries, Blog quotes and links

History “Sociograms” were invented in 1933 by Moreno.

In a sociogram, the actors are represented as points in a two-dimensional space. The location of each actor is significant. E.g. a “central actor” is plotted in the center, and others are placed in concentric rings according to “distance” from this actor.

Actors are joined with lines representing ties, as in a social network. In other words a social network is a graph, and a sociogram is a particular 2D embedding of it.

These days, sociograms are rarely used (most examples on the web are not sociograms at all, but networks). But methods like MDS (Multi-Dimensional Scaling) can be used to lay out Actors, given a vector of attributes about them.

Social Networks were studied early by researchers in graph theory (Harary et al. 1950s). Some social network properties can be computed directly from the graph.

Others depend on an adjacency matrix representation (Actors index rows and columns of a matrix, matrix elements represent the tie strength between them).

Social Network Analysis of 9/11 Terrorists (www.orgnet.com)

Early in 2000, the CIA was informed of two terrorist suspects linked to al-Qaeda. Nawaf Alhazmi and Khalid Almihdhar were photographed attending a meeting of known terrorists in Malaysia. After the meeting they returned to Los Angeles, where they had already set up residence in late 1999.

Social Network Analysis of 9/11 Terrorists

What do you do with these suspects? Arrest or deport them immediately? No, we need to use them to discover more of the al-Qaeda network.

Once suspects have been discovered, we can use their daily activities to uncloak their network. Just like they used our technology against us, we can use their planning process against them. Watch them, and listen to their conversations to see...

•who they call / email •who visits with them locally and in other cities •where their money comes from

The structure of their extended network begins to emerge as data is discovered via surveillance.


A suspect being monitored may have many contacts -- both accidental and intentional. We must always be wary of 'guilt by association'. Accidental contacts, like the mail delivery person, the grocery store clerk, and neighbor may not be viewed with investigative interest.

Intentional contacts are like the late afternoon visitor, whose car license plate is traced back to a rental company at the airport, where we discover he arrived from Toronto (got to notify the Canadians) and his name matches a cell phone number (with a Buffalo, NY area code) that our suspect calls regularly. This intentional contact is added to our map and we start tracking his interactions -- where do they lead? As data comes in, a picture of the terrorist organization slowly comes into focus.

How do investigators know whether they are on to something big? Often they don't. Yet in this case there was another strong clue that Alhazmi and Almihdhar were up to no good -- the attack on the USS Cole in October of 2000. One of the chief suspects in the Cole bombing [Khallad] was also present [along with Alhazmi and Almihdhar] at the terrorist meeting in Malaysia in January 2000.

Once we have their direct links, the next step is to find their indirect ties -- the 'connections of their connections'. Discovering the nodes and links within two steps of the suspects usually starts to reveal much about their network. Key individuals in the local network begin to stand out. In viewing the network map in Figure 2, most of us will focus on Mohammed Atta because we now know his history. The investigator uncloaking this network would not be aware of Atta's eventual importance. At this point he is just another node to be investigated.


Figure 2 shows the two suspects and


We now have enough data for two key conclusions: • All 19 hijackers were within 2 steps of the two original suspects uncovered in 2000! • Social network metrics reveal Mohammed Atta emerging as the local leader

With hindsight, we have now mapped enough of the 9-11 conspiracy to stop it. Again, the investigators are never sure they have uncovered enough information while they are in the process of uncloaking the covert organization. They also have to contend with superfluous data. This data was gathered after the event, so the investigators knew exactly what to look for. Before an event it is not so easy.

As the network structure emerges, a key dynamic that needs to be closely monitored is the activity within the network. Network activity spikes when a planned event approaches. Is there an increase of flow across known links? Are new links rapidly emerging between known nodes? Are money flows suddenly going in the opposite direction? When activity reaches a certain pattern and threshold, it is time to stop monitoring the network, and time to start removing nodes.

The author argues that this bottom-up approach of uncloaking a network is more effective than a top down search for the terrorist needle in the public haystack -- and it is less invasive of the general population, resulting in far fewer "false positives".

Social Network Analysis of Steroid Usage in Baseball (www.orgnet.com)


When the Mitchell Report on steroid use in Major League Baseball [MLB], was published, people were surprised at who and how many players were mentioned. The diagram below shows a human network created from data found in the Mitchell Report. Baseball players are shown as green nodes. Those who were found to be providers of steroids and other illegal performance enhancing substances appear as red nodes. The links reveal the flow of chemicals -- from provider to player.

Knowledge Sharing in Organizations: Finding Experts


Knowledge Sharing Network: Finding Experts (www.orgnet.com)


Organizational leaders are preparing for the potential loss of expertise and knowledge flow due to turnover, downsizing, outsourcing, and the coming retirements of the baby boom generation. The model network (previous chart) is used to illustrate the knowledge continuity analysis process.

Each node in this sample network (previous chart) represents a person that works in a knowledge domain. Some people have more / different knowledge than others. Employees who will retire in 2 years or less have their nodes colored red. Those who will retire in 3-4 years are colored yellow. Those retiring in 5 years or later are colored green.

A gray, directed line is drawn from the seeker of knowledge to the source of expertise. A-->B indicates that A seeks expertise / advice from B. Those with many arrows pointing to them are sought often for assistance.

The top subject matter experts -- SMEs -- in this group are nodes 29, 46, 100, 41, 36 and 55. The SMEs were discovered using a network metric in InFlow that is similar to how the Google search engine ranks web pages -- using both direct and indirect links.

Of the top six SMEs in this group, half are colored red[100] or yellow[46, 55]. The loss of person 46 has the greatest potential for knowledge loss. 90% of the network is within 3 steps of accessing this key knowledge source.

Social Networks: Security and Privacy Issues: European Network and Information Security Agency

The European Network and Information Security Agency (ENISA) has released its first

issue paper “Security Issues and Recomendations for Online Social Networks".

http://www.enisa.europa.eu/doc/pdf/deliverables/enisa_pp_social_networks.pdf

Four groups of threats: privacy related threats, variants of traditional network and

information security threats, identity related threats, social threats.

Recommendations are given for governments (oversight and adaption of existing data

protection legislation), companies that run such networks, technology developers, and

research and standardisation bodies.

Some concenrs: recommnendation to use automated filters against "offensive, litigious or

illegal content". This brings potential freedom of speech issues. European Digital Rights

has started a campaign against a similar recommendation by the Council of Europe.

Issue of portability of profiles social graphs are also addressed. However what is missing

is that “Information about social links is not about only one user, but also the others

which he is linked to. They have to agree if this information is moved to different

platforms”.

Social Networks: Security and Privacy Issues: Microsoft Recommendations http://www.microsoft.com/protect/yourself/personal/communities.mspx

Online communities require you to provide personal information. Profiles are public.

Comments you post are permanently recorded on the community site.You might even

mention when you plan to be out of town.

E-mail and phishing scammers count on the appealing sense of trust that is often

fostered in online communities to steal your personal information. The more you reveal

in profiles and posts, the more vulnerable you are to scams, spam, and identity theft.

Here are some features to look for when you're considering joining an online community:

- •Privacy policies that explain exactly what information the service will collect and

how it might be used.• User guidelines that outline a basic code of conduct for users

on their sites. Sites have the option to penalize reported violators with account

suspension or termination.•Special provisions for children and their parents, such

as family-friendly options geared towards protecting children under a certain

age.•Password protection to help keep your account secure..•E-mail address hiding,

which lets you display only part of your e-mail address on the site's membership

lists. Filtering options: Offered on blogging sites, these tools let you to choose

which subscribers can see what you've written.

Role of Semantic Web

FOAF (Friend of a Friend)

Social Graph represented in RDF

Use the reasoning tools and analyze the social network for suspicious events

Protect the privacy of individuals

FOAF: http://www.foaf-project.org/abouthttp://en.wikipedia.org/wiki/FOAF_(software)

FOAF (an acronym of Friend of a Friend) is a machine-readable ontology describing persons, their activities and their relations to other people and objects. Anyone can use FOAF to describe him or herself. FOAF allows groups of people to describe social networks without the need for a centralised database.

FOAF's descriptive vocabulary is expressed using RDF Resource Description Framework and OWL Web Ontology Language.

Computers may use these FOAF profiles to find, for example, all people living in Europe, or to list all people both you and a friend of you know. This is accomplished by defining relationships between people. Each profile has a unique identifier (such as the person's e-mail addresses, a URI of the homepage or weblog of the person), which is used when defining these relationships.


The FOAF project, which defines and extends the vocabulary of a FOAF profile, was started in 2000 by and . It can be considered the first Social Semantic Web application, in that it combines RDF technology with 'Social Web' concerns.

Tim Berners-Lee in a recent essay redefined the Semantic web concept into something he calls the Giant Global Graph, where relationships transcend networks/documents. He considers the GGG to be on equal grounds with Internet and World Wide Web, stating that "I express my network in a FOAF file, and that is a start of the revolution."

The following FOAF profile (written in XML format) states that Jimmy Wales is the name of the person described here. His e-mail address, homepage and depiction are resources, which means that each of them can be described using RDF as well. He has Wikipedia as an interest, and knows Angela Beesley (which is the name of a 'Person' resource).

<rdf:RDF xmlns:foaf="http://xmlns.com/foaf/0.1/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"> <foaf:Person rdf:about="#JW"> <foaf:name>Jimmy Wales</foaf:name> <foaf:mbox rdf:resource="mailto:[email protected]" /> <foaf:homepage rdf:resource="http://www.jimmywales.com/" /> <foaf:nick>Jimbo</foaf:nick> <foaf:depiction rdf:resource="http://www.jimmywales.com/aus_img_small.jpg" /> <foaf:interest rdf:resource="http://www.wikimedia.org" rdfs:label="Wikipedia" /> <foaf:knows> <foaf:Person> <foaf:name>Angela Beesley</foaf:name>  </foaf:Person> </foaf:knows> </foaf:Person> </rdf:RDF>

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