Governance Policies for Privacy Access and their Interactions

ICFI-2005

Waël Hassan1 & Luigi Logrippo2

1 University of OttawaSchool of information technology and engineering

2Université de Québec en OutaouaisDepartment of Computer Science & Engineering

Goal

Detecting policy interactions in privacy governance policies

How

• By using formal models

• Proposing a privacy model

Agenda

• Policy Drivers– Convergence of control and policy systems– Requirements of new privacy models

• Conflict detection using formal models– Delegation, separation, alloy

• Proposed process based privacy model• Evaluation

– Support of existing concepts– Advantages over existing models

• Verification• Conclusion

Policy Model Drivers

• Convergence of control and policy systems– From operational to rules of governance– Activity or trigger based to data based

• Requirements of new privacy models– Release information based on purpose– Control flow of information– Ability to specify separation of concerns

Layers

ActionsFeaturesTransactions

FunctionalHierarchies(Roles)

ProcessLevel

Conflicts in Enterprise Governance

• Policies of Access to information can cause conflict depending on their scope– Logically contradicting policies will interact if their scope over lapped.– A subject roaming in multiple scopes can cause a rule conflict– A subject delegating authority of an object can cause a conflict– An object shared by multiple subjects can cause conflict

• Policies of privacy access can interact if the reason (purpose) of access is conflicting

Overlapping scope (PoliciesxRoles)

CEO

Vice President Sales

Vice President Marketing

Vice President Development

Manager Manager Manager

Vice PresidentOperations

Manager Manager Manager Manager

EmployeeEmployee Employee Employee

RoamingShared Delegation

Examples

• Rule: An employee cannot have access to both customers’ address and credit card information

(Card Number, expiry date, PIN, and last 4 digits on the back of card) ; • Process

– one of the tasks of issuing a new card (CreateAccount), includes the mailing of the credit card to the consumer.

– (Process) CreateAccount:- (Step)LeaveTraceInSystem, (Process) CreateCard, (Process) MailCard.

• Result– Interaction

Separation of concerns• Rule:

– No one person is allowed to create and delete accounts

– (Process) CreditCardApp:- (Process) ReceiveCardApplication, (Process) CallCreditCheck,(Process) IssueCard, (Process) CreateAccount.

– (Process) WithdrawApplication:- (Process) DeleteAccount, (Step) NotifyClient.

In this instance Alloy was able to detect violations of such rule.%

Delegation Interaction

• Rule: Information collected for the purpose of credit verification should not be generally available to employees in loan processing

Loan Processing Process includes Verify Credit

• Employee delegates Role to manager

Loan Processing

Receive Loan Verify Credit Reject Loan

Process Based Governance

Governance of organizations by

specifying control of access

(to information)

by applying policies

to processes

Process Based Control

• A business process is a unit that can be composed of steps and/or processes.

• Steps in a process are sequential

Process

In a business process environment it should be • Easy to tie purposes to actions• Possible to apply invariants for a complete structure• Easy to trace policy modifications

Business Process

Loan Processing

Receive Loan Verify Credit Reject Loan

Verify Credit

Receive Card Application Call CreditCheck Process Answer

Provide FeedbackCreate

CardMail Response

PPM Approach Supports

• Flow of information (Bell Lapadula)

• Separation of concerns (Chinese Wall)

Bell-Lapadula

Intended for military applications,

Flow Based

1. Security Clearances

2. Security Requirement

A can access y iff – clearance of A > requirement of y

A can forward access to y for B iff – clearance of B > requirement of y

A

X

By Level

Bell-Lapadula• Lattice based model

U

C

S

TS

Leq

U Unclassified

C Classified

S Secret

TS Top-Secret

Leq

Leq

Leq

Partial-Order• Reflexive• Transitive• Anti-Symmetric

Chinese Wall

Originally intended for banking applications• Creates separation of concerns groups• Group A & Group B cannot share access to an object

set {x,y,z}

A BX

Y

z

CW / SOD - Separation of duties

User

Role

Role Centric• Irreflexive• User cannot fill two conflicting Roles• Inherit conflict groups

Assigned

User Centric• Irreflexive• 2 conflicting users cannot collectively

fill 2 roles in conflict. • Inherit conflict groups

Privacy Process Model

Users

Roles

Processes

Steps

Permissions

Operations ObjectsPermissionAssignment

Process Hierarchy

Role Hierarchy

Two Variations

• The process has all the properties and people are simply assigned to steps (activities) as per their roles

• Steps retain properties and people are as assigned as per their roles

UsersProcesses

Steps

Process Hierarchy

UsersProcesses

Steps

Process Hierarchy

User-Process User-Step

Privacy Process Model - User-Step

Users

Roles

Processes

Steps

Permissions

Operations ObjectsPermissionAssignment

Process Hierarchy

Role Hierarchy

Sequence

PermissionAssignment

Privacy Process Model- User-Process

Users

Roles

Processes

Steps

Permissions

Operations Objects

Process Hierarchy

Role Hierarchy

Sequence

Information flow

• A part of standard procedures is delegating work to others.– Example: delegate meeting announcement to

secretary

• Using process model– Action delegate meeting, allowed in a process – Action meeting cancellation cannot be

delegated

Separation of Concerns

• In the banking industry, different groups may not share access to particular resources.

• Using process model we can set rules to separate groups– Example:

• No data that admission and scholarship share• Finance and Marketing share no information

Advantages of PPM

• Captures context

• Simplifies management (privacy)

Captures Context

• As a part of credit application process (x,y,z,t), an employee A receives access to credit information in step z.– Using standard security model, A can download all credit

information of all customers on file

• When using a process model, – access is granted or revoked based on the sequence of

operations. – Therefore, under the process model, an employee A will only

have access If steps x & y have been performed– Access will be revoked after operation t is completed

x y z t

Simplifies Management

• Privacy is dependent on the application and not on the identity

• An identity can have a role which is involved in several functions. However Its privileges are dependent on process.

• Grouping policies per process reduces time and management policies that are based on roles.

• Example:– Old

• If rank is General, then grant access• If rank is secretary and name is Lise then grant access

– New:• Secretary allow-access step 3• General allow-access process change-direction

Implementation and Validation

• A validation environment is provided by the language Alloy

• A formal language based on set theory and first order predicate calculus – Model analyser– Consistency checker– Being developed at MIT

AlloySignatures or elements are the basic constructs of an Alloy model; they are a cluster of relationships grouped in a class like structure.

1. Sig [abstract] enterprise {2. root : CEO3. }{4. [lone] root5. }

1. abstract sig process {2. parent : lone process, 3. composedOf : set steps4. }

Process

abstract sig policy { attachedTo : lone process, permitted: role -> process, denied : role -> process

Policy

Enterprise

}no permitted & denied role.permitted in attachedTo role.denied in attachedTo }

Facts & Rules

Alloy Process

Architecture

UML Model

Verification

Alloy Meta Model

Alloy Policy Specification

TranslationManual Translation

Manual

ManualVerification

XACML

ebXML

ManualVerification

Pragmatic Goals

• GUIs to formulate validated policies• Able to answer questions:

– Given an enterprise model and a set of policies• Who can/cannot and under what circumstances• Given circumstances, who can/cannot?• Is there inconsistency ?• Is the system compliant to a set of Policies?

• Automatic translation between – GUI representation– XACML representation– Formal representation (Alloy or other)

Conclusion & Future Work

Privacy requires a native model; We were able to model system and detect basic

interactions using a formal tool.

We plan to use a process based model that attaches policies to processes which are

composed of activities,

We use Alloy as model analyzer to verify properties.

Thanks from

Waël Hassan, Luigi Logrippowael@ieee.org, luigi@uqo.ca

Extra

• (Process) CreditCardApp:- (Process) ReceiveCardApplication, (Process) CallCreditCheck, (Process) IssueCard, (Process) CreateAccount.

• (Process) CreateAccount:- (Step)LeaveTraceInSystem, (Process) CreateCard, (Process) MailCard.

• (Process) DeleteAccount:- (Step)LeaveTraceInSystem, (Step)RemoveAccount.

• (Process) WithdrawApplication:- (Process) DeleteAccount, (Step) NotifyClient.

Security

• Basic:- – Identity Access Right

• An identity justifies an access-right– Example: given I am a wael, I can access my lab

• Extended:-– Identity1, Identity2 Forwarding Right (object)

• A right is owned and can be forwarded (delegated)– Example: given I am an assistant,

» I own the right to access personal student file,» I can allow Jasmine access to my file

• Combined:-– Identity1, Identity2 Concurrent Access(object)

• Two subjects may be allowed to have concurrent access to an object

Privacy

• Basic:-– Purpose Access-Right (Identity)

• A purpose justifies access-right • Example: To update student profile,

– Jo-Anne needs to have access to accepted student application data

• Extended:- – Step Forwarding Right (Identity1, Identity2)

• A step which can be owned by a person in a process suggests a right, and that right may be forwarded (delegated) iff the recipient has access to the process/step.

– Example: given that Jo-Anne participates in the admissions procedure, » She is assigned access to activity open personal student file,» She can allow Jasmine (another officer) access to the same file as long as

she has the authority and she is assigned to the process

• Combined:-– Process1, Process2 Concurrent Access (object)

• Two subjects participating in two processes may or not have concurrent access to certain objects.