Transcript Artificial Neural Networks in Detection of Apples Damage

Access Control in
Collaborative Systems
Authors: Emis Simo
David Naco
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Overview
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Introduction
Collaborative Access Control
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Requirements of Access Control in Collaborative systems
Access Control models
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Intermediate Access Controls
The Matrix Access Control
Space Model
Role-Based Access Control (RBAC)
Task-Based Access Control (TBAC)
Team-Based Access Control (TMAC)
Evaluation Criteria
Conclusion
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Introduction
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Collaborative systems are becoming used
extensively in the last decade
The aim of such systems is to achieve
communication and collaboration between users
concerned with common tasks
Need of security emerges in such systems
Access control is one the most import aspects of
security in collaborative systems
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Not only authentication, but authorization also
Traditional Access Control Models for collaboration,
satisfy requirements??
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Collaborative Access Control
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Intermediate Access Controls
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Privileges
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If you are allowed to do something in a system, you usually
have a certain level of privilege to be able to use the
operating system functions or perform some actions. This
introduces a concept called least privilege. It requires that a
user be given no more privilege than necessary to perform a
job.
Protection Rings
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Protection Rings have been mainly used for integrity
protection. The representative examples are system/user
protection in operating system design and the machine
language protection for microprocessor design.
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Intermediate Access Controls
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Intermediate Abilities
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Group and Negative Permissions
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More flexible and have more internal structure,
convenient for mathematical analysis,
experimental stage
Define group forbiddance of accessing objects
RBAC
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Fundamental way of implementing intermediate
layer of various access control policies
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Requirements for Access Control
in Collaborative Systems
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Multiple, dynamic user roles
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Collaboration rights
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The model should allow users access rights to be inferred
from their roles. Moreover, it should allow users to take
multiple roles simultaneously and change these roles
dynamically during different phases of collaboration
operations whose results can affect multiple users should be
protected by collaboration rights
Flexibility
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The system should support fine - grained subjects, objects,
and access rights
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Requirements for Access Control
in Collaborative Systems
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Easy specification
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Efficient storage and evaluation
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The storage of access definitions and evaluation of the access
checking rule should be efficient
Automation
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Access control models must allow high-level specification of access
rights
Easy to implement access control in multi-user applications.
Performance and resource costs should be kept within acceptable
bounds
Meta-access control
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Support for fine-grained protection, assignment of administrators,
joint and multiple ownership issues, and the delegation and
revocation of access rights
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Collaborative Access Control
Models
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Matrix Access Control
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Object
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Subject
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The basic resource entity controlled by the computer.
Entity initiating an activity to objects.
The access matrix is a basic model specifying the
rights that subjects have to objects.
Each subject and object correspond to a row and
column, respectively.
Each cell in the matrix denotes the access authorized
for the object in the column by the subject in the row.
The main objective of the access control system is to
strictly execute the operations imposed by the access
matrix.
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Implementations of Matrix Access
Control
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Implementations of Matrix Access Control involve
splitting the matrix in more manageable parts in order
to obtain acceptable performance for the
authorization operations.
Access Control Lists (ACL)
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Stores the matrix by columns
Provides convenient access review with respect to the object
Capability Lists (C-Lists)
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Stores the matrix by rows
Provides convenient access review with respect to the
subject
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Implementation (Matrix Access
Control) cont
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Shortcomings (Matrix Access
Control)
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A collaborative organization ownership might not be
at the discretion of the user:
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Change of Responsibilities
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The system might own resources.
ACL and C-List lack the ability to support dynamic changes
of access rights.
More sophisticated access policies are difficult to be
provided without access rights that are associated
with a subject's credentials.
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Least Privilege
Conflict-of-Interest Rules
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SPACE Model
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The basic idea behind this model consists of two
concepts: Boundaries and Access Graph.
Environment is divided into small manageable regions by
boundaries.
In each region, a certain level access control policy is
applied.
Within a region, access control is granted as the same
level.
An access graph is built to summarize the constrains on
movement among regions
Two matrices called adjacency and classification matrices
are created by using standard mathematical means
The two matrices are the kernel of the SPACE model
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SPACE Model
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Shortcomings (SPACE)
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Provides navigational access requirements in
collaborative environments and does not provide for
fine-grained control
It is not provably secure
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users can create insecure regions
SPACE model lacks the complexity needed for
systems where the level of security provided is
important
Application domain is restricted to systems that can
be represented in terms of regions and boundaries
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Role-Base Access Control
(RBAC)
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The fundamental principal of RBAC is that the
decision to allow access to objects is based on the
role of the user
A role can represent specific task competency
RBAC offers a new way of assigning access rights to
individuals in an enterprise
First a role is established and least privileges are
assigned to it. Then an individual derive their access
rights of a role by being assigned to membership of
that role which describes his job or responsibility in
that enterprise
The determination of the role membership is
determined by the organization's security policy
RBAC is flexible and easy to manage
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RBAC
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Shortcomings (RBAC)
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In early implementations of RBAC, the set of roles
and the membership functions as well, were defined
early in the life-time of a session
Supports the notion of role activation within sessions,
but it does not go far enough in encompassing the
overall context associated with any collaborative
activity
Traditional RBAC lacks the ability to specify a finegrained control on individual users in certain roles
and on individual object instances.
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Task-Based Access Control
(TBAC)
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Extend the traditional access models, by introducing
domains that include task-based contextual
information.
Two basic fundamental abstractions:
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Authorization Step
Task Templates
The protection state of each authorization step is
unique and disjoint from the protection states of other
steps.
TBAC recognizes the notion of a life-cycle and
associated processing steps for authorizations.
Dynamically manages permissions as authorizations
progress to completion.
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Shortcomings (TBAC)
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Permissions are activated and
deactivated in a just-in-time manner.
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Problem: across workflows and race
conditions
Collaborative systems require much
broader definition of context
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Nature of collaboration cannot always be
easily partitioned into tasks with usage
counts
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Team Based Access Control
(TMAC)
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The model defines the team components as a set of
users in various roles
Team permission is a set of permissions that are
defined across team roles and objects.
Context-Based TMAC (C-TMAC)
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Variation of TMAC
Consists of five sets: role, user, context, permission, and
session
Team is used as a context to group users in various roles to
access other contexts that have some resources or
environmental factors such as time and location.
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Shortcomings (TMAC and CTMAC)
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The models lack the self administration
of assignment relations between entities
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Need to reflect multidimensional
definitions of rich collaborative contexts:
such as: organizational entities, workflow
tasks, groupware's environmental
components
Both models have not yet been fully
developed
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Requirements Satisfaction
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Evaluation Criteria
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Simple Mechanism (Expressability)
Groups of Users
Easy of Use
Policy Specifications
Policy Enforcement
Fine-Grained Control
Contextual Information
Active/Passive
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Summary
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The traditional Access Models
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The Matrix Access Control
Space Model
Role-Based Access Control (RBAC)
Task-Based Access Control (TBAC)
Team-Based Access Control (TMAC)
Not all requirements for Collaborative Access
Control are satisfied by traditional models
Need for new Access Control Models
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