An Access Control Model for Video Database Systems As a joint work of: Elisa Bertino1, Ahmed K. Elmagarmid 2 and Moustafa M. Hammad2 1Dipartimento di Scienze dell'Informazione. Universit degli Studi di Milano. Via Comelico, 39/41 20135 Milano,

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An Access Control Model for Video Database
SystemsAs a joint work of Elisa Bertino1,
Ahmed K. Elmagarmid 2 and Moustafa M.
Hammad21Dipartimento di Scienze
dell'Informazione. Universit degli Studi di
Milano. Via Comelico, 39/41 20135 Milano, Italy.
bertino_at_dsi.unimi.it. 2Computer Science
Department, Purdue University. 1398 Computer
Science Bld., West Lafayette IN 47907.
ake,mhammad_at_cs.purdue.edu.
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Introduction

• Video data possess unique features that
  distinguished them from other data types. ( e.g.
  different media types - visual, audio and text-,
  schemaless, massive volume, time and
  space-variant, rich semantic contents - a picture
  worth 1000 words, what about video????)
• Different approaches to model video data like
• Segmentation-based, physical features oriented
  color histogram, textures, audio, text.
• Annotation-based, semantic features oriented.
  Video description is used to access video.
• Large amount of digital video gt 1.8 M Gbytes, and
  a large investments, MPEG-2 has created the
  entirely new digital television industry worth
  30 billion .
• Hence a need to provide secure and organized
  access to video database !!!! or access control.
• Is Access Control based on physical or semantic
  content?
• Our work is focused on access control based
  on video semantics to exploit the expressive
  power in video.

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Topics of Discussion

• Video data model.
• Authorization model for video database.
• Access control techniques.
• System architecture.
• Conclusion and future work.

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Video Data Model
Physical video segment
Physical video stream
Hot Object
Life time interval or logical video segment
John plying with his bicycle
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Authorization Model

• Closed system access control ( no access
  permission unless explicitly specified in the
  system).
• User access requests are checked against
  authorization rules.
• Authorization rule specification entails
• Subject Specification,
• Object Specification, and
• Mode Specification.

Access request
Authorization rules
Request satisfies authorization rules
Yes
No
Grant
Deny
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Subject Specification

• Use of credential
• Characteristic and attributes of users (user
  profiles) instead of only user identifiers.
• Example (Name John, Age 8, Job student,).
• Suitable for video data.
• Credential type (schema), credential and
  credential expression.
• We specify a simple language for credential
  expressions.
• Examples of credential expressions
• Student(x) representing all users that are
  students.
• x.age lt 18 denoting all users having age lt 18.
• Student(x) AND x.age lt 18 Students with age lt
  18.
• Credential expression is finally evaluated to a
  set of user identifiers.
• Subject is specified as either
• list of users identifiers or credential
  expression.

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Object Specification

• We base our access model on logical video level
  to
• be easy to apply and modify, and
• allow specification of access based on semantic
  video contents.
• Video objects possess more than just physical
  characteristic (semantic contents).
• Annotations describe video semantic and one can
  extract concepts from video annotation. (e.g.
  FIAT and MAZDA are CARS).
• In its simplest form concepts represent just
  annotation keywords.
• We use concepts that describe video semantics to
  specify video security.

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Object Specification (Cont.)

• Concept expression involves one or more concepts
  with video operators between them. Video
  operators are either spatial, temporal,
  spatio-temporal or Boolean operators.
• Concept expression
• The set CPE of concept expressions is built from
  atoms and operation ? , video operation.
• Atoms can be of the following types
• c , where c ? set of concepts.
• c1 ? c2 , where c1, c2 are concepts and ? ? set
  of video operations.
• Then the set CPE of concept expressions is
  recursively defined as follows
• Every atom is a concept expression.
• If CpE1 and CpE2 are concept expressions, then
  CpE1 ? CpE1, CpE1 ? CpE1, ? CpE1 , (CpE1) are
  also concept expressions.

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Object Specification (Cont.)

• Concepts expression finally evaluates to set of
  logical video segments that contain concepts
  satisfying the expression.
• Examples of concept expressions
• World War II ? Digol denotes all frame
  intervals that have General Digol as a hot object
  and deal with World War II.
• Ortiga DURING drug trial denotes all frame
  intervals that have former Colombian president
  Ortiga during the drug trial in court video.
• DISCOVERY CLOSE spying satellite denotes all
  frame intervals that have DISCOVERY space shuttle
  fixing or close to a spying satellite in NASA
  video library.
• Video Object can be specified either
• by providing a set of logical video elements.
• by providing concept expression.

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Authorized Object

• Consists of two parts
• protected objects (po) which represent video
  elements user wants to access, and
• restricted objects (ro) which represent video
  elements user is restricted to access.
• Authorized objects (ao) is defined as the
  following expression
• ao po ro, where is defined as the
  exclusion of restricted object from protected
  ones.

Restricted object
Protected object
Authorized Object
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Relations Between Different Object Specification
Terms
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Mode Specification

• low level operations like (read and write) are
  not suitable in video access control.
• More abstract level operations are used to
  specify different access modes
• View (annotations), View(Rframes), Play(period,
  quality), Edit(annotation), Edit(logical-video),
  Edit(Physical-video).
• Those operations are in increasing power, the
  successor subsumes the predecessor.

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Access Control Mechanism

• A user submits a request to access video element,
• The access control routine checks the
  authorization rule repository for an
  authorization rule satisfies
• User is one of the subjects,
• The accessed object is one of the protected
  objects,
• The operation is equal or less than the specified
  mode.
• If not found, user is unauthorized.
• Else If the object is a restricted one
• Then apply operator and authorize the
  subject to
  the new object.
• Else authorize the subject.

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System Architecture
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Conclusion and future work

• Provide access control based on video semantic
  not only physical features.
• Support for different video granularity access
  control.
• Not a dump guard but smart manager (apply filter
  effects).
• Provide categories of video privileges.
• Use of credentials instead of just identifiers.
• Providing modular access control architecture.
• The model can be adapted to video models that
  provide content description mechanisms (MPEG-7).

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Conclusion and future work (cont.)

• Real time provision of access control.
• Distributed implementation.
• PICS (Platform for Internet Content Selection).