Composite Decentralized Access Control Petar Tsankov , Srdjan - - PowerPoint PPT Presentation

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Composite Decentralized Access Control Petar Tsankov , Srdjan - - PowerPoint PPT Presentation

Sep 03, 2022 432 likes •920 views

Composite Decentralized Access Control Petar Tsankov , Srdjan Marinovic, Mohammad Torabi Dashtj, David Basin Instjtute of Informatjon Security ETH Zurich Example: SweGrid Goal Provides computatjonal and storage resources to researchers

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Composite Decentralized Access Control

Petar Tsankov, Srdjan Marinovic, Mohammad Torabi Dashtj, David Basin Instjtute of Informatjon Security ETH Zurich

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Example: SweGrid

Access Control Requirements

– A project leader delegates his authority

  • ver resources to principals

– A project leader composes the principals'

policies (e.g., using permit-override)

Goal

Provides computatjonal and storage resources to researchers

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Delegatjon

Multjple principals can issue access rights

Researchers access rights access rights delegatjons Project leader Dave Project Leader Bob Researchers

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Delegatjon

Multjple principals can issue access rights

Researchers access rights access rights delegatjons

Decentralized Access Control

Project leader Dave Project Leader Bob Researchers

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Compositjon

Policy decisions in large-scale systems

– Grant, Deny, Not-applicable, Confmict

Dave Project leader

+

Bob

Compositjon

  • perators, e.g.:
  • Permit-override
  • Deny-override
  • Confmict-override

+

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Composite Access Control

Compositjon

Policy decisions in large-scale systems

– Grant, Deny, Not-applicable, Confmict

Dave Project leader

+

Bob

Compositjon

  • perators, e.g.:
  • Permit-override
  • Deny-override
  • Confmict-override

+

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System Model

Subjects Resources

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System Model

Requirements control access Subjects Resources Principals

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System Model

PEP PDP Requirements control access Subjects Resources Principals Policies

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Related Work

Systems and standards Formal foundatjons

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Related Work

Systems and standards Formal foundatjons DKAL ('08)

RT ('01) SecPAL for Grid

Delegatjon

KeyNote PDP (RFC 2704)

...

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Related Work

Systems and standards Formal foundatjons

XACML v2.0 D-Algebra ('09) PTaCL ('12) PBel ('08) DKAL ('08) RT ('01) SecPAL for Grid

Delegatjon Compositjon

KeyNote PDP (RFC 2704)

... ...

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Related Work

Systems and standards Formal foundatjons

XACML v2.0 D-Algebra ('09) SweGrid PTaCL ('12) PBel ('08) DKAL ('08) RT ('01) XACML v3.0 ('13) SecPAL for Grid WSO2 ID Server

Delegatjon Compositjon Delegatjon + Compositjon

KeyNote PDP (RFC 2704)

... ...

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Related Work

Systems and standards Formal foundatjons

XACML v2.0 D-Algebra ('09) SweGrid PTaCL ('12) PBel ('08) DKAL ('08) RT ('01) XACML v3.0 ('13) SecPAL for Grid WSO2 ID Server

BelLog

Delegatjon Compositjon Delegatjon + Compositjon

KeyNote PDP (RFC 2704)

... ...

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How to Build Access Control Systems

Specify Policy Verify Policy Construct PDP

➔ Formal semantjcs ➔ Support for

delegatjon

➔ Support for

compositjon

➔ Analysis language ➔ Decision algorithms ➔ Effjcient evaluatjon

algorithm

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How to Build Access Control Systems

Specify Policy Verify Policy Construct PDP

➔ Formal semantjcs ➔ Support for

delegatjon

➔ Support for

compositjon

➔ Analysis language ➔ Decision algorithms ➔ Effjcient evaluatjon

algorithm

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Belnap Logic + Datalog = BelLog

(Program) (rule) (literal) (atom) Truth ordering Knowledge ordering

Belnap Logic (stratjfjed) Datalog

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Belnap Logic + Datalog = BelLog

(Program) (rule) (literal) (atom) Truth ordering Knowledge ordering

Belnap Logic (stratjfjed) Datalog

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Belnap Logic + Datalog = BelLog

(Program) (rule) (literal) (atom) Truth ordering Knowledge ordering

Belnap Logic (stratjfjed) Datalog

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Belnap Logic + Datalog = BelLog

(Program) (rule) (literal) (atom) Truth ordering Knowledge ordering

Belnap Logic (stratjfjed) Datalog

BelLog

(Program) (rule) (literal) (atom) Negatjon on truth Negatjon on knowledge

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Belnap Logic + Datalog = BelLog

(Program) (rule) (literal) (atom) Truth ordering Knowledge ordering

Belnap Logic (stratjfjed) Datalog

BelLog

(Program) (rule) (literal) (atom) Negatjon on truth Negatjon on knowledge

Semantjcs

Extend stratjfjed Datalog to four- valued fjxed-point semantjcs

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BelLog Examples

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BelLog Examples

Transitjve delegatjon

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BelLog Examples

Transitjve delegatjon Policy targets

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BelLog Examples

Transitjve delegatjon Policy targets Agreement

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BelLog Examples

Transitjve delegatjon Confmict-override Policy targets Agreement

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BelLog Examples

Transitjve delegatjon Confmict-override Policy targets Agreement

Other idioms?

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➔ Formal semantjcs ➔ Support for

delegatjon

➔ Support for

compositjon

➔ Analysis language ➔ Decision algorithms ➔ Effjcient evaluatjon

algorithm

How to Build Access Control Systems

Specify Policy Verify Policy Construct PDP

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Policy Analysis

Does the policy meet its requirements?

Requirements Policy

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Policy Analysis

Does the policy meet its requirements?

Requirements Policy Questjons

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Policy Analysis

Does the policy meet its requirements?

Requirements Policy Questjons Analyzer

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Policy Analysis

Does the policy meet its requirements?

Requirements Policy Questjons Analyzer

Counter- example Policy checked

Fix

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Policy Analysis

Does the policy meet its requirements?

Requirements Policy Questjons Analyzer

Counter- example Policy checked

Fix

How do we write this?

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Policy Analysis

Does the policy meet its requirements?

Requirements Policy Questjons Analyzer

Counter- example Policy checked

Fix

How do we write this? Decidability? Complexity?

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Analysis Questjons

Syntax

– Is policy P2 more permissive than P1 for all inputs

that satjsfy the conditjon c?

(conditjon) (questjon)

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Analysis Questjons

All requests

Requests granted by P2 Requests granted by P1

Syntax

– Is policy P2 more permissive than P1 for all inputs

that satjsfy the conditjon c?

(conditjon) (questjon)

For a given input:

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Analysis Questjons

All requests

Requests granted by P2 Requests granted by P1

Syntax

– Is policy P2 more permissive than P1 for all inputs

that satjsfy the conditjon c?

(conditjon) (questjon)

For a given input:

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Analysis Questjons

All requests

Requests granted by P2 Requests granted by P1

Syntax

– Is policy P2 more permissive than P1 for all inputs

that satjsfy the conditjon c?

(conditjon) (questjon)

For a given input: Check for all inputs that satjsfy the conditjon

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Example: Analysis Questjon

Requirement

If the requester is a project leader, then grant access.

Policy

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Example: Analysis Questjon

Requirement

If the requester is a project leader, then grant access.

Analysis Questjon Policy

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Analysis

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Analysis

Theorem 1

Policy containment is undecidable

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Analysis

Theorem 2

Policy containment for unary-input policies* is in CO-NEXP-COMPLETE

Theorem 1

Policy containment is undecidable

*Unary-input policies

– Example:

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Analysis

Theorem 3

Policy containment for a fjnite universe is in CO-NP-COMPLETE

Theorem 2

Policy containment for unary-input policies* is in CO-NEXP-COMPLETE

Theorem 1

Policy containment is undecidable

*Unary-input policies

– Example:

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➔ Formal semantjcs ➔ Support for

delegatjon

➔ Support for

compositjon

➔ Analysis language ➔ Decision algorithms ➔ Effjcient evaluatjon

algorithm

How to Build Access Control Systems

Specify Policy Verify Policy Construct PDP

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Constructjng PDPs

Policy Interpreter htup://bellog.org GitHub htups://github.com/ptsankov/bellog/ Theorem 4

Policy entailment is in PTIME

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Limitatjons

– Analysis of administratjve changes – Analysis complexity and tool support – Usability

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BelLog Contributjons

A foundatjon for composite decentralized access control Policy analysis framework BelLog PDP (www.bellog.org)