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Usage policies for end point access controlUsage policies for end point access control

XACML is Oasis standard to express enterprise security policies with a common XML based policy language

http://docs.oasis-open.org/xacml/2.0/access_control-xacml-2.0-core-spec-os.pdf 103 pgs.

Provides mechanism for EKM to define USEAGE rules at point of key distribution.

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Common termsCommon terms

PAP – Policy Administration Point. This would be the EKM

PDP - Policy Decision Point. An entity that evaluates an access request against one or more policies to produce an access decision. This is essentially a rules engine.

PEP – Policy Enforcement Point. An entity that enforces access control for one or more resources. When a resource access is attempted, a PEP sends an access request describing the attempted access to a PDP. The PDP returns an access decision that the PEP then enforces.

policy – A set of rules indicating which subjects are permitted to access which resources using which actions under which conditions. XACML has two different schema elements used for policies: <Policy> and <PolicySet>. A <Policy> contains actual access control rules.

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Typical XACML componentsTypical XACML components

PEP

contexthandler

4. requestnotification

PIP

6. attributequery

11. responsecontext

1. policy

8. attribute

environment

resource

subjects

7b. environmentattributes

PAP

obligationsservice

13. obligations

PDP

accessrequester

2. access request

9. resourcecontent

3. request 12. response

7c. resourceattributes

7a. subjectattributes

5. attributequeries

10. attributes

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Factors in rulesFactors in rules

Common notion of SUBJECT, RESOURCE, ACTION Attributes used in rules

Must be able to define factors applicable to end points

Rules have different combination algorithms, such as first applicable [IMHO, Sufficient], or deny-overrides.

When a rule fires, the PEP must execute the rules “Obligations”. From our focus, may be things such as Encrypt Audit

If you can’t execute an obligation, service denied

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Basic role of a Policy Enforcement PointBasic role of a Policy Enforcement Point

An application functions in the role of the PEP if it guards access to a set of resources and asks the PDP for an authorization decision.

Recommend “Deny-biased” PEP approach If the decision is "Permit", then the PEP SHALL permit access. If obligations accompany the decision, then the PEP SHALL permit access only if it understands and it can and will discharge those obligations.

All other decisions SHALL result in the denial of access. Note: other actions, e.g. consultation of additional PDPs,

reformulation/resubmission of the decision request, etc., are not prohibited..

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More to come….More to come….

Need subset easily implemented in C