< draft-ietf-geopriv-common-policy-09.txt   draft-ietf-geopriv-common-policy-10.txt >
GEOPRIV H. Schulzrinne GEOPRIV H. Schulzrinne
Internet-Draft Columbia U. Internet-Draft Columbia U.
Expires: October 21, 2006 H. Tschofenig Expires: November 22, 2006 H. Tschofenig
Siemens Siemens
J. Morris J. Morris
CDT CDT
J. Cuellar J. Cuellar
Siemens Siemens
J. Polk J. Polk
Cisco
J. Rosenberg J. Rosenberg
Cisco Systems Cisco
April 19, 2006 May 21, 2006
A Document Format for Expressing Privacy Preferences Common Policy: An XML Document Format for Expressing Privacy Preferences
draft-ietf-geopriv-common-policy-09.txt draft-ietf-geopriv-common-policy-10.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 1, line 43 skipping to change at page 1, line 42
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on October 21, 2006. This Internet-Draft will expire on November 22, 2006.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
This document defines a framework for authorization policies This document defines a framework for authorization policies
controlling access to application specific data. This framework controlling access to application specific data. This framework
combines common location- and presence-specific authorization combines common location- and presence-specific authorization
aspects. An XML schema specifies the language in which common policy aspects. An XML schema specifies the language in which common policy
skipping to change at page 3, line 29 skipping to change at page 2, line 35
7.1. Identity Condition . . . . . . . . . . . . . . . . . . . . 14 7.1. Identity Condition . . . . . . . . . . . . . . . . . . . . 14
7.1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . 14 7.1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . 14
7.1.2. Matching One Entity . . . . . . . . . . . . . . . . . 14 7.1.2. Matching One Entity . . . . . . . . . . . . . . . . . 14
7.1.3. Matching Multiple Entities . . . . . . . . . . . . . . 15 7.1.3. Matching Multiple Entities . . . . . . . . . . . . . . 15
7.2. Single Entity . . . . . . . . . . . . . . . . . . . . . . 19 7.2. Single Entity . . . . . . . . . . . . . . . . . . . . . . 19
7.3. Sphere . . . . . . . . . . . . . . . . . . . . . . . . . . 19 7.3. Sphere . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.4. Validity . . . . . . . . . . . . . . . . . . . . . . . . . 21 7.4. Validity . . . . . . . . . . . . . . . . . . . . . . . . . 21
8. Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 8. Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
9. Transformations . . . . . . . . . . . . . . . . . . . . . . . 24 9. Transformations . . . . . . . . . . . . . . . . . . . . . . . 24
10. Procedure for Combining Permissions . . . . . . . . . . . . . 25 10. Procedure for Combining Permissions . . . . . . . . . . . . . 25
10.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 25 10.1. Algorithm . . . . . . . . . . . . . . . . . . . . . . . . 25
10.2. Algorithm . . . . . . . . . . . . . . . . . . . . . . . . 25 10.2. Example . . . . . . . . . . . . . . . . . . . . . . . . . 26
10.3. Example . . . . . . . . . . . . . . . . . . . . . . . . . 26
11. Meta Policies . . . . . . . . . . . . . . . . . . . . . . . . 29 11. Meta Policies . . . . . . . . . . . . . . . . . . . . . . . . 29
12. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 12. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
13. XML Schema Definition . . . . . . . . . . . . . . . . . . . . 31 13. XML Schema Definition . . . . . . . . . . . . . . . . . . . . 31
14. Security Considerations . . . . . . . . . . . . . . . . . . . 34 14. Security Considerations . . . . . . . . . . . . . . . . . . . 34
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
15.1. Common Policy Namespace Registration . . . . . . . . . . . 35 15.1. Common Policy Namespace Registration . . . . . . . . . . . 35
15.2. Content-type registration for 15.2. Content-type registration for
'application/auth-policy+xml' . . . . . . . . . . . . . . 35 'application/auth-policy+xml' . . . . . . . . . . . . . . 35
15.3. Common Policy Schema Registration . . . . . . . . . . . . 37 15.3. Common Policy Schema Registration . . . . . . . . . . . . 37
16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 38 16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 38
skipping to change at page 4, line 18 skipping to change at page 4, line 18
for access to application specific data. This framework is the for access to application specific data. This framework is the
result of combining the common aspects of single authorization result of combining the common aspects of single authorization
systems that more specifically control access to presence and systems that more specifically control access to presence and
location information and that previously had been developed location information and that previously had been developed
separately. The benefit of combining these two authorization systems separately. The benefit of combining these two authorization systems
is two-fold. First, it allows to build a system which enhances the is two-fold. First, it allows to build a system which enhances the
value of presence with location information in a natural way and value of presence with location information in a natural way and
reuses the same underlying authorization mechanism. Second, it reuses the same underlying authorization mechanism. Second, it
encourages a more generic authorization framework with mechanisms for encourages a more generic authorization framework with mechanisms for
extensibility. The applicability of the framework specified in this extensibility. The applicability of the framework specified in this
document is not limited to policies controling access to presence and document is not limited to policies controlling access to presence
location information data, but can be extended to other application and location information data, but can be extended to other
domains. application domains.
The general framework defined in this document is intended to be The general framework defined in this document is intended to be
accompanied and enhanced by application-specific policies specified accompanied and enhanced by application-specific policies specified
elsewhere. The common policy framework described here is enhanced by elsewhere. The common policy framework described here is enhanced by
domain-speific policy documents, including presence [6] and location domain-specific policy documents, including presence [7] and location
[7]. This relationship is shown in Figure 1. [8]. This relationship is shown in Figure 1.
+-----------------+ +-----------------+
| | | |
| Common | | Common |
| Policy | | Policy |
| | | |
+---+---------+---+ +---+---------+---+
/|\ /|\ /|\ /|\
| | | |
+-------------------+ | | +-------------------+ +-------------------+ | | +-------------------+
skipping to change at page 4, line 48 skipping to change at page 4, line 48
| Location-specific | | | | Presence-specific | | Location-specific | | | | Presence-specific |
| Policy |----+ +----| Policy | | Policy |----+ +----| Policy |
| | | | | | | |
+-------------------+ +-------------------+ +-------------------+ +-------------------+
Figure 1: Common Policy Enhancements Figure 1: Common Policy Enhancements
This document starts with an introduction to the terminology in This document starts with an introduction to the terminology in
Section 2, an illustration of basic modes of operation in Section 3, Section 2, an illustration of basic modes of operation in Section 3,
a description of goals (see Section 4) and non-goals (see Section 5) a description of goals (see Section 4) and non-goals (see Section 5)
of the authorization policy framework, followed by the data model in of the policy framework, followed by the data model in Section 6.
Section 6. The structure of a rule, namely conditions, actions and The structure of a rule, namely conditions, actions and
transformations, are described in Section 7, in Section 8 and in transformations, is described in Section 7, in Section 8 and in
Section 9. The procedure for combining permissions is explained in Section 9. The procedure for combining permissions is explained in
Section 10 and used when more than one rule fires. A short Section 10 and used when more than one rule fires. A short
description of meta policies is given in Section 11. An example is description of meta policies is given in Section 11. An example is
provided in Section 12. The XML schema will be discussed in provided in Section 12. The XML schema will be discussed in
Section 13. IANA considerations in Section 15 follow security Section 13. IANA considerations in Section 15 follow the security
considerations Section 14. considerations from Section 14.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT","RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT","RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [1]. document are to be interpreted as described in RFC 2119 [1].
This document introduces the following terms: This document introduces the following terms:
PT - Presentity / Target: The PT is the entity about whom information PT - Presentity / Target: The PT is the entity about whom information
has been requested. has been requested. RFC 3693 [9] uses the term Target to identify
the object or person of which location information is requested.
RM - Rule Maker: RM is an entity which creates the authorization The presence model described in RFC 2778 [10] uses the term
rules which restrict access to data items. presentity to describe the entity that provides presence
information to a presence service. We introduce a neutral term
here to avoid confusion or loose generality.
RM - Rule Maker: RM is an entity that creates the authorization rules
which restrict access to data items.
PS - (Authorization) Policy Server: This entity has access to both PS - (Authorization) Policy Server: This entity has access to both
the authorization policies and to the data items. In location- the authorization policies and to the data items. In location-
specific applications, the entity PS is labeled as location server specific applications, the entity PS is labeled as location server
(LS). (LS).
WR - Watcher / Recipient: This entity requests access to data items WR - Watcher / Recipient: This entity requests access to data items
of the PT. An access operation might be either be a read, write of the PT. An access operation might be either be a read, write
or be any other operation. In case of access to location or be any other operation. In case of access to location
information it might be a read operation. information is likely to be a read operation.
An 'authorization policy' is given by a 'rule set'. A 'rule set'
contains an unordered list of 'rules'. A 'rule' has a 'conditions',
an 'actions' and a 'transformations' part.
The term 'permission' indicates the action and transformation The receiver of the requested data items is the Location Recipient
components of a 'rule'. (LR) in the terminology of RFC 3693 [9]. A watcher, i.e., an
entity that requests presence information about a presentity, is a
recipient in presence systems (see [10]).
The terms 'authorization policy', 'policy' and 'rule set' are used A policy is given by a 'rule set' that contains an unordered list of
interchangeably. 'rules'. A 'rule' has a 'conditions', an 'actions' and a
'transformations' part.
The terms 'authorization policy rule', 'policy rule' and 'rule' are The term 'permission' refers to the action and transformation
used interchangeable. components of a 'rule'.
The term 'using protocol' is defined in [8]. It refers to the The term 'using protocol' is defined in [9]. It refers to the
protocol which is used to request access to and to return privacy protocol that is used to request access to and to return privacy
sensitive data items. sensitive data items.
3. Modes of Operation 3. Modes of Operation
The abstract sequence of operations can roughly be described as The abstract sequence of operations can roughly be described as
follows. The PS receives a query for data items for a particular PT, follows. The PS receives a query for data items for a particular PT,
via the using protocol. The using protocol provides the identity of via the using protocol. The using protocol (or more precisely the
the requestor (or more precisely the authentication protocol), either authentication protocol) provides the identity of the requestor,
at the time of the query or at the subscription time. The either at the time of the query or at the subscription time. The
authenticated identity of the WR, together with other information authenticated identity of the WR, together with other information
provided by the using protocol or generally available to the server, provided by the using protocol or generally available to the server,
is then used for searching through the rule set. All matching rules is then used for searching through the rule set. All matching rules
are combined according to a permission combining algorithm described are combined according to a permission combining algorithm described
in Section 10. The combined rules are applied to the application in Section 10. The combined rules are applied to the application
data, resulting in the application of privacy based on the data, resulting in the application of privacy based on the
transformation policies. The resulting application data is returned transformation policies. The resulting application data is returned
to the WR. to the WR.
Three different modes of operation can be distinguished: Three different modes of operation can be distinguished:
skipping to change at page 7, line 42 skipping to change at page 7, line 42
resolution of elements. resolution of elements.
3.2. Active Request-Response - PS as Client (Initiator) 3.2. Active Request-Response - PS as Client (Initiator)
Alternatively, the PS may contact the WR and convey data items. Alternatively, the PS may contact the WR and convey data items.
Examples include HTTP, SIP session setup (INVITE request), H.323 Examples include HTTP, SIP session setup (INVITE request), H.323
session setup or SMTP. session setup or SMTP.
3.3. Event Notification 3.3. Event Notification
Event notification adds a subscription phase to the "PS as client" Event notification adds a subscription phase to the "Active Request-
mode of operation. A watcher or subscriber asks to be added to the Response - PS as Client (Initiator)" mode of operation. A watcher or
notification list for a particular presentity or event. When the subscriber asks to be added to the notification list for a particular
presentity changes state or the event occurs, the PS sends a message presentity or event. When the presentity changes state or the event
to the WR containing the updated state. (Presence is a special case occurs, the PS sends a message to the WR containing the updated
of event notification; thus, we often use the term interchangeably.) state. (Presence is a special case of event notification; thus, we
often use the term interchangeably.)
In addition, the subscriber may itself add a filter to the In addition, the subscriber may itself add a filter to the
subscription, limiting the rate or content of the notifications. If subscription, limiting the rate or content of the notifications. If
an event, after filtering by the rulemaker-provided rules and by the an event, after filtering by the rule maker-provided rules and by the
subscriber-provided rules, only produces the same notification subscriber-provided rules, only produces the same notification
content that was sent previously, no event notification is sent. content that was sent previously, no event notification is sent.
A single PS may authorize access to data items in more than one mode. A single PS may authorize access to data items in more than one mode.
Rather than having different rule sets for different modes all three Rather than having different rule sets for different modes all three
modes are supported with a one rule set schema. Specific instances modes are supported with a one rule set schema.
of the rule set can omit elements that are only applicable to the
subscription model.
4. Goals and Assumptions 4. Goals and Assumptions
Below, we summarize our design goals and constraints. Below, we summarize our design goals and constraints.
Table representation: Table representation:
Each rule must be representable as a row in a relational database. Each rule must be representable as a row in a relational database.
This design goal should allow efficient policy rule implementation This design goal should allow efficient policy implementation by
by utilizing standard database optimization techniques. utilizing standard database optimization techniques.
Permit only: Permit only:
Rules only provide permissions rather than denying them. Removing Rules only provide permissions rather than denying them. Removing
a rule can never increase permissions. Allowing both 'permit' and a rule can never increase permissions. Allowing both 'permit' and
'deny' actions would require some rule ordering which had 'deny' actions would require some rule ordering that has
implications on the update operations executed on these rules. implications on the update operations executed on these rules.
Additionally, it would make distributed rule sets more Additionally, it would make distributed rule sets more
complicated. Hence, only 'permit' actions are allowed which complicated. Hence, only 'permit' actions are allowed that result
result in more efficient rule processing. This also implies that in more efficient rule processing. This also implies that rule
rule ordering is not important. Consequently, to make a policy ordering is not important.
decision requires processing all policy rules.
Additive permissions: Additive permissions:
A query for access to data items is matched against the rules in A query for access to data items is matched against the rules in
the rule database. If several rules match, then the overall the rule database. If several rules match, then the overall
permissions granted to the WR are the union of those permissions. permissions granted to the WR are the union of those permissions.
A more detailed discussion is provided inSection 10. A more detailed discussion is provided in Section 10.
Upgradeable: Upgradeable:
It should be possible to add additional rules later, without It should be possible to add additional rules later, without
breaking PSs that have not been upgraded. Any such upgrades must breaking PSs that have not been upgraded. Any such upgrades must
not degrade privacy constraints, but PSs not yet upgraded may not degrade privacy constraints, but PSs not yet upgraded may
reveal less information than the rulemaker would have chosen. reveal less information than the rule maker would have chosen.
Versioning support: Capability support:
In addition to the previous goal, a RM should be able to determine In addition to the previous goal, a RM should be able to determine
which types of rules are supported by the PS. The mechanism used the extensions that are supported by the PS. The mechanism used
to determine the capability of a PS is outside the scope of this to determine the capability of a PS is outside the scope of this
specification. specification.
Protocol-independent: Protocol-independence:
The rule set supports constraints on both notifications or queries The rule set supports constraints on both notifications or queries
as well as subscriptions for event-based systems such as presence as well as subscriptions for event-based systems such as presence
systems. systems.
No false assurance: No false assurance:
It appears more dangerous to give the user the impression that the It appears more dangerous to give the user the impression that the
system will prevent disclosure automatically, but fail to do so system will prevent disclosure automatically, but fail to do so
with a significant probability of operator error or with a significant probability of operator error or
skipping to change at page 12, line 15 skipping to change at page 12, line 15
6. Basic Data Model and Processing 6. Basic Data Model and Processing
A rule set (or synonymously, a policy) consists of zero or more A rule set (or synonymously, a policy) consists of zero or more
rules. The ordering of these rules is irrelevant. The rule set can rules. The ordering of these rules is irrelevant. The rule set can
be stored at the PS and conveyed from RM to PS as a single document, be stored at the PS and conveyed from RM to PS as a single document,
in subsets or as individual rules. A rule consists of three parts - in subsets or as individual rules. A rule consists of three parts -
conditions (see Section 7), actions (see Section 8), and conditions (see Section 7), actions (see Section 8), and
transformations (see Section 9). transformations (see Section 9).
The conditions part is a set of expressions, each of which evaluates The conditions part is a set of expressions, each of which evaluates
to either TRUE or FALSE, i.e. each of which is equipped with a value to either TRUE or FALSE, i.e., each of which is equipped with a value
of either TRUE or FALSE by the PS. When a WR asks for information of either TRUE or FALSE by the PS. When a WR asks for information
about a PT, the PS goes through each rule in the rule set. For each about a PT, the PS goes through each rule in the rule set. For each
rule, it evaluates the expressions in the conditions part. If all of rule, it evaluates the expressions in the conditions part. If all of
the expressions evaluate to TRUE, then the rule is applicable to this the expressions evaluate to TRUE, then the rule is applicable to this
request. Generally, each expression specifies a condition based on request. Generally, each expression specifies a condition based on
some variable that is associated with the context of the request. some variable that is associated with the context of the request.
These variables can include the identity of the WR, the domain of the These variables can include the identity of the WR, the domain of the
WR, the time of day, or even external variables, such as the WR, the time of day, or even external variables, such as the
temperature or the mood of the PT. temperature or the mood of the PT.
Assuming that the rule is applicable to the request, the actions and Assuming that the rule is applicable to the request, the actions and
transformations (commonly referred to as permissions) in the rule transformations (commonly referred to as permissions) in the rule
specify how the PS is supposed to handle this request. If the specify how the PS is supposed to handle this request. If the
request is to view the location of the PT, or to view its presence, request is to view the location of the PT, or to view its presence,
the typical action is "permit", which allows the request to proceed. the typical action is "permit" that allows the request to proceed.
Assuming the action allows the request to proceed, the Assuming the action allows the request to proceed, the
transformations part of the rule specifies how the information about transformations part of the rule specifies how the information about
the PT - their location information, their presence, etc. - is the PT - their location information, their presence, etc. - is
modified before being presented to the WR. These transformations are modified before being presented to the WR. These transformations are
in the form of positive permissions. That is, they always specify a in the form of positive permissions. That is, they always specify a
piece of information which is allowed to be seen by the WR. When a piece of information that is allowed to be seen by the WR. When a PS
PS processes a request, it takes the transformations specified across processes a request, it takes the transformations specified across
all rules that match, and creates the union of them. For computing all rules that match, and creates the union of them. For computing
this union the data type, such as Integer, Boolean, Set, or the Undef this union the data type, such as Integer, Boolean, Set, or the Undef
data type, plays a role. The details of the algorithm for combining data type, plays a role. The details of the algorithm for combining
permissions is described in Section 10. The resulting union permissions is described in Section 10. The resulting union
effectively represents a "mask" - it defines what information is effectively represents a "mask" - it defines what information is
exposed to the WR. This mask is applied to the actual location or exposed to the WR. This mask is applied to the actual location or
presence data for the PT, and the data which is permitted by the mask presence data for the PT, and the data which is permitted by the mask
is shown to the WR. If the WR request a subset of information only is shown to the WR. If the WR request a subset of information only
(such as city-level civil location data only, instead of the full (such as city-level civil location data only, instead of the full
civil location information), the information delivered to the WR MUST civil location information), the information delivered to the WR MUST
skipping to change at page 13, line 26 skipping to change at page 13, line 26
from existing optimized indexing, access control, scaling and from existing optimized indexing, access control, scaling and
integrity constraint mechanisms. Smaller-scale implementations may integrity constraint mechanisms. Smaller-scale implementations may
well choose different implementations, e.g., a simple traversal of well choose different implementations, e.g., a simple traversal of
the set of rules. the set of rules.
6.1. Identification of Rules 6.1. Identification of Rules
Each rule is equipped with a parameter that identifies the rule. Each rule is equipped with a parameter that identifies the rule.
This rule identifier is an opaque token chosen by the RM. A RM MUST This rule identifier is an opaque token chosen by the RM. A RM MUST
NOT use the same identifier for two rules that are available to the NOT use the same identifier for two rules that are available to the
PS at the same time for a given PT. PS at the same time for a given PT. If more than one RM modifies the
same rule set then it needs to be ensured that a unique identifier is
chosen for each rule. A RM can accomplish this goal by retrieving
the already specified ruleset and to choose a new identifier for a
rule that is different from the values used by the rules in the rule
set.
6.2. Extensions 6.2. Extensions
The authorization policy framework defined in this document is meant The policy framework defined in this document is meant to be
to be extensible towards specific application domains. Such an extensible towards specific application domains. Such an extension
extension is accomplished by defining conditions, actions and is accomplished by defining conditions, actions and transformations
transformations that are specific to the desired application domain. that are specific to the desired application domain. Each extension
Each extension MUST define its own namespace. MUST define its own namespace.
Extensions cannot change the schema defined in this document, and Extensions cannot change the schema defined in this document, and
this schema is not expected to change excepting a revision to this this schema is not expected to change excepting a revision to this
specification, and that no versioning procedures for this schema or specification, and that no versioning procedures for this schema or
namespace are therfore provided. namespace are therefore provided.
7. Conditions 7. Conditions
The access to data items needs to be matched with the rule set stored The access to data items needs to be matched with the rule set stored
at the PS. Each instance of a request has different attributes at the PS. Each instance of a request has different attributes
(e.g., the identity of the requestor) which are used for (e.g., the identity of the requestor) that are used for
authorization. A rule in a rule set might have a number of authorization. A rule in a rule set might have a number of
conditions which need to be met before executing the remaining parts conditions that need to be met before executing the remaining parts
of a rule (i.e., actions and transformations). Details about rule of a rule (i.e., actions and transformations). Details about rule
matching are described in Section 10. This document specifies only a matching are described in Section 10. This document specifies only a
few conditions (namely identity, sphere, and validity). Other few conditions (i.e., identity, sphere, and validity). Further
conditions are left for extensions of this document. condition elements can be added via extensions to this document.
7.1. Identity Condition 7.1. Identity Condition
7.1.1. Overview 7.1.1. Overview
The identity condition restricts matching of a rule either to a The identity condition restricts matching of a rule either to a
single entity or a group of entitites. Only authenticated entities single entity or a group of entities. Only authenticated entities
can be matched; acceptable means of authentication are defined in can be matched; acceptable means of authentication are defined in
protocol-specific documents. If the <identity> element is absent, or protocol-specific documents. If the <identity> element is absent, or
it is present but is empty (meaning that there are no child it is present but is empty (meaning that there are no child
elements), identities are not considered, and thus, other conditions elements), identities are not considered, and thus, other conditions
in the rule apply to any user, authenticated or not. in the rule apply to any user, authenticated or not.
The <identity> condition is considered TRUE if any of its child The <identity> condition is considered TRUE if any of its child
elements (e.g., the <one/> and the <many/> elements defined in this elements (e.g., the <one/> and the <many/> elements defined in this
document) evaluate to TRUE, i.e., the results of the individual child document) evaluate to TRUE, i.e., the results of the individual child
element are combined using a logical OR. element are combined using a logical OR.
skipping to change at page 16, line 18 skipping to change at page 16, line 18
the comparison succeeds and the remaining steps are skipped. the comparison succeeds and the remaining steps are skipped.
2. Translate percent-encoding for either string and repeat (1). 2. Translate percent-encoding for either string and repeat (1).
3. Convert both domain strings using the toASCII operation described 3. Convert both domain strings using the toASCII operation described
in RFC 3490 [2]. (Naturally, if one of the strings already in RFC 3490 [2]. (Naturally, if one of the strings already
begins with the ACE prefix xn--, the conversion operation has begins with the ACE prefix xn--, the conversion operation has
already been performed.) already been performed.)
4. Compare the two domain strings for ASCII equality, for each 4. Compare the two domain strings for ASCII equality, for each
label. label. If the string comparison for each label indicates
equality, the comparison succeeds. Otherwise, the domains are
not equal.
If the conversion fails in step (3), the domains are not equal. If the conversion fails in step (3), the domains are not equal.
7.1.3.1. Matching Any Authenticated Identity 7.1.3.1. Matching Any Authenticated Identity
The <many/> element without any child elements or attributes matches The <many/> element without any child elements or attributes matches
any authenticated user. any authenticated user.
The following example shows such a rule that matches any The following example shows a rule that matches any authenticated
authenticated user: user:
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<ruleset xmlns="urn:ietf:params:xml:ns:common-policy"> <ruleset xmlns="urn:ietf:params:xml:ns:common-policy">
<rule id="f3g44r5"> <rule id="f3g44r5">
<conditions> <conditions>
<identity> <identity>
<many/> <many/>
</identity> </identity>
</conditions> </conditions>
<actions/> <actions/>
<transformations/> <transformations/>
</rule> </rule>
</ruleset> </ruleset>
The following rule, in comparison, would match any user, 7.1.3.2. Matching Any User, Authenticated and Unauthenticated
authenticated and unauthenticated:
If the <identity> element is used without child elements then it
matches any user, authenticated and unauthenticated. The same is
true for a rule where the <identity> element is omitted.
The following example shows two rules that match any user,
authenticated and unauthenticated.
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<ruleset xmlns="urn:ietf:params:xml:ns:common-policy"> <ruleset xmlns="urn:ietf:params:xml:ns:common-policy">
<rule id="f3g44r5"> <rule id="f3g44r5">
<conditions> <conditions>
<identity/> <identity/>
</conditions> </conditions>
<actions/> <actions/>
<transformations/> <transformations/>
</rule> </rule>
<rule id="f3g44r57">
<conditions/>
<actions/>
<transformations/>
</rule>
</ruleset> </ruleset>
7.1.3.2. Matching Any Authenticated Identity Excepting Enumerated 7.1.3.3. Matching Any Authenticated Identity Excepting Enumerated
Domains/Identities Domains/Identities
The <many> element enclosing one or more <except domain="..."/> The <many> element enclosing one or more <except domain="..."/>
elements matches any user from any domain except those enumerated. elements matches any user from any domain except those enumerated.
The <except id="..."/> element excludes particular users. The The <except id="..."/> element excludes particular users. The
semantic of the 'id' attribute of the <except> element is described semantic of the 'id' attribute of the <except> element is described
in Section 7.2. The results of the child elements of the <many> in Section 7.2. The results of the child elements of the <many>
element are combined using a logical OR. element are combined using a logical OR.
An example is shown below: An example is shown below:
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<ruleset xmlns="urn:ietf:params:xml:ns:common-policy"> <ruleset xmlns="urn:ietf:params:xml:ns:common-policy">
<rule id="f3g44r1"> <rule id="f3g44r1">
<conditions> <conditions>
<sphere value="work"/>
<identity> <identity>
<many> <many>
<except domain="example.com"/> <except domain="example.com"/>
<except domain="example.org"/> <except domain="example.org"/>
<except id="sip:alice@bad.example.net"/> <except id="sip:alice@bad.example.net"/>
<except id="sip:bob@good.example.net"/> <except id="sip:bob@good.example.net"/>
<except id="tel:+1-212-555-1234" /> <except id="tel:+1-212-555-1234" />
<except id="sip:alice@example.com"/> <except id="sip:alice@example.com"/>
</many> </many>
</identity> </identity>
<validity>
<from>2003-12-24T17:00:00+01:00</from>
<until>2003-12-24T19:00:00+01:00</until>
</validity>
</conditions> </conditions>
<actions/> <actions/>
<transformations/> <transformations/>
</rule> </rule>
</ruleset> </ruleset>
This example matches all users except any user in example.com, or any This example matches all users except any user in example.com, or any
user in example.org or the particular users alice@bad.example.net, user in example.org or the particular users alice@bad.example.net,
bob@good.example.net and the user with the telephone number bob@good.example.net and the user with the telephone number
'tel:+1-212-555-1234'. The last 'except' element is redundant since 'tel:+1-212-555-1234'. The last 'except' element is redundant since
alice@example.com is already excluded through the first line. alice@example.com is already excluded through the following statement
<except domain="example.com"/> in the example.
7.1.3.3. Matching Any Authenticated Identity Within a Domain Excepting 7.1.3.4. Matching Any Authenticated Identity Within a Domain Excepting
Enumerated Identities Enumerated Identities
The <many> element with a 'domain' attribute and zero or more <except The <many> element with a 'domain' attribute and zero or more <except
id="..."/> elements matches any authenticated user from the indicated id="..."/> elements matches any authenticated user from the indicated
domain except those explicitly enumerated. The semantic of the 'id' domain except those explicitly enumerated. The semantic of the 'id'
attribute of the <except> element is described in Section 7.2. attribute of the <except> element is described in Section 7.2.
It is nonsensical to have domains in the 'id' attribute that do not It is nonsensical to have domains in the 'id' attribute that do not
match the value of the 'domain' attribute in the enclosing <many> match the value of the 'domain' attribute in the enclosing <many>
element. element.
skipping to change at page 19, line 36 skipping to change at page 19, line 36
7.2. Single Entity 7.2. Single Entity
The 'id' attribute used in the <one> and in the <except> element The 'id' attribute used in the <one> and in the <except> element
refers to a single entity. In the subsequent text we use the term refers to a single entity. In the subsequent text we use the term
'single-user' entity as a placeholder for the <one> and the <except> 'single-user' entity as a placeholder for the <one> and the <except>
element. The <except> element fulfills the purpose of excluding element. The <except> element fulfills the purpose of excluding
elements from the solution set. elements from the solution set.
A single-user entity matches the authenticated identity (as contained A single-user entity matches the authenticated identity (as contained
in the 'id' attribute) of exactly one entity or user. If there is a in the 'id' attribute) of exactly one entity or user. If there is a
match, the single-user entity is considered TRUE. The single- user match, the single-user entity is considered TRUE. The single-user
entity MUST NOT contain a 'domain' attribute. entity MUST NOT contain a 'domain' attribute.
The 'id' attribute contains an identity that MUST first be expressed The 'id' attribute contains an identity that MUST be expressed as
as a URI. Applications using this framework must describe how the URI. Applications using this framework must describe how the
identities they are using can be expressed as a URIs. identities they are using can be expressed as a URIs.
7.3. Sphere 7.3. Sphere
The <sphere> element belongs to the group of condition elements. It The <sphere> element belongs to the group of condition elements. It
can be used to indicate a state (e.g., 'work', 'home', 'meeting', can be used to indicate a state (e.g., 'work', 'home', 'meeting',
'travel') the PT is currently in. A sphere condition matches only if 'travel') the PT is currently in. A sphere condition matches only if
the PT is currently in the state indicated. The state may be the PT is currently in the state indicated. The state may be
conveyed by manual configuration or by some protocol. For example, conveyed by manual configuration or by some protocol. For example,
RPID [9] provides the ability to inform the PS of its current sphere. RPID [11] provides the ability to inform the PS of its current
The application domain needs to describe in more detail how the sphere. The application domain needs to describe in more detail how
sphere state is determined. Switching from one sphere to another the sphere state is determined. Switching from one sphere to another
causes a switch between different modes of visibility. As a result causes a switch between different modes of visibility. As a result
different subsets of rules might be applicable. different subsets of rules might be applicable.
The content of the 'value' attribute of the <sphere> element MAY The content of the 'value' attribute of the <sphere> element MAY
contain more than one token. The individual tokens MUST be separated contain more than one token. The individual tokens MUST be separated
by a blank character. A logical OR is used for the matching the by a blank character. A logical OR is used for the matching the
tokens against the sphere settings of the PT. As an example, if the tokens against the sphere settings of the PT. As an example, if the
the content of the 'value' attribute in the sphere attribute contains content of the 'value' attribute in the sphere attribute contains two
two tokens 'work' and 'home' then this part of the rule matches if tokens 'work' and 'home' then this part of the rule matches if the
the sphere for a particular PT is either 'work' OR 'home'. To sphere for a particular PT is either 'work' or 'home'. To compare
compare the content of the 'value' attribute in the <sphere> element the content of the 'value' attribute in the <sphere> element with the
with the stored state information about the PT's sphere setting a stored state information about the PT's sphere setting a case
case insensitive string comparison MUST be used for each individual insensitive string comparison MUST be used for each individual token.
token. There is no registry for these values nor a language specific There is no registry for these values nor a language specific
indication of the sphere content. As such, the tokens are treated as indication of the sphere content. As such, the tokens are treated as
opaque strings. opaque strings.
The rule example below illustrates that the rule with the entity
andrew@example.com matches if the sphere is been set to 'work'. In
the second rule with the entity allison@example.com matches if the
sphere is set to 'home'. The third rule also matches if the sphere
is set to 'home' since the value in the sphere element also contains
the token 'home'.
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<ruleset xmlns="urn:ietf:params:xml:ns:common-policy"> <ruleset xmlns="urn:ietf:params:xml:ns:common-policy">
<rule id="f3g44r2"> <rule id="f3g44r2">
<conditions> <conditions>
<sphere value="work"/> <sphere value="work"/>
<identity> <identity>
<one id="sip:andrew@example.com"/> <one id="sip:andrew@example.com"/>
</identity> </identity>
</conditions> </conditions>
skipping to change at page 21, line 42 skipping to change at page 21, line 42
<identity> <identity>
<one id="sip:john@doe.example.com"/> <one id="sip:john@doe.example.com"/>
</identity> </identity>
<sphere value="home work"/> <sphere value="home work"/>
</conditions> </conditions>
<actions/> <actions/>
<transformations/> <transformations/>
</rule> </rule>
</ruleset> </ruleset>
The rule example above illustrates that the rule with the entity
andrew@example.com matches if the sphere is been set to 'work'. In
the second rule with the entity allison@example.com matches if the
sphere is set to 'home'. The third rule also matches since the the
value in the sphere element also contains the token 'home'.
7.4. Validity 7.4. Validity
The <validity> element is the third condition element specified in The <validity> element is the third condition element specified in
this document. It expresses the rule validity period by two this document. It expresses the rule validity period by two
attributes, a starting and a ending time. The validity condition is attributes, a starting and a ending time. The validity condition is
TRUE if the current time is greater than or equal to at least one TRUE if the current time is greater than or equal to at least one
<from> child, but less than the <until> child after it. This <from> child, but less than the <until> child after it. This
represents a logical OR operation across each <from> and <until> represents a logical OR operation across each <from> and <until>
pair. Times are expressed in XML dateTime format. A rule maker pair. Times are expressed in XML dateTime format.
might not have always access to the PS to invalidate some rules which
grant permissions. Hence this mechanism allows to invalidate granted A rule maker might not always have access to the PS to invalidate
rules. Hence, this mechanism allows to invalidate granted
permissions automatically without further interaction between the permissions automatically without further interaction between the
rule maker and the PS. The PS does not remove the rules instead the rule maker and the PS. The PS does not remove the rules instead the
rule maker has to clean them up. rule maker has to clean them up.
An example of a rule fragment is shown below: An example of a rule fragment is shown below:
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<ruleset xmlns="urn:ietf:params:xml:ns:common-policy"> <ruleset xmlns="urn:ietf:params:xml:ns:common-policy">
<rule id="f3g44r3"> <rule id="f3g44r3">
skipping to change at page 23, line 17 skipping to change at page 23, line 17
While conditions are the 'if'-part of rules, actions and While conditions are the 'if'-part of rules, actions and
transformations build the 'then'-part of them. The actions and transformations build the 'then'-part of them. The actions and
transformations parts of a rule determine which operations the PS transformations parts of a rule determine which operations the PS
MUST execute after having received from a WR a data access request MUST execute after having received from a WR a data access request
that matches all conditions of this rule. Actions and that matches all conditions of this rule. Actions and
transformations only permit certain operations; there is no 'deny' transformations only permit certain operations; there is no 'deny'
functionality. Transformations exclusively specify PS-side functionality. Transformations exclusively specify PS-side
operations that lead to a modification of the data items requested by operations that lead to a modification of the data items requested by
the WR. Regarding location data items, for instance, a the WR. Regarding location data items, for instance, a
transformation could force the PS to lower the precision of the transformation could force the PS to lower the precision of the
location information which is returned to the WR. location information that is returned to the WR.
Actions, on the other hand, specify all remaining types of operations Actions, on the other hand, specify all remaining types of operations
the PS is obliged to execute, i.e., all operations that are not of the PS is obliged to execute, i.e., all operations that are not of
transformation type. Actions are defined by application specific transformation type. Actions are defined by application specific
usages of this framework. The reader is referred to the usages of this framework. The reader is referred to the
corresponding extensions to see examples of such elements. corresponding extensions to see examples of such elements.
9. Transformations 9. Transformations
Two sub-parts follow the conditions part of a rule: transformations Two sub-parts follow the conditions part of a rule: transformations
skipping to change at page 25, line 7 skipping to change at page 25, line 7
operations that the PS MUST execute and that modify the result which operations that the PS MUST execute and that modify the result which
is returned to the WR. This functionality is particularly helpful in is returned to the WR. This functionality is particularly helpful in
reducing the granularity of information provided to the WR, as for reducing the granularity of information provided to the WR, as for
example required for location privacy. Transformations are defined example required for location privacy. Transformations are defined
by application specific usages of this framework. by application specific usages of this framework.
A simple transformation example is provided in Section 10. A simple transformation example is provided in Section 10.
10. Procedure for Combining Permissions 10. Procedure for Combining Permissions
10.1. Introduction
This section describes the mechanism to evaluate the final result of This section describes the mechanism to evaluate the final result of
a rule evaluation. The result is reflected in the action and a rule evaluation. The result is reflected in the action and
transformation part of a rule. This procedure is sometimes referred transformation part of a rule. This procedure is sometimes referred
as conflict resolution. as conflict resolution.
We use the following terminology (which in parts has already been To simplify the description of the algorithm we introduce the term
introduced in previous sections): The term 'permission' stands for an 'item' to refer to child elements and attributes of these child
action or a transformation. The notion 'attribute' terms a elements that apear in the condition, action and transformation part
condition, an action, or a transformation. An attribute has a name, of a rule. An item has a name and a data type. A value may be
and a certain data type. A value may be assigned to an attribute or assigned to an item or it may be undefined, in case it does not have
it may be undefined, in case it does not have a value associated with a value associated with the item. The values of a particular item
the attribute. For example, the name of the <sphere> attribute have the same data type. For example, the name of the item <sphere>
discussed in Section 7 is 'sphere', its data type is 'string', and discussed in Section 7 is 'sphere', its data type is 'string', and
its value may be set to 'home'. To evaluate a condition means to its value may be set to 'home'. To evaluate a condition means to
associate either TRUE or FALSE to the condition. Please note that associate either TRUE or FALSE to the condition.
the <identity> element is a condition whereas the <id> element is a
parameter of that condition. A rule matches if all conditions
contained in the conditions part of a rule evaluate to TRUE.
When the PS receives a request for access to privacy-sensitive data When the PS receives a request for access to privacy-sensitive data
then it needs to be matched against a rule set. The conditions part then it needs to be matched against a rule set. The conditions part
of each individual rule is evaluated and as a result one or more of each individual rule is evaluated and as a result one or more
rules might match. If only a single rule matches then the result is rules might match. If only a single rule matches then the result is
determined by executing the actions and the transformations part determined by executing the actions and the transformations part
following the conditions part of a rule. However, it can also be the following the conditions part of a rule. However, it can also be the
case that two or more matching rules contain a permission of the same case that two or more matching rules contain a permission of the same
name (e.g., two rules contain a permission named 'precision of name (e.g., two rules contain a permission named 'precision of
geospatial location information'), but do not specify the same value geospatial location information'), but do not specify the same value
for that permission (e.g., the two rule might specify values of '10 for that permission (e.g., the two rule might specify values of '10
km' and '200 km', respectively, for the permission named 'precision km' and '200 km', respectively, for the permission named 'precision
of geospatial location information'). This section describes the of geospatial location information'). This section describes the
procedure for combining permissions in such cases. procedure for combining permissions in such cases.
10.2. Algorithm The combining operation will result in the largest value for an
integer type, the OR operation for a boolean type, and union for a
set.
The combining rules are simple and depend on the data types of the As such, applications should define values such that, for integers,
values of permissions: Let P be a policy. Let M be the subset of P the lowest value corresponds to the most privacy, for booleans, false
consisting of rules r in P that match with respect to a given corresponds to the most privacy, and for sets, the empty set
request. Let n be a name of a permission contained in a rule r in M, corresponds to the most privacy.
and let M(n) be the subset of M consisting of rules r in M that have
a permission of name n. For each rule r in M(n), let v(r,n) and 10.1. Algorithm
d(r,n) be the value and the data type, respectively, of the attribute
of r with name n. Finally, let V(n) be the combined value of all the The algorithm for combining permissions is simple and depends on the
permissions values v(r,n), r in M(n). The combining rules that lead data types of the values of items: Let P be a rule set. Let M be the
to the resulting value V(n) are the following: subset of P consisting of rules r in P that match with respect to a
given request. Let n be a name of an item contained in a rule r in
M, and let M(n) be the subset of M consisting of rules r in M that
have a item of name n. For each rule r in M(n), let v(r,n) and
d(r,n) be the value and the data type, respectively, of the item of r
with name n. Finally, let V(n) be the combined value of all the
values v(r,n), r in M(n). The algorithm that leads to the resulting
value V(n) is the following:
CR 1: If d(r,n)=Boolean for all r in M(n), then V(n) is given as CR 1: If d(r,n)=Boolean for all r in M(n), then V(n) is given as
follows: If there is a r in M(n) with v(r,n)=TRUE, then V(n)=TRUE. follows: If there is a r in M(n) with v(r,n)=TRUE, then V(n)=TRUE.
Otherwise, V(n)=FALSE. Otherwise, V(n)=FALSE.
CR 2: If d(r,n)=Integer for all r in M(n), then V(n) is given as CR 2: If d(r,n)=Integer for all r in M(n), then V(n) is given as
follows: If v(r,n)=undefined for all r in M(n), then V(n) is not follows: If v(r,n)=undefined for all r in M(n), then V(n) is not
specified by this specification. Otherwise, V(n)=max{v(r,n) | r specified by this specification. Otherwise, V(n)=max{v(r,n) | r
in M(n)}. in M(n)}.
CR 3: If d(r,n)=Set for all r in M(n), then V(n) is given as CR 3: If d(r,n)=Set for all r in M(n), then V(n) is given as
follows: V(n)=union of all v(r,n), the union to be computed over all follows: V(n)=union of all v(r,n), the union to be computed over all
r in M(n) with v(r,n)!=undefined. r in M(n) with v(r,n)!=undefined.
The combining operation will result in the largest value for an 10.2. Example
Integral type, the OR operation for boolean, and union for set.
As a result, applications should define values such that, for
integers, the lowest value corresponds to the most privacy, for
booleans, false corresponds to the most privacy, and for sets, the
empty set corresponds to the most privacy.
10.3. Example
In the following example we illustrate the process of combining In the following example we illustrate the process of the combining
permissions. We will consider three conditions for our purpose, permissions algorithm. We will consider three items in the
namely those of name identity, sphere, and validity. For editorial conditions part in our example, namely identity, sphere, and
reasons the rule set in this example is represented in a table. validity. For editorial reasons the rule set in this example is
Furthermore, the domain part of the identity of the WR is omitted. represented in a table. Furthermore, the domain part of the identity
For actions we use two permissions with names X and Y. The values of of the WR is omitted. For actions we use two items in the action
X and Y are of data types Boolean and Integer, respectively. part of the rule with names X and Y. The values of X and Y are of
Permission X might, for example, represent the <sub-handling> action. data types boolean and integer, respectively. For transformations we
For transformations we use the attribute with the name Z whose value use the item with the name Z whose value can be set either to '+'(or
can be set either to '+'(or 1), 'o' (or 2) or '-' (or 3). Permission 1), 'o' (or 2) or '-' (or 3). Item Z allows us to show the
Z allows us to show the granularity reduction whereby a value of '+' granularity reduction whereby a value of '+' shows the corresponding
shows the corresponding information unrestricted and '-' shows information unrestricted and '-' shows nothing. This item might be
nothing. This permission might be related to location information or related to location information or other presence attributes like
other presence attributes like mood. Internally we use the data type mood. Internally we use the data type integer for computing the
Integer for computing the permission of this attribute. permission of this item.
Conditions Actions/Transformations Conditions Actions/Transformations
+---------------------------------+---------------------+ +---------------------------------+----------------------+
| Id WR-ID sphere from until | X Y Z | | Id WR-ID sphere from until | X Y Z |
+---------------------------------+---------------------+ +---------------------------------+----------------------+
| 1 bob home A1 A2 | TRUE 10 o | | 1 bob home A1 A2 | TRUE 10 o |
| 2 alice work A1 A2 | FALSE 5 + | | 2 alice work A1 A2 | FALSE 5 + |
| 3 bob work A1 A2 | TRUE 3 - | | 3 bob work A1 A2 | TRUE 3 - |
| 4 tom work A1 A2 | TRUE 5 + | | 4 tom work A1 A2 | TRUE 5 + |
| 5 bob work A1 A3 | undef 12 o | | 5 bob work A1 A3 | undef 12 o |
| 6 bob work B1 B2 | FALSE 10 - | | 6 bob work B1 B2 | FALSE 10 - |
+---------------------------------+---------------------+ +---------------------------------+----------------------+
Again for editorial reasons, we use the following abbreviations for For editorial reasons we use the items 'from' and 'until' to refer to
the two <validity> attributes 'from' and 'until': validity and we use the following abbreviations for the values:
A1=2003-12-24T17:00:00+01:00 A1=2003-12-24T17:00:00+01:00
A2=2003-12-24T21:00:00+01:00 A2=2003-12-24T21:00:00+01:00
A3=2003-12-24T23:30:00+01:00 A3=2003-12-24T23:30:00+01:00
B1=2003-12-22T17:00:00+01:00 B1=2003-12-22T17:00:00+01:00
B2=2003-12-23T17:00:00+01:00 B2=2003-12-23T17:00:00+01:00
Note that B1 < B2 < A1 < A2 < A3. Note that B1 < B2 < A1 < A2 < A3.
The entity 'bob' acts as a WR and requests data items. The policy P The entity 'bob' acts as a WR. The policy P consists of the six
consists of the six rules shown in the table and identified by the rules shown in the table and identified by the values 1 to 6 in the
values 1 to 6 in the 'Id' column. The PS receives the query at 2003- 'Id' column. The PS receives the query at 2003-12-24T17:15:00+01:00
12-24T17:15:00+01:00 which falls between A1 and A2. The value of the which falls between A1 and A2. The value of the item 'sphere'
attribute with name 'sphere' indicating the state the PT is currently indicates that the sphere of PT is currently set to 'work'.
in is set to 'work'.
Rule 1 does not match since the sphere condition does not match. Rule 1 does not match since the sphere condition does not match.
Rule 2 does not match as the identity of the WR (here 'alice') does Rule 2 does not match as the identity of the WR (here 'alice') does
not equal 'bob'. Rule 3 matches since all conditions evaluate to not equal 'bob'. Rule 3 matches since all conditions evaluate to
TRUE. Rule 4 does not match as the identity of the WR (here 'tom') TRUE. Rule 4 does not match as the identity of the WR (here 'tom')
does not equal 'bob'. Rule 5 matches. Rule 6 does not match since does not equal 'bob'. Rule 5 matches. Rule 6 does not match since
the rule is not valid anymore. Therefore, the set M of matching the rule is not valid anymore. Therefore, the set M of matching
rules consists of the rules 3 and 5. These two rules are used to rules consists of the rules 3 and 5. These two rules are used to
compute the combined permission V(X), V(Y), and V(Z) for each of the compute the combined permission V(X), V(Y), and V(Z) for each of the
permissions X, Y, and Z: permissions X, Y, and Z:
Actions/Transformations Actions/Transformations
+-----+-----------------------+ +-----+-----------------------+
| Id | X Y Z | | Id | X Y Z |
+-----+-----------------------+ +-----+-----------------------+
| 3 | TRUE 3 - | | 3 | TRUE 3 - |
| 5 | undef 12 o | | 5 | undef 12 o |
+-----+-----------------------+ +-----+-----------------------+
The results of the permission combining algorithm is shown below. The results of the permission combining algorithm is shown below.
The combined value V(X) regarding the permission with name X equals The combined value V(X) regarding the permission with name X equals
TRUE according to the first combining rule listed above. The maximum TRUE according to the first combining rule listed above. The maximum
skipping to change at page 29, line 7 skipping to change at page 29, line 7
Actions/Transformations Actions/Transformations
+-----+-----------------------+ +-----+-----------------------+
| Id | X Y Z | | Id | X Y Z |
+-----+-----------------------+ +-----+-----------------------+
| 5 | TRUE 12 - | | 5 | TRUE 12 - |
+-----+-----------------------+ +-----+-----------------------+
11. Meta Policies 11. Meta Policies
Meta policies authorize a rulemaker to insert, update or delete a Meta policies authorize a rule maker to insert, update or delete a
particular rule or an entire rule set. Some authorization policies particular rule or an entire rule set. Some authorization policies
are required to prevent unauthorized modification of rule sets. Meta are required to prevent unauthorized modification of rule sets. Meta
policies are outside the scope of this document. policies are outside the scope of this document.
A simple implementation could restrict access to the rule set only to A simple implementation could restrict access to the rule set only to
the PT but more sophisticated mechanisms could be useful. As an the PT but more sophisticated mechanisms could be useful. As an
example of such policies one could think of parents configuring the example of such policies one could think of parents configuring the
policies for their children. policies for their children.
12. Example 12. Example
skipping to change at page 34, line 7 skipping to change at page 34, line 7
<xs:any namespace="##other" <xs:any namespace="##other"
processContents="lax" minOccurs="0" maxOccurs="unbounded"/> processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence> </xs:sequence>
</xs:restriction> </xs:restriction>
</xs:complexContent> </xs:complexContent>
</xs:complexType> </xs:complexType>
</xs:schema> </xs:schema>
14. Security Considerations 14. Security Considerations
This document describes a framework for authorization policy rules. This document describes a framework for policies. This framework is
This framework is intended to be enhanced elsewhere towards intended to be enhanced elsewhere towards application domain specific
application domain specific data. Security considerations are to a data. Security considerations are to a great extent application data
great extent application data dependent, and therefore need to be dependent, and therefore need to be covered by documents that extend
covered by documents that extend the framework defined in this the framework defined in this specification. RFC 3693 [9] and RFC
specification. However, new action and transformation permissions 3694 [3] are good sources to consider for the type of analysis
along with their allowed values must be defined in a way so that the required by such documents and applications.
usage of the permissions combining rules of Section 10 does not lower
the level of privacy protection. See Section 10 for more details on Extensions to the action and transformation elements must be defined
this privacy issue. in a way so that the usage of the permissions combining rules of
Section 10 does not lower the level of privacy protection. This is
particularly important when defining the semantic of the a more
detailed description of the values for the defined attributes and
elements. See Section 10 for more details on this privacy aspect.
15. IANA Considerations 15. IANA Considerations
This section registers a new XML namespace, a new XML schema and a This section registers a new XML namespace, a new XML schema and a
new MIME-type. This section registers a new XML namespace per the new MIME-type. This section registers a new XML namespace per the
procedures in [3]. procedures in [4].
15.1. Common Policy Namespace Registration 15.1. Common Policy Namespace Registration
URI: urn:ietf:params:xml:ns:common-policy URI: urn:ietf:params:xml:ns:common-policy
Registrant Contact: IETF Geopriv Working Group, Henning Schulzrinne Registrant Contact: IETF Geopriv Working Group, Henning Schulzrinne
(hgs+geopriv@cs.columbia.edu). (hgs+geopriv@cs.columbia.edu).
XML: XML:
skipping to change at page 35, line 44 skipping to change at page 35, line 44
[NOTE TO IANA/RFC-EDITOR: [NOTE TO IANA/RFC-EDITOR:
Please replace XXXX with the RFC number of this Please replace XXXX with the RFC number of this
specification.]</a>.</p> specification.]</a>.</p>
</body> </body>
</html> </html>
END END
15.2. Content-type registration for 'application/auth-policy+xml' 15.2. Content-type registration for 'application/auth-policy+xml'
This specification requests the registration of a new MIME type This specification requests the registration of a new MIME type
according to the procedures of RFC 2048 [4] and guidelines in RFC according to the procedures of RFC 4288 [5] and guidelines in RFC
3023 [5]. 3023 [6].
MIME media type name: application MIME media type name: application
MIME subtype name: auth-policy+xml MIME subtype name: auth-policy+xml
Mandatory parameters: none Mandatory parameters: none
Optional parameters: charset Optional parameters: charset
Indicates the character encoding of enclosed XML. Indicates the character encoding of enclosed XML.
Encoding considerations: Encoding considerations:
Uses XML, which can employ 8-bit characters, depending on the Uses XML, which can employ 8-bit characters, depending on the
character encoding used. See RFC 3023 [5], Section 3.2. character encoding used. See RFC 3023 [6], Section 3.2.
Security considerations: Security considerations:
This content type is designed to carry authorization policies. This content type is designed to carry authorization policies.
Appropriate precautions should be adopted to limit disclosure of Appropriate precautions should be adopted to limit disclosure of
this information. Please refer to Section 14 of RFCXXXX [NOTE TO this information. Please refer to Section 14 of RFCXXXX [NOTE TO
IANA/RFC-EDITOR: Please replace XXXX with the RFC number of this IANA/RFC-EDITOR: Please replace XXXX with the RFC number of this
specification.] and to the security considerations described in specification.] and to the security considerations described in
Section 10 of RFC 3023 [5] for more information. Section 10 of RFC 3023 [6] for more information.
Interoperability considerations: None Interoperability considerations: None
Published specification: RFCXXXX [NOTE TO IANA/RFC-EDITOR: Please Published specification: RFCXXXX [NOTE TO IANA/RFC-EDITOR: Please
replace XXXX with the RFC number of this specification.] this replace XXXX with the RFC number of this specification.] this
document document
Applications which use this media type: Applications which use this media type:
Presence- and location-based systems Presence- and location-based systems
skipping to change at page 38, line 15 skipping to change at page 38, line 15
16. References 16. References
16.1. Normative References 16.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", March 1997. Levels", March 1997.
[2] Faltstrom, P., Hoffman, P., and A. Costello, "Internationalizing [2] Faltstrom, P., Hoffman, P., and A. Costello, "Internationalizing
Domain Names in Applications (IDNA)", RFC 3490, March 2003. Domain Names in Applications (IDNA)", RFC 3490, March 2003.
[3] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, [3] Danley, M., Mulligan, D., Morris, J., and J. Peterson, "Threat
Analysis of the Geopriv Protocol", RFC 3694, February 2004.
[4] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004. January 2004.
[4] Freed, N., Klensin, J., and J. Postel, "Multipurpose Internet [5] Freed, N. and J. Klensin, "Media Type Specifications and
Mail Extensions (MIME) Part Four: Registration Procedures", Registration Procedures", BCP 13, RFC 4288, December 2005.
BCP 13, RFC 2048, November 1996.
[5] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", [6] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types",
RFC 3023, January 2001. RFC 3023, January 2001.
16.2. Informative References 16.2. Informative References
[6] Rosenberg, J., "Presence Authorization Rules", [7] Rosenberg, J., "Presence Authorization Rules",
draft-ietf-simple-presence-rules-05 (work in progress), draft-ietf-simple-presence-rules-06 (work in progress),
March 2006. May 2006.
[7] Schulzrinne, H., "A Document Format for Expressing Privacy [8] Schulzrinne, H., "A Document Format for Expressing Privacy
Preferences for Location Information", Preferences for Location Information",
draft-ietf-geopriv-policy-08 (work in progress), February 2006. draft-ietf-geopriv-policy-08 (work in progress), February 2006.
[8] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J. [9] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J.
Polk, "Geopriv Requirements", RFC 3693, February 2004. Polk, "Geopriv Requirements", RFC 3693, February 2004.
[9] Schulzrinne, H., "RPID: Rich Presence Extensions to the Presence [10] Day, M., Rosenberg, J., and H. Sugano, "A Model for Presence
Information Data Format (PIDF)", draft-ietf-simple-rpid-10 and Instant Messaging", RFC 2778, February 2000.
(work in progress), December 2005.
[11] Schulzrinne, H., "RPID: Rich Presence Extensions to the
Presence Information Data Format (PIDF)",
draft-ietf-simple-rpid-10 (work in progress), December 2005.
Appendix A. Contributors Appendix A. Contributors
We would like to thank Christian Guenther for his help with initial We would like to thank Christian Guenther for his help with initial
versions of this document. versions of this document.
Appendix B. Acknowledgments Appendix B. Acknowledgments
This document is partially based on the discussions within the IETF This document is partially based on the discussions within the IETF
GEOPRIV working group. Discussions at the Geopriv Interim Meeting GEOPRIV working group. Discussions at the Geopriv Interim Meeting
skipping to change at page 40, line 26 skipping to change at page 40, line 26
Peterson <jon.peterson@neustar.biz> for discussing a number of Peterson <jon.peterson@neustar.biz> for discussing a number of
details with us. They helped us to improve the quality of this details with us. They helped us to improve the quality of this
document. Allison, Ted and Andrew also helped us to make good document. Allison, Ted and Andrew also helped us to make good
progress with the internationalization support of the identifier/ progress with the internationalization support of the identifier/
domain attributes. domain attributes.
Furthermore, we would like to thank the IETF SIMPLE working group for Furthermore, we would like to thank the IETF SIMPLE working group for
their discussions of J. Rosenberg's draft on presence authorization their discussions of J. Rosenberg's draft on presence authorization
policies. We would also like to thank Stefan Berg, Murugaraj policies. We would also like to thank Stefan Berg, Murugaraj
Shanmugam, Christian Schmidt, Martin Thomson, Markus Isomaki, Aki Shanmugam, Christian Schmidt, Martin Thomson, Markus Isomaki, Aki
Niemi, Eva Maria Leppanen and Mark Baker for their comments. Martin Niemi, Eva Maria Leppanen, Mark Baker, Tim Polk and Brian Carpenter
Thomson helped us with the XML schema. Mark Baker provided a review for their comments. Martin Thomson helped us with the XML schema.
of the media type. Mark Baker provided a review of the media type. Scott Brim provided
a review on behalf of the General Area Review Team.
Authors' Addresses Authors' Addresses
Henning Schulzrinne Henning Schulzrinne
Columbia University Columbia University
Department of Computer Science Department of Computer Science
450 Computer Science Building 450 Computer Science Building
New York, NY 10027 New York, NY 10027
USA USA
skipping to change at page 42, line 13 skipping to change at page 42, line 13
Email: Jorge.Cuellar@siemens.com Email: Jorge.Cuellar@siemens.com
James Polk James Polk
Cisco Cisco
2200 East President George Bush Turnpike 2200 East President George Bush Turnpike
Richardson, Texas 75082 Richardson, Texas 75082
USA USA
Email: jmpolk@cisco.com Email: jmpolk@cisco.com
Jonathan Rosenberg Jonathan Rosenberg
Cisco Systems Cisco
600 Lanidex Plaza 600 Lanidex Plaza
Parsippany, New York 07054 Parsippany, New York 07054
USA USA
Email: jdrosen@cisco.com Email: jdrosen@cisco.com
URI: http://www.jdrosen.net URI: http://www.jdrosen.net
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
 End of changes. 83 change blocks. 
218 lines changed or deleted 241 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/