GEOPRIV H. Schulzrinne, Ed.
Internet-Draft Columbia University
Intended status: Standards Track H. Tschofenig, Ed.
Expires: December 28, 2008 Nokia Siemens Networks
J. Morris
CDT
J. Cuellar
Siemens
J. Polk
Cisco
June 26, 2008
Geolocation Policy: A Document Format for Expressing Privacy Preferences
for Location Information
draft-ietf-geopriv-policy-17.txt
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Abstract
This document defines an authorization policy language for
controlling access to location information. It extends the Common
Policy authorization framework to provide location-specific access
control. More specifically, this document defines condition elements
specific to location information in order to restrict access based on
the current location of the Target. Furthermore, it offers location-
specific transformation elements to reduce the granularity of the
returned location information.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Generic Processing . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Structure of Geolocation Authorization Documents . . . . . 8
3.2. Rule Transport . . . . . . . . . . . . . . . . . . . . . . 8
4. Location-specific Conditions . . . . . . . . . . . . . . . . . 9
4.1. Geodetic Location Condition Profile . . . . . . . . . . . 9
4.2. Civic Location Condition Profile . . . . . . . . . . . . . 10
5. Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6. Transformations . . . . . . . . . . . . . . . . . . . . . . . 12
6.1. Set Retransmission-Allowed . . . . . . . . . . . . . . . . 12
6.2. Set Retention-Expiry . . . . . . . . . . . . . . . . . . . 12
6.3. Set Note-Well . . . . . . . . . . . . . . . . . . . . . . 12
6.4. Keep Ruleset Reference . . . . . . . . . . . . . . . . . . 13
6.5. Provide Location . . . . . . . . . . . . . . . . . . . . . 13
6.5.1. Civic Location Profile . . . . . . . . . . . . . . . . 14
6.5.2. Geodetic Location Profile . . . . . . . . . . . . . . 15
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.1. Rule Example with Civic Location Condition . . . . . . . . 16
7.2. Rule Example with Geodetic Location Condition . . . . . . 17
7.3. Rule Example with Civic and Geodetic Location Condition . 17
7.4. Rule Example with Location-based Transformations . . . . . 18
8. XML Schema for Basic Location Profiles . . . . . . . . . . . . 20
9. XML Schema for Geolocation Policy . . . . . . . . . . . . . . 21
10. XCAP Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 23
10.1. Application Unique ID . . . . . . . . . . . . . . . . . . 23
10.2. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . 23
10.3. Default Namespace . . . . . . . . . . . . . . . . . . . . 23
10.4. MIME Type . . . . . . . . . . . . . . . . . . . . . . . . 23
10.5. Validation Constraints . . . . . . . . . . . . . . . . . . 23
10.6. Data Semantics . . . . . . . . . . . . . . . . . . . . . . 23
10.7. Naming Conventions . . . . . . . . . . . . . . . . . . . . 23
10.8. Resource Interdependencies . . . . . . . . . . . . . . . . 24
10.9. Authorization Policies . . . . . . . . . . . . . . . . . . 24
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11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
11.1. Geolocation Policy XML Schema Registration . . . . . . . . 25
11.2. Geolocation Policy Namespace Registration . . . . . . . . 25
11.3. Geolocation Policy Location Profile Registry . . . . . . . 26
11.4. Basic Location Profile XML Schema Registration . . . . . . 26
11.5. Basic Location Profile Namespace Registration . . . . . . 27
11.6. XCAP Application Usage ID . . . . . . . . . . . . . . . . 27
12. Security Considerations . . . . . . . . . . . . . . . . . . . 29
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30
13.1. Normative References . . . . . . . . . . . . . . . . . . . 30
13.2. Informative References . . . . . . . . . . . . . . . . . . 30
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 32
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 33
Intellectual Property and Copyright Statements . . . . . . . . . . 35
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1. Introduction
Location information needs to be protected against unauthorized
access to preserve the privacy of humans. In RFC 3693 [7], a
protocol-independent model for access to geographic information is
defined. The model includes a Location Generator (LG) that
determines location information, a Location Server (LS) that
authorizes access to location information, a Location Recipient (LR)
that requests and receives location information, and a Rule Maker
(RM) that writes authorization policies. An authorization policy is
a set of rules that regulates an entity's activities with respect to
privacy-sensitive information, such as location information.
The data object containing location information in the context of
this document is referred to as a Location Object (LO). The basic
rule set defined in the Presence Information Data Format Location
Object (PIDF-LO) [8] can restrict how long the Location Recipient is
allowed to retain the information, and it can prohibit further
distribution. It also contains a reference to an enhanced rule set
and a human readable privacy policy. The basic rule set, however,
does not allow to control access to location information based on
specific Location Recipients. This document describes an enhanced
rule set that provides richer constraints on the distribution of LOs.
The rule set allows the entity that uses the rules defined in this
document to restrict the retention and to enforce access restrictions
on location data, including prohibiting any dissemination to
particular individuals, during particular times or when the Target is
located in a specific region. The RM can also stipulate that only
certain parts of the Location Object are to be distributed to
recipients or that the resolution of parts of the Location Object is
reduced.
The typical sequence of operations is as follows. A Location Server
receives a query for location information for a particular Target,
via the using protocol [7]. The using protocol provides the identity
of the requestor, either at the time of the query or when subscribing
to the location information. The authenticated identity of the
Location Recipient, together with other information provided by the
using protocol or generally available to the server, is then used for
searching through the rule set. If more than one rule matches the
condition element, then the combined permission is evaluated
according to the description in Section 10 of [1]. The result of the
rule evalation is applied to the location information, yielding a
possibly modified Location Object that is delivered to the Location
Recipient.
This document does not describe the protocol used to convey location
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information from the Location Server to the Location Recipient (i.e.,
the using protocol; see RFC 3693 [7]).
This document extends the Common Policy framework defined in [1].
That document provides an abstract framework for expressing
authorization rules. As specified there, each such rule consists of
conditions, actions and transformations. Conditions determine under
which circumstances the entity executing the rules, for example a
Location Server, is permitted to apply actions and transformations.
Transformations regulate in a location information context how a
Location Server modifies the information elements that are returned
to the requestor, for example, by reducing the granularity of
returned location information.
The XML schema defined in Section 9 extends the Common Policy schema
by introducing new child elements to the condition and transformation
elements. This document does not define child elements for the
action part of a rule.
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2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [2].
This document reuses the terminology of RFC 3693 [7], such as
Location Server (LS), Location Recipient (LR), Rule Maker (RM),
Target, Location Generator (LG) and Location Object (LO). This
document uses the following terminology:
Presentity or Target:
RFC 3693 [7] uses the term Target to identify the object or person
of which location information is required. The presence model
described in RFC 2778 [9] uses the term presentity to describe the
entity that provides presence information to a presence service.
A Presentity in a presence system is a Target in a location
information system.
Watcher or Location Recipient:
The receiver of location information is the Location Recipient
(LR) in the terminology of RFC 3693 [7]. A watcher in a presence
system, i.e., an entity that requests presence information about a
presentity, is a Location Recipient in a location information
system.
Authorization policy:
An authorization policy is given by a rule set. A rule set
contains an unordered list of (policy) rules. Each rule has a
condition, an action and a transformation component.
Permission:
The term permission refers to the action and transformation
components of a rule.
The term 'using protocol' is defined in [7] and refers to the
protocol that is used to request access to and to return privacy
sensitive data items.
In this document we use the term Location Servers as the entities
that evaluate the geolocation authorization policies. The
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geolocation privacy architecture is, as motivated in RFC 4079 [10],
aligned with the presence architecture and a Presence Server is
therefore an entity that distributes location information along with
other presence-specific XML data elements.
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3. Generic Processing
3.1. Structure of Geolocation Authorization Documents
A geolocation authorization document is an XML document, formatted
according to the schema defined in [1]. Geolocation authorization
documents inherit the MIME type of common policy documents,
application/auth-policy+xml. As described in [1], this document is
composed of rules which contain three parts - conditions, actions,
and transformations. Each action or transformation, which is also
called a permission, has the property of being a positive grant of
information to the Location Recipient. As a result, there is a well-
defined mechanism for combining actions and transformations obtained
from several sources. This mechanism is privacy safe, since the lack
of any action or transformation can only result in less information
being presented to a Location Recipient.
3.2. Rule Transport
There are two ways how the authorization rules described in this
document may be conveyed between different parties:
o RFC 4119 [8] allows enhanced authorization policies to be
referenced via a Uniform Resource Locator (URL) in the 'ruleset-
reference' element. The ruleset-reference' element is part of the
basic rules that always travel with the Location Object.
o Authorization policies might, for example, also be stored at a
Location Server / Presence Server. The Rule Maker therefore needs
to use a protocol to create, modify and delete the authorization
policies defined in this document. Such a protocol is available
with the Extensible Markup Language (XML) Configuration Access
Protocol (XCAP) [11].
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4. Location-specific Conditions
This section describes the location-specific conditions of a rule,
namely the civic and geodetic location conditions. The <conditions>
element contains zero, one or an unbounded number of <location-
condition> child element(s). Providing more than one <location-
condition> child element may not be useful since all child elements
of the <conditions> element must evaluate to TRUE in order for the
<conditions> element to be TRUE. The <location-condition> element
MUST contain at least one <location> child element. The <location-
condition> element evaluates to TRUE if any of its child elements is
TRUE, i.e., a logical OR.
A location profile needs to describe under what conditions each
<location> element evaluates to TRUE. This document defines two
location profiles, one civic and one geodetic location profile.
The <location-condition> and the <location> elements provide
extension points. If an extension is not understood by the entity
evaluating the rules then this rule evaluates to FALSE.
4.1. Geodetic Location Condition Profile
The geodetic location profile is identified by the token 'geodetic-
condition'. Rule Makers use this profile by placing a GML [3]
<Circle> element within the <location> element (as described in
Section 5.2.3 of [4]).
The <location> element containing the information for the geodetic
location profile evaluates to TRUE if the current location of the
Target is within the described location. Note that the Target's
actual location might be represented by any of the location shapes
described in [4]. If the geodetic location of the Target is unknown
then the <location> element containing the information for the
geodetic location profile evaluates to FALSE.
Implementations are REQUIRED to support the following coordinate
reference system based on WGS 84 [5] based on the European Petroleum
Survey Group (EPSG) Geodetic Parameter Dataset (as formalized by the
Open Geospatial Consortium (OGC)):
2D: WGS 84 (latitude, longitude), as identified by the URN
"urn:ogc:def:crs:EPSG::4326". This is a two dimensional CRS.
A CRS MUST be specified using the above URN notation only,
implementations do not need to support user-defined CRSs.
Implementations MUST specify the CRS using the "srsName" attribute on
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the outermost geometry element. The CRS MUST NOT be changed for any
sub-elements. The "srsDimension" attribute MUST be omitted, since
the number of dimensions in these CRSs is known.
4.2. Civic Location Condition Profile
The civic location profile is identified by the token 'civic-
condition'. Rule Makers use this profile by placing a <civicAddress>
element, defined in [6], within the <location> element.
All child elements of <location> element that carry civicAddress
elements MUST evaluate to TRUE (i.e., logical AND) in order for the
<location> element to evaluate to TRUE. For each child element, the
value of that element is compared to the value of the same element in
the Target's civic location. The child element evaluates to TRUE if
the two values are identical based on a bit-by-bit comparison.
If the civic location of the Target is unknown, then the <location>
element containing the information for the civic location profile
evaluates to FALSE. This case may occur, for example, if location
information has been removed by earlier transmitters of location
information or if only the geodetic location is known. In general,
it is RECOMMENDED behavior for a LS not to apply a translation from
geodetic location to civic location (i.e., geocode the location).
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5. Actions
This document does not define location-specific actions.
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6. Transformations
This document defines several elements that allow Rule Makers to
specify transformations that
o reduce the accuracy of the returned location information, and
o set the basic authorization policies carried inside the PIDF-LO.
6.1. Set Retransmission-Allowed
This element asks the LS to change or set the value of the
<retransmission-allowed> element in the PIDF-LO. The data type of
the <set-retransmission-allowed> element is a boolean.
If the value of the <set-retransmission-allowed> element is set to
TRUE then the <retransmission-allowed> element in the PIDF-LO MUST be
set to TRUE. If the value of the <set-retransmission-allowed>
element is set to FALSE, then the <retransmission-allowed> element in
the PIDF-LO MUST be set to FALSE.
If the <set-retransmission-allowed> element is absent then the value
of the <retransmission-allowed> element in the PIDF-LO MUST be kept
unchanged or, if the PIDF-LO is created for the first time, then the
value MUST be set to FALSE.
6.2. Set Retention-Expiry
This transformation asks the LS to change or set the value of the
<retention-expiry> element in the PIDF-LO. The data type of the
<set-retention-expiry> element is an integer.
The value provided with the <set-retention-expiry> element indicates
seconds and these seconds are added to the current date.
If the <set-retention-expiry> element is absent then the value of the
<retention-expiry> element in the PIDF-LO is kept unchanged or, if
the PIDF-LO is created for the first time, then the value MUST be set
to the current date.
6.3. Set Note-Well
This transformation asks the LS to change or set the value of the
<note-well> element in the PIDF-LO. The data type of the <set-note-
well> element is a string.
The value provided with the <set-note-well> element contains a
privacy statement as a human readable text string and an 'xml:lang'
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attribute denotes the language of the human readable text.
If the <set-note-well> element is absent, then the value of the
<note-well> element in the PIDF-LO is kept unchanged or, if the
PIDF-LO is created for the first time, then no content is provided
for the <note-well> element.
6.4. Keep Ruleset Reference
This transformation allows to influence whether the <external-
ruleset> element in the PIDF-LO carries the extended authorization
rules defined in [1]. The data type of the <keep-rule-reference>
element is Boolean.
If the value of the <keep-rule-reference> element is set to TRUE,
then the <external-ruleset> element in the PIDF-LO is kept unchanged
when included. If the value of the <keep-rule-reference> element is
set to FALSE, then the <external-ruleset> element in the PIDF-LO MUST
NOT contain a reference to an external rule set. The reference to
the ruleset is removed and no rules are carried as MIME bodies (in
case of CID URIs).
If the <keep-rule-reference> element is absent, then the value of the
<external-ruleset> element in the PIDF-LO is kept unchanged when
available or, if the PIDF-LO is created for the first time then the
<external-ruleset> element MUST NOT be included.
6.5. Provide Location
The <provide-location> element contains child elements of a specific
location profile that controls the granularity of returned location
information. This document defines two location profiles, namely:
o If the <provide-location> element has a <provide-civic> child
element then civic location information is disclosed as described
in Section 6.5.1, subject to availability.
o If the <provide-location> element has a <provide-geo> child
element then geodetic location information is disclosed as
described in Section 6.5.2, subject to availability.
The <provide-location> element MUST contain the 'profile' attribute
if it contains child elements and the 'profile' attribute MUST match
with the contained child elements. The <provide-location> element
MUST contain the 'profile' attribute if it contains child elements.
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If the <provide-location> element has no child elements then civic,
as well as, geodetic location information is disclosed without
reducing its granularity, subject to availability. In this case the
profile attribute MUST NOT be included.
6.5.1. Civic Location Profile
This profile uses the token 'civic-transformation'. This profile
allows civic location transformations to be specified by means of the
<provide-civic> element that restricts the level of civic location
information the LS is permitted to disclose. The symbols of these
levels are: 'country', 'region', 'city', 'building', 'full'. Each
level is given by a set of civic location data items such as
<country> and <A1>, ..., <POM>, as defined in [6]. Each level
includes all elements included by the lower levels.
The 'country' level includes only the <country> element; the 'region'
level adds the <A1> element; the 'city' level adds the <A2> and <A3>
elements; the 'building' level and the 'full' level add further civic
location data as shown below.
full
{<country>, <A1>, <A2>, <A3>, <A4>, <A5>, <A6>, <PRD>, <POD>,
<STS>, <HNO>, <HNS>, <LMK>, <LOC>, <PC>, <NAM>, <FLR>,
<BLD>,<UNIT>,<ROOM>,<PLC>, <PCN>, <POBOX>, <ADDCODE>, <SEAT>
<RD>, <RDSEC>, <RDBR>, <RDSUBBR>, <PRM>, <POM>}
|
|
building
{<country>, <A1>, <A2>, <A3>, <A4>, <A5>, <A6>, <PRD>
<POD>, <STS>, <HNO>, <HNS>, <LMK>, <PC>,
<RD>, <RDSEC>, <RDBR>, <RDSUBBR> <PRM>, <POM>}
|
|
city
{<country>, <A1>, <A2>, <A3>}
|
|
region
{<country>, <A1>}
|
|
country
{<country>}
|
|
none
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{}
The default value is "none".
The schema of the <provide-civic> element is defined in Section 8.
6.5.2. Geodetic Location Profile
This profile uses the token 'geodetic-transformation' and refers only
to the Coordinate Reference System (CRS) WGS 84
(urn:ogc:def:crs:EPSG::4326, 2D). This profile allows geodetic
location transformations to be specified by means of the <provide-
geo> element that may restrict the returned geodetic location
information based on the value provided in the 'radius' attribute.
The value of the 'radius' attribute expresses the radius in meters.
The schema of the <provide-geo> element is defined in Section 8.
For each rule in the policy specification containing a <provide-geo>
element, the LS chooses a circle with a radius F given by the
'radius' attribute of the <provide-geo> element. The center of the
circle is chosen randomly, under the constraint that the circle MUST
contain the Target's location, which may be a point or another
location shape. In response to queries matching this rule, the LS
MUST return a shape containing this circle; while the returned shape
may change from one query to another, the chosen circle remains
constant as long as the Target's location (whether a point or a
region) remains completely within the circle. An LS may, for
example, store the location of the center or compute it based on a
hash function that includes the target's identity. If the Target's
location moves within the chosen circle, the LS MAY choose a new
random center point, but when the Target's location moves outside the
chosen circle, the LS MUST choose a new random center point.
The above-described procedure aims to satisfy the following design
goals:
1. The circle returned must contain the actual location of the
Target.
2. In general, no point in the circle must be more likely than
others to contain the Target.
3. Repeated queries must not reveal the likely location of the
Target.
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7. Examples
This section provides a few examples for authorization rules using
the extensions defined in this document.
7.1. Rule Example with Civic Location Condition
This example illustrates a single rule that employs the civic
location condition. It matches if the current location of the Target
equal the content of the child elements of the <location> element.
Requests match only if the Target is at a civic location with country
set to 'Germany', state (A1) set to 'Bavaria', city (A3) set to
'Munich', city division (A4) set to 'Perlach', street name (A6) set
to 'Otto-Hahn-Ring' and house number (HNO) set to '6'.
No actions and transformation child elements are provided in this
rule example. The actions and transformation could include presence
specific information when the Geolocation Policy framework is applied
to the Presence Policy framework (see [12]).
<?xml version="1.0" encoding="UTF-8"?>
<ruleset xmlns="urn:ietf:params:xml:ns:common-policy"
xmlns:gp="urn:ietf:params:xml:ns:geolocation-policy">
<rule id="AA56i09">
<conditions>
<gp:location-condition>
<gp:location profile="civic-condition"
xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
<country>DE</country>
<A1>Bavaria</A1>
<A3>Munich</A3>
<A4>Perlach</A4>
<A6>Otto-Hahn-Ring</A6>
<HNO>6</HNO>
</gp:location>
</gp:location-condition>
</conditions>
<actions/>
<transformations/>
</rule>
</ruleset>
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7.2. Rule Example with Geodetic Location Condition
This example illustrates a rule that employs the geodetic location
condition. The rule matches if the current location of the Target is
inside the area specified by the polygon. The polygon uses the EPSG
4326 coordinate reference system. No altitude is included in this
example.
<?xml version="1.0" encoding="UTF-8"?>
<ruleset
xmlns="urn:ietf:params:xml:ns:common-policy"
xmlns:gp="urn:ietf:params:xml:ns:geolocation-policy"
xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0">
<rule id="BB56A19">
<conditions>
<gp:location-condition>
<gp:location profile="geodetic-condition">
<gs:Circle srsName="urn:ogc:def:crs:EPSG::4326">
<gml:pos>-34.410649 150.87651</gml:pos>
<gs:radius uom="urn:ogc:def:uom:EPSG::9001">1500
</gs:radius>
</gs:Circle>
</gp:location>
</gp:location-condition>
</conditions>
<transformations/>
</rule>
</ruleset>
7.3. Rule Example with Civic and Geodetic Location Condition
This example illustrates a rule that employs a mixed civic and
geodetic location condition. Depending on the available type of
location information, namely civic or geodetic location information,
one of the location elements may match.
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<?xml version="1.0" encoding="UTF-8"?>
<ruleset
xmlns="urn:ietf:params:xml:ns:common-policy"
xmlns:gp="urn:ietf:params:xml:ns:geolocation-policy"
xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0">
<rule id="AA56i09">
<conditions>
<gp:location-condition>
<gp:location profile="civic-condition"
xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
<country>DE</country>
<A1>Bavaria</A1>
<A3>Munich</A3>
<A4>Perlach</A4>
<A6>Otto-Hahn-Ring</A6>
<HNO>6</HNO>
</gp:location>
<gp:location profile="geodetic-condition">
<gs:Circle srsName="urn:ogc:def:crs:EPSG::4326">
<gml:pos>-34.410649 150.87651</gml:pos>
<gs:radius uom="urn:ogc:def:uom:EPSG::9001">1500
</gs:radius>
</gs:Circle>
</gp:location>
</gp:location-condition>
</conditions>
<actions/>
<transformations/>
</rule>
</ruleset>
7.4. Rule Example with Location-based Transformations
This example shows the transformations specified in this document.
The <provide-civic> element indicates that the available civic
location information is reduced to building level granularity. If
geodetic location information is requested then a granularity
reduction is provided as well.
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<?xml version="1.0" encoding="UTF-8"?>
<ruleset xmlns="urn:ietf:params:xml:ns:common-policy"
xmlns:gp="urn:ietf:params:xml:ns:geolocation-policy"
xmlns:lp="urn:ietf:params:xml:ns:basic-location-profiles">
<rule id="AA56i09">
<conditions/>
<actions/>
<transformations>
<gp:set-retransmission-allowed>false
</gp:set-retransmission-allowed>
<gp:set-retention-expiry>86400</gp:set-retention-expiry>
<gp:set-note-well xml:lang="en">My privacy policy goes in here.
</gp:set-note-well>
<gp:keep-rule-reference>false
</gp:keep-rule-reference>
<gp:provide-location
profile="civic-transformation">
<lp:provide-civic>building</lp:provide-civic>
</gp:provide-location>
<gp:provide-location
profile="geodetic-transformation">
<lp:provide-geo radius="500"/>
</gp:provide-location>
</transformations>
</rule>
</ruleset>
The following rule describes the short-hand notation for making the
current location of the Target available to Location Recipients
without granularity reduction.
<?xml version="1.0" encoding="UTF-8"?>
<ruleset xmlns="urn:ietf:params:xml:ns:common-policy"
xmlns:gp="urn:ietf:params:xml:ns:geolocation-policy">
<rule id="AA56ia9">
<conditions/>
<actions/>
<transformations>
<gp:provide-location/>
</transformations>
</rule>
</ruleset>
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8. XML Schema for Basic Location Profiles
This section defines the location profiles used as child elements of
the transformation element.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:basic-location-profiles"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<!-- profile="civic-transformation" -->
<xs:element name="provide-civic" default="none">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="full"/>
<xs:enumeration value="building"/>
<xs:enumeration value="city"/>
<xs:enumeration value="region"/>
<xs:enumeration value="country"/>
<xs:enumeration value="none"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
<!-- profile="geodetic-transformation" -->
<xs:element name="provide-geo">
<xs:complexType>
<xs:attribute name="radius" type="xs:integer"/>
</xs:complexType>
</xs:element>
</xs:schema>
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9. XML Schema for Geolocation Policy
This section presents the XML schema that defines the Geolocation
Policy schema described in this document. The Geolocation Policy
schema extends the Common Policy schema (see [1]).
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:geolocation-policy"
xmlns:gp="urn:ietf:params:xml:ns:geolocation-policy"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<!-- Import Common Policy-->
<xs:import namespace="urn:ietf:params:xml:ns:common-policy"/>
<!-- This import brings in the XML language attribute xml:lang-->
<xs:import namespace="http://www.w3.org/XML/1998/namespace"
schemaLocation="http://www.w3.org/2001/xml.xsd"/>
<!-- Geopriv Conditions -->
<xs:element name="location-condition"
type="gp:locationconditionType"/>
<xs:complexType name="locationconditionType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:choice minOccurs="1" maxOccurs="unbounded">
<xs:element name="location" type="gp:locationType"
minOccurs="1" maxOccurs="unbounded"/>
<xs:any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:choice>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="locationType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:choice minOccurs="1" maxOccurs="unbounded">
<xs:any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:choice>
<xs:attribute name="profile" type="xs:string"/>
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</xs:restriction>
</xs:complexContent>
</xs:complexType>
<!-- Geopriv transformations -->
<xs:element name="set-retransmission-allowed"
type="xs:boolean" default="false"/>
<xs:element name="set-retention-expiry"
type="xs:integer" default="0"/>
<xs:element name="set-note-well"
type="gp:notewellType"/>
<xs:element name="keep-rule-reference"
type="xs:boolean" default="false"/>
<xs:element name="provide-location"
type="gp:providelocationType"/>
<xs:complexType name="notewellType">
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute ref="xml:lang" />
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="providelocationType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:choice>
<xs:attribute name="profile" type="xs:string" />
</xs:restriction>
</xs:complexContent>
</xs:complexType>
</xs:schema>
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10. XCAP Usage
The following section defines the details necessary for clients to
manipulate geolocation privacy documents from a server using XCAP.
If used as part of a presence system, it uses the same AUID as those
rules. See [12] for a description of the XCAP usage in context with
presence authorization rules.
10.1. Application Unique ID
XCAP requires application usages to define a unique application usage
ID (AUID) in either the IETF tree or a vendor tree. This
specification defines the "geolocation-policy" AUID within the IETF
tree, via the IANA registration in Section 11.
10.2. XML Schema
XCAP requires application usages to define a schema for their
documents. The schema for geolocation authorization documents is
described in Section 9.
10.3. Default Namespace
XCAP requires application usages to define the default namespace for
their documents. The default namespace is
urn:ietf:params:xml:ns:geolocation-policy.
10.4. MIME Type
XCAP requires application usages to defined the MIME type for
documents they carry. Geolocation privacy authorization documents
inherit the MIME type of common policy documents, application/
auth-policy+xml.
10.5. Validation Constraints
This specification does not define additional constraints.
10.6. Data Semantics
This document discusses the semantics of a geolocation privacy
authorization.
10.7. Naming Conventions
When a Location Server receives a request to access location
information of some user foo, it will look for all documents within
http://[xcaproot]/geolocation-policy/users/foo, and use all documents
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found beneath that point to guide authorization policy.
10.8. Resource Interdependencies
This application usage does not define additional resource
interdependencies.
10.9. Authorization Policies
This application usage does not modify the default XCAP authorization
policy, which is that only a user can read, write or modify his/her
own documents. A server can allow privileged users to modify
documents that they do not own, but the establishment and indication
of such policies is outside the scope of this document.
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11. IANA Considerations
There are several IANA considerations associated with this
specification.
11.1. Geolocation Policy XML Schema Registration
URI: urn:ietf:params:xml:schema:geolocation-policy
Registrant Contact: IETF Geopriv Working Group, Hannes Tschofenig
(hannes.tschofenig@nsn.com).
XML: The XML schema to be registered is contained in Section 9. Its
first line is
<?xml version="1.0" encoding="UTF-8"?>
and its last line is
</xs:schema>
11.2. Geolocation Policy Namespace Registration
URI: urn:ietf:params:xml:ns:geolocation-policy
Registrant Contact: IETF Geopriv Working Group, Hannes Tschofenig
(hannes.tschofenig@nsn.com).
XML:
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BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Geolocation Policy Namespace</title>
</head>
<body>
<h1>Namespace for Geolocation Authorization Policies</h1>
<h2>urn:ietf:params:xml:schema:geolocation-policy</h2>
<p>See <a href="[URL of published RFC]">RFCXXXX
[NOTE TO IANA/RFC-EDITOR:
Please replace XXXX with the RFC number of this
specification.]</a>.</p>
</body>
</html>
END
11.3. Geolocation Policy Location Profile Registry
This document seeks to create a registry of location profile names
for the Geolocation Policy framework. Profile names are XML tokens.
This registry will operate in accordance with RFC 2434 [13],
Standards Action.
This document defines the following profile names:
geodetic-condition: Defined in Section 4.1.
civic-condition: Defined in Section 4.2.
geodetic-transformation: Defined in Section 6.5.2.
civic-transformation: Defined in Section 6.5.1.
11.4. Basic Location Profile XML Schema Registration
URI: urn:ietf:params:xml:schema:basic-location-profiles
Registrant Contact: IETF Geopriv Working Group, Hannes Tschofenig
(hannes.tschofenig@nsn.com).
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XML: The XML schema to be registered is contained in Section 8. Its
first line is
<?xml version="1.0" encoding="UTF-8"?>
and its last line is
</xs:schema>
11.5. Basic Location Profile Namespace Registration
URI: urn:ietf:params:xml:ns:basic-location-profiles
Registrant Contact: IETF Geopriv Working Group, Hannes Tschofenig
(hannes.tschofenig@nsn.com).
XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Basic Location Profile Namespace</title>
</head>
<body>
<h1>Namespace for Basic Location Profile</h1>
<h2>urn:ietf:params:xml:schema:basic-location-profiles</h2>
<p>See <a href="[URL of published RFC]">RFCXXXX
[NOTE TO IANA/RFC-EDITOR:
Please replace XXXX with the RFC number of this
specification.]</a>.</p>
</body>
</html>
END
11.6. XCAP Application Usage ID
This section registers an XCAP Application Usage ID (AUID) according
to the IANA procedures defined in [11].
Name of the AUID: geolocation-policy
Description: Geolocation privacy rules are documents that describe
the permissions that a Target has granted to Location Recipients that
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access information about his/her geographic location.
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12. Security Considerations
This document aims to make it simple for users to prevent the
unintended disclosure of private information to third parties. This
is accomplished through the usage of authorization policies.
Security requirements are described in [7] and a discussion of
generic security threats is available with [14]. Aspects of
combining permissions in cases of multiple occurrence are treated in
[1]).
When the Target is moving then the location transformations reveal
information when switching from one privacy region to another one.
For example, when a transformation indicates that civic location is
provided at a 'building' level of granularity. Hence, room numbers,
floors etc. would be hidden. However, when the Target moves from one
building to the next one then the movement would still be
recognizable as the disclosed location information would be reflected
by the new civic location information indicating the new building.
With additional knowledge about building entrances and streets it
would be possible to learn a certain amont of information. It is
therefore important to ensure that selected privacy regions are not
chosen too small when mobility is a concern and that a random number
to is added to the position of the Target, with an absolute value of
half the privacy region. The latter aspect is only applicable for
geodetic information or when geodetic information is translated to
civic information by the Location Server.
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13. References
13.1. Normative References
[1] Schulzrinne, H., Tschofenig, H., Morris, J., Cuellar, J., Polk,
J., and J. Rosenberg, "Common Policy: A Document Format for
Expressing Privacy Preferences", RFC 4745, February 2007.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", March 1997.
[3] OpenGIS, "OpenGIS Geography Markup Language (GML)
Implementation Specification, Version 3.00, OGC 02 023r4",
http://www.opengeospatial.org/docs/02-023r4.pdf, January 2003.
[4] Winterbottom, J., Thomson, M., and H. Tschofenig, "GEOPRIV
PIDF-LO Usage Clarification, Considerations and
Recommendations", draft-ietf-geopriv-pdif-lo-profile-11 (work
in progress), February 2008.
[5] OpenGIS, "US National Imagery and Mapping Agency, "Department
of Defense (DoD) World Geodetic System 1984 (WGS 84), Third
Edition, NIMA TR8350.2", , January 2000.
[6] Thomson, M. and J. Winterbottom, "Revised Civic Location Format
for Presence Information Data Format Location Object
(PIDF-LO)", RFC 5139, February 2008.
13.2. Informative References
[7] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J.
Polk, "Geopriv Requirements", RFC 3693, February 2004.
[8] Peterson, J., "A Presence-based GEOPRIV Location Object
Format", RFC 4119, December 2005.
[9] Day, M., Rosenberg, J., and H. Sugano, "A Model for Presence
and Instant Messaging", RFC 2778, February 2000.
[10] Peterson, J., "A Presence Architecture for the Distribution of
GEOPRIV Location Objects", RFC 4079, July 2005.
[11] Rosenberg, J., "The Extensible Markup Language (XML)
Configuration Access Protocol (XCAP)", RFC 4825, May 2007.
[12] Rosenberg, J., "Presence Authorization Rules", RFC 5025,
December 2007.
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[13] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[14] Danley, M., Mulligan, D., Morris, J., and J. Peterson, "Threat
Analysis of the Geopriv Protocol", RFC 3694, February 2004.
[15] Thomson, M., "Geodetic Shapes for the Representation of
Uncertainty in PIDF-LO", draft-thomson-geopriv-geo-shape-03
(work in progress), December 2006.
[16] Thomson, M. and J. Winterbottom, "Representation of Uncertainty
and Confidence in PIDF-LO",
draft-thomson-geopriv-uncertainty-01 (work in progress),
June 2008.
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Appendix A. Acknowledgments
This document is informed by the discussions within the IETF GEOPRIV
working group, including discussions at the GEOPRIV interim meeting
in Washington, D.C., in 2003.
We particularly want to thank Allison Mankin <mankin@psg.com>,
Randall Gellens <rg+ietf@qualcomm.com>, Andrew Newton
<anewton@ecotroph.net>, Ted Hardie <hardie@qualcomm.com>, Jon
Peterson <jon.peterson@neustar.biz> for their help in improving the
quality of this document.
We would like to thank Christian Guenther for his help with an
earlier version of this document. Furthermore, we would like to
thank Johnny Vrancken for his document reviews in September 2006,
December 2006 and January 2007. James Winterbottom provided a
detailed review in November 2006. Richard Barnes gave a detailed
review in February 2008.
This document uses text from [15]. Therefore, we would like to thank
Martin Thomson for his work in [15]. We would also like to thank
Martin Thomson, Matt Lepinski and Richard Barnes for their comments
regarding the geodetic location transformation procedure. Richard
provided us with a detailed text proposal.
We would like to thank Dan Romascanu, Yoshiko Chong and Jari
Urpalainen for their last call comments.
Finally, we would like to thank the following individuals for their
feedback as part of the IESG, GenArt, and SecDir review: Jari Arkko,
Eric Gray, Russ Housley, Carl Reed, Martin Thomson, Lisa Dusseault,
Chris Newman, Jon Peterson, Sam Hartman, Cullen Jennings, Tim Polk,
and Brian Rosen.
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Authors' Addresses
Henning Schulzrinne (editor)
Columbia University
Department of Computer Science
450 Computer Science Building
New York, NY 10027
USA
Phone: +1 212 939 7042
Email: schulzrinne@cs.columbia.edu
URI: http://www.cs.columbia.edu/~hgs
Hannes Tschofenig (editor)
Nokia Siemens Networks
Linnoitustie 6
Espoo 02600
Finland
Phone: +358 (50) 4871445
Email: Hannes.Tschofenig@gmx.net
URI: http://www.tschofenig.priv.at
John B. Morris, Jr.
Center for Democracy and Technology
1634 I Street NW, Suite 1100
Washington, DC 20006
USA
Email: jmorris@cdt.org
URI: http://www.cdt.org
Jorge R. Cuellar
Siemens
Otto-Hahn-Ring 6
Munich, Bavaria 81739
Germany
Email: Jorge.Cuellar@siemens.com
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James Polk
Cisco
2200 East President George Bush Turnpike
Richardson, Texas 75082
USA
Email: jmpolk@cisco.com
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Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
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