GEOPRIV H. Schulzrinne
Internet-Draft Columbia U.
Expires: January 19, 2006 H. Tschofenig
Siemens
J. Morris
CDT
J. Cuellar
Siemens
J. Polk
Cisco
July 18, 2005
A Document Format for Expressing Privacy Preferences for Location
Information
draft-ietf-geopriv-policy-06.txt
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Abstract
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This document defines an authorization policy language for controling
access to location information. It extends the authorization
framework of the common policy markup language to provide location-
specific access control.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Basic Data Model and Processing . . . . . . . . . . . . . . . 6
4. Rule Transport . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Securing the Location Object . . . . . . . . . . . . . . . . . 8
6. Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1 Civic Location Condition . . . . . . . . . . . . . . . . . 10
6.2 Geospatial Location Condition . . . . . . . . . . . . . . 10
6.2.1 Polygon . . . . . . . . . . . . . . . . . . . . . . . 10
6.2.2 Altitude . . . . . . . . . . . . . . . . . . . . . . . 11
7. Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8. Transformations . . . . . . . . . . . . . . . . . . . . . . . 13
8.1 Distribution Transformation . . . . . . . . . . . . . . . 13
8.2 Retention Transformation . . . . . . . . . . . . . . . . . 13
8.3 Keep Rules Transformation . . . . . . . . . . . . . . . . 14
8.4 Civic Location Transformation . . . . . . . . . . . . . . 14
8.5 Geospatial Location Transformation . . . . . . . . . . . . 15
9. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9.1 Rule Example with Civic Location Condition . . . . . . . . 17
9.2 Rule Example with Geospatial Location Information . . . . 18
10. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . 22
11. Security Considerations . . . . . . . . . . . . . . . . . . 25
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
12.1 Normative References . . . . . . . . . . . . . . . . . . . 26
12.2 Informative References . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 27
A. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 29
B. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30
Intellectual Property and Copyright Statements . . . . . . . . 31
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1. Introduction
Location information needs to be protected against unauthorized
access to preserve the privacy of the subject of the location
information. In [RFC3693], a protocol-independent model for access
to geographic information was defined. The model includes a Location
Generator (LG) that produces Location Information (LI), a Location
Server (LS) that authorizes access to LI, a location recipient (LR)
that requests and receives information, and a Rulemaker (RM) that
provides authorization policy rules. An authorization policy is a
set of rules that regulate an entity's activities with respect to
privacy-sensitive information such as location information. The data
object containing LI is referred to as Location Object (LO).
The basic rule set defined in PIDF-LO [I-D.ietf-geopriv-pidf-lo] can
restrict how long the receiver can retain the information and it can
prohibitfurther distribution of the information. It does not allow
to customize information to specific receivers, for example. This
document describes an enhanced rule set that provides richer
constraints on the distribution of LOs.
We refer to any entity that uses the rules in this document to
restrict the retention or distribution of information as a Rule
Enforcer (RE). The rule set allows the RE 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 limited.
The sequence of operations is as follows. The location server
receives a query for location information for a particular Target,
via the using protocol. 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. All matching rules are combined
according to a merging algorithm described in [I-D.ietf-geopriv-
common-policy]. The resulting rule is applied to the location data,
yielding a possibly modified location object that is delivered to the
location recipient.
This document does not describe or mandate the protocol used to
deliver location information from the location server to the location
recipient, nor the protocol to update the policies or the protocol
that is used by the location generator to convey location information
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to the location server.
This document extends the framework defined in [I-D.ietf-geopriv-
common-policy]. That document provides an abstract framework for
expressing authorization policy rules. As specified there, each such
rule consists of conditions, actions and transformations.'Conditions
determine under which circumstances the location server is permitted
to perform actions and transformations. Transformations regulate how
a location server handles location objects; it might limit when and
how data and policy can be distributed and may modify the information
elements that are returned to the requestor, e.g., reducing the
granularity of location information).
The XML schema in Section 10 extends the XML-based authorization
framework (see [I-D.ietf-geopriv-common-policy]) by introducing new
members of the condition and transformation substitution groups
defined there. The schema does not define new actions. To express
civic location information, it makes use of that schema in [I-D.ietf-
geopriv-pidf-lo] that defines the 'civicAddress' complex type.
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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 [RFC2119].
This document reuses the terminology of [RFC3693], e.g., the terms
Location Server (LS) and Location Recipient (LR). This document and
the common policy document [I-D.ietf-geopriv-common-policy] share the
following terminology:
Presentity or target: RFC 3693 uses the term Target to identify the
object or person of which location information is required. The
presence model described in RFC 2778 [RFC2778] uses the term
presentity to describe the entity that provides presence
information to a presence service. In a presence system, the
target is the presentity.
Watcher or Location Recipient: The receiver of location information
is the Location Recipient (LR) in the terminology of RFC 3693. A
watcher, i.e., an entity that requests presence information about
a presentity, is a location recipient in presence systems.
Authorization policy: 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.
Permission: The term permission indicates the action and
transformation components of a rule.
The terms 'authorization policy', 'policy' and 'rule set' are used
interchangeable. The terms 'authorization policy rule', 'policy
rule' and 'rule' are used interchangeable.
The term 'using protocol' is defined in [RFC3693]. It refers to the
protocol which is used to request access to and to return privacy
sensitive data items.
The geo privacy policy markup language refers to the authorization
language defined in this document. The common policy markup language
refers to the authorization language described in [I-D.ietf-geopriv-
common-policy].
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3. Basic Data Model and Processing
Since the geo privacy policy markup language defined in Section 10
extends the common policy markup language in [I-D.ietf-geopriv-
common-policy], this document adopts the basic data model as
introduced in Section 6 of [I-D.ietf-geopriv-common-policy].
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4. Rule Transport
The XML data format of the GEOPRIV location object is specified in[I-
D.ietf-geopriv-pidf-lo]. The definition of the location object there
allows enhanced authorization policies associated to the location
object to be referenced via a URL in the 'ruleset-reference' element
containing an URI that indicates where a rule set related to the
location object can be found.
One of the transformations of the rule set is the removal of the rule
set described here before transmission. Only the whole rule set can
be removed and not individual elements such as only some conditions.
Before transmitting the rules to the location recipient, unless
explicitly permitted by the authorization policy, the rule set MUST
be removed from the location object, since the rule set might
disclose which entities the rule maker trusts (see Section 8).
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5. Securing the Location Object
The GEOPRIV requirements document [RFC3693] addresses the minimal
security protection required for the LO, namely mutual end-point
authentication, data object integrity, data object confidentiality
and replay protection. As proposed in[I-D.ietf-geopriv-pidf-lo],
S/MIME SHOULD be used. Protection for the location object also
includes an attached rule set.
Protection is likely to be necessary against adversaries who
eavesdrop on the communication between the location server and the
location recipient or the location generator and the location server,
who tamper with the location object or who replay previously recorded
location objects. Securing the communication between rule maker and
location server depends on the protocol which is used to perform the
desired actions (e.g., https). The communication between the
location generator and the location server can also be secured using
channel security.
If the location object is integrity and confidentiality-protected,
then the receiving entity (location server or location recipient) has
to be able to decrypt and to verify the location object. Since the
authorization policy rules described in this document allow the
modification of the location object, by granularity reduction or by
setting flags, it is not possible to forward the location object
without reapplying the cryptographic protection. This applies
especially to the location server as it is not the final consumer of
the location object.
When the location server protects the location object for
transmission to the location recipient after successful
authorization, then the authenticated identity can be used to select
a security association to apply proper protection of the location
object. Securing the location object for multiple recipients is
currently not provided.
Instead of encrypting the location object, the location generator
could digitally sign the location object, offering integrity
protection, but no confidentiality. However, if the location server
needs to modify the location object, it would have to break the
digital signature and then apply its own digital signature.
Since the location object is generally distributed to more than one
location recipient, the location generator lacks the necessary
information about the recipient and thus cannot usually apply
confidentially protection.
By default, the location server re-signs location objects if the
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signed location object has been modified according to the rule set.
If the location server receives a location object that it cannot
decrypt, it discards it if and only if the rule requires modification
of the content.
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6. Conditions
This section describes the location-specific conditions in a rule,
namely the civic and geo-spatial location conditions. The XML
elements and attributes shown below are defined by the XML schema in
Section 10.
6.1 Civic Location Condition
The <civic-loc-condition> element matches if the current location of
the target matches all the values specified in the child elements of
this element. The <civic-loc-condition> is of the 'civicAddress'
complex type defined in [I-D.ietf-geopriv-pidf-lo]. It includes a
number of fields, including the country, expressed as a two-letter
ISO 3166 code, and the administrative units A1 through A6 of
[I-D.ietf-geopriv-dhcp-civil]. This designation offers street-level
precision.
If the civic location of the target is not known, rules that contain
a civic location condition never match. This case may occur, for
example, if location information has been removed by earlier
transmitters of location information or if only the geospatial
location is known.
If any of the elements <A1> through <A6> are specified, <country>
MUST also be specified. The schema does not enforce that the
specification uniquely identifies a particular location. For
example, it would be possible to omit the region and match only on
city name, so that any city sharing that name within a country would
match. This feature is primarily designed to deal with users that
may not know the administrative divisions between county and city
level. For example, many users may not know the county for cities in
the United States.
6.2 Geospatial Location Condition
The geospatial location condition allows to make authorization
decisions based on the current geospatial location of the target. A
rule matches if the current location of the Target is contained in
either the identified polygon (see Section 6.2.1) or between a range
of altitude values (see Section 6.2.2).
6.2.1 Polygon
The condition matches if the longitude and latitude values of the
polygon, interpreted as x and y coordinates on a plane, enclose the
current location of the target.
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There are a number of algorithms for determining whether a point is
inside a polygon. A common algorithm draws a ray from the test point
to the right. The test point is inside if and only if the ray
intersects the line segments making up the polygon an odd number of
times.
The listed points, which constitute the polygon, MUST be listed as
they appear in a clockwise direction all the way around the perimeter
of the single plane shape. This is the defined concept of a "Ring"
within GML [GML]. The final point MUST be a repeat of the first
point listed to enclose the polygon.
6.2.2 Altitude
The altitude condition matches if the target altitude is defined and
falls between the low and high altitude stated in the rule, measured
in meters above the WGS84 sphere. If either element is omitted, the
altitude range is an open range.
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7. Actions
According to the common policy framework [I-D.ietf-geopriv-common-
policy], actions and transformations included in a rule determine
which operations the location server MUST execute after having
received a location data access request from a location recipient
that matches all conditions of this rule. Transformations regulate
the location server operations that directly influence the handling
of location information. Actions, on the other hand, specify all
remaining types of operations the location server is obliged to
execute, i.e., all operations that are not of transformation type.
This document does not define new, location-specific actions.
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8. Transformations
This policy markup language defines several elements by means of
which rulemakers can specify transformations. These transformations
determine whether the location server may distribute the location
object at all and, if so, limits the accuracy of the location object
passed by the location server to the recipient.
All transformations defined in this section are privacy-safe in the
sense that if the evaluation of the authorization policy related to a
given location object does not produce an explicit transformation
instruction, the location server MUST execute the transformation in
question to ensure minimal discloure of privacy-sensitive
information.
Extensions to this document may define other transformations.
8.1 Distribution Transformation
This transformation can be specified by means of the <distribution-
transformation> element whose value is of boolean type. A location
server is allowed to distribute this location object if and only if
all of the following conditions are satisfied:
1. the authorization policy related to the location object contains
a rule with a <distribution-transformation> element,
2. at least one of the rules safisfying (1) matches, and
3. the combined value of this permission is 'true' (see [I-D.ietf-
geopriv-common-policy] for the term 'combined value').
In all other cases, the location server MUST NOT distribute the
location object in question. In particular, this also comprises the
case of an authorization policy that does not contain a rule with a
<distribution-transformation> element.
8.2 Retention Transformation
This transformation can be specified by means of the <retention-
transformation> element whose value is of integer type. A location
server is allowed to retain a location object for the maximum
retention time after receiving the location object, if and only if
all of the following conditions are satisfied:
1. the authorization policy related to the location object contains
a rule with a <retention-transformation> element,
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2. at least one of the rules satisfying (1) matches, and
3. the combined value of this permission is the retention time.
In all other cases, the location server MUST delete the location
object immediately after completing the service that makes use of the
location object, such as delivering it to current subscribers in a
presence system.
8.3 Keep Rules Transformation
This transformation can be specified by means of the <keep-rules-
transformation> element whose value is of boolean type. For a
location object subject to this rule, a location server is allowed to
keep all authorization policy rules in the location object when
delivering it to the location recipient if and only if all of the
following econditions are satisfied:
1. the authorization policy related to the location object contains
a rule with a <keep-rules-transformation> element,
2. at least one of the rules satisfying (1) matches, and
3. the combined value of this permission is 'true'.
In all other cases, the location server MUST remove all authorization
policy rules from the location object. The rules are referenced from
PDIF-LO via the 'ruleset-reference' element either using a URI or a
CID URI scheme as described in Section 2.2.2 of [I-D.ietf-geopriv-
pidf-lo].
The reference to the ruleset is removed and no rules are carried as
MIME bodies (in case of CID URIs).
8.4 Civic Location Transformation
The civic location transformation can be specified by means of the
<civic-loc-transformation> element to restrict the level of civic
location information the LS is permitted to provide. From lowest to
highest level, the names of these levels are: 'null', 'country',
'region', 'city', 'building', 'full'. Each level is given by a set
of civic location data items such as <country> and <A1>, ..., <A6>,
as defined in [I-D.ietf-geopriv-pidf-lo]. 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
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location data as shown below:
full
{<country>, <A1>, <A2>, <A3>, <A4>, <A5>, <A6>, <PRD>, <POD>,
<STS>, <HNO>, <HNS>, <LMK>, <LOC>, <PC>, <NAM>, <FLR>, <ZIP>}
|
building
{<country>, <A1>, <A2>, <A3>, <A4>, <A5>, <A6>,
<PRD>, <POD>, <STS>, <HNO>, <HNS>, <LMK>, <PC>, <ZIP>}
|
city
{<country>, <A1>, <A2>}
|
region
{<country>, <A1>}
|
country
{<country>}
|
null
{}
With respect to a given LO, a LS is permitted to pass civic location
information corresponding to the given LO on at the level L (L =
'country', 'region', 'city', 'building', or 'full'), if and only if
all of the following conditions are satisfied:
1. the authorization policy related to the LO contains a rule with a
<civic-loc-transformation> element,
2. at least one of the rules satisfying 1) matches, and
3. the combined value of this permission is the level L.
In all other cases, including the case in which no rule of the
authorization policy related to the given location object contains a
<civic-loc-transformation> element, the location server MUST remove
all civic location information from the LO before passing it on,
thereby providing the 'null' level of civic location information.
8.5 Geospatial Location Transformation
The geospatial location transformation can be specified by means of
the <geospatial-loc-transformation> element to restrict the
resolution of the geospatial location information to the value
provided in the <latitude-resolution>, <longitude-resolution> and
<altitude-resolution> child elements of the <geospatial-loc-
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transformation> element. The resolution is specified as a positive,
non-zero number r. If n is the nominal coordinate value (longitude
or latitude), the rounded value is computed as
floor(n/r + 0.5) * r.
For example, if the latitude is n=38.89868 and r=0.01, the latitude
value rendered to the recipient of the location object is 38.90. If
the longitude is n=77.03723 and r=0.01, the longitude is rendered as
77.04. This computation also works for r that are not integer powers
of 10 or r > 1. For example, to round longitude to timezone
accuracy, one would use r=15 and obtain a value of 75 in this
example.
For a given LO, a LS is allowed to pass the longitude or latitude
value corresponding to the given LO on at the resolution value r, if
and only if all of the following conditions are satisfied:
1. the authorization policy related to the location object contains
a rule with a <geospatial-loc-transformation> element that has a
<latitude> element,
2. at least one of the rules satisfying (1) matches, and
3. the combined value of this permission is r.
In all other cases, the LS MUST remove the coordinate value from the
geospatial location information.
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9. Example
This section gives two simple examples for authorization policy rules
that make use of the civic and the geospatial location condition.
9.1 Rule Example with Civic Location Condition
This example illustrates a single rule that employs the civic
location condition which matches if the current location of the
target is inside the area specified by the child elements of the
<civic-loc-condition> element. The syntax of this content complies
with the 'civicAddress' complex type defined in [I-D.ietf-geopriv-
pidf-lo]. In this example, requests match only if the Target is at
his main office in a Siemens site in Munich.
The rule is valid for one year as specified by the <validity>
element. No actions are imposed on LSs. The <transformations>
section indicates that LSs are allowed to distribute the LOs with
authorization policy included and the full set of civic location
information, and to pass latitude and longitude values of geospatial
location information on at quite a high level of resolution. Since
the policy does not contain a rule with a <retention-transformation>,
LSs have to delete LOs immediately upon service completion.
<?xml version="1.0" encoding="UTF-8"?>
<cp:ruleset
xmlns:cp="urn:ietf:params:xml:ns:common-policy"
xmlns:gp="urn:ietf:params:xml:ns:geopriv-policy"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"urn:ietf:params:xml:ns:common-policy cp02.xsd
urn:ietf:params:xml:ns:geopriv-policy gp03.xsd">
<cp:rule id="AA56i09">
<cp:conditions>
<cp:validity>
<cp:from>2004-11-01T00:00:00+01:00</cp:from>
<cp:until>2005-11-01T00:00:00+01:00</cp:until>
</cp:validity>
<gp:civic-loc-condition>
<country>DE</country>
<A1>Bavaria</A1>
<A3>Munich</A3>
<A4>Perlach</A4>
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<A6>Otto-Hahn-Ring</A6>
<HNO>6</HNO>
</gp:civic-loc-condition>
</cp:conditions>
<cp:actions></cp:actions>
<cp:transformations>
<gp:distribution-transformation>
true
</gp:distribution-transformation>
<gp:keep-rules-transformation>
true
</gp:keep-rules-transformation>
<gp:civic-loc-transformation>full</gp:civic-loc-transformation>
<gp:geospatial-loc-transformation>
<gp:lat-resolution>0.00001</gp:lat-resolution>
<gp:lon-resolution>0.00001</gp:lon-resolution>
</gp:geospatial-loc-transformation>
</cp:transformations>
</cp:rule>
</cp:ruleset>
9.2 Rule Example with Geospatial Location Information
This example illustrates a rule that employs the geospatial location
condition. The rule matches if the current location of the target is
inside the area specified by the <point> child elements of the
<polygon> element. The individual points of the polygon have to be
interpreted as points of the WGS-84 coordinate reference system, as
specified by the value of the 'crsName' attribute of the <polygon>
element. This coordinate reference systems is also used by GPS. The
given four points specify a quadrangle on the surface of the
rotational ellipoid being part of the WGS-84 system, corresponding to
a certain area in Washington, DC, USA.
The transformation part of the example rule allows the location
server to distribute location objects from which all authorization
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policy rules or pointers to them have been removed. The location
server is permitted to retain the location objects related to the
target for at most one hour. They are allowed to provide civic
location information about the target at city level of precision, and
geospatial location information at roughly the first decimal of
precision.
<?xml version="1.0" encoding="UTF-8"?>
<cp:ruleset
xmlns:cp="urn:ietf:params:xml:ns:common-policy"
xmlns:gp="urn:ietf:params:xml:ns:geopriv-policy"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"urn:ietf:params:xml:ns:common-policy cp02.xsd
urn:ietf:params:xml:ns:geopriv-policy gp03.xsd">
<cp:rule id="BB56A09">
<cp:conditions>
<cp:validity>
<cp:from>2004-11-01T00:00:00+01:00</cp:from>
<cp:until>2005-11-01T00:00:00+01:00</cp:until>
</cp:validity>
<gp:geospatial-loc-condition>
<gp:polygon
crsName="urn:ietf:params:xml:ns:geopriv-policy:crs:wgs84">
<gp:point>
<gp:lat>38.8986</gp:lat>
<gp:lon>-77.03724</gp:lon>
</gp:point>
<gp:point>
<gp:lat>38.8986</gp:lat>
<gp:lon>-77.03722</gp:lon>
</gp:point>
<gp:point>
<gp:lat>38.8987</gp:lat>
<gp:lon>-77.03722</gp:lon>
</gp:point>
<gp:point>
<gp:lat>38.8987</gp:lat>
<gp:lon>-77.03724</gp:lon>
</gp:point>
</gp:polygon>
</gp:geospatial-loc-condition>
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</cp:conditions>
<cp:transformations>
<gp:distribution-transformation>
true
</gp:distribution-transformation>
<gp:keep-rules-transformation>
false
</gp:keep-rules-transformation>
<gp:retention-transformation>
3600
</gp:retention-transformation>
<gp:civic-loc-transformation>city</gp:civic-loc-transformation>
<gp:geospatial-loc-transformation>
<gp:lat-resolution>0.2</gp:lat-resolution>
<gp:lon-resolution>0.1</gp:lon-resolution>
</gp:geospatial-loc-transformation>
</cp:transformations>
</cp:rule>
</cp:ruleset>
The next ruleset indicates that the target has to be at an altitude
between 1500 and 4000 meters in order for this rule to match.
<?xml version="1.0" encoding="UTF-8"?>
<cp:ruleset
xmlns:cp="urn:ietf:params:xml:ns:common-policy"
xmlns:gp="urn:ietf:params:xml:ns:geopriv-policy"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"urn:ietf:params:xml:ns:common-policy cp02.xsd
urn:ietf:params:xml:ns:geopriv-policy gp03.xsd">
<cp:rule id="BB56A19">
<cp:conditions>
<cp:validity>
<cp:from>2004-11-01T00:00:00+01:00</cp:from>
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<cp:to>2005-11-01T00:00:00+01:00</cp:to>
</cp:validity>
<gp:geospatial-loc-condition>
<gp:altitude>
<cp:min>1500.0</cp:min>
<cp:max>4000.0</cp:max>
</gp:altitude>
</gp:geospatial-loc-condition>
</cp:conditions>
<cp:transformations>
<gp:distribution-transformation>
true
</gp:distribution-transformation>
<gp:keep-rules-transformation>
false
</gp:keep-rules-transformation>
<gp:retention-transformation>
3600
</gp:retention-transformation>
<gp:civic-loc-transformation>city</gp:civic-loc-transformation>
<gp:geospatial-loc-transformation>
<gp:lat-resolution>0.3</gp:lat-resolution>
<gp:lon-resolution>0.2</gp:lon-resolution>
</gp:geospatial-loc-transformation>
</cp:transformations>
</cp:rule>
</cp:ruleset>
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10. XML Schema
This section presents the XML schema that defines the geo policy
language described in the previous sections. The policy markup
language introduced by this schema extends the common policy markup
language (see[I-D.ietf-geopriv-common-policy]) by introducing new
members of the 'condition' and 'transformation' substitution groups
whose heads (namely the elements <condition> and <transformation>)
are specified by the common policy schema ([I-D.ietf-geopriv-common-
policy]).
To express civic location conditions, it imports the 'civicAddress'
complex type as defined in [I-D.ietf-geopriv-pidf-lo].
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:geopriv-policy"
xmlns:gp="urn:ietf:params:xml:ns:geopriv-policy"
xmlns:cp="urn:ietf:params:xml:ns:common-policy"
xmlns:cl="urn:ietf:params:xml:ns:pidf:geopriv10:civilLoc"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<xs:import namespace="urn:ietf:params:xml:ns:common-policy"
schemaLocation="20050421common-policy-05.xsd"/>
<xs:import
namespace="urn:ietf:params:xml:ns:pidf:geopriv10:civilLoc"
schemaLocation="pidf-lo-03-civilLoc.xsd"/>
<!-- Geopriv conditions -->
<xs:element name="civic-loc-condition" type="cl:civilAddress"/>
<xs:element name="geospatial-loc-condition">
<xs:complexType>
<xs:choice>
<xs:element name="polygon">
<xs:complexType>
<xs:sequence>
<xs:element name="point"
minOccurs="3" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="lat" type="xs:double"/>
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<xs:element name="lon" type="xs:double"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="crsName" type="xs:anyURI"/>
</xs:complexType>
</xs:element>
<xs:element name="altitude">
<xs:complexType>
<xs:sequence>
<xs:element name="min" type="xs:double"/>
<xs:element name="max" type="xs:double"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:any namespace="##other" processContents="lax"/>
</xs:choice>
</xs:complexType>
</xs:element>
<!-- Geopriv transformations -->
<xs:element name="distribution-transformation"
type="xs:boolean" />
<xs:element name="retention-transformation"
type="xs:integer" />
<xs:element name="keep-rules-transformation" type="xs:boolean" />
<xs:element name="civic-loc-transformation">
<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:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="geospatial-loc-transformation">
<xs:complexType>
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<xs:sequence>
<xs:element name="lat-resolution" type="xs:double"
minOccurs="0" maxOccurs="1" />
<xs:element name="lon-resolution" type="xs:double"
minOccurs="0" maxOccurs="1"/>
<xs:element name="alt-resolution" type="xs:double"
minOccurs="0" maxOccurs="1"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
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11. Security Considerations
This document aims to make it simple for users to prevent the
unintended disclosure of private information to third parties.
Security threats are described in [RFC3694] and are applicable to
this draft as well. Security requirements are addressed in
[RFC3693]. Section 5 addresses issues of protecting the policy rules
within the location object and location information itself. Aspects
of combining permissions in cases of multiple occurrence are treated
in [I-D.ietf-geopriv-common-policy]). How the behavior of location
servers can be regulated in terms of location object handling in a
privacy-safe fashion is specified in Section 8.
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12. References
12.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[RFC3693] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and
J. Polk, "Geopriv Requirements", RFC 3693, February 2004.
[RFC3694] Danley, M., Mulligan, D., Morris, J., and J. Peterson,
"Threat Analysis of the Geopriv Protocol", RFC 3694,
February 2004.
12.2 Informative References
[GML] OpenGIS, "OpenGIS Geography Markup Language (GML)
Implementation Specification, Version 3.00, OGC 02 023r4",
http://www.opengeospatial.org/docs/02-023r4.pdf,
January 2003.
[I-D.ietf-geopriv-common-policy]
Schulzrinne, H., "A Document Format for Expressing Privacy
Preferences", draft-ietf-geopriv-common-policy-04 (work in
progress), February 2005.
[I-D.ietf-geopriv-dhcp-civil]
Schulzrinne, H., "Dynamic Host Configuration Protocol
(DHCPv4 and DHCPv6) Option for Civic Addresses
Configuration Information",
draft-ietf-geopriv-dhcp-civil-06 (work in progress),
May 2005.
[I-D.ietf-geopriv-pidf-lo]
Peterson, J., "A Presence-based GEOPRIV Location Object
Format", draft-ietf-geopriv-pidf-lo-03 (work in progress),
September 2004.
[I-D.ietf-simple-xcap]
Rosenberg, J., "The Extensible Markup Language (XML)
Configuration Access Protocol (XCAP)",
draft-ietf-simple-xcap-07 (work in progress), June 2005.
[RFC2518] Goland, Y., Whitehead, E., Faizi, A., Carter, S., and D.
Jensen, "HTTP Extensions for Distributed Authoring --
WEBDAV", RFC 2518, February 1999.
[RFC2778] Day, M., Rosenberg, J., and H. Sugano, "A Model for
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Presence and Instant Messaging", RFC 2778, February 2000.
[RFC3825] Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host
Configuration Protocol Option for Coordinate-based
Location Configuration Information", RFC 3825, July 2004.
Authors' Addresses
Henning Schulzrinne
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
Siemens
Otto-Hahn-Ring 6
Munich, Bavaria 81739
Germany
Email: Hannes.Tschofenig@siemens.com
URI: http://www.tschofenig.com
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
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Jorge R. Cuellar
Siemens
Otto-Hahn-Ring 6
Munich, Bavaria 81739
Germany
Email: Jorge.Cuellar@siemens.com
James Polk
Cisco
2200 East President George Bush Turnpike
Richardson, Texas 75082
USA
Email: jmpolk@cisco.com
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Appendix A. Contributors
We would like to thank Christian Guenther for his help with this
document:
Christian Guenther
Siemens
Otto-Hahn-Ring 6
Munich, Bavaria 81730
Germany
EMail: Christian.Guenther@siemens.com
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Appendix B. 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.
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