GEOPRIV H. Schulzrinne
Internet-Draft Columbia U.
Expires: January 17, 2005 J. Morris
CDT
H. Tschofenig
J. Cuellar
Siemens
J. Polk
Cisco
July 19, 2004
A Document Format for Expressing Privacy Preferences for Location
Information
draft-ietf-geopriv-policy-02
Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
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 towards
location-specific access control needs.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Basic Data Model and Processing . . . . . . . . . . . . . . . 6
4. Rule Transport . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1 HTTP . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2 SIP Message Body . . . . . . . . . . . . . . . . . . . . . 7
4.3 Location Object . . . . . . . . . . . . . . . . . . . . . 7
5. Securing the Location Object . . . . . . . . . . . . . . . . . 9
6. Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1 Civil Location . . . . . . . . . . . . . . . . . . . . . . 10
6.2 Geospatial Location . . . . . . . . . . . . . . . . . . . 10
7. Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8. Transformations . . . . . . . . . . . . . . . . . . . . . . . 13
8.1 Set D (Distribute) Flag . . . . . . . . . . . . . . . . . 13
8.2 Set R (Retention) Time . . . . . . . . . . . . . . . . . . 13
8.3 Keep Rule (RR) . . . . . . . . . . . . . . . . . . . . . . 13
8.4 Provide Civil Location . . . . . . . . . . . . . . . . . . 13
8.5 Provide Geospatial Location . . . . . . . . . . . . . . . 14
8.6 Provide Timezone Flag . . . . . . . . . . . . . . . . . . 16
9. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
10. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . 19
11. Security Considerations . . . . . . . . . . . . . . . . . . 21
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
12.1 Normative References . . . . . . . . . . . . . . . . . . . . 22
12.2 Informative References . . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 23
A. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 25
B. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26
Intellectual Property and Copyright Statements . . . . . . . . 27
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1. Introduction
Location information needs to be protected against unauthorized
access to preserve the privacy of the owner of the location
information. Therefore 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 policy rules to the LS which enforce access control policies
on access to a target.
Two policy namespaces have been defined. The first basic rule set
[I-D.peterson-geopriv-pres] can restrict how long the receiver can
retain the information and it can prohibit any further 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 the
Location Objects (LOs). We assume that a basic location
object[I-D.peterson-geopriv-pres] can contain a reference to
additional rule sets.
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 or during particular times.
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 can be described as follows. The LS
receives either a query for location information of a particular
Target, via the using protocol. The using protocol provides the
identity of the requestor, either at the time of the query or
subscription to the location information. The authenticated identity
of the LR, 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.
Note that the protocols used to query location information (between
LS and LR), update policies at the LS and the protocol between the LG
to LS and from LS to LR do not have to be the same. This document
does not mandate a specific protocol for any of them.
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This document is part of extends the framework defined
in[I-D.ietf-geopriv-common-policy]. That document provides an
abstract authorization framework for expressing policy rules. As
specified there, each such rule consists of 'conditions', 'actions'
and 'transformations'. Conditions determine under which
circumstances the LS is permitted to perform 'actions'.
'Transformations' implement a mechanism to optionally modify
information elements returned to the requestor (e.g., to reduce the
granularity of location information). The term 'transformation' is
also known as 'provisional action'.
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. To express civil location information, it makes use
of the schema in Section 2.2.3 of [I-D.ietf-geopriv-pidf-lo] that
defines the 'civilAddress' 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]. We subsequently
refer to the terminology used in [RFC3693] as Geopriv. This section
assists in the alignment between the terminology defined in
[I-D.ietf-geopriv-common-policy] and in this document. This document
uses the terms LS, LR and RM.
PT - Presentity / Target: Geopriv uses the term Target to identify
the object or person of which location information is required.
RM - Rule Maker: The entity RM corresponds to the Geopriv Rulemaker.
PS - (Authorization) Policy Server: The PS corresponds to the
Location Server (LS) in the Geopriv terminology.
WR - Watcher / Recipient: The WR represents the Location Recipient
(LR) in the Geopriv terminology.
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
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 Geopriv 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
As the Geopriv 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
We make no assumption as to how rules are conveyed to entities within
the network. Purely as examples, we below describe a few plausible
options. None of the rule elements depend on the properties of how
rule sets are conveyed to an LS or LR. Mechanisms may allow partial
updates of rule sets. A partial update is an update which modifies
only parts of the rule set in contrast to a full update. To simplify
such partial updates, each rule is labelled with an identifier (see
[I-D.ietf-geopriv-common-policy]).
Transaction semantics for policy rule updates are not required since
'permit only' and 'additive permissions' properties have to be used.
These properties also prevent inconsistency during concurrent query
and update operations.
4.1 HTTP
A rule set could be uploaded to the LS via an HTTP POST operation or
more fully-featured WEBDAV [RFC2518]. Each rule could be modeled as
a single 'file', with the rule identifier as a file name. (Since
multiple rules may have the LR identity in the condition part of the
rule, the LR identity cannot be used.) One example of this approach
includes XCAP[I-D.ietf-simple-xcap].
The rule set can also be referenced from within a location object.
The attribute 'ruleset-reference' specified in Section 2.2.2 of
[I-D.peterson-geopriv-pres] contains an URI that indicates where a
rule set related to this object can be found. The URI MAY
alternatively use the CID URI scheme in which case it MUST denote a
MIME body carried with the Location Object by the using protocol.
4.2 SIP Message Body
The rule set can be carried, as a separate MIME message body, in the
SIP message that conveys location information from a LG (a SIP UAC)
via an LS (a SIP proxy) to an LR (a SIP UAS). The rule set would
then govern the behavior expected of the LR.
4.3 Location Object
The rule set can be carried in LOs in two ways: by reference and by
value. In either case the 'ruleset-reference' attribute inside the
LO [I-D.peterson-geopriv-pres] points to the location of the rules.
The LG or the LS can attach the rule set (or a pointer to it) to the
location object.
One of the transformations of the rule set is the removal of the rule
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set described here before further transmission. Only the whole rule
set can be removed and not individual elements (for example, some
conditions). Before transmitting the rules to the LR, the rule set
SHOULD be removed since the rule set might disclose prefences of the
rule maker which entities to trust and to which other entities no
trust is available. Revealing this information might have negative
implication for the RM itself.
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5. Securing the Location Object
The Geopriv requirements draft [RFC3693] addresses the minimal
security protection required for the LO: 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 LO also includes an attached
rule set.
Protection is likely to be necessary against adversaries who
eavesdrop on the communication between the LS and the LR or the LG
and the LS, who tamper with the LO or who replay previously recorded
LOs. Securing the communication between RM and LS depends on the
protocol which is used to perform the desired actions (e.g., https).
The communication between the LG and the LS can also be secured using
channel security.
If the LO is integrity and confidentiality-protected then the
receiving entity (LS or LR) has to be able to decrypt and to verify
the LO. Since the policy rules described in this document allow the
modification of the LO (via granularity reduction or by setting
flags), it is not possible to forward the LO without reapplying the
cryptographic protection. This is particularly true for the LS as it
is not the final consumer of the LO.
When the LS protects the LO for transmission to the LR (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 LO for multiple LRs is not
provided.
Instead of encrypting the LO, the LG could digitally sign the LO,
offering integrity, but no confidentiality. However, if the LS needs
to perform modifications on the LO, then it would have to break the
digital signature and may apply its own digital signature.
Since the LO is generally distributed to more than one LR, the LG
lacks the necessary information about the recipient and thus cannot
usually apply confidentially protection.
By default, the LS re-signs LOs if the signed LO has been modified
according to the rule set. If the LS receives an LO that it cannot
decrypt, it discards it if and only if the rule requires modification
of the content.
It remains for further study whether there should be an action that
discards an LO that is signed or encrypted and needs to be modified
according to the matching rule set.
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6. Conditions
This section describes the location-specific conditions of a rule,
namely the civil and geo-spatial location conditions.
6.1 Civil Location
The <civil-loc-condition> element matches if the current location of
the target matches all the values specified in the child elements of
this element. The <civil-loc-condition> is of the 'civilAddress'
complex type defined in Section 2.2.3 of [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 civil location of the target is not known, rules that contain
a civil location 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 country and city
level. For example, many users may not know the county for cities in
the United States.
6.2 Geospatial Location
Geospatial location conditions can be expressed by means of the
<geospatial-loc-condition> element. Such a condition makes the rule
match if the Target is currently located within the trapezoid on the
surface of the earth that is bounded by the values of longitude and
latitude elements <longitude1>, <longitude2>, <latitude1>, and
<latitude2>, regardless of the altitude value, if present; Figure 1
shows this. The northern boundary of this trapezoid is on the
latitude given by the value of the <latitude1> element
correspondingly, the southern boundary is given by the value of the
<latitude2> element. The western boundary of this trapezoid is on
the longitude given by the value of the <longitude1> element, and its
eastern boundary is on the longitude given by the value of the
<longitude2> element.
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<latitude1>
_________________________
/ \
/ \
/ _________ \
<longitude1> / / \ \<longitude2>
/ / Target \ \
/ / \ \
/ /---------------\ \
/ \
/ \
/ \
/---------------------------------------------\
<latitude2>
Figure 1: Example Trapezoids North of the Equator
The Target knows where it is (shown as the inner trapezoid). This
trapezoid might be greater in size than the dimensions of the Target
due to precision of the measuring device issues. The rule is a match
if the outer trapezoid completely encloses the inner trapezoid.
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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 LS
MUST execute after having received from a LR a location data access
request that matches all conditions of this rule. Transformations
exclusively specify LS-side operations that lead to a modification of
the location data items requested by the LR. Actions, on the other
hand, specify all remaining types of operations the LS 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
In addition to the transformations below, the LS MAY translate, add
or remove location information. For example, they may add timezone
information based on civil information.
All transformations are privacy-safe, i.e., if a transformation is
NULL (i.e., if the attribute is not present or empty in a policy
rule), the LS removes the corresponding location information from the
LO and leaves the LO flags undisturbed.
Extensions to this document may define other transformations.
8.1 Set D (Distribute) Flag
This transformation sets the D flag in the location object to either
'true' or 'false'. A value of 'true' means the recipient of the LO
is allowed to further distribute it. A value of 'false' prevents
further distribution.
The value NULL keeps the D flag in the LO as is. The default value
is 'false'.
8.2 Set R (Retention) Time
The retention transformation sets the retention value in the location
object to the current time plus the time provided in the element,
measured in seconds.
The value NULL keeps the retention time in the LO as is. If the LO
did not contain a value then the LS sets it to a configured default
value.
8.3 Keep Rule (RR)
If the Keep Rule (RR) flag is set, any extended rules included in the
location object are kept.
8.4 Provide Civil Location
The Provide Civil Location transformation restricts the civil
location to one of six levels, from lowest to highest: null, country,
region, city, building, full. 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 civil location data as shown below.
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If this action is NULL, all civil information is removed from the LO.
The values for this attribute are used in the following hiearchy:
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'
{}
8.5 Provide Geospatial Location
The Provide Geospatial Location transformation restricts the
resolution of the geospatial location information to the number of
bits provided, separately for longitude and latitude, and altitude
(if present) . The default value is zero.
For purposes of this transformation, longitude and latitude are
treated as a 34 bit fixed point value consisting of 9 bits of integer
and 25 bits of fraction. Altitude is treated as a fixed-point 22-bit
integer part with a 8-bit fraction, measured in meters. This
corresponds to the representation in [RFC3825], but does not
constrain the representation in the location object.
Longitude, latitude and altitude are not to be conveyed in is 2s-
complement form in the this text based protocol, but rather in
decimal form for easier reading. Conversation between the two forms
is for resolution altering. For example (as given in the appendix of
[RFC3825], the civic address of the White House in Washington, DC
(US) is:
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White House
1600 Pennsylvania Ave. NW
Washington, DC 20006
which is equivalent to the coordinates (using the WGS84 datum):
Latitude 38.89868 degrees North (or +38.89868 degrees)
Using 2s complement, 34 bit fixed point, 25 bit fraction
Latitude = 0x04dcc1fc8,
Latitude = 0001001101110011000001111111001000
Longitude 77.03723 degrees West (or -77.03723 degrees)
Using 2s complement, 34 bit fixed point, 25 bit fraction
Longitude = 0xf65ecf031,
Longitude = 1101100101111011001111000000110001
All three values above (each for latitude and for longitude) are
equivalent (barring rounding). Using 2 forms that are of the same
representation (decimal, hex and 2s-complement binary), the size of
the point a numbering pair represent is approximately 3.11mm by
2.62mm. When reducing the resolution of the 'point' one is
conveying, reducing the length of the raw binary number increases the
size of the point (to the point of not being a point, but a square
with an upper and lower bound to all that is within this area).
For example, if
o the resolution were reduced (here using the LaRes and LoRes values
within the DHCP Option) to 22 (0x16 or 010110), for each - it
would describe a geo-location area that is latitude 38.896816
north to latitude 38.8985596 and extends from -77.0372314 degrees
to -77.0371094 degrees longitude. This is an area of
approximately 143 square meters (10.5m x 13.6m).
o the resolution were reduced (here using the LaRes and LoRes values
within the DHCP Option) to 18 (0x12 or 010010), for each - it
would describe a geo-location area that is latitude 38.8984375
north to latitude 38.9003906 and extends from -77.0390625 degrees
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to -77.0371094 degrees longitude. This is an area of
approximately 36,600 square meters (169m x 217m).
o the resolution were reduced (here using the LaRes and LoRes values
within the DHCP Option) to 5 (0x05 or 000101), for each - it would
describe a geo-location area that is latitude 32 north of the
equator to latitude 48 and extends from -64 degrees to -80 degrees
longitude. This is approximately an east-west boundary of a time
zone, an area of approximately 700,000 square nm.
All 3 examples above were from the same 3.11mm x 2.62mm point, merely
with a reduced resolution.
The altitude value was not adjusted in any example. It is:
Altitude 15 (meters is the unit) being precise for the White
House.
If the transformation value is NULL, all geospatial location
information is removed from the LO.
8.6 Provide Timezone Flag
The 'Provide Timezone' transformation indicates the inclusion or
removal of timezone information of the target, i.e., the offset from
UTC. The value of 'false' causes timezone information to be excluded
from the LO.
If the transformation value is NULL, all timezone information is
removed from the LO.
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9. Example
The example of this section illustrates a rule set with a single
rule. The conditions given in this rule match to a location
requestor named ted@example.com (provided as a SIP URI in our
example). The rule is valid for one year (2003-10-01 to 2004-10-01).
Requests only match if the target is at his main office in a Siemens
site in Munich. This is specified by means of the content of the
<civil-loc-condition> element. The syntax of this content complies
with the 'civilAddress' complex type defined in Section 2.2.3 of
[I-D.ietf-geopriv-pidf-lo]. The <transformations> section indicates
that all civil location information is provided to the location
requestor. The distribution flag is set to 'false' and the rules
included in the LO are left unmodified.
<?xml version="1.0" encoding="UTF-8"?>
<common-policy:ruleset
xmlns:geopriv-policy="urn:ietf:params:xml:ns:geopriv-policy"
xmlns:common-policy="urn:ietf:params:xml:ns:common-policy"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"urn:ietf:params:xml:ns:geopriv-policy geopriv-policy01.xsd
urn:ietf:params:xml:ns:common-policy common-policy00.xsd">
<common-policy:rule id="AA56i09">
<common-policy:conditions>
<common-policy:validity>
<common-policy:from>2003-10-01T17:00:00+01:00
</common-policy:from>
<common-policy:to>2004-10-01T00:00:00+01:00
</common-policy:to>
</common-policy:validity>
<geopriv-policy:civil-loc-condition>
<country>DE</country>
<A1>Bavaria</A1>
<A3>Munich</A3>
<A4>Perlach</A4>
<A6>Otto-Hahn-Ring</A6>
<HNO>6</HNO>
</geopriv-policy:civil-loc-condition>
</common-policy:conditions>
<common-policy:actions> </common-policy:actions>
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<common-policy:transformations>
<geopriv-policy:civil-loc-transformation>full
</geopriv-policy:civil-loc-transformation>
<geopriv-policy:set-distribution>false
</geopriv-policy:set-distribution>
<geopriv-policy:keep-rules>true</geopriv-policy:keep-rules>
</common-policy:transformations>
</common-policy:rule>
</common-policy:ruleset>
In case of a policy consisting of more than one rule and a request
for location information that let multiple rules match, there must be
a procedure for combining the permissions contained in the matching
rules. This procedure is defined in
[I-D.ietf-geopriv-common-policy], Section 10.
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10. XML Schema
This section specifies an XML schema for the authorization policies
described in the previous sections. The Geopriv 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 (once again,
see[I-D.ietf-geopriv-common-policy]). This way, the Geopriv policy
markup language specializes the common rules markup language towards
location-based presence information. To this end, the following
schema imports the vocabulary of the common policy markup language.
Furthermore, to express civil location information, it imports the
'civilAddress' complex type as defined in section 2.2.3
of[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="cp00.xsd"/>
<xs:import
namespace="urn:ietf:params:xml:ns:pidf:geopriv10:civilLoc"
schemaLocation="civilLoc.xsd"/>
<!-- Geopriv conditions -->
<xs:element name="civil-loc-condition" type="cl:civilAddress"
substitutionGroup="cp:condition"/>
<xs:element name="geospatial-loc-condition"
substitutionGroup="cp:condition">
<xs:complexType>
<xs:all>
<xs:element name="longitude1" type="xs:double"/>
<xs:element name="longitude2" type="xs:double"/>
<xs:element name="latitude1" type="xs:double"/>
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<xs:element name="latitude2" type="xs:double"/>
</xs:all>
</xs:complexType>
</xs:element>
<!-- Geopriv transformations -->
<xs:element name="civil-loc-transformation"
substitutionGroup="cp: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="set-retention" type="xs:integer"
substitutionGroup="cp:transformation"/>
<xs:element name="set-distribution" type="xs:boolean"
substitutionGroup="cp:transformation"/>
<xs:element name="keep-rules" type="xs:boolean"
substitutionGroup="cp:transformation"/>
<xs:element name="longitude-resolution" type="xs:integer"
substitutionGroup="cp:transformation"/>
<xs:element name="latitude-resolution" type="xs:integer"
substitutionGroup="cp:transformation"/>
<xs:element name="altitude-resolution" type="xs:integer"
substitutionGroup="cp:transformation"/>
<xs:element name="provide-timezone" type="xs:boolean"
substitutionGroup="cp:transformation"/>
</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. Requirements are addressed in [RFC3693].
Section 5 addresses issues of protecting the policy rules within the
LO and location information itself. Aspects of combining permissions
in a privacy-safe fashion are illustrated in Section 8.
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12. References
12.1 Normative References
[I-D.ietf-geopriv-common-policy]
Schulzrinne, H., Morris, J., Tschofenig, H., Cuellar, J.,
Polk, J. and J. Rosenberg, "A Document Format for
Expressing Privacy Preferences",
draft-ietf-geopriv-common-policy-01 (work in progress),
July 2004.
[I-D.ietf-geopriv-pidf-lo]
Peterson, J., "A Presence-based GEOPRIV Location Object
Format", draft-ietf-geopriv-pidf-lo-01 (work in progress),
February 2004.
[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
[I-D.ietf-geopriv-dhcp-civil]
Schulzrinne, H., "Dynamic Host Configuration Protocol
(DHCPv4 and DHCPv6) Option for Civic Addresses",
draft-ietf-geopriv-dhcp-civil-02 (work in progress), March
2004.
[I-D.ietf-simple-xcap]
Rosenberg, J., "The Extensible Markup Language (XML)
Configuration Access Protocol (XCAP)",
draft-ietf-simple-xcap-02 (work in progress), February
2004, <reference.I-D.ietf-simple-xcap.xml>.
[I-D.peterson-geopriv-pres]
Peterson, J., "A Presence Architecture for the
Distribution of Geopriv Location Objects",
draft-peterson-geopriv-pres-00 (work in progress),
February 2003.
[RFC2518] Goland, Y., Whitehead, E., Faizi, A., Carter, S. and D.
Jensen, "HTTP Extensions for Distributed Authoring --
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WEBDAV", RFC 2518, February 1999.
[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
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
Hannes Tschofenig
Siemens
Otto-Hahn-Ring 6
Munich, Bayern 81739
Germany
EMail: Hannes.Tschofenig@siemens.com
URI: http://www.tschofenig.com
Jorge R. Cuellar
Siemens
Otto-Hahn-Ring 6
Munich, Bayern 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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Appendix A. Contributors
We would like to thank Christian Guenther for his help with the XML
schema in this document.
Christian Guenther
Siemens AG
Corporate Technology
81730 Munich
Email: christian.guenther@siemens.com
Germany
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Appendix B. Acknowledgments
This document is partially based on the discussions within the IETF
GEOPRIV working group. Discussions at the Geopriv Interim Meeting
2003 in Washington, D.C. helped the working group to make progress
on the authorization policies based on the discussions among the
participants.
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 time discussing a
number of details with us. They helped us to improve the quality of
this document.
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