Geopriv H. Tschofenig Internet-Draft Siemens Expires: April
5,21, 2005 F. Adrangi Intel A. Lior M. Jones Bridgewater October 5,21, 2004 Carrying Location Objects in RADIUS draft-ietf-geopriv-radius-lo-00.txtdraft-ietf-geopriv-radius-lo-01.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 5,21, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract This document describes RADIUS attributes for conveying the Access Network's operational ownership and location information based on a civil and geospatial location locationformat. The distribution of location information is privacy sensitive. Dealing with mechanisms to preserve the user's privacy is important and addressed in this document. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 43 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 54 3. Delivery Methods for Location Information . . . . . . . . . . 65 3.1 Authentication/Authorization Phase Delivery . . . . . . . 65 3.2 Mid-session Delivery . . . . . . . . . . . . . . . . . . . 76 4. Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . 98 4.1 Use CaseScenario 1 - Use of Location Information in AAA . . . . . 98 4.2 Scenario 2 - Use of Location Information for other Services . . . . . . . . . . . . . . . . . . . . . . . . . 98 5. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 1110 5.1 Operator-Name Attribute . . . . . . . . . . . . . . . . . 1110 5.2 Location-Information Attribute . . . . . . . . . . . . . . 1110 5.2.1 Civil Location Information . . . . . . . . . . . . . . 1211 5.2.2 Geospatial Location Information . . . . . . . . . . . 1412 6. Basic- and Extended-Policy-Rule Attributes . . . . . . . . . . 1514 7. Location-Type Attribute . . . . . . . . . . . . . . . . . . . 1615 8. Billing-Description Attribute . . . . . . . . . . . . . . . . 17 9.Diameter RADIUS Interoperability . . . . . . . . . . . . . . . 18 10.16 9. Attributes . . . . . . . . . . . . . . . . . . . . . . . . . 19 10.1. 17 9.1 Operator-Name Attribute . . . . . . . . . . . . . . . . . 19 10.217 9.2 Location-Information Attribute . . . . . . . . . . . . . . 19 10.317 9.3 Basic Policy Rules Attribute . . . . . . . . . . . . . . . 23 10.421 9.4 Extended Policy Rules Attribute . . . . . . . . . . . . . 24 10.522 9.5 Location-Type Attribute . . . . . . . . . . . . . . . . . 25 10.6 Billing-Description Attribute . . . . . . . . . . . . . . 25 11.23 10. Table of Attributes . . . . . . . . . . . . . . . . . . . . 26 12.24 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . 27 13.25 12. Matching with Geopriv Requirements . . . . . . . . . . . . . 28 13.126 12.1 Distribution of Location Information at the User's Home Network . . . . . . . . . . . . . . . . . . . . . . . 28 13.226 12.2 Distribution of Location Information at the Visited Network . . . . . . . . . . . . . . . . . . . . . . . . . 29 13.327 12.3 Requirements matching . . . . . . . . . . . . . . . . . . 30 14.28 13. Example . . . . . . . . . . . . . . . . . . . . . . . . . . 35 15.33 14. Privacy Considerations . . . . . . . . . . . . . . . . . . . 36 15.134 14.1 Entity in the visited network . . . . . . . . . . . . . . 36 15.234 14.2 Entity in the home network . . . . . . . . . . . . . . . . 37 16.35 15. Security Considerations . . . . . . . . . . . . . . . . . . 40 17.38 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 43 18.41 17. References . . . . . . . . . . . . . . . . . . . . . . . . . 44 18.142 17.1 Normative References . . . . . . . . . . . . . . . . . . . . 44 18.242 17.2 Informative References . . . . . . . . . . . . . . . . . . . 4442 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 4644 Intellectual Property and Copyright Statements . . . . . . . . 4745 1. Introduction Wireless LAN (WLAN) Access Networks (AN) are being deployed in public places such as airports, hotels, shopping malls, and coffee shops by a diverse set of incumbentoperators such as cellular carriers (GSM and CDMA), Wireless Internet Service Providers (WISP), and fixed broadband operators. When a user executes the network access authentication procedure to such a network, information about the location and operational ownership of this network needs to be conveyed to the users'suser's home network to which the user has a contractal relationship. The main intent of this document is to enable location aware billing (e.g., determine the appropriate tariff and taxation),taxation in dependence of the location of the access network/user), location aware subscriber authentication and authorization for roaming environments and to enable location aware services. This document describes AAA attributes that are used by a AAA client or a local AAA server in an access network for conveying location-related information to the user's home AAA server. This document defines attributes for RADIUS . Although the proposed attributes in this draft are intended for wireless LAN deployments, they can also be used in other wireless and wired networks where location-aware services are required. Location information needs to be protected against unauthorized access and distribution to preserve privacy of the owner ofthe user's privacy with regard to location information. With  requirements for a protocol-independent model for the access to geographic location information was defined. The model includes a Location Generator (LG) that creates Location Information,location information, a Location Server (LS) that authorizes access to Location Information,location information, a Location Recipient (LR) that requests and receives information, and a Rule Maker (RM) that provides authorization policies to the LS which enforceenforces access control policies on accessrequests to location information of a target. 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 . RADIUS specific terminology is reused from  and . Terminology related to privacy issues, location information and authorization policy rules are taken from . 3. Delivery Methods for Location Information Location Infomation Objects defined in this documentObjects, which consist of location information and privacy rules, are transported over the RADIUS protocol from visited access network to the home AAA server. The informationTo embedd a Location Object into RADIUS a number of AVPs are used, such as Location-Information AVP, Basic-Policy-Rules AVP, Extended-Policy-Rules AVP, Location-Type AVP and Operator-Name AVP. These AVPs can be delivered to the RADIUS server during the authentication/authorization phase described in Section 3.1, or in the mid-session using the dynamic authorization protocol framework described in Section 3.2. This section describes messages flow for both delivery methods. 3.1 Authentication/Authorization Phase Delivery Figure 1 shows an example message flow for delivering Location Informationlocation information during the network access authentication/authorization procedure. Upon a network authentication request from an access network client, the NAS submits a RADIUS Access-Request message which contains location information attributes among other required attributes. The authentication and/or authorization procedure is completed based on a number of criteria, including the newly defined Location-Information, Operator-Name, Location-Type, Policy-Information attributes. A RADIUS Accounting Request message is againalso allowed to carry location specific attributes. +---------+ +---------+ +---------+ | Access | | Network | | AAA | | Network | | Access | | Server | | Client | | Server | | | +---------+ +---------+ +---------+ | | | | Authentication phase | | | begin | | |---------------------->| | | | | | | | | | RADIUS | | | Access-Request | | | + Location-Information | | | attributes | | |----------------------------->| | | | : : : : Multiple Protocol Exchanges to perform : : Authentication, Key Exchange and Authorization : : ...continued... : : : ...continued... :: | | | |RADIUS | | | Access-Accept | | | + Rule set Information | | |<-----------------------------| | Authentication | | | Accept | | |<----------------------| | | | | | | RADIUS | | | Accounting Request | | | + Location-Information | | | attributes | | |----------------------------->| | | | Figure 1: Message Flow: Authentication/Authorization Phase Delivery 3.2 Mid-session Delivery Mid-session delivery method uses the Change of Authorization (COA) message as defined in . In accordance to , atAt anytime during the session the AAA server may send the access network a COA message containing session identification attributes (see  for the possible options).attributes. The COA message may instruct the access network to generate an Authorize-Only Access-Request (Access-Request with Service-Type set to "Authorize-Only") in which case it is instructing the access network to send the location information attributes. Figure 2 shows the approach graphically. Access network AAA server | | | COA + Service-Type "Authorize Only" | |<----------------------------------------------| | | | COA NAK + Service-Type "Authorize Only" | | + Error-Cause "Request Initiated" | |---------------------------------------------->| | | | Access-Request + Service-Type "Authorize Only"| | + Location Information attributes | | + Location Information policy | |---------------------------------------------->| | | | Access-Accept | |<----------------------------------------------| | | Figure 2: Message Flow: Mid-session Delivery Upon receiving the Authorize-Only message from the Accessaccess network, the AAA server MUST respond with either an Access-Accept message or an Access-Reject message. 4. Scenarios In the following subsections we describe two scenarios for use of location information. The location infomration may refer to network or user location information which in some cases may be identical. How the network obtains the user's location information is out of scope of this document. There are two consumers of the location information: the AAA servers and other location-based services. The privacy implications of these scenarios are described in Section 15.14. 4.1 Use CaseScenario 1 - Use of Location Information in AAA An OperatorThe home network operator requires Location Informaionlocation informaion for Authorizationauthorization and Billingbilling purposes. The operator may deny service if Location Informationlocation information is not available. Or it may offer limited service. The NAS delivers Location Informationlocation information to the Homehome AAA server. The user's location is transferred from the NAS to the RADIUS server and theserver. The NAS and intermediaries (if any) are not allowed to use that information other then to forward it to the home network. The RADIUS server authenticates and authorizes the session. If the user's location policies are available to the RADIUS server, the RADIUS server maymust deliver those policies in an Access Accept.Accept to the RADIUS client. This information may be needed if intermediaries or other elements want to act as Location Servers (see Section 4.2). In the absence of receiving the policies intermediaries MUST NOT divulge the location information. Location Information may also be reported in accouning messages. Accounting messages are generated when the session starts, stops and periodically. Accounting messages may also be generated when the user roams during handoff. This information may be needed by the billing system to calculate the usersuser's bill. For example, there may be different tarrifa rates applied based on the location and their maybethere may be different tax rates applied based on the location. Unless otherwise specified,specified by authorization rules, location information in the accounting stream may not be transmitted to third parties. The location information in the accounting stream MUST only be sent in the proxy chain to the home network (unless specified otherwise). 4.2 Scenario 2 - Use of Location Information for other Services Location Servers are entities that receive the user's location information and transmit it to other entities. For the purpose ofIn this scenariosecond scenario, Location servers areServers comprise also the NAS,NAS and RADIUS servers.server roles. The RADIUS servers are in the home network, in the visited network, or in broker networks. Unless otherwise specified, excludingThe Location Server MUST NOT transmit location information to parties other than members of the proxy chain from the NAS to the Home RADIUS, the Location Server may not transmit the location information to other parties.home RADIUS server. Upon authentication and authorization, the Homehome RADIUS mayserver must transmit the Rule setruleset (if available) in an Access-Accept to the other Location Server allowing them to transmit Location Information. Then and only then theyAccess-Accept. The RADIUS client, intermediate proxies are allowed to share the information.location information if they received ruleset indicates that it is allowed. Note that the NAS is the source of all Location Informationlocation information that is disseminated by RADIUS, the NAS could tag the Location Informationlocation information with the policy rules or a reference for the policy rules received in an Access-Accept. All Location Informationlocation information in the accounting stream will now be tagged. 5. Overview Location Informationinformation and operationalownership of the access network is conveyed in the following RADIUS attributes: Operator-Name, Location-Information, Location-TypeLocation-Information and Billing-Description.Location-Type. Furthermore, the Basic-Policy-Rules and the Extended-Policy-Rules attributes are attached to the Location-Information attribute turning Location Informationlocation information into a Location Object as defined in . 5.1 Operator-Name Attribute This attribute contains an operator name which uniquely identifies the ownership of an access network. The Attributeattribute value is a non-NULL terminated string whose Length MUST NOT exceed 253 bytes. The attribute value is comprised of thea prefix and thean identity, separated by a colon. The prefix identifies the operator type; example: GSM, CDMA, and REALM. The identity uniquely identifies the operator name within the scope of the operator type. As an example consider the string 'GSM:TADIG' where GSM is a prefix indicating an operator type and TADIC is a unique globally known GSM operator ID. This document defines three operator type prefixes which are: GSM, CDMA, and REALM. The GSM prefix can be used to indicate operator names based on GSMA TADIG codes. REALM can be used by any domain name acquired from IANA. Possible forthcoming operator types MUST be associated with an ogranizationorganization responsible for assigning/managing operator names. 5.2 Location-Information Attribute This document describes two formats for conveying location information: civil and geospatial location information. Section 5.2.1 defines the civil location information format. Section 5.2.2 defines the geospatial location information format. Additionally, a few additionalthe following fields provide more details about the transmitted Location Information.location information. The 'Precision' field provides information aboutof the accuracy about the provided Location Information. When the user's home network receives a Location Object within RADIUS then this field gives further indication about the accuracy.location information. Location information can refer to the Access Point, the user, the or the RADIUS server or the network itself. With large networks the Location Informationlocation information of each of these entities might be different. The 'Precision' field allows to give a hint about the precision of the provided location information. The 'Method' field describes the way that the location information was derived or discovered. Possible values for this field include, as an example GPS or manual configuration. The inclusion of this field should help the user's home network deduce further information about the accuracy and to provide an easier translation into a GeoprivLocation Object for transmission to third party entities.entities (e.g., using SIP). Note that the values for this field are reused from . 5.2.1 Civil Location Information Civil location is a popular way to describe the location of an entity. Using an unstructured (as a text string) or a custom format for civil location format is dangerous since the automatic processing capabilities are limited. For this documentdocument, we reuse the civil location format defined in . The civil location format includes a number of fields, including the country (expressed as a two-letter ISO 3166 code) and the administrative units of A1 through A6.A6 of  . This designation offers street-level precision. For completeness we include more detailed information from  with regard to the defined civil location elements (A1 through A6):elements: +----------------------+----------------------+---------------------+ | Label | Description | Example | +----------------------+----------------------+---------------------+ | country | The country is | US | | | identified by the | | | | two-letter ISO 3166 | | | | code. | | | | | | | A1 | national | New York | | | subdivisions (state, | | | | region, province, | | | | prefecture) | | | | | | | A2 | county, parish, gun | King's County | | | (JP), district (IN) | | | | | | | A3 | city, township, shi | New York | | | (JP) | | | | | | | A4 | city division, | Manhattan | | | borough, city | | | | district, ward, chou | | | | (JP) | | | | | | | A5 | neighborhood, block | Morningside Heights | | | | | | A6 | street | Broadway | | | | | | PRD | Leading street | N, W | | | direction | | | | | | | POD | Trailing street | SW | | | suffix | | | | | | | STS | Street suffix | Avenue, Platz, | | | | Street | | | | | | HNO | House number, | 123 | | | numeric part only. | | | | | | | HNS | House number suffix | A, 1/2 | | | | | | LMK | Landmark or vanity | Low Library | | | address | | | | | | | LOC | Additional location | Room 543 | | | information | | | | | | | FLR | Floor | 5 | | | | | | NAM | Name (residence, | Joe's Barbershop | | | business or office | | | | occupant) | | | | | | | PC | Postal code | 10027-0401 | +----------------------+----------------------+---------------------+ Table 1 Additional CA types are definedMore description of these civil location elements can be found in Section 3.4 of . These types are usefulelements can be used to express further information about the location, language specific settings via the 'language' item and encoding information via the 'script' item. Section 1413 shows usage examples of this attribute. All attributes are optional and can appear in any order. The values are encoded using UTF-8 . 5.2.2 Geospatial Location Information This document reusingreuses geospatial location information from  which defines latitude, longitude, and altitude, with resolution indicators for each. The value in the Altitude field either indicates meters or floors (via the Altitude Type field). As a coordinate reference system Section 2.1 of  defines (via extensible mechanism using IANA registration) three values in the Datum field: WGS 84, NAD 83 (with the associated vertical datum for the North American Vertical Datum of 1988), NAD 83 (with the associated vertical datum for the Mean Lower Low Water (MLLW). WGS 84 is used by the GPS system. During a protocol run it is possible to return Location-Information attributes which provide both location information elements. If only one location information element is provided then civil location MUST be included in the request. Additionally, geospatial location MAY be provided. 6. Basic- and Extended-Policy-Rule Attributes In some environments it is possible for the user to attach information about its privacy preferences. These preferences allow the visited network, intermediate RADIUS proxies and the home network to authorize the distribution of the user's location information. Without the user providing authorization information two approaches are possible: o The user hides its location information from the access network and from intermediate networks using the appropriate network access authentication mechanism. Section 1514 discusses these issues in more details. o The access network attaches default authorization policies which prevents intermediate networks and the home network to distribute the location information to other entities. Additionally, the home network might have authorization policies which control distribution of location information. Users can dynamically change their policies using the authroization framework defined in  and . With regard to authorization policies this document reuses work done in  and encodes it in an non-XML format. Two fields ('sighting time' and 'time-to-live') are additionally included in the Location-Information attribute to conform to the Geopriv Requirements , Section 2.7. Two RADIUS attributes are used for this purpose: Basic-Policy-Rule and Extended-Policy-Rule attribute;attribute. The Basic-Policy-Rule attribute contains a fixed set of privacy relevant fields whereas the Extended-Policy-Rule attribute contains a reference to a more extensive authorization rule set. 7. Location-Type Attribute This document defines a separate attribute for the type of the location. Instead of the values of the 'type-of-place' attribute defined in Section 4.6 of  which is reused by  we define our own list of values for the Location-Type attribute. The reason for this is given by the size constraints of the attribute, dependence to other documents and to the location names required for the RADIUS context. Consequently, CA type '25' which equals the placetype is not used in the Location-Information attribute as described in Section 5.2. 0 Reserved 1 Coffee Shop 2 Hotel 3 Airport 4 Mall 5 Restaurant 6 Bus 7 Library 8 Convention Center 9 School 10 Office 11 Airplane 12 Train 13 Ship 14 Educational Institute 15 Public Place 16 Other Using these attribute types it is possible to describe the area in more detail. 8. Billing-Description Attribute The Billing-Description Attribute contains unstructured text to be printed on the users bill. 9.Diameter RADIUS Interoperability In deployments where bothRADIUS clients talkingtalk with Diameter ServersDIAMETER servers or Diameter Client talkingDIAMETER clients talk with RADIUS serverservers then a translation agent will be deployed and operate in accordance to the NASREQ specification . 10.9. Attributes This section defines attributes for access network operational ownership, Location Name, Location Informationthe Operator-Name AVP, Location-Information AVP, Basic Policy Rules AVP, Extended Policy Rules AVP and Billing Description. 10.1the Location-Type AVP. 9.1 Operator-Name Attribute Operator-Name Attribute SHOULD be sent in Access-Request, and Accounting-Request records where the Acc-Status-Type is set to Start, Interim, or Stop. A summary of the Operator-Name Attribute is shown below. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Operator-Name ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: To Be Assigned by IANA - Operator-Name Length: >= 3 Bytes Operator-Name: The text field contains an Access Network Operator Name in prefix-based format as describe above.format. Example: REALM:anyisp.com 10.29.2 Location-Information Attribute Location-Information attribute SHOULD be sent in Access-Request, and Accounting-Request records where the Acc-Status-Type is set to Start, Interim or Stop if available. The Location-Information Attribute has two variations depending on civil or geospatial location information. The format is shown below. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Code | Precision | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sighting Time ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sighting Time | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Time-to-Live ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Time-to-Live | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Method | Location-Info ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type (8 bits): To Be Assigned by IANA - Location-Information Length (8 bits): >= 3 Bytes Code (8 bits): Describes which location format is carried in this attribute: (0) describes civil location information (1) describes geospatial location information All other bites of the Code field is reserved and required for alignment. Precision (8 bits): Describes which location this attribute refers to: (0) describes the location of the NAS (1) describes the location of the AAA server (2) describes the location of the end host (user) (3) describes the location of the network Sighting Time (64 bits): NTP timestamp for the 'sighting time' field. Time-to-Live (64 bits): NTP timestamp for the 'time-to-live' field. Method (8 bits): Describes the way that the location information was derived or discovered. The following values are currently defined: (0) Global Positioning System (GPS) (1) GPS with assistance (A-GPS) (2) Manual configured information (3) Provided by DHCP (4) Triangulation: triangulated from time-of-arrival, signal strength or similar measurements (5) Cell: location of the cellular radio antenna (6) IEEE 802.11 WLAN access point Location-Info (variable): Contains either civilcivic or geospatial location information attributes. The following two fields need some explanation: sighting time: This field indicates when the Location Information was accurate. The data type of this field is a string and the format is a 64 bit NTP timestamp . time-to-live: This field gives a hint until when it should be considered current. Note that the time-to-live field is different than the 'retention-expires' rule. The data type of this field is a string and the format is a 64 bit NTP timestamp . For civil location information the Location-Info field in the above structure is defined as followed: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Countrycode | Civic address elements ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Countrycode (16 bits): Two-letter ISO 3166 country code in capital ASCII leters.letters. Civic address elements (variable): The text field contains location information element. The format of the civic address elements is described in Section 3.3 of  with a TLV pair (whereby the Type and Length fields are one-octedone-octet long). An example is given in Section 14.13. For geospatial location information the Location-Info field is defined as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LaRes | Latitude + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Latitude | LoRes | Longitude + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Longitude | AT | AltRes | Altitude + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Altitude | Datum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ LaRes (6 bits): Latitude resolution Latitude (34 bits) LoRes (6 bits): Longitude resolution. Longitude (34 bits) Altitude (30 bits) AltRes (6 bits): Altitude resolution AT (4 bits): Altitude Type for altitude. The following codes are defined: (1) Meters (2) Floors Datum (8 bits): Coordinate reference system The following codes for the this field are defined: (1) WGS 84 (2) NAD 83 (with the associated vertical datum for the North American Vertical Datum of 1988) (3) NAD 83 (with the associated vertical datum for the Mean Lower Low Water (MLLW)) The length of the Location-Information Attribute MUST NOT exceed 253 octets. The length of the geospatial location information format is fixed with 16 bytes plus a four byte header. The Datum field contains an identifier for the coordinate system used to interpret the values of Latitude, Longitude and Altitude. The field with value (2) and the value (3) both represent the NAD 83 coordinate reference system but they differ from each other with regard to their vertical datum representation as briefly noted in Section 5.2.2 and described in more detail in . 10.39.3 Basic Policy Rules Attribute The Basic-Policy-Rules attribute MUST be sent in Access-Accept, Access-Challenge, Access-and Access-Reject messages if Location Informationlocation information is transmitted with this exchange. If authorization policy rules are available to the RADIUS client then the Access-Request MUST carry the Basic-Policy-Rules attribute to to the RADIUS server. A summary of the Basic-Policy-Rules attribute is shown below. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length |R| Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Retention Expires ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Retention Expires | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Note Well ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type : To Be Assigned by IANA - Basic-Policy-Rules Length: > 3 Bytes Flag (16 bits)bits): Only the first bit (R) is defined an corresponds to the retransmission-allowed field. All other bits are reserved. Retention Expires (64 bits)bits): NTP timestamp for the 'retention-expires' field. Note Well (variable) Contains(variable): This field contains a textURI with human readable privacy instructions. Its length MUST NOT exceed 64 octets. For thisThis document we reuse the followingreuses fields of the 'usage-rules' element, described in :. These fields have the following meaning: retransmission-allowed: When the value of this element is '0', then the recipient of this Location Object is not permitted to share the enclosed Location Information,location information, or the object as a whole, with other parties. The value of '1' allows to share the Location Informationlocation information with other parties by considering the extended policy rules. retention-expires: This field specifies an absolute date at which time the Recipient is no longer permitted to possess the location information. The data type of this field is a string and the format is a 64 bit NTP timestamp . note-well: This field contains a block of textURI with generichuman readable privacy directives which are human-readable only.instructions. This field is useful when Location Informationlocation information is distributed to third party entities, which can include humans in a location based service. RADIUS entities are not supposed to process this field. 10.49.4 Extended Policy Rules Attribute The Extended-Policy-Rules attribute SHOULD be sent in Access-Accept, Access-Challenge, Access-and Access-Reject messages if Location Informationlocation information is transmitted with this exchange. If authorization policy rules are available to the RADIUS client then the Access-Request MUST carry the Basic-Policy-Rules attribute to to the RADIUS server. ThisRuleset reference field of this attribute contains ais of variable length ruleset reference. This attributelength. It contains a URI that indicates where a fullerricher ruleset of policies related to this object can be found.is available. The full ruleset SHOULD be fetched using Transport Layer Security (TLS). As a deviation from  this field only contains a reference and does not carry an attached rule set. This modification is motivated by the size limitations imposed by RADIUS. A summary of the Extended-Policy-Rules attribute is shown below. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Ruleset reference ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type : To Be Assigned by IANA - Extended-Policy-Rules Length: > 3 Bytes Ruleset reference: The text field contains a reference to the policy rules (see 'usage-rules' field description). Its length MUST NOT exceed 64 octets. 10.5rules. 9.5 Location-Type Attribute Location-Type Attribute SHOULD be sent in Access-Request, and Accounting-Request records where the Acc-Status-Type is set to Start, Interim, or Stop if available. A summary of the Location-Type Attribute is shown below. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Loc-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type (8 bits): To Be Assigned by IANA - Location-Name Length (8 bits): 4 Bytes Loc-Type (16 bits): The content of this field corresponds to the integer codes for access network location type. 10.6 Billing-Description Attribute The Billing-Description attribute contains unstructured text to be printed on the users bill. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Billing-Text ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type (8 bits): To Be Assigned by IANA - Billing-Description Length (8 bits): >= 3 Bytes Billing-Text (variable): The content of this field contains textThese integer codes for billing purpose. The length ofthe Billing-Description attribute MUST NOT exceed 32 octets. 11.location type can be found in Section 7. 10. Table of Attributes The following table provides a guide towhich attributes may be found in which kinds of packets,RADIUS messages, and in what quantity. Request Accept Reject Challenge Accounting # Attribute Request 0-1 0 0 0 0-1 TBD Operator-Name 0+ 0 0 0 0+ TBD Location-Information 0-1 0-1 0-1 0-1 0-1 TBD Basic-Policy-Rules 0-1 0-1 0-1 0-1 0-1 TBD Extended-Policy-Rules 0-1 0 0 0 0-1 TBD Location-Type 0-1 0 0 0 0-1 TBD Billing-DescriptionThe Location-Information attribute may appear more than once. This is useful if the size of one Location-Information attribute exceeds the maximum size of an AVP. This might happen in case of civil location information which has a variable number of fields. The fields used for the civil location information format of the Location-Information AVP (see Section 5.2.1 MUST NOT appear more than once. 12.11. IANA Considerations This document requires the assignment of four new RADIUS attribute numbers for the following attributes: Operator-Name Location-Information Basic-Policy-Rules Extended-Policy-Rules Location-Name Billing-DescriptionPlease refer to Section 1110 for the registered list of numbers. 13.12. Matching with Geopriv Requirements This section compares the Geopriv requirements described in  and the approach of distributing Location ObjectsObjects with RADIUS. The main usage scenario aimed for Location Object transport in RADIUS assumes that the Location Server and the Location Recipient are co-located at a single entity with RADIUS. First, we differentiate between the two scenarios inregard to location based network access authorization, taxation and billing. In Section 13.112.1 and Section 13.2. These two scenarios focus on the12.2 we discuss privacy related aspects descrbed in Section 4.implications when RADIUS is not used according to these usage scenario. In Section 13.3 then matches the12.3 Geopriv requirements are matched against these two scenarios. 13.112.1 Distribution of Location Information at the User's Home Network This paragraphsection focuses on a scenario whereby the RADIUS protocol transport iocationlocation information transport from the Location Generator (e.g.,local AAA server) toserver (acting as the Location Server (e.g.,Generator) to the home AAA server).server (acting as the Location Server). To use a more generic scenario we assume that the visited AAA and the home AAA server belong to different administrative domains. The Location Recipient obtains location information about a particular Target via protocols specified outside the scope this document (e.g., SIP, HTTP or an API). Please note that the main usage scenario defined in this document assumes that the Location Server and the Location Recipient are co-located into a single entity with regard to location based network access authorization, taxation and billing. The usage of SIP or HTTP to distribute location information to third party entities is not the main envised use case. However, the authors are aware of the fact that the user's location information might be used in a non-intended way. To reflect the users privacy even in these cases it is necessary to offer appropriate mechanisms also for this environments. The Target is the user requesting network access. Thesubsequent figure shows the interacting entities graphically. visited network | home network | | +----------+ | | Rule | | | Holder | | | | | +----+-----+ | | | rule|interface | V +----------+ | +----------+ +----------+ |Location | publication | Location | notification |Location | |Generator |<------------->| Server |<------------->|Recipient | | | interface | | interface | | +----------+ | +----------+ +----------+ | Local AAA RADIUS Home AAA SIP/HTTP/API/etc. Server | Server | Figure 15:14: Location Server at the Home Network 13.2The term 'Rule Holder' in Figure 14 denotes the entity which creates the authorization ruleset. 12.2 Distribution of Location Information at the Visited Network This paragraphsection describes a scenario which might happen during the deployment butwhere Location Information is not withindistributed by the focus of this document.visited network. In order for this scenario to be applicable a few assumptions must hold: o The visited network deploys a Location Server and wants to distribute Location Objects of a user o The visited network is able to learn the user identity of the user The visited network provides location information to a Location Recipient (e.g., via SIP or HTTP). During the network access authentication procedure the visited network is able to retrieve authorization policies of the user via RADIUS from the home AAA server. The subsequent figure shows the interacting entities graphically. The transport of the Location Object is not shown in this figure since this aspect is already covered in the previous paragraph. visited network | home network | +----------+ | |Location | | |Recipient | | | | | +----------+ | ^ | +----------+ | | | Rule | | | | Holder | notification | | | interface | +----+-----+ | | | | | rule|interface v | V +----------+ | +----------+ |Location | Rule Transport| Home AAA | |Generator |<------------->| Server | |& Server | RADIUS | | +----------+ | +----------+ | Figure 16:15: Location Server at the Visited Network 13.312.3 Requirements matching Section 7.1 of  details the requirements of a "Location Object". There are: Req. 1. (Location Object generalities): * Regarding requirement 1.1, the Location Object has to be understood by the RADIUS server (and possibly a Diameter server in case of interworking between the two) as defined in this document. Due to the encoding of the Location Object it is possible to convert it to the format used in GMLv3. The same civil location information format is used in PIDF-LO and this document. * Regarding requirement 1.2, some fields of the Location Object defined in this document are optional. See Section 5.2.1 as an example. * Regarding requirement 1.3, the inclusion of the Location-Type attribute which gives a further classification of the location. This attribute can be seen as an extension. * Regarding requirement 1.4, the Location Object is extensible in the same fashion as RADIUS is extensible. * Regarding requirement 1.5, the Location Object is useful for both receiving and sending location information as described in this document. * Regarding requirement 1.6, the Location Object contains both, location information and privacy rules. Location information is described in Section 5.2 and the corresponding privacy rules are detailed in Section 10.39.3 and in Section 10.4.9.4. * Regarding requirement 1.7, the Location Object is usable in a variety of protocols. The format of the object is reused from other documents as detailed in the respective sections (see Section 5.2, Section 10.39.3 and in Section 10.4).9.4). * Regarding requirement 1.8, the encoding of the Location Object has an emphasis on a lighweightlightweight encoding format. As such it is useable on constrained devices. Req. 2. (Location Object fields): * Regarding requirement 2.1, the Target Identifier is carried within the network access authentication protocol (e.g., within the EAP-Identity Response when EAP is used and/or within the EAP method itself). As described in Section 1514 it has a number of advantages if this identifier is not carried in clear text. This is possible with cetaincertain EAP methods whereby the identity in the EAP-Identity Response only contains information relevant for routing the response to the users home network. The true user identity is protected by the authentication and key exchange protocol. * Regarding requirement 2.2, the Location Recipient Identity is, in the main scenario the home AAA server. This entity is located using the structure of the Network Access Identifier. For a scenario where the Location Recipient is obtaining Location Information from the Location Server via HTTP or SIP the respective mechanisms defined in these protocols are used to identify the recipient. The Location Generator cannot, a priori, know the recipients if they are not defined in this protocol. * Regarding requirement 2.3, the credentials of the Location Recipient are known to the RADIUS entities based on the security mechanisms defined in the RADIUS protocol itself. Section 1615 describes these security mechanisms offered by the RADIUS protocol. The same is true for requirement 2.4. * Regarding requirement 2.5, Section 5.2 describes the content of the Location Field. Motion and direction vectors as listed in requirement 2.6 are not provided as attributes. It is, however, possible to deduce the motion and direction of an entity via the Mid-session Delivery mechanism as shown in Figure 2. * Regarding requirement 2.6, this document only describes one Location Data Type for civil and for geospatial location information, respectively. No negotiation needs to take place. * Regarding requirement 2.7, timing information is provided with 'sighting time' and 'time-to-live' field defined in Section 10.3.9.3. * Regarding requirement 2.8, a reference to an external (more detailed ruleset) is provided with the Section 10.49.4 attribute. * Regarding requirement 2.9, security headers and trailers are provided as part of the RADIUS protocol or even as part of IPsec. * Regarding requirement 2.10, a version number in RADIUS is provided with the IANA registration of the attributes. New attributes are assigned a new IANA number. Req. 3. (Location Data Types): * Regarding requirement 3.1, this document defines two Location Data Types as described in Section 5.2. * With the support of civil and geospatial location information support requirement 3.2 is fullfilled.fulfilled. * Regarding requirement 3.3, geospatial location information only supports absolute coordinates rather than a delta. However, the granualitygranularity of the location information can be reduced with the help of the AltRes, LoRes, LaRes fields described in the Location-Information attribute (see Section 10.2).9.2). * Regarding requirement 3.4, further Location Data Types can be added via new coordinate reference systems (CRSs) (see Datum field in the Location-Information attributattribute of Section 5.2), extensions to existing fields (e.g., new location types as shown in Section 7) or via additional attributes. Section 7.2 of  details the requirements of a "Using Protocol". There are: Req. 4.: The using protocol has to obey the privacy and security instructions coded in the Location Object and in the corresponding Rules regarding the transmission and storage of the LO. This document requires, that RADIUS entities sending or receiving location MUST obey such instructions. Req. 5.: The using protocol will typically facilitate that the keys associated with the credentials are transported to the respective parties, that is, key establishment is the responsibility of the using protocol. Section 1615 specifies how security mechanisms are used in RADIUS and how they can be reused to provide security protection for the Location Object. Additionally, the privacy considerations (see Section 15)14) are also applicable for this discussion. Req. 6. (Single Message Transfer): In particular, for tracking of small target devices, the design should allow a single message/packet transmission of location as a complete transaction. The encoding of the Location Object is specifically tailored towards the inclusion into a single message that even respects the (Path) MTU size. The concept of a transaction is not immediately applicable to RADIUS. Section 7.3 of  details the requirements of a "Rule based Location Data Transfer". There are: Req. 7. (LS Rules): With the scenario shown in Figure 1514 the decision of a Location Server to provide a Location Recipient access to location information is based on Rule Maker-defined Privacy Rules which are stored at the home network or are accessible for the home network. With regard to the scenario shown in Figure 1615 the Rule Maker-defined Privacy Rules are sent from the home network to the visited network as part of the Policy-Information attribute (see Section 10.3,9.3, Section 10.49.4 and Section 1514 for more details). Req. 8. (LG Rules): It is possible for the non-initial transmission (i.e., mid-session delivery) of a Location Object to enforce the users privacy rules. For the initial transmission of a Location Object the user would have to use network access authentication methods which provide user identity confidentiality which would render the Location Object completely useless for the visited network. For the scenario shown in Figure 1514 the visited network is already in possession of the users location information prior to the authentication and authorization of the user (which might require several roundtrips). A correlation between the location and the user identity might, however, still not be possible for the visited network (as explained in Section 15).14). The visited network MUST evaluate ruleset provided by the home AAA server as soon as possible. Req. 9. (Viewer Rules): The Rule Maker might define (via mechanisms outside the scope of this document) which policy rules are disclosed to other entities. Req. 10. (Full Rule language): Geopriv has defined a rule language capable of expressing a wide range of privacy rules which is applicable in this area concerning the distribution of Location Objects. A basic ruleset is provided with the Basic-Policy-Rules attribute Section 10.3.9.3. A reference to the extended ruleset is carried in Section 10.4.9.4. The format of these rules are described in  and . Req. 11. (Limited Rule language): A limited (or basic) ruleset is provided by the Policy-Information attribute Section 10.39.3 (and as introduced with PIDF-LO ). Section 7.4 of  details the requirements of a "Location Object Privacy and Security". There are: Req. 12 (Identity Protection): Support for unlinkable pseudonyms is provided by the usage of a corresponding authentication and key exchange protocol. Such protocols are available, for example, with the support of EAP as network access authentication methods. Some EAP methods support passive user identitiyidentity confidentiality whereas others even support active user identity confidentiality. This issue is further discussed in Section 16.15. The importance for user identity confidentiality and identity protection has already been recognized (see for example a document on 'EAP Method Requirements for Wireless LANs' ). Req. 13. (Credential Requirements): As described in Section 1615 RADIUS signaling messages can be protected with IPsec. This allows a number of authentication and key exchange protocols to be used as part of IKE, IKEv2 or KINK. Req. 14. (Security Features): Geopriv defines a few security requirements for the protection of Location Objects such as mutual end-point authentication, data object integrity, data object confidentiality and replay protection. As described in Section 1615 these requirements are fullfilledfulfilled with the usage of IPsec if the mutual authentication refers to the RADIUS entities (acting as various Geopriv entities) which directly communicate with each other. Req. 15. (Minimal Crypto): A minimum of security mechanisms are mandated by the usage of RADIUS. Security for Location Objects is provided by the RADIUS protocol (including IPsec and its dynamic key management framework) rather than on relying on object security via S/SIME (which is not available with RADIUS). The handling of emergency calls is not specified as part of the RADIUS protocol and subject for an architectural investigation. As such it might not even be applicable to RADIUS itself. 14.13. Example This section provides an example for a civil location information format within the Location-Information attribute. The size of the geo-spatial location information object is fixed and well-described examples can be found in the Appendix of . Due to the size limitations of the RADIUS attributes we give a more detailed example borrowed from Section 4 of . +-------------+-----------+-------------------+ | Type | Length | Value | +-------------+-----------+-------------------+ | Type | 8 bits | TBD | | Length | 8 bits | 43 | | Code | 16 bits | 1 | | Precision | 8 bits | 2 | | Countrycode | 16 bits | DE | | CAtype | 8 bits | 1 | | CAlength | 8 bits | 7 | | CAvalue | 7 bytes | Bavaria | | CAtype | 8 bits | 3 | | CAlength | 8 bits | 6 | | CAvalue | 6 byte | Munich | | CAtype | 8 bits | 6 | | CAlength | 8 bits | 11 | | CAvalue | 11 bytes | Marienplatz | | CAtype | 8 bits | 19 | | CAlength | 8 bits | 1 | | CAvalue | 1 byte | 8 | | CAtype | 8 bits | 24 | | CAlength | 8 bits | 5 | | CAvalue | 5 bytes | 80331 | +-------------+-----------+-------------------+ The Length element provides the length of the entire payload minus the length of the initial 'Type', the 'Length' and the 'Code' attribute. The Precision field has a value of '2' which refers to the location of the end host (user). The CountryCode is set to 'DE'. Note that the subsequent attributes are in Type-Length-Value format. Type '1' indicates the region of 'Bavaria', '3' refers to the city 'Munich', '6' to the street 'Marienplatz', the house number '8' is indicated by the type '19' and the zip code of '80331' is of type '24'. The total sum of these attributes is 46 bytes. 15.14. Privacy Considerations This section discusses privacy implications for the distribution of location lnformationinformation within RADIUS. In many cases the location information of the network also reveals the current location of the user with a certain degree of precision depending on the mechanism used, the positioning system, update frequence,frequency, where the location was generated, size of the network and other mechanisms (such as movement traces or interpolation). Two entities might act as Location Servers as shown in Section 4, Figure 1514 or in Figure 16: 15.115: 14.1 Entity in the visited network In this scenario it is bedifficult to obtain authorization policies from the end host (or user) immediately when the user attaches to the network. In this case we have to assume that the visited network does not allow unrestricted distribution of location information other than the intended recipients (e.g,(e.g., to third party entities) immediately. The visited network MUST behave according to the following guidelines: o Per default only the home network is allowed to receive location information. The visited network MUST NOT distribute location information to third parties without seeing the user's privacy rule se. o If the home network provides the Basic-Policy-Rules attribute either as part of the Access-Accept, the Access-Reject or the Access-Challenge message then the visited network MUST follow the guidance given with these rules. o If the home network provides the Extended-Policy-Rules attributes either as part of the Access-Accept, the Access-Reject or the Access-Challenge message then the visited network MUST fetch the full ruleset at the indicated URL and MUST follow the guidance given with these rules. o If the RADIUS client in the visited network learns the basic rule set or a reference to the extended rule set by means outside the RADIUS protocol (e.g., provided by the end host) then it MUST include the Basic-Policy-Rules and the Extended-Policy-Rules attribute in the Access-Request message towards the home AAA server. Furthermore, the visited network MUST evaluate these rules prior to the transmission of Location Informationlocation information either to the home network or a third party. The visited network MUST follow the guidance given with these rules. o If the RADIUS client in the visited network receivedreceives the Basic-Policy-Rules attribute with Access-Accept or the Access-Challenge message then the Basic-Policy-Rules MUST be attach in subsequent RADIUS messages which contain the Location-Information attribute (such as interim accounting messages). o If the RADIUS client in the visited network receivedreceives the Extended-Policy-Rules attribute with Access-Accept or the Access-Challenge message then the Basic-Policy-Rules attribute MUST be attach in subsequent RADIUS messages which contain the Location-Information attribute (such as interim accounting messages). 15.214.2 Entity in the home network The AAA server in the home network might be an ideal place for storing authorization policies. The user typically has a contractual relationship to his home network and hence the trust relationship between them are higher. Once the infrastructure is deployed and useful applications are available there might be a strong desire to use location information for other purposes as well (such as location aware applications). Authorization policy rules described in  and in  are tailored for this environment. These policies might be useful for preventing further distribution of the user's location to other location based services. The home AAA server (or a similar entity) thereby acts as a location server for access to location services. The home network MUST behave according to the following guidelines: o As a default policy the home network MUST NOT distribute the user's location information to third party entities. o If a user providedprovides basic authorization policies then these rules MUST be returned to the visited network in the Access-Accept, the Access-Reject or the Access-Challenge message. o If a user providedprovides basic authorization policies then these rules MUST be returned to the visited network in the Access-Accept, the Access-Reject or the Access-Challenge message. o If a user providedprovides extended authorization policies then they MUST be accessible for the visited networking using a reference to these rule set. The Extended-Policy-Rules attribute MUST include the reference and they MUST be sent to the visited network in the Access-Accept, the Access-Reject or the Access-Challenge message. o The home network MUST follow the user provided rule set for both local storage and for further distribution. With regard to the usage of these rules the home network MUST ensure that the users preferences are taken care of within the given boundaries (such as legal regulations or operational considerations). For example, a user might not want the home network to store information about its Location Informationlocation information beyond a indicated time frame. However, a user might on the other hand want to ensure that disputes concerning the billed amount can be resolved. Location Informationlocation information might help to resolve the dispute. The user might, for example, be able to show that he has never been at the indicated place. o If the policy rules provided by the user indicate that location information must not be distributed at all then the home network MUST provide the Basic-Policy-Rules to the RADIUS entity in the visited network via an Access-Accept, the Access-Reject or the Access-Challenge message. The RADIUS server in the user's home network would set the 'Retention-Expires' and the 'Retransmission-allowed' field to the user indicated value. and the Extended-Policy-Rules to particular recipientsFor the envisioned usage scenarios the network access authentication procedure is tighlytightly coupled to the transfer of location information. If the authentication mechanism allows the visited network or AAA brokers to learn the user's identity then it is possible to correleatecorrelate location information with a particular user. As such, it allows the visited network and brokers to learn movement patterns of users. A scenario where the user is attached to the home network is, from a privacy point of view, simpler than a scenario where a user roams into a visited network since the NAS and the home AAA are in the same administrative domain. No direct relationship between the visited and the home network operator may be available availableand some AAA brokers need to be consulted. With subscription-based network access as used today the user has a contractual relationship with the home network provider which could allow higher privacy considerations to be applied (including policy rules stored at the home network itself for the purpose of restricting further distribution). In many cases it is necessary to secure the transport of location information along the RADIUS infrastructure. Mechanism to achieve this functionality are discussed in Section 16.15. One way to ensure that the visited network and intermediate networks are incapable to learn the user identity is to use EAP methods that hide the user's identity either actively or passively. Some EAP methods (such as ) protect the user's identity against passive adversaries by utilizing temporal identities. In some cases the visited network is still able to retrieve the plaintext identity of the user and user identity confidentiality is only provided against eavesdroppers at the wireless link. Depending on the movement patters of the user, the network topology and available roaming agreements it is possible that a AAA broker is able to see both the plaintext user identity and subsequent temporal identities. Associating location information and the user identity is possible in these cases. It is assumed that the true username is not carried within the initial EAP-Identity Request/Response message exchange. Support for username privacy is supported with . For stronger security and privacy protection active user identity confidentiality is highly suggested. EAP methods such as  or  provide such a protection. Unfortunately, most users are not educated about the importance of user identity confidentiality and many EAP methods do not provide active user identity confidentiality. User identity confidentiality is often treated as an exotic featuresfeature which mainly aims to prevent eavesdroppers on the wireless link to learn the user identity of the attached users. Awareness for this threat type does often not exist. In many cases it is even not possible for users to freely select their favorite authentication and key exchange protocol (based on their security requirements). Instead the choice is often predetermined by a given architecture. It was noted that different granularity of location information can be provided to the home network. From a privacy point of view lower granularity is preferrable.preferable. The user, however, has no control over the granularity and cannot lie about its location. 16.15. Security Considerations Requirements for the security protection of a Location Object is defined in : Mutual end-point authentication, data object integrity, data object confidentiality and replay protection. The distribution of location information can be restricted with the help of authorization policies. Basic authorization policies are attached to the location information itself, in the same fashion as described in . It is possible that the user was already able to transfer some authorization policies to the access network to restrict the distribution of location information. This is, however, rather unlikely in case of roaming users. Hence, it will be primarily the NAS creating the Location Object which also sets the authorization policies. If no authorization information is provided by the user then the visited network MUST set the authorization policies to only allow the home AAA server to use the provided location information. Other entities, such as the visited network and possibly AAA brokers MUST NOT use the location information for a purpose other than described in this document. More extensible authorization policies can be stored at the user's home network. These policies are useful when location information is distributed to other entities in a location-based service. This scenario is, however, outside the scope of this document. It is necessary to use authorization policies to prevent the unauthorized distribution of location information. The security requirements which are created based on  are inline with threats which appear in the relationship with disclosure of location information as described in .  proposes S/MIME to protect the Location Object against modifications and against eavesdropping. To provide mutual authentication confidentiality protection and a digital signature is necessary. Furthermore, to offer replay protection a guranteeguarantee of freshness is necessary (for example, based on timestamps). The security of S/SIME is based on public key cryptography which raises performance, deployment and size considerations. Encryption requires that the local AAA server or the NAS knows the recipient's public key (e.g., the public key of the home AAA server). Knowing the final recipient of the location information is in fact impossible for RADIUS entities. Some sort of public key infrastructure would be required to obtain the public key and to verify the digital signature (at the home network). Providing per-object cryptographic protection is, both at the home and at the visited network, computationally expensive. If no authentication, integrity and replay protection between the participating RADIUS entities is provided then an adversaries can spoof and modify transmitted AVPs. Two security mechanisms are proposed for RADIUS: o  proposes the usage of a static key which might raise some concerns about the lack dynamic key management. o RADIUS over IPsec  allows to run standard key management mechanisms, such as KINK , IKE and IKEv2 , to establish IPsec security associations. Confidentiality protection MUST be used to prevent eavesdropper gaining access to location information. Confidentiality protection is not only a property required by this document, it is also required for the transport of keying material in the context of EAP authentication and authorization. Hence, this requirement is, in many environments, already fulfilled. Mutual authentication must be provided between the local AAA server and the home AAA server to prevent man-in-the-middle attacks. This is another requirement raised in the area of key transport with RADIUS and does not represent a deployment obstacle. The performance advantages a superior compared to the usage of S/MIME and object security since the expensive authentication and key exchange protocol run needs to be provided only once (at for a long time). Symmetric channel security with IPsec is highly efficient. Since IPsec protection is suggested as a mechanism to protect RAIDUS already no additional considerations need to be addressed beyond those described in . Where an untrusted AAA intermediary is present, the Location Object MUST NOT be provided to the intermediary. In case that IPsec protection is not available for some reason and RADIUS specific security mechanisms have to be used then the following considerations apply. The Access-Request message is not integrity protected. This would allow an adversary to change the contents of the Location Object or to insert and modify attributes and fields or to delete attributes. To address these problems the Message-Authenticator (80) can be used to integrity protect the entire Access-Request packet. The Message-Authenticator (80) is also required when EAP is used and hence is supported by many modern RADIUS servers. Access-Request packets including Location attribute(s) without a Message-Authenticator(80) attribute SHOULD be silently discarded by the RADIUS server. A RADIUS server supporting the Location attributes MUST calculate the correct value of the Message-Authenticator(80) and MUST silently discard the packet if it does not match the value sent. Access-Accept, including Location attribute(s) without a Message-Authenticator(80) attribute SHOULD be silently discarded by the NAS. A NAS supporting the Location attribute MUST calculate the correct value of a received Message-Authenticator(80) and MUST silently discard the packet if it does not match the value sent. RADIUS and DIAMETER make some assumptions about the trust between traversed AAA entities in sense that object level security is not provided by neither RADIUS nor DIAMETER. Hence, some trust has to be placed on the AAA entities to behave according to the defined rules. Furthermore, the AAA protocols do not involve the user in their protocol interaction except for tunneling authentication information (such as EAP messages) through their infrastructure. RADIUS and DIAMETER have even become a de-facto protocol for key distribution. Hence, in the past there were some concerns about the trust placed into the infrastructure particularly from the security area when it comes to keying.  documents this keying infrastructure and the security implications. The uniqueness of the AAA infrastructure therefore raises some concerns about the interpretation of the retention and redistribution restrictions. The privacy guidelines listed in Section 1514 are applicable in this context. 17.16. Acknowledgments The authors would like to thank the following people for their help with a previous version of this draft and for their input: Chuck Black Paul Congdon Jouni Korhonen Sami Ala-luukko Farooq Bari Ed Van Horne Mark Grayson Jukkat Tuomi Jorge Cuellar Christian Guenther Henning Schulzrinne provided the civil location information content found in this draft. The geospatial location information format is based on work done by J. Polk, J. Schnizlein and M. Linsner. The authorization policy format is based on the work done by Jon Peterson. The authors would like to thank Victor Lortz, Jose Puthenkulam, Bernrad Aboba, Jari Arkko, Parviz Yegani, Serge Manning, Kuntal Chowdury, Pasi Eronen, Blair Bullock and Eugene Chang for their feedback to an initial version of this draft. This document is based on the discussions within the IETF GEOPRIV working group. Therefore, the authors thank Henning Schulzrinne, James Polk, John Morris, Allison Mankin, Randall Gellens, Andrew Newton, Ted Hardie, Jon Peterson for their time to discuss a number of issues with us. We think Stephen Hayes for aligning this work with 3GPP activities. 18.17. References 18.117.1 Normative References  Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000.  Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", March 1997.  Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.  Chiba, M., Dommety, G., Eklund, M., Mitton, D. and B. Aboba, "Dynamic Authorization Extensions to Remote Authentication Dial In User Service (RADIUS)", RFC 3576, July 2003.  Schulzrinne, H., "Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Option for Civic Addresses", draft-ietf-geopriv-dhcp-civil-03Addresses Configuration Information", draft-ietf-geopriv-dhcp-civil-04 (work in progress), JulyOctober 2004.  Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, November 2003.  Polk, J., Schnizlein, J. and M. Linsner, "Dynamic Host Configuration Protocol Option for Coordinate-based Location Configuration Information", RFC 3825, July 2004. 18.217.2 Informative References  Cuellar, J., Morris, J., Mulligan, D., Peterson, D. and D. Polk, "Geopriv Requirements", RFC 3693, February 2004.  Peterson, J., "A Presence-based GEOPRIV Location Object Format", draft-ietf-geopriv-pidf-lo-03 (work in progress), September 2004.  Schulzrinne, H., "A Document Format for Expressing Privacy Preferences", draft-ietf-geopriv-common-policy-01draft-ietf-geopriv-common-policy-02 (work in progress), JulyOctober 2004.  Schulzrinne, H., "A Document Format for Expressing Privacy Preferences for Location Information", draft-ietf-geopriv-policy-02draft-ietf-geopriv-policy-03 (work in progress), JulyOctober 2004.  Schulzrinne, H., Gurbani, V., Kyzivat, P. and J. Rosenberg, "RPID: Rich Presence: Extensions to the Presence Information Data Format (PIDF)", draft-ietf-simple-rpid-03 (work in progress), March 2004.  Calhoun, P., Zorn, G., Spence, D. and D. Mitton, "Diameter Network Access Server Application", draft-ietf-aaa-diameter-nasreq-17 (work in progress), July 2004.  Mills, D., "Network Time Protocol (Version 3) Specification, Implementation", RFC 1305, March 1992.  Stanley, D., Walker, J. and B. Aboba, "EAP Method Requirements for Wireless LANs", draft-walker-ieee802-req-04 (work in progress), August 2004.  Arkko, J. and H. Haverinen, "EAP AKA Authentication", draft-arkko-pppext-eap-aka-12 (work in progress), April 2004.  Aboba, B., "The Network Access Identifier", draft-arkko-roamops-rfc2486bis-02 (work in progress), July 2004.  Josefsson, S., Palekar, A., Simon, D. and G. Zorn, "Protected EAP Protocol (PEAP) Version 2", draft-josefsson-pppext-eap-tls-eap-08draft-josefsson-pppext-eap-tls-eap-09 (work in progress), JulyOctober 2004.  Tschofenig, H. and D. Kroeselberg, "EAP IKEv2 Method (EAP-IKEv2)", draft-tschofenig-eap-ikev2-04 (work in progress), July 2004.  Danley, M., "Threat Analysis of the Geopriv Protocol", RFC 3694, September 2003, <reference.RFC3694.xml>.  Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication Dial In User Service) Support For Extensible Authentication Protocol (EAP)", RFC 3579, September 2003.  Thomas, M. and J. Vilhuber, "Kerberized Internet Negotiation of Keys (KINK)", draft-ietf-kink-kink-06 (work in progress), July 2004.  Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", draft-ietf-ipsec-ikev2-17 (work in progress), October 2004.  Aboba, B., "Extensible Authentication Protocol (EAP) Key Management Framework", draft-ietf-eap-keying-03 (work in progress), July 2004.  Adrangi, F., "Access Network Bandwidth Capability", draft-adrangi-radius-bandwidth-capability-01 (work in progress), July 2004. Authors' Addresses Hannes Tschofenig Siemens Otto-Hahn-Ring 6 Munich, Bayern 81739 Germany EMail: Hannes.Tschofenig@siemens.com F. Adrangi Intel Corporatation 2111 N.E. 25th Avenue Hillsboro OR USA EMail: email@example.com Avi Lior Bridgewater Systems Corporation 303 Terry Fox Drive Ottawa, Ontario K2K 3J1 CANADA EMail: firstname.lastname@example.org Mark Jones Bridgewater Systems Corporation 303 Terry Fox Drive Ottawa, Ontario K2K 3J1 CANADA EMail: email@example.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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