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draft-ietf-rap-rsvp-authsession-02.txt --> draft-ietf-rap-rsvp-authsession-03.txt

Internet Draft B. Gage
Expires August 31, 2002
M. Broda
Document: draft-ietf-rap-rsvp-authsession-03.txt Nortel Networks
B. Kosinski
University of Alberta
Hugh Shieh
AT&T Wireless
February
June 2002

Session Authorization for RSVP

draft-ietf-rap-rsvp-authsession-02.txt

Status of this Memo

This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026 [1]. RFC2026.

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
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The list of current Internet-Drafts can be accessed at
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The distribution of this memo is unlimited. This memo is filed as
<draft-ietf-rap-rsvp-authsession-02.txt>,
<draft-ietf rap-rsvp-authsession-03.txt>, and expires August 31, November,
2002. Please send comments to the authors.

Abstract

This document describes the representation of session authorization
information in the POLICY_DATA object [POL-EXT] (RFC 2750) for supporting
policy-based per-session authorization and admission control in
RSVP. The goal of session authorization is to allow the exchange of
information between network elements in order to authorize the use
of resources for a service and to co-ordinate actions between the
signaling and transport planes. This document describes how a
process on a system authorizes the reservation of resources by a
host and then provides that host with a session authorization policy
element which can be inserted into the RSVP PATH message to
facilitate proper and secure reservation of those resources within
the network. We describe the encoding of media authorization
information as RSVP policy elements and provide details relating to
operations, processing rules and error scenarios.

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Contents

Status of this Memo................................................1
Copyright Notice...................................................1
Abstract...........................................................1
1. Conventions used in this document...............................3
2. Introduction....................................................3
3. Policy Element for Session Authorization Data...................4
3.1 Policy Data Object Format......................................4
3.2 Session Authorization Data Policy Element......................4
3.3 Session Authorization Attributes...............................4
3.3.1 Authorizing Entity Identifier................................6
3.3.2 Session Identifier...........................................7
3.3.3 Source Address...............................................7
3.3.4 Destination Address..........................................9
3.3.5 Start time..................................................10
3.3.6 End time....................................................11
3.3.7 Resources Authorized........................................11
3.3.8 Authentication data.........................................12
4. Integrity of the AUTH_SESSION policy element...................13
4.1 Shared private keys...........................................13
4.1.1 Operational Setting using shared private keys...............13
4.2 Kerberos......................................................14
4.2.1. Operational Setting using Kerberos.........................14
4.3 Public Key....................................................15
4.3.1. Operational Setting for public key based authentication....15
5. Framework......................................................16
5.1 The coupled model.............................................16
5.2 The associated model with one policy server...................16
5.3 The associated model with two policy servers..................17
5.4 The non-associated model......................................17
6. Message Processing Rules.......................................17
6.1 Message Generation (RSVP Host)................................17
6.2 Message Reception (Router)....................................18
6.3 Authorization (Router/PDP)....................................18
7. Error Signaling................................................18
8. IANA Considerations............................................19
9. Security Considerations........................................20
10. Acknowledgments...............................................21
11. Normative References..........................................21
12. Informative References........................................23
13. Author Information............................................23
14. Full Copyright Statement......................................24
15. Notices.......................................................24
16. RFC Editor Considerations.....................................25

Internet Draft Session Authorization for RSVP February June 2002

1. Conventions used in this document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in [RFC-2119].

2. Introduction

RSVP [RFC-2205] is a resource reservation setup protocol designed
for an integrated services [RFC-1633] or DiffEdge [RFC-2998]
Internet. Integrated Services over
Diffserv networks [RFC-2998]. The RSVP protocol is used by a host to
request specific
qualities of service services from the network for particular
application data streams or flows. RSVP is also used by routers to deliver
quality-of-service (QoS) requests to all nodes routers along the path(s)
of the flows and to establish and maintain state to provide the
requested quality of service. RSVP requests will generally result
in resources being reserved in each node router along the data path.
RSVP allows users to obtain preferential access to network
resources, under the control of an admission control mechanism.
Such admission control is often based on user or application
identity
[I-REP], [RFC-3182], however, it is also valuable to provide the
ability for per-session admission control.

In order to allow for per-session admission control, it is necessary
to provide a mechanism for ensuring an RSVP request from use of resources by a host has
been properly pre-authorized authorized before allowing the reservation of those
resources. In order to meet this requirement, there must be
information in the RSVP message which may be used to verify the
validity of the RSVP request. This may can be done by providing the
host with a token upon authorization which may be is inserted into the RSVP
PATH message and verified by the network.

We describe

This document describes the session authorization element
(AUTH_SESSION) contained in the POLICY_DATA object. The user
process must obtain an AUTH_SESSION object from an authorizing
entity, which it may then
pass passes to the RSVP process (service) on the
originating host. The RSVP service then inserts the AUTH_SESSION
object into the RSVP PATH message to allow verification of the
network resource request. Network elements, such as routers, elements verify the request and
then admit process the RSVP message based on admission policy.

[S-AUTH] describes a framework in which a session authorization
policy element may be utilized to contain information relevant to
the network's decision to grant a reservation request.

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3. Policy Element for Session Authorization Data

3.1 Policy Data Object Format

POLICY_DATA objects contain policy information and are carried by
RSVP messages. A detail detailed description of the format of POLICY_DATA
object can be found in "RSVP Extensions for Policy Control" [POL-
EXT]. [RFC-
2750].

3.2 Session Authorization Data Policy Element

In this section we describe a policy element (PE) called session
authorization data (AUTH_SESSION). The AUTH_SESSION policy element
contains a list of fields which describe the session, along with
other attributes.

+-------------+-------------+-------------+-------------+
| Length | P-Type = AUTH_SESSION |
+-------------+-------------+-------------+-------------+
// Session Authorization Attribute List //
+-------------------------------------------------------+

Length

Length: 16 bits
The length of the policy element (including the Length and
P-Type) is in number of octets (MUST be in multiples of 4) and
indicates the end of the session authorization information block.

P-Type

P-Type: 16 bits (Session Authorization Type)
AUTH_SESSION = TBD-by-IANA
The Policy element type (P-type) of this element. The
Internet Assigned Numbers Authority (IANA) acts as a registry
for policy element types for identity as described in
[POL-EXT]. The definition for AUTH_SESSION is currently to be
defined.
[RFC-2750].

Session Authorization Attribute List List: variable length
The session authorization attribute list is a collection of
objects which describes the session and provides other
information necessary to verify the RSVP request. An initial set
of valid objects is described in Section 3.

3.3 Session Authorization Attributes

A session authorization attribute may contain a variety of
information and has both an attribute type and subtype. The
attribute itself MUST be a multiple of 4 octets in length, and any
attributes that are not a multiple of 4 octets long MUST be padded
to a 4-octet boundary.

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Length

Length: 16 bits
The length field is two octets and indicates the actual length
of the attribute (including Length, S-Type and SubType fields)
in number of octets. The length does NOT include any bytes
padding to the value field to make the attribute a multiple of
4 octets long.

S-Type

S-Type: 8 bits
Session authorization attribute type (S-Type) field is one
octet. IANA SHALL act acts as a registry for S-Types as described
in section 7, IANA Considerations. Initially, the registry
contains the following S-Types:

1 AUTH_ENT_ID The unique identifier of the entity
which authorized the session.

2 AUTH_ENT_CRED The credentials of the authorizing
entity, such as a digital
certificate.

3 SESSION_ID Unique identifier for this session.

3 SOURCE_ADDR Address specification for the
session originator.

4 DEST_ADDR Address specification for the
session end-point.

5 START_TIME The starting time for the session.

6 END_TIME The end time for the session.

7 RESOURCES The resources which the user is
authorized to request.

9 DIGITAL_SIGNATURE Digital signature

8 AUTHENTICATION_DATA Authentication data of the session
authorization policy element.

SubType

SubType: 8 bits
Session authorization attribute sub-type is one octet in
length. The value of the SubType depends on the S-Type.

Value

Value: variable length
The attribute specific information.

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3.3.1 Authorizing Entity Identifier

AUTH_ENT_ID is used to identify the entity which authorized the
initial service request and generated the session authorization
policy element. The AUTH_ENT_ID may be represented in various
formats, and the SubType is used to define the format for the ID.
The format for AUTH_ENT_ID is as follows:

Length
Length of the attribute, which MUST be >= > 4.

S-Type
AUTH_ENT_ID

SubType
The following sub-types for AUTH_ENT_ID are defined. IANA
SHALL act
acts as a registry for AUTH_ENT_ID sub-types as described
in section 7, IANA Considerations. Initially, the registry
contains the following sub-types of AUTH_ENT_ID:

1 IPV4_ADDRESS IPv4 address represented in 32 bits

2 IPV6_ADDRESS IPv6 address represented in 128 bits

3 FQDN Fully Qualified Domain Name as defined
in RFC-1034 as an ASCII string.

4 ASCII_DN X.500 Distinguished name as defined
in RFC-2253 as an ASCII string.

5 UNICODE_DN X.500 Distinguished name as defined
in RFC-2253 as a UNICODE string.

6 URI Universal Resource Identifier, as
defined in RFC-2396.

7 KRB_PRINCIPAL Fully Qualified Kerberos Principal name
represented by the ASCII string of a
principal followed by the @ realm name as
defined in
RFC-1510. RFC-1510 (e.g.
principalX@realmY).

8 KRB_REALM Kerberos realm as defined in RFC-1510.

OctetString
Contains the authorizing entity identifier.

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3.3.2 Authorizing Entity Credentials

AUTH_ENT_CRED contains the credentials of the authorizing entity,
which can then be used by the network to ensure that the entity
which generated this session authorization policy element is a
valid trusted entity.

Length
Length of the attribute, which MUST be >= 4.

S-Type
AUTH_ENT_CRED

SubType
The type of credentials contained in this attribute. IANA
SHALL act as a registry for AUTH_ENT_CRED sub-types as
described in section 7, IANA Considerations. Initially, the
registry contains the following sub-types:

1 ASCII_ID The authorizing entity identification in a
plain ASCII text string.

2 UNICODE_ID The authorizing entity identification in a
plain UNICODE text string.

3 X509_V3_CERT A chain of authorizing entity's X.509 V3
digital certificates.

Internet Draft Session Authorization for RSVP June 2002

9 PGP_CERT The PGP digital certificate of the
authorizing entity.

OctetString
Contains the authorizing entity credentials.

3.3.3 identifier.

3.3.2 Session Identifier

SESSION_ID is a unique identifier for this session. used by the authorizing entity to
identify the request. It may be used for a number of purposes,
including replay detection, or even
mapping to correlate this request to a policy
decision entry made by the authorizing entity. The For example, the
SESSION_ID can be based on simple sequence number or on a standard
NTP timestamp.

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Length
Length of the attribute, which MUST be >= > 4.
Dependant on the environment,

S-Type
SESSION_ID

SubType
No subtypes for SESSION ID are currently defined; this field MUST
be set to zero. The authorizing entity is the session identifier will have
different lengths in order only network entity
that needs to ensure uniqueness during interpret the
lifetime contents of a token (equal the SESSION ID therefore the
contents and format are implementation dependent.

OctetString
Contains the session identifier.

3.3.3 Source Address

SOURCE_ADDR is used to identify the lifetime source address specification of
the session).
We recommend using an octet string of a minimum of 32 bit, but
a value of 64 bit authorized session. This S-Type may be required useful in some environments.

S-Type
SESSION_ID

SubType
The following sub-types for SESSION_ID are defined. IANA
SHALL act as a registry for SESSION_ID sub-types as described
in section 7, IANA Considerations. Initially, the registry
contains the following sub-types of SESSION_ID:

1 ASCII_ID Simple plain ASCII string identifier.

2 UNICODE_ID Simple plain UNICODE string identifier.

3 OCTET_ID Raw octet string identifier.

4 NTP_TIMESTAMP NTP Timestamp Format as defined in
RFC-1305.

OctetString
Contains the actual session identifier.

3.3.4 Source Address

SOURCE_ADDR is used to identify the source address specification of
the authorized session. This S-Type MAY be useful in some scenarios
to make sure the resource request has been authorized scenarios
to make sure the resource request has been authorized for that
particular source IP address and/or port.

Internet Draft Session Authorization for RSVP June 2002

Length
Length of the attribute, which MUST be >= > 4.

S-Type
SOURCE_ADDR

SubType
The following sub types for SOURCE_ADDR are defined. IANA
SHALL act
acts as a registry for SOURCE_ADDR sub-types as
described in section 7, IANA Considerations. Initially, the
registry contains the following sub types for SOURCE_ADDR:

1 IPV4_ADDRESS IPv4 address represented in 32 bits

2 IPV6_ADDRESS IPv6 address

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3 FQDN Fully Qualified Domain Name as defined
in RFC-1034 as an ASCII string.

4 ASCII_DN X.500 Distinguished name as defined
in RFC-2253 as an ASCII string.

5 UNICODE_DN X.500 Distinguished name as defined
in RFC-2253 as a UNICODE string.

6 UDP_PORT LIST list of UDP port specification

4 specifications,
represented as 16 bits per list entry.

7 TCP_PORT LIST list of TCP port specification specifications,
represented as 16 bits per list entry.

OctetString
The OctetString contains the source address information.

3.3.5 Destination Address

DEST_ADDR is used to identify the destination

In scenarios where a source address is required (see Section 5), at
least one of the
authorized session. This S-Type MAY subtypes 1 through 5 (inclusive) MUST be useful included
in some scenarios to
make sure the resource request has every Session Authorization Data Policy Element. Multiple SOURCE
ADDR attributes MAY be included if multiple addresses have been authorized for that
particular destination IP
authorized. The source address and/or port.

Length
Length field of the attribute, which RSVP datagram MUST match
one of the SOURCE ADDR attributes contained in this Session
Authorization Data Policy Element when resolved to an IP address.

At most, one instance of subtype 6 MAY be >= 4.

S-Type
DEST_ADDR

SubType
The following sub types for DEST_ADDR are defined. IANA SHALL
act as a registry for DEST_ADDR sub-types as described included in
section 7, IANA Considerations. Initially, the registry
contains the following sub types for DEST_ADDR:

1 IPV4_ADDRESS IPv4 address

2 IPV6_ADDRESS IPv6 address

3 UDP_PORT UDP port specification

4 TCP_PORT TCP port specification

OctetString
The OctetString contains the destination address specification.

3.3.6 Start time

START_TIME is used to identify the start time every Session
Authorization Data Policy Element. At most, one instance of the authorized
session. This S-Type subtype
7 MAY be useful included in some scenarios to specify every Session Authorization Data Policy
Element. Inclusion of a
start time for subtype 6 attribute does not prevent
inclusion of a subtype 7 attribute (i.e. both UDP and TCP ports may
be authorized).

If no PORT attributes are specified, then all ports are considered
valid; otherwise, only the specified ports are authorized session.

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Length
Length of the attribute, which MUST

Every source address and port list must be >= 4.

S-Type
START_TIME

SubType
The following sub types for START_TIME are defined. IANA SHALL
act as a registry for START_TIME sub-types as described in
section 7, IANA Considerations. Initially, the registry
contains the following sub types for START_TIME:

1 NTP_TIMESTAMP NTP Timestamp Format as defined included in
RFC-1305.

OctetString
The OctetString contains the start time.

3.3.7 End time

END_TIME a separate
SOURCE_ADDR attribute.

3.3.4 Destination Address

DEST_ADDR is used to identify the end time destination address of the
authorized session. This S-Type MAY may be useful in some scenarios to specify a
end time for
make sure the resource request has been authorized session. for that
particular destination address and/or port.

Length
Length of the attribute, which MUST be >= > 4.

S-Type
END_TIME
DEST_ADDR

SubType
The following sub types for END_TIME DEST_ADDR are defined. IANA SHALL
act
acts as a registry for END_TIME DEST_ADDR sub-types as described in
section 7, IANA Considerations. Initially, the registry
contains the following sub types for END_TIME: DEST_ADDR:

1 NTP_TIMESTAMP NTP Timestamp Format as defined IPV4_ADDRESS IPv4 address represented in
RFC-1305.

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2 IPV6_ADDRESS IPv6 address represented in 128 bits

3 FQDN Fully Qualified Domain Name as defined
in RFC-1034 as an ASCII string.

4 ASCII_DN X.500 Distinguished name as defined
in RFC-2253 as an ASCII string.

5 UNICODE_DN X.500 Distinguished name as defined
in RFC-2253 as a UNICODE string.

6 UDP_PORT LIST list of UDP port specifications,
represented as 16 bits per list entry.

7 TCP_PORT LIST list of TCP port specifications,
represented as 16 bits per list entry.

OctetString
The OctetString contains the destination address specification.

Internet Draft Session Authorization for RSVP February June 2002

OctetString

In scenarios where a destination address is required (see Section
5), at least one of the subtypes 1 through 5 (inclusive) MUST be
included in every Session Authorization Data Policy Element.
Multiple DEST ADDR attributes MAY be included if multiple addresses
have been authorized. The OctetString contains destination address field of the end time.

3.3.8 Resources Authorized

RESOURCES is used to define RSVP
datagram MUST match one of the characteristics DEST ADDR attributes contained in
this Session Authorization Data Policy Element when resolved to an
IP address.

At most, one instance of subtype 6 MAY be included in every Session
Authorization Data Policy Element. At most, one instance of subtype
7 MAY be included in every Session Authorization Data Policy
Element. Inclusion of a subtype 6 attribute does not prevent
inclusion of a subtype 7 attribute (i.e. both UDP and TCP ports may
be authorized).

If no PORT attributes are specified, then all ports are considered
valid; otherwise, only the specified ports are authorized
session. This S-Type MAY for use.

Every destination address and port list must be useful included in some scenarios a
separate DEST_ADDR attribute.

3.3.5 Start time

START_TIME is used to specify identify the start time of the
specific resources authorized
Session and can be used to ensure prevent replay attacks. If the
AUTH_SESSION policy element is presented in a resource request, the
network SHOULD reject the request fits if it is not received within a few
seconds of the
authorized specifications. start time specified.

Length
Length of the attribute, which MUST be >= > 4.

S-Type
RESOURCES
START_TIME

SubType
The following sub-types for RESOURCES sub types for START_TIME are defined. IANA SHALL
act
acts as a registry for RESOURCES START_TIME sub-types as described in
section 7, IANA Considerations. Initially, the registry
contains the following sub types for RESOURCES: START_TIME:
1 BANDWIDTH Maximum bandwidth (kbps) authorized.

2 FLOW_SPEC Flow spec specification as defined in
RFC-2205.

3 SDP SDP Media Descriptor as defined in
RFC-2327.

4 DSCP Differentiated services codepoint NTP_TIMESTAMP NTP Timestamp Format as defined in RFC-2474.
RFC-1305.

Internet Draft Session Authorization for RSVP June 2002

OctetString
The OctetString contains the resources specification.

3.3.9 Digital Signature

The DIGITAL_SIGNATURE attribute contains start time.

3.3.6 End time

END_TIME is used to identify the digital signature end time of the AUTH_SESSION policy element authorized
session and signs all the data in the
policy element up to the DIGITAL_SIGNATURE. If the
DIGITAL_SIGNATURE attribute has been included in the AUTH_SESSION
policy element, it MUST can be used to limit the last attribute in the list.

A summary amount of DIGITAL_SIGNATURE attribute format is described below.

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Length
Length of the attribute, which MUST be >= > 4.

S-Type
DIGITAL_SIGNATURE
END_TIME

SubType
The following sub-types sub types for DIGITAL_SIGNATURE END_TIME are defined. IANA SHALL act
acts as a registry for DIGITAL_SIGNATURE END_TIME sub-types as described in
section 7, IANA Considerations. Initially, the registry
contains the following sub types for DIGITAL_SIGNATURE: END_TIME:

1 DSA_SHA1 DSA signature using SHA1 [X.509].

2 RSA_SHA1 RSA signature using SHA1 [X.509].

3 RSA_MD5 RSA signature using MD5 [X.509].

4 HMAC_SHA1 HMAC with SHA1 [RFC 2104].

5 HMAC_MD5 HMAC with MD5 [RFC 2104]. NTP_TIMESTAMP NTP Timestamp Format as defined in
RFC-1305.

OctetString
The OctetString contains the digital signature of end time.

3.3.7 Resources Authorized

RESOURCES is used to define the AUTH_SESSION.

4. Framework

[S-AUTH] describes a framework in which characteristics of the session authorization
policy element authorized
session. This S-Type may be utilized useful in some scenarios to transport information specify the
specific resources authorized to ensure the request fits the
authorized specifications.

Length
Length of the attribute, which MUST be > 4.

S-Type

Internet Draft Session Authorization for use in
authorizing resource reservation RSVP June 2002

RESOURCES

SubType
The following sub-types for media flows.

5. Message Processing Rules

5.1 Message Generation (RSVP Host)

An RSVP message is created RESOURCES are defined. IANA
acts as specified a registry for RESOURCES sub-types as described in [RFC-2205] with
section 7, IANA Considerations. Initially, the registry
contains the following
modifications.

1. RSVP message MUST contain at most one AUTH_SESSION policy element.

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2. A Session Authorization policy element (AUTH_SESSION) is created
and RESOURCES:

1 BANDWIDTH Maximum bandwidth (kbps) authorized.

2 FLOW_SPEC Flow spec specification as defined in
RFC-2205.

3 SDP SDP Media Descriptor as defined in
RFC-2327.

4 DSCP Differentiated services codepoint as
defined in RFC-2474.

OctetString
The OctetString contains the IdentityType field resources specification.

In scenarios where a resource specification is set to indicate required (see Section
5), at least one of the identity type subtypes 1 through 4 (inclusive) MUST be
included in the policy element. Only the required every Session Authorization Data Policy Element.
Multiple RESOURCE attributes are added.

3. POLICY_DATA object (containing MAY be included if multiple types of
resources have been authorized (e.g. DSCP and BANDWIDTH).

3.3.8 Authentication data

The AUTHENTICATION_DATA attribute contains the authentication data
of the AUTH_SESSION policy element)
is inserted in element and signs all the RSVP message data in the appropriate place.

5.2 Message Reception (Router)

RSVP message is processed as specified in [RFC-2205] with following
modifications.

1. If router is
policy aware then it SHOULD send the RSVP
message element up to the PDP and wait for response. AUTHENTICATION_DATA. If the router is
policy unaware then it ignores
AUTHENTICATION_DATA attribute has been included in the AUTH_SESSION
policy data objects and
continues processing element, it MUST be the RSVP message.

2. Reject last attribute in the message if list. The
algorithm used to compute the response from the PDP is negative.

3. Continue processing authentication data depends on the RSVP message.

5.3 Authorization (Router/PDP)

1. Retrieve
AUTH_ENT_ID SubType field. See Section 4 entitled Integrity of the
AUTH_SESSION policy element. Check

A summary of AUTHENTICATION_DATA attribute format is described
below.

Length

Internet Draft Session Authorization for RSVP June 2002

Length of the PE type attribute, which MUST be > 4.

S-Type
AUTHENTICATION_DATA

SubType
No sub types for AUTHENTICATION_DATA are currently defined. This
field and return an error if MUST be set to 0.

OctetString
OctetString contains the identity type is not supported.

2. Verify authentication data of the authorizing entity credentials and message integrity.

- Pre-shared key authentication: Get entity ID, identify
appropriate pre-shared key for AUTH_SESSION.

4. Integrity of the authorizing entity, and
validate signature.

- Public Key: Validate AUTH_SESSION policy element

This section describes how to ensure the certificate chain against
trusted Certificate Authority (CA) and valide integrity of the
message signature policy
element is preserved.

4.1 Shared private keys

In shared private key environments, the AUTH_ENT_ID MUST be of
subtypes: IPV4_ADDR, IPV6_ADDR, FQDN, ASCII_DN, UNICODE_DN or URI.
An example AUTH_SESSION policy element is shown below.

4.1.1 Operational Setting using shared private keys

This assumes both the public key.

- Kerberos Ticket: Request a ticket Authorizing Entity and the Network router/PDP
are provisioned with shared private keys and with policies detailing
which algorithm to be used for computing the authorizing entity
from authentication data.

Key maintenance is outside the local KDC. Use scope of this document, but
AUTH_SESSION implementations MUST at least provide the ticket ability to access the authorizing
entity
manually configure keys and obtain their parameters locally. The key used
to produce the authentication data is identified by the AUTH_ENT_ID
field. Each key must also be configured with lifetime parameters for
the message (e.g. time period within which it is valid as well as an associated
cryptographic algorithm parameter specifying the algorithm to be
used with the key. At a minimum, all AUTH_SESSION implementations

Internet Draft Session Authorization for RSVP June 2002

MUST support the HMAC-MD5-96 [RFC-2104][FRC-1321] cryptographic
algorithm for computing the authentication data.

It is good practice to regularly change keys. Keys MUST be
configurable such that their lifetimes overlap allowing smooth
transitions between keys. At the midpoint of the lifetime overlap
between two keys, senders should transition from using the current
key to the next/longer-lived key. Meanwhile, receivers simply accept
any identified key received within its configured lifetime and
reject those that are not.

4.2 Kerberos

In a Kerberos environment, the AUTH_ENT_ID MUST be of the subtype
KRB_PRINCIPAL. Kerberos [RFC 1510] authentication uses a trusted
third party (the Kerberos Distribution Center - KDC) to provide for
authentication of the AUTH_SESSION to a network server. It is
assumed that a KDC is present and both host and verifier of
authentication information (authorizing entity and router/PDP)
implement Kerberos authentication.

An example of the Kerberos AUTH_DATA policy element is shown below.

4.2.1. Operational Setting using Kerberos

An authorizing entity is configured to construct the AUTH_SESSION
policy element that designates use of the Kerberos authentication
method (KRB_PRINCIPAL). Upon reception of the RSVP request, the
router/PDP contacts the local KDC to request a ticket for the
authorizing entity (principal@realm). The router/PDP uses the ticket
to access the authorizing entity and obtain authentication data for
the message.

For cases where the authorizing entity is in a different realm (i.e.
administrative domain, organizational boundary), the router/PDP
needs to fetch a cross-realm Ticket Granting Ticket (TGT) from its
local KDC. This TGT can be used to fetch authorizing entity tickets

Internet Draft Session Authorization for RSVP June 2002

from the KDC in the remote realm. Note that for performance
considerations, tickets are typically cached for extended periods.

4.3 Public Key

In a public key environment, the AUTH_ENT_ID MUST be of the
subtypes: X509_V3_CERT or PGP_CERT. The authentication data is used
for authenticating the authorizing entity. An example of the public
key AUTH_SESSION policy element is shown below.

4.3.1. Operational Setting for public key based authentication

Public key based authentication assumes following:

- Authorizing entities have a pair of keys (private key and
public key).

- Private key is secured with the authorizing entity.

- Public keys are stored in digital certificates and a
trusted party, certificate authority (CA) issues these
digital certificates.

- The verifier (PDP or router) has the ability to verify the
digital certificate.

Authorizing entity uses its private key to generate
AUTHENTICATION_DATA. Authenticators (router, PDP) use the
authorizing entity's public key (stored in the digital certificate)
to verify and authenticate the policy element.

Internet Draft Session Authorization for RSVP June 2002

5. Framework

[S-AUTH] describes a framework in which the AUTH_SESSION
policy element may be utilized to transport information required for
authorizing resource reservation for media flows. [S-AUTH]
introduces 4 different models:
1- the coupled model
2- the associated model with one policy server
3- the associated model with two policy servers
4- the non-associated model.

The fields that are required in an AUTH SESSION policy element is
dependent on which of the models is used.

5.1 The coupled model

In the Coupled Model, the only information that MUST be included in
the policy element is the SESSION ID; it is used by the Authorizing
Entity to correlate the resource reservation request with the media
authorized during session set up. Since the End Host is assumed to
be untrusted, the Policy Server SHOULD take measures to ensure that
the integrity of the SESSION ID is preserved in transit; the exact
mechanisms to be used and the format of the SESSION ID are
implementation dependent.

5.2 The associated model with one policy server

In this model, the contents of the AUTH_SESSION policy element MUST
include:

- A session identifier - SESSION_ID. This is information that the
authorizing entity can use to correlate the resource reservation
request with the media authorized during session set up.

- The identity of the authorizing entity _ AUTH_ENT_ID. This
information is used by the Edge Router to determine which
authorizing entity (Policy Server) should be used to solicit
resource policy decisions.

In some environments, an Edge Router may have no means for
determining if the identity refers to a legitimate Policy Server
within its domain. In order to protect against redirection of
authorization requests to a bogus authorizing entity, the
AUTH_SESSION MUST also include:

- AUTHENTICATION_DATA. This authentication data is calculated over
all other fields of the AUTH_SESSION policy element.

Internet Draft Session Authorization for RSVP June 2002

5.3 The associated model with two policy servers

The content of the AUTH_SESSION Policy Element is identical to the
associated model with one policy server.

5.4 The non-associated model

In this model, the AUTH_SESSION MUST contain sufficient information
to allow the Policy Server to make resource policy decisions
autonomously from the authorizing entity. The policy element is
created using information about the session by the authorizing
entity. The information in the AUTH_SESSION policy element MUST
include:

- Calling party IP address or Identity (e.g. FQDN) - SOURCE_ADDR S-
TYPE
- Called party IP address or Identity (e.g. FQDN) - DEST_ADDR S-
TYPE
- The characteristics of (each of) the media stream(s) authorized
for this session - RESOURCES S-TYPE
- The authorization lifetime - START_TIME S-TYPE
- The identity of the authorizing entity to allow for validation of
the token in shared private key and Kerberos schemes -
AUTH_ENT_ID S-TYPE
- The credentials of the authorizing entity in a public-key scheme
- AUTH_ENT_ID S-TYPE
- Authentication data used to prevent tampering with the
AUTH_SESSION policy element - AUTHENTICATION_DATA

Furthermore, the AUTH_SESSION policy element MAY contain:

- The lifetime of (each of) the media stream(s) - END_TIME S-TYPE
- Calling party port number - SOURCE_ADDR S-TYPE
- Called party port number - DEST_ADDR S-TYPE

All AUTH_SESSION fields MUST match with the resource request. If a
field does not match, the request SHOULD be denied.

6. Message Processing Rules

6.1 Message Generation (RSVP Host)

An RSVP message is created as specified in [RFC-2205] with following
modifications.

1. RSVP message MUST contain at most one AUTH_SESSION policy
element.

2. A Session Authorization policy element (AUTH_SESSION) is created
and the IdentityType field is set to indicate the identity type

Internet Draft Session Authorization for RSVP June 2002

in the policy element. Only the required Session Authorization
attributes are added.

3. POLICY_DATA object (containing the AUTH_SESSION policy element)
is inserted in the RSVP message in the appropriate place.

6.2 Message Reception (Router)

RSVP message is processed as specified in [RFC-2205] with following
modifications.

1. If router is policy aware then it SHOULD send the RSVP
message to the PDP and wait for response. If the router is
policy unaware then it ignores the policy data objects and
continues processing the RSVP message.

2. Reject the message if the response from the PDP is negative.

3. Continue processing the RSVP message.

6.3 Authorization (Router/PDP)

1. Retrieve the AUTH_SESSION policy element. Check the PE type
field and return an error if the identity type is not supported.

2. Verify the message integrity.

- Shared private key authentication: Get authorizing entity ID,
identify appropriate algorithm and shared private key for the
authorizing entity, and validate signature.

- Public Key: Validate the certificate chain against
trusted Certificate Authority (CA) and validate the
message signature using the public key.

- Kerberos Ticket: If the AUTH_ENT_ID is of subtype KRB_PRINCIPAL,
Request a ticket for the authorizing entity (principal@realm)
from the local KDC. Use the ticket to access the authorizing
entity and obtain authentication data for the message.

3. Verify the requested resources do not exceed the authorized QoS.

7. Error Signaling

If a PDP fails to verify the AUTH_SESSION policy element then it
MUST return a policy control failure (Error Code = 02) to the PEP.
The error values are described in [RFC-2205] and [RFC-2750]. Also
the PDP SHOULD supply a policy data object containing an AUTH_DATA
Policy Element with A-Type=POLICY_ERROR_CODE containing more
details on the Policy Control failure [RFC-3182]. The PEP

Internet Draft Session Authorization for RSVP June 2002

MUST include this Policy Data object in the outgoing RSVP Error
message.

8. IANA Considerations

Following the policies outlined in [IANA-CONSIDERATIONS], Standard
RSVP Policy Elements (P-type values) are assigned by IETF Consensus
action as described in [RFC-2750].

P-Type AUTH_SESSION is assigned the value TBD-by-IANA.

Following the policies outlined in [IANA-CONSIDERATIONS], session
authorization attribute types (S-Type)in the range 0-127 are
allocated through an IETF Consensus action; S-Type values between
128-255 are reserved for Private Use and are not assigned by IANA.

S-Type AUTH_ENT_ID is assigned the value 1.
S-Type SESSION_ID is assigned the value 2.
S-Type SOURCE_ADDR is assigned the value 3.
S-Type DEST_ADDR is assigned the value 4.
S-Type START_TIME is assigned the value 5.
S-Type END_TIME is assigned the value 6.
S-Type RESOURCES is assigned the value 7.
S-Type AUTHENTICATION_DATA is assigned the value 8.

Following the policies outlined in [IANA-CONSIDERATIONS],
AUTH_ENT_ID SubType values in the range 0-127 are allocated through
an IETF Consensus action, SubType values between 128-255 are
reserved for Private Use and are not assigned by IANA.

AUTH_ENT_ID SubType IPV4_ADDRESS is assigned the value 1.
SubType IPV6_ADDRESS is assigned the value 2.
SubType FQDN is assigned the value 3.
SubType ASCII_DN is assigned the value 4.
SubType UNICODE_DN is assigned the value 5.
SubType URI is assigned the value 6.
SubType KRB_PRINCIPAL is assigned the value 7.
SubType X509_V3_CERT is assigned the value 8.
SubType PGP_CERT is assigned the value 9.

Following the policies outlined in [IANA-CONSIDERATIONS],
SOURCE_ADDR SubType values in the range 0-127 are allocated through
an IETF Consensus action, SubType values between 128-255 are
reserved for Private Use and are not assigned by IANA.

SOURCE_ADDR SubType IPV4_ADDRESS is assigned the value 1.
SubType IPV6_ADDRESS is assigned the value 2.
SubType FQDN is assigned the value 3.
SubType ASCII_DN is assigned the value 4.
SubType UNICODE_DN is assigned the value 5.
SubType UDP_PORT_LIST is assigned the value 6.

Internet Draft Session Authorization for RSVP June 2002

SubType TCP_PORT_LIST is assigned the value 7.

Following the policies outlined in [IANA-CONSIDERATIONS],
DEST_ADDR SubType values in the range 0-127 are allocated through an
IETF Consensus action, SubType values between 128-255 are reserved
for Private Use and are not assigned by IANA.

DEST_ADDR SubType IPV4_ADDRESS is assigned the value 1.
SubType IPV6_ADDRESS is assigned the signing key) or value 2.
SubType FQDN is assigned the data itself. value 3. Verify
SubType ASCII_DN is assigned the requested QoS does not exceed value 4.
SubType UNICODE_DN is assigned the authorized QoS.

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Internet Draft Session Authorization for RSVP February 2002 value 5.
SubType UDP_PORT_LIST is assigned the value 6. Error Signaling

If PDP fails to verify
SubType TCP_PORT_LIST is assigned the AUTH_SESSION policy element then it MUST
return policy control failure (Error Code = 02) to value 7.

Following the PEP. The
error policies outlined in [IANA-CONSIDERATIONS],
START_TIME SubType values are described in [RFC-2205] and [POL-EXT]. Also PDP
SHOULD supply a policy data object containing an AUTH_DATA
Policy Element with A-Type=POLICY_ERROR_CODE containing more
details on the Policy Control failure [I-REP]. The PEP
will include this Policy Data object in range 0-127 are allocated through
an IETF Consensus action, SubType values between 128-255 are
reserved for Private Use and are not assigned by IANA.

START_TIME SubType NTP_TIMESTAMP is assigned the outgoing RSVP Error
message.

7. IANA Considerations value 1.

Following the policies outlined in [IANA-CONSIDERATIONS], session
authorization attribute types (S-Type)in
END TIME SubType values in the range 0-127 are allocated through an
IETF Consensus action, S-Type SubType values between 128-255 are reserved
for Private Use and are not assigned by IANA.

END TIME SubType NTP_TIMESTAMP is assigned the value 1.

Following the policies outlined in [IANA-CONSIDERATIONS],
AUTH_ENT_ID, AUTH_ENT_CRED, SESSION_ID, START_TIME, STOP_TIME,
SOURCE_IP, DEST_IP,
RESOURCES and DIGITAL_SIGNATURE SubType values in the range 0-127 are allocated through an
IETF Consensus action, SubType values between 128-255 are reserved
for Private Use and are not assigned by IANA.

RESOURCES SubType BANDWIDTH is assigned the value 1.
SubType FLOW_SPEC is assigned the value 2.
SubType SDP is assigned the value 3.
SubType DSCP is assigned the value 4.

9. Security Considerations

The purpose of this draft is to describe a mechanism for session
authorization to prevent theft of service.

Replay attacks MUST be prevented. In order the non-associated model, the
AUTH_SESSION policy element MUST include a START_TIME field. The
start time is used to verify that the request is not being replayed
at a later time. In all other models, the SESSION_ID is used by the

Internet Draft Session Authorization for RSVP June 2002

Policy Server to ensure that the resource request successfully
correlates with records of an authorized session. If a AUTH_SESSION
is replayed, it MUST be detected by the policy server (using
internal algorithms) and the request MUST be rejected.

To ensure that the integrity of the token policy element is preserved in
some
untrusted environments, the digital signature AUTHENTICATION_DATA attribute SHOULD MUST be used.
included.

In fact, since order to keep the token is AUTH_SESSION policy element size to a strict
minimum, in environments where shared private keys are possible,
they should be relayed through the end host,
which used. This is usually considered untrusted, we strongly recommend the
use of especially true in wireless
environments where the digital signature attribute.

Simple AUTH_SESSION policy element is sent over-the-
air. The shared private keys authentication (e.g. plain ASCII or UNICODE) does not
contain credential that can option MUST be securely authenticated and is
inherently less secured.

The supported
by all AUTH_SESSION implementations.

If shared private keys are not a valid option, the Kerberos
authentication mechanism is reasonably well secured.
Kerberos secured and efficient in
terms of AUTH_SESSION size. The AUTH_SESSION only needs to contain
the principal@realm name of the authorizing entity. This is much
more efficient than the PKI mechanism from
computational point of view. authentication option.

PKI authentication option should provide highest provides a high level of security and good
scalability, however it requires infrastructure
support and may have performance impacts.

9. the presence of credentials in the
AUTH_SESSION policy element which impacts its size.

10. Acknowledgments

We would like to thank Louis LeVay, Francois Audet, Don Wade, Hamid
Syed, Kwok Ho Chan and many others for their valuable comments.

In addition, we would like to thank S. Yadav, et al, for their
efforts on RFC 3182, as this document borrows from their work.

10.

11. Normative References

[I-REP] S. Yadav et al, "Identity Representation for
RSVP", RFC 3182, October 2001

[S-AUTH] L-N. Hamer et al., Hamer, L.-N., Gage, B., Shieh, H., "Framework
for session setup with media authorization",
Internet-Draft,
draft-hamer-rap-session-auth-03.txt,
February
draft-ietf-rap-session-auth-04.txt,
June 2002.

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Internet Draft Session Authorization for RSVP February 2002

[ASCII] Coded Character Set -- 7-Bit American
Standard Code for Information Interchange,
ANSI X3.4-
1986.

[IANA-CONSIDERATIONS] Alvestrand, H. and T. Narten, "Guidelines for
Writing an IANA Considerations Section in
RFCs", BCP 26, RFC 2434, October 1998.

[POL-EXT] X3.4-1986.

[RFC-2750] Herzog, S., "RSVP Extensions for Policy
Control", RFC 2750, January 2000.

[POL-FRAME]

Internet Draft Session Authorization for RSVP June 2002

[RFC-2753] Yavatkar, R., Pendarakis, D. and R. Guerin, "A
Framework for Policy-based Admission Control
RSVP", RFC 2753, January 2000.

[RFC-1034] Mockapetris, P.V., "Domain names - concepts
and facilities", RFC 1034, November 1987.

[RFC-1305] Mills, David L., "Network Time Protocol
(Version 3) Specification, Implementation, and
Analysis", RFC 1305, March 1992.

[RFC-1321] Rivest, R., "The MD5 Message-Digest
Algorithm",RFC 1321, April 1992.

[RFC-1510] Kohl, J. and C. Neuman, "The Kerberos Network
Authentication Service (V5)", RFC 1510,
September 1993.

[RFC-1633] Braden, R., Clark, D., Shenker, S.,
"Integrated Services in the Internet
Architecture: An Overview",

[RFC-2104] Krawczyk, H., Bellare, M. and R. Canetti,
"HMAC: Keyed-Hashing for Message
Authentication", RFC 1633,
June 1994. 2104, February 1997.

[RFC-2253] Wahl, M. et al., "UTF-8 String
Representation of Distinguished Names",
RFC 2253, December 1997.

[RFC-2205] Braden, R., Zhang, L., Berson, S., Herzog, S.
and S. Jamin, "Resource ReSerVation Protocol
(RSVP) - Version 1 Functional Specification",
RFC 2205, September 1997.

[RFC-2209] Braden, R. and L. Zhang, "Resource
ReSerVation Protocol (RSVP) - Version 1
Message Processing Rules", RFC 2209,
September 1997.

[RFC-2327] Handley, M., Jacobson, V., "SDP: Session
Description Protocol", RFC 2327, October
1998.

[RFC-2396] Berners-Lee, T., Fielding, R., Irvine, U.C.,
Masinter, L., "Uniform Resource Identifiers
(URI): Generic Syntax", RFC 2396, August
1998.

[RFC-2474] Nichols, K., Blake, S., Baker, F., Black, D.,
"Definition of the Differentiated Services
Field (DS Field) in the IPv4 and IPv6
Headers", RFC 2474, December 1998.

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Internet Draft Session Authorization for RSVP February June 2002

[RFC-2998] Bernet, Y., Ford, P., Yavatkar, R., Baker, F.,
Zhang, L., Speer, M., Braden, R., Davie, B.,
Wroclawski, J., Felstaine, E., "A Framework
for Integrated Services Operation over
Diffserv Networks", RFC 2998, November 2000.

[UNICODE] The Unicode Consortium, "The Unicode Standard,
Version
Standard,Version 2.0", Addison-Wesley,
Reading, MA, 1996.

[X.509] Housley, R., Ford, W., Polk, W. and D. Solo,
"Internet X.509 Public Key Infrastructure
Certificate and CRL Profile", RFC 2459,
January 1999.

[X.509-ITU] ITU-T (formerly CCITT) Information technology -
Open Systems Interconnection - The Directory:
Authentication Framework Recommendation X.509
ISO/IEC 9594-8

11.

12. Informative References

[RFC-3182] S. Yadav et al, "Identity Representation for
RSVP", RFC 3182, October 2001

[RFC-2998] Bernet, Y., Ford, P., Yavatkar, R.,
Baker, F.,Zhang, L., Speer, M., Braden, R.,
Davie, B., Wroclawski, J., Felstaine, E., "A
Framework for Integrated Services Operation
over Diffserv Networks", RFC 2998, November
2000.

[RFC-1633] Braden, R., Clark, D., Shenker, S.,
"Integrated Services in the Internet
Architecture: An Overview", RFC 1633,
June 1994.

[IANA-CONSIDERATIONS] Alvestrand, H. and T. Narten, "Guidelines for
Writing an IANA Considerations Section in
RFCs", BCP 26, RFC 2434, October 1998.

13. Author Information

Louis-Nicolas Hamer
Nortel Networks
PO Box 3511 Station C
Ottawa, Ontario
Canada K1Y 4H7
Phone: +1 613.768.3409
EMail: nhamer@nortelnetworks.com

Brett Kosinski
University of Alberta
Edmonton, Alberta
Canada T6G 2M7
EMail: kosinski@cs.ualberta.ca

Internet Draft Session Authorization for RSVP June 2002

Bill Gage
Nortel Networks
PO Box 3511 Station C
Ottawa, Ontario
Canada K1Y 4H7
Phone: +1 613.763.4400
EMail: gageb@nortelnetworks.com

Matt Broda
Nortel Networks
PO Box 3511 Station C
Ottawa, Ontario
Canada K1Y 4H7
Phone: +1 613.763.7399
EMail: mbroda@nortelnetworks.com

Hugh Shieh
AT&T Wireless
7277 164th Avenue NE
Redmond, WA
USA 98073-9761
Phone: +1 425.580.6898
Email: hugh.shieh@attws.com

12.

14. Full Copyright Statement

Copyright (C) The Internet Society (2002). All Rights Reserved. This
document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organisations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into.

Expiration Date

15. Notices

"The IETF takes no position regarding the validity or scope of
any intellectual property 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; neither does
it represent that it has made any effort to identify any such
rights. Information on the IETF's procedures with respect to

Internet Draft Session Authorization for RSVP June 2002

rights in standards-track and standards-related documentation
can be found in BCP-11. Copies of claims of rights made
available for publication and any assurances of licenses to
be made available, or the result of an attempt made
to obtain a general license or permission for the use of such
proprietary rights by implementors or users of this
specification can be obtained from the IETF Secretariat."

"The IETF invites any interested party to bring to its
attention any copyrights, patents or patent applications, or
other proprietary rights which may cover technology that may be
required to practice this standard. Please address the
information to the IETF Executive Director."

16. RFC Editor Considerations

This memo document references an IETF Internet-Draft that is filed in the IESG
last call stage. Please use the corresponding RFC number prior to
publishing of this document as <draft-ietf-rap-rsvp-authsession-02.txt>, and
expires August 31, 2002.

Expires August 2002 [Page 15] a RFC. The referenced IETF I-D is
[S-AUTH].

----