SPARTA, Inc. H Harney (SPARTA)
INTERNET-DRAFT A Colegrove (SPARTA)
E Harder (NSA)
U Meth (SPARTA)
R Fleischer (SPARTA)
SPARTA, Inc., National Security Agency
draft-ietf-msec-tgsakmp-00.txt May 2003
Tunneled Group Secure Association Key Management Protocol
Status of this memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026. Internet-Drafts are working documents
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Document expiration: October 31, 2003
Abstract
The Tunneled Group Secure Association Key Management Protocol
(T-GSAKMP) provides a security framework for creating cryptographic
groups on a network. It is designed to provide key distribution
services under the cryptographic protection of a pairwise SA,
like IPSec. T-GSAKMP relies on the pairwise SA to provide data
confidentiality services for policy, DoS mitigation services,
and protection from "man-in-the-middle" attacks. It provides
mechanisms to disseminate group security policy, perform access
control based upon PKI certificates, generate group keys,
INTERNET-DRAFT T-GSAKM Protocol May 2003
and recover from compromise. This framework addresses group
scalability issues by facilitating delegation of process-intensive
actions in a secure and controlled manner.
Copyright Notice
Copyright (c) The Internet Society (2003). All Rights Reserved.
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Contents
1 Background 7
2 Overview 7
2.1 T-GSAKMP Overview . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Document Organization . . . . . . . . . . . . . . . . . . . . . . . 9
3 Terminology 10
3.1 T-GSAKMP Terminology . . . . . . . . . . . . . . . . . . . . . . . 10
4 GROUP LIFE-CYCLE 13
4.1 Group Establishment . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1.1Group Establishment without the Use of an Underlying SA . . . . 15
4.1.2Create Group Key . . . . . . . . . . . . . . . . . . . . . . . 15
4.1.3Distribute Group Key . . . . . . . . . . . . . . . . . . . . . . 15
4.2 Group Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.1Member Joins/Leaves . . . . . . . . . . . . . . . . . . . . . . 20
4.2.2Rekey Events . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3 Group Removal/Destruction . . . . . . . . . . . . . . . . . . . . . 20
5 Message formats 22
5.1 T-GSAKMP Header . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.2 Generic Payload Header . . . . . . . . . . . . . . . . . . . . . . 25
5.3 Data Attributes Payload . . . . . . . . . . . . . . . . . . . . . . 25
5.4 Policy Token Payload . . . . . . . . . . . . . . . . . . . . . . . 26
5.5 Key Download Payload . . . . . . . . . . . . . . . . . . . . . . . 27
5.5.1GTEK Key Packet . . . . . . . . . . . . . . . . . . . . . . . . 28
5.5.2Rekey Key Packet . . . . . . . . . . . . . . . . . . . . . . . . 29
5.6 Rekey Event Payload . . . . . . . . . . . . . . . . . . . . . . . . 30
5.7 Identification Payload . . . . . . . . . . . . . . . . . . . . . . 31
5.8 Authorization Payload . . . . . . . . . . . . . . . . . . . . . . . 32
5.9 Certificate Payload . . . . . . . . . . . . . . . . . . . . . . . . 33
5.10Certificate Request Payload . . . . . . . . . . . . . . . . . . . . 34
5.11Signature Payload . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.12Notification Payload . . . . . . . . . . . . . . . . . . . . . . . 37
5.12.1Notification Data - Acknowledgement (ACK) Message Type . . . . 39
5.13Vendor ID Payload . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.14Key Creation Payload . . . . . . . . . . . . . . . . . . . . . . . 41
5.15Nonce Payload . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
6 T-GSAKMP State Diagram 44
7 APPENDIX A -- Rekey Packet data format 46
7.1 Rekey Event Header . . . . . . . . . . . . . . . . . . . . . . . . 46
7.2 Rekey Event Packet Data(s) . . . . . . . . . . . . . . . . . . . . 47
7.3 Key Pack Data . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.4 Pack Data Formats . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.4.1GTEK Pack Data . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.4.2LKH Pack Data . . . . . . . . . . . . . . . . . . . . . . . . . 49
7.5 Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8 References and Authors Addresses 51
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8.1 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.2 Authors Addresses . . . . . . . . . . . . . . . . . . . . . . . . . 52
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List of Figures
1 Group Establishment Ladder Diagram . . . . . . . . . . . . . . . . 14
2 T-GSAKMP Header Format . . . . . . . . . . . . . . . . . . . . . . 22
3 Generic Payload Header . . . . . . . . . . . . . . . . . . . . . . 25
4 Data Attributes Payload . . . . . . . . . . . . . . . . . . . . . . 26
5 Policy Token Payload Format . . . . . . . . . . . . . . . . . . . . 26
6 Key Download Payload Format . . . . . . . . . . . . . . . . . . . . 27
7 Rekey Event Payload Format . . . . . . . . . . . . . . . . . . . . 30
8 Identification Payload Format . . . . . . . . . . . . . . . . . . . 31
9 Authorization Payload Format . . . . . . . . . . . . . . . . . . . 32
10 Certificate Payload Format . . . . . . . . . . . . . . . . . . . . 33
11 Certificate Request Payload Format . . . . . . . . . . . . . . . . 35
12 Signature Payload Format . . . . . . . . . . . . . . . . . . . . . 36
13 Notification Payload Format . . . . . . . . . . . . . . . . . . . . 37
14 Notification Data - Acknowledge Message Type Format . . . . . . . . 39
15 Vendor ID Payload Format . . . . . . . . . . . . . . . . . . . . . 41
16 Key Creation Payload Format . . . . . . . . . . . . . . . . . . . . 41
17 Nonce Payload Format . . . . . . . . . . . . . . . . . . . . . . . 42
18 T-GSAKMP State Diagram . . . . . . . . . . . . . . . . . . . . . . 44
19 A.1: Rekey Event Header Format . . . . . . . . . . . . . . . . . . 46
20 A.2: Rekey Event Packet Data Format . . . . . . . . . . . . . . . 47
21 A.3: Key Pack Data Format . . . . . . . . . . . . . . . . . . . . 48
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List of Tables
1 Request to Join Message Definition . . . . . . . . . . . . . . . . 16
2 Invitation to Join Message Definition . . . . . . . . . . . . . . . 16
3 Invitation Response Message Definition . . . . . . . . . . . . . . 18
4 Key Download Message Definition . . . . . . . . . . . . . . . . . . 18
5 Key Download Message with Insufficient SA Definition . . . . . . . 19
6 Acknowledgment Message Definition . . . . . . . . . . . . . . . . . 19
7 Rekey Event Message Definition . . . . . . . . . . . . . . . . . . 21
8 Group Removal/Destruction Message Definition . . . . . . . . . . . 21
9 Group Identification Types . . . . . . . . . . . . . . . . . . . . 22
10 Payload Types . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
11 Exchange Types . . . . . . . . . . . . . . . . . . . . . . . . . . 24
12 Policy Token Types . . . . . . . . . . . . . . . . . . . . . . . . 27
13 Key Download Data Types . . . . . . . . . . . . . . . . . . . . . . 28
14 Rekey Event Types . . . . . . . . . . . . . . . . . . . . . . . . . 30
15 Identification Types . . . . . . . . . . . . . . . . . . . . . . . 32
16 Authorization Types . . . . . . . . . . . . . . . . . . . . . . . . 33
17 Certificate Payload Types . . . . . . . . . . . . . . . . . . . . . 34
18 Signature Types . . . . . . . . . . . . . . . . . . . . . . . . . . 36
19 Notify Messages Types . . . . . . . . . . . . . . . . . . . . . . . 38
20 Notify Messages -- Status Types . . . . . . . . . . . . . . . . . . 39
21 Acknowledgement Types . . . . . . . . . . . . . . . . . . . . . . . 40
22 Types Of Key Creation Information . . . . . . . . . . . . . . . . . 42
23 Nonce Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
24 State Transition Events . . . . . . . . . . . . . . . . . . . . . . 45
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1 Background
T-GSAKMP is the forebearer of GSAKMP. It was first proposed in 1999 in the
IRTF Secure Multicast Group and later was proposed to the IETF Multcast
Security Group. T-GSAKMP was replaced with a simplified GSAKMP in 2002.
GSAKMP does not rely on a secure underlying SA for any protections and
reduces the number of messages in the key distribution protocol from five
(5) to three (3). T-GSAKMP, unlike GSAKMP, provides no default initial
security parameters nor does it make assumptions about the announcement
of those parameters through supporting infrastructure. GSAKMP is more
compliant with the IETF MSEC charter.
In order to retain the original design concept and to provide key management
for those groups wishing to create groups under a secure association, the
original GSAKMP specification is now being transferred to the experimental
rfc area. The specification is titled Tunneled Group Secure Association Key
Managment Protocol (T-GSAKMP) to reflect that this version of GSAKMP relies
on the existance of a secure tunnel to protect the initial communication.
2 Overview
The Tunneled Group Secure Association Key Management Protocol (T-GSAKMP)
provides symmetric key to groups of users on a network. It provides
mechanisms to disseminate group policy, perform access control decisions
during group establishment, generate group keys, recover from the compromise
of group members, delegate group security functions and destroy the group.
The goals of the T-GSAKMP are to create a protocol that:
1. Distributes group policy,
2. Provides mechanisms for distributing the group key, and
3. Provides mechanisms for a Rekey of the group.
2.1 T-GSAKMP Overview
Protecting information requires the definition of a security policy and the
enforcement of that policy by capable parties. Control and access to the
cryptographic key is the primary mechanism to enforce the access control
policy. The T-GSAKMP provides these mechanisms to control access to the
group key.
This document identifies the T-GSAKMP Message Passing Requirements. The
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group key(s) are created by the group controller. The group controller
must start the group access control, policy enforcement process. The group
controller needs to have the access rules defined for joining the group
and should be able to identify and verify the permissions of the members to
which they will distribute keys.
The potential group members need to have ``knowledge'' of the access control
policy for the group, an unambiguous identification of any party downloading
keys to them, and verifiable chain of authority for key download. The group
members also need to verify that the key creator is authorized to act in
that capacity.
In order to establish a group Secure Association (SA) to support these
activities, the identity of each party in the security/access control
process must be unambiguously stated/asserted and authenticated to ensure
that they are authorized to be a member of the group as defined by the
group's security policy. The security characteristics of the establishment
protocol for the SA should include:
1. Coherent permission topology,
2. Group policy,
3. Group policy dissemination,
4. Peer SA to protect data, and
5. Access control checking.
2.2 Assumptions
T-GSAKMP makes the following assumptions of the underlying host:
1. The operating system can provide the process and data separation
services to support software encryption.
2. A separate SA mechanism is present that is sufficient to protect the
distribution of the group key.
3. The host and all the applications on that host share the same
certificate identities (at least initially).
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2.3 Document Organization
Section 1 presents an overview of secure group communications. Section 2
presents the terminology and concepts used to present the requirements of
this protocol. Section 3 describes the group management life-cycle and
Section 4 presents the message types and formats used during each phase of
the life-cycle. Section 5 presents a discussion of the states encountered
in the protocol.
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3 Terminology
The following terminology is used throughout the T-GSAKMP paper.
3.1 T-GSAKMP Terminology
Group Member: A group member (GM) is any entity with access to the group
keys. Regardless of how a member becomes a part of the group or how the
group is structured, GMs will perform the following actions:
1. Validate the GC's authorization to perform actions;
2. Accept group keys from the GC;
3. Request group keys from the GC;
4. Maintain local Certificate Revocation Lists (CRLs);
5. Enforce the cooperative group policies as stated in the group
policy token;
6. Perform peer review of key management actions; and
7. Manage their local key.
Group Secure Association (GSA): A cryptographic group is a logical
association of users or hosts that share cryptographic key(s). This
group may be established to support associations between applications or
communication protocols.
Group Policy: The group policy completely describes the protection
mechanisms and security relevant behaviors of the group. This policy
must be commonly understood and enforced by the group for coherent
secure operations.
Policy Token/Certificate: The policy token is a mechanism used to
disseminate the group policy. The policy token is issued and signed
by an authorized source. Each member of the group must verify the
token, meet the group join policy , and enforce the policy of the group.
The group policy data element will contain a variety of information
including:
1. T-GSAKMP protocol format,
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2. Key creation method,
3. Key dissemination policy,
4. Access control policy,
5. Group architecture policy, and
6. Compromise recovery policy.
The policy token layout will be fully presented in the Group Policy
Token Specification document.
Group Controller: The Group Controller (GC) is a group member with
authority to perform any critical protocol actions including:
1. Creating and distributing keys;
2. Maintain the Rekey infrastructure; and
3. Building and maintaining the Rekey arrays.
As the group evolves, it may become desirable to have multiple
controllers perform these functions (e.g., Rekey Controller and Group
Key Controller).
Subordinate Controller: Any group member, as defined in the group policy,
has the capability to act as a Subordinate Controller (SC) thus allowing
the group processing and communication requirements to be distributed
equitably throughout the network. If the group is structured in
such a way, the delegated group members would be identified via the
policy token. The SCs may perform actions delegated to them by the GC
including:
1. Dissemination of the group key and
2. Management of the status of the local group.
The ease of managing a very large group may also be improved by
delegating the creation of subordinate LKH arrays to the SCs. The
SCs would have the authority and mechanisms necessary to create and
disseminate the LKH arrays for the members under their control. A
more detailed discussion of LKH arrays may be found in the Logical Key
Hierarchy (LKH) Protocol document.
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Peer-to-Peer SA: Peer-to-Peer SA keys can be created by using any number
of key generation protocols including the Internet Secure Association
Key Management Protocol (ISAKMP)/IPSec and HS/SSL. These protocols
rely on cooperative key generation algorithms and on peer review of
permissions. Modern SA protocols are specifically developed to support
this task. Once the peer-to-peer SA is established, the group protocol
can use that SA mechanism for secure confidential peer communications
throughout the life of the group.
GSA Keys: GSA keys can be created using strong randomization key
generation protocols. These protocols rely on a cooperatively conferred
policy. Once the group keys are created and disseminated to the
group members, the group protocol can use that SA mechanism for secure
confidential group communications throughout the life of the group.
Group Traffic Encryption Key (GTEK): The key or keys created for
encrypting the group data.
Logical Key Hierarchy (LKH) array: The group of keys created to
facilitate the LKH compromise recovery methodology.
Compromise Recovery: The act of recovering a secure operating state after
detecting that a group member cannot be trusted.
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4 GROUP LIFE-CYCLE
The management of a cryptographic group follows a life-cycle: group
definition, group establishment, group maintenance, and group removal.
Each of these life-cycle phases is discussed in the following sections.
A cryptographic group is established based on some need for secure
communications among a group of individuals. The activities involved in
creating a cryptographic group include:
1. Determine Access Policy: Group Join
2. Determine Authorization Policy: Key Dissemination, Computer Trust, and
Architecture Authorization
3. Determine Mechanisms: Algorithms and Infrastructure
4. Determine Architecture: Key Dissemination and Compromise Recovery
5. Create Group Policy Token
For the purposes of this document, it is assumed that the group definition
activity has occurred and the group information has been broadcast on a key
management channel or through a directory service.
4.1 Group Establishment
The Group Establishment Ladder diagram, Figure 1, is presented to illustrate
the process of establishing a cryptographic group. The left side of the
diagram represents the actions of the GC. The right side of the diagram
represents the actions of the GMs. The components of each message shown in
the diagram are presented in the Message Definitions sections following the
diagram.
Potential GMs may join a group in two ways: by invitation (push) or request
(pull). For purposes of illustration, the diagram presents a ``Request to
Join Group'', a ``pull'', message sent from a potential GM.
At this point, the GC must accept or deny the request. ``Process RTJ``
indicates a provision for refusing the connection due to some specified
reason (e.g., no group, group full, repetitive attempts to join). If the
results of ``Process RTJ`` indicate that the GC should reject the request,
the session is terminated.
If the results of Processing the Request to Join indicate that the GC
should accept the request, the session continues. The message traffic to
an invited potential member also begins at this point on the diagram.
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CONTROLLER MESSAGE MEMBER
!<------------Request to Join-------------!
<Process RTJ> ! !
!<============SA ESTABLISHMENT===========>!(Outsid T-GSAKMP)
! !
!-------------Invitation----------------->!
! !<Process Inv.>
!<------------Invitation Response-------->!
<Process Inv. Rsp.> ! !
!-------------Key Download--------------->!
! !<Process Key DL>
!<------------Acknowledgment--------------!
<Process ACK> ! !
!<=======SHARED KEYED GROUP SESSION======>!
Figure 1: Group Establishment Ladder Diagram
The area of the diagram specified as ``Outside T-GSAKMP'' is merely
illustrative to show the confidentiality between the GC and GM. It is
assumed, for the purposes of this document, that the GC and GM are able to
establish a SA using protocols like ISAKMP and IPSec. The GC will specify
the security characteristics of the SA to the outside application. The
level of protection shall be as good or stronger than the SA characteristics
specified in the group policy token. A suggested minimal SA security level
is confidentiality with integrity.
To facilitate a well ordered group creation, security policy information
must be passed between the GC and the GMs using a group policy token. The
group policy token must include the group's address, group permissions,
group join policy, group controller identity, group management information,
and digital signature of the policy creation authority.
Standard design principles for secure protocols mandate the use of explicit
identification of senders and recipients of messages. The signature payload
of each message identifies the signer of the message and therefore satisfies
the sender requirement. Within the T-GSAKMP header is a group ID. Because
the member may be served by any Key Server within a group, this ID provides
sufficient granularity for the recipient ID for the Request to Join message.
Other messages sent by the potential member will contain the recipient
ID for the GCKS serving that member. The Invitation message provides no
authority to join the group (authorization information is contained in
the signed token), but merely provides information to a potential member.
Because of this, unintended receipt of this message by someone would not
cause harm. The recipient ID for this message is therefore optional. The
Key Download message also contains a required explicit ID.
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4.1.1 Group Establishment without the Use of an Underlying SA
Group Establishment, as specified in Section 3.1, uses an underlying
Security Association to protect the contents of the Token and subsequent key
download.
In the cases where token contents are not sensitive, T-GSAKMP can provide
secure member joins and associated secure policy and key downloads without
any reliance on an underlying secure protocol subsystem.
In both of these cases, it is assumed that the data portion of the Key
Download payload is encrypted. The details of the encryption of this data
is provided in the Key Download payload itself. The key determination for
this encryption may be done through a two-party contributory system (a la
Diffie-Hellman) using the Key Creation Payloads to carry the contributions
of the participants to this key, or may be transferred with the encrypted
contents using public key encryption and an enveloping scheme (e.g., RFC
2630 Enveloped Data with Key Transport.)
4.1.2 Create Group Key
There are two options: key generation at a single point and shared
generation. In shared generation, the first member must cooperate with the
GC to create the group key. There are several established software-based
key creation protocols, including Diffie-Hellman and RSA, that support two
group members cooperating to create a cryptographic key. However, for this
document, the following discussion presents single-point key generation.
Prior to the first member join, the GC will have created the GTEK and the
Rekey array.
4.1.3 Distribute Group Key
Potential GMs may join a group and receive the group key in two ways: by
invitation (push) or request (pull). The following message definition shows
a Request to Join message from a potential GM. The initial message from the
GM would contain the following:
1. GSA request and
2. GM Certificate (optional).
The components of a Request to Join message are are shown in Table 1:
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Table 1: Request to Join Message Definition
Message Name : Request to Join
Dissection : {HDR, GrpID, Nonce_I, GSA RQ} SigM, [CertM]
Payload Types : T-GSAKMP Header, Nonce, Notification, Signature,
[Certificate], [Certificate Request], [Vendor
ID], [Identification], [Authorization]
SigM : Signature of Group Member
CertM : Certificate of Group Member
{}SigX :Indicates minimum fields used in Signature
[] : Indicate an optional data item
The following message definition shows an ``Invitation to Join'' message
from the GC to a potential GM. The initial message from the GC would contain
the following:
1. Signed group policy token,
2. GSA request, and
3. GC Certificate (optional).
The components of an Invitation to Join message are shown in Table 2:
Table 2: Invitation to Join Message Definition
Message Name : Invitation to Join
Dissection : {HDR, GrpID, Policy Token, (Nonce_R, Nonce_C) OR
Nonce_I, [Key Creation], GSA RQ}SigC, [CertC],
[SigSC], [CertSC]
Payload Types : T-GSAKMP Header, Policy Token, Nonce,
Notification, Signature, [Certificate],
[Signature], [Certificate], [Key Creation],
[Certificate Request], [Vendor ID], [Identification],
[Authorization]
SigC : Signature of Group Controller
SigSC : Signature of Subordinate Group Controller
CertC : Certificate of Group Controller
CertSC : Certificate of Subordinate Group Controller
{}SigX :Indicates minimum fields used in Signature
[] : Indicate an optional data item
For purposes of discussion, this section presents a ``Invitation to Join''
as presented in Table 2.
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The GM will receive this message and process it according to the provisions
of Processing the Invitation. The GSA RQ contains the identity of the
message source in enough detail to allow the potential member to verify
the signature. The GSA RQ also contains the ID of the invited member. In
``Process Invitation'' the potential GM will initially verify that the
signature on the message is authentic. If the message signature does not
verify, the session is terminated. T-GSAKMP sends a properly authenticated
message with a Notification Payload of type NACK to indicate termination.
If the message signature is authentic, then the potential GM will look
at who signed the message, verify the signer's authorization, and make
a decision to proceed. If the potential GM decides not to proceed, the
session is terminated. T-GSAKMP sends a properly authenticated message with
a Notification Payload of type NACK to indicate termination.
If the GM initiated a pull by sending a Request to Join message, the
Invitation to Join message received must contain the Nonce_R and Nonce_C
payloads. If the GM is being invited to join the group via a push by
the GCKS, the Invitation to Join message received must contain a Nonce_I
payload.
NOTE: When not using an underlying Security Association (SA), or the SA is
not sufficient to protect the key data in the Key Download message, the
Key Creation payload is required in this message if using a pairwise key
determination system.
If the potential GM has decided to continue, they will examine the
information within the policy token to determine if this is a group they are
authorized and interested in joining. If the decision is not to join, the
session is terminated. T-GSAKMP sends a properly authenticated message with
a Notification Payload of type NACK to indicate termination.
If the potential GM is satisfied with the received information and decides
to join the group, he will pass back a message containing the following:
1. Signed GSA response, and
2. GM's certificate (optional).
The components of an Invitation Response message are shown in Table 3:
The GC receives this message and processes it according to the provisions of
Processing the Invitation Response. In this procedure, the GC will verify
the signature on the message to ensure its authenticity. If the message
signature does not verify, the session is terminated. T-GSAKMP sends a
properly authenticated message with a Notification Payload of type NACK to
indicate termination.
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Table 3: Invitation Response Message Definition
Message Name : Invitation Response
Dissection : {HDR, GrpID, (Nonce_R, Nonce_C) OR Nonce_C, [ID_R],
[Key Creation], GSA RS}SigM, [CertM]
Payload Types : T-GSAKMP Header, Nonce, [Identification],
Notification, Signature, [Key Creation],
[Certificate], [Vendor ID], [Authorization]
SigM : Signature of Group Member
CertM : Certificate of Group Member
{}SigX :Indicates minimum fields used in Signature
[] : Indicate an optional data item
If this negotiation was initiated by the GC via a push, the Invitation
Response message received must contain the Nonce_R and Nonce_C payloads. If
this negotiation was initiated by the GM via a pull, the Invitation Response
message received must contain a Nonce_C payload.
NOTE: When not using an underlying Security Association (SA), or the SA is
not sufficient to protect the key data in the Key Download message, the
Key Creation payload is required in this message if using a pairwise key
determination system.
If the message signature is verified, and the GM passes the GC's access
control checks, the GC will create and send a signed message containing the
GTEK and the Rekey array to the GM.
The components of a Key Download message are shown in Table 4:
Table 4: Key Download Message Definition
Message Name : Key Download
Dissection : {HDR, GrpID, Nonce_C, ID_R, [(]Key Data[)*]}SigC,
[SigSC], [CertSC]
Payload Types : T-GSAKMP Header, Nonce, Identification, Key
Download, Signature, [Authorization], [Vendor ID]
SigC : Signature of Group Controller
SigSC : Signature of Subordinate Group Controller
CertC : Certificate of Group Controller
CertSC : Certificate of Subordinate Group Controller
{}SigX :Indicates minimum fields used in Signature
[] : Indicate an optional data item
(data)* : Indicates encrypted information
The GM receives this message and processes it according to the provisions
of Processing the Key Download. In this procedure, the GM will verify the
following information: signature on the message to ensure its authenticity,
the contents of the nonce payload, and the identity information contained in
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the Identification payload is the GM identity information. If the message
signature, nonce, or identification information does not verify, the session
is terminated. T-GSAKMP sends a properly authenticated message with a
Notification Payload of type NACK to indicate termination.
NOTE: When not using an underlying Security Association (SA), or the SA
is not sufficient to protect the key data in the Key Download message, the
Key Data section of the Key Download message must be encrypted. An example
format for this message is shown in Table 5:
Table 5: Key Download Message with Insufficient SA Definition
Message Name : Key Download
Dissection : {HDR, GrpID, Nonce_C, ID_R, (Key Data)*}SigC,
[SigSC], [CertSC]
Payload Types : T-GSAKMP Header, Nonce, Identification, Key
Download, Signature, [Authorization], [Vendor ID]
SigC : Signature of Group Controller
SigSC : Signature of Subordinate Group Controller
CertC : Certificate of Group Controller
CertSC : Certificate of Subordinate Group Controller
{}SigX :Indicates minimum fields used in Signature
[] : Indicate an optional data item
(data)* : Indicates encrypted information
If the message signature, nonce, and identification are verified, the GM
will create a signed acknowledgment message to return to the GC.
The components of an Acknowledgment message are shown in Table 6:
Table 6: Acknowledgment Message Definition
Message Name : Acknowledgment
Dissection : {HDR, GrpID, Nonce_C, [ID_R], ACK}SigM, [CertM]
Payload Types : T-GSAKMP Header, Nonce, [Identification],
Notification, Signature, [Certificate], [Vendor
ID], [Identification], [Authorization]
SigM : Signature of Group Member
CertM : Certificate of Group Member
{}SigX :Indicates minimum fields used in Signature
[] : Indicate an optional data item
The GC receives the signed acknowledgment and processes it according to
the provision of Processing the Acknowledgement. In this procedure, the
GC will verify the signature on the message to ensure its authenticity and
the nonce value. If the message signature or nonce does not verify, the
session is terminated. T-GSAKMP sends a properly authenticated message with
a Notification Payload of type NACK to indicate termination.
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If the message signature and nonce are verified, then the GC and GM have
established a Shared Keyed Group Session.
4.2 Group Maintenance
The Group Maintenance phase includes member joins and leaves, group rekey
activities, and the management of Rekey events. These activities are
presented in the following sections.
4.2.1 Member Joins/Leaves
The addition of group members to a previously established group will closely
follow the processing presented in Section 3.1 -- Group Establishment. With
the exception of the pure group establishment tasks (e.g., creation of
policy token, GTEK, and Rekey array), an entity becomes a GM using the same
message exchanges described in Section 3.1.
A member who elects to voluntarily leave the group will be responsible for
destroying his key. Any further action for a voluntary leave should be
specifically addressed in the group's security policy.
4.2.2 Rekey Events
A Rekey event is any action, including compromises, that involves the
creation and dissemination of a new group key and/or Rekey information.
Once it has been identified, using the group's security policy, that a Rekey
event has occurred, the GC must create and send a signed message containing
the GTEK and Rekey array to the group.
Each GM who receives this message must verify the signature on the message
to ensure its authenticity. If the message signature does not verify, the
session is terminated. T-GSAKMP sends a properly authenticated message
with a Notification Payload of type NACK to indicate termination. Upon
verification the GM will find the appropriate Rekey download packet and
decrypt the information with a stored Rekey key.
The components of a Rekey Event message are shown in Table 7:
4.3 Group Removal/Destruction
At this point in the group's life-cycle, there has been a decision to
destroy the group and the notification is broadcast on a key management
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Table 7: Rekey Event Message Definition
Message Name : Rekey Event
Dissection : {HDR, GrpID, [Policy Token], Rekey Array}SigC,
[CertC]
Payload Types : T-GSAKMP Header, [Policy Token], Rekey Event,
Signature, [Certificate], [Vendor ID]
SigC : Signature of Group Controller
CertC : Certificate of Group Controller
{}SigX :Indicates minimum fields used in Signature
[] : Indicate an optional data item
channel or through a directory service.
The components of a Group Removal/Destruction message are shown in Table 8:
Table 8: Group Removal/Destruction Message Definition
Message Name : Group Removal/Destruction
Dissection : {HDR, GrpID, [Policy Token], Destruct}SigC,
[CertC]
Payload Types : T-GSAKMP Header, [Policy Token], Notification,
Signature, [Certificate], [Vendor ID]
SigC : Signature of Group Controller
CertC : Certificate of Group Controller
{}SigX :Indicates minimum fields used in Signature
[] : Indicate an optional data item
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5 Message formats
5.1 T-GSAKMP Header
The T-GSAKMP Header fields are defined in Figure 2:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
!Group ID Type ! Group ID Value ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
~ ! Next Payload ! Version ! Exchange Type !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Sequence ID !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 2: T-GSAKMP Header Format
Group Identification Type (1 octet) - Table 9 presents the group
identification types.
Table 9: Group Identification Types
Grp ID Type Value
_____________________
IPSec IPv4 0
IPSec IPv6 1
TLS 2
SMIME 3
Other 4-255
Group Identification Value (8 octets) - Indicates the name/title of the
group.
Next Payload (1 octet) - Indicates the type of the first payload in the
message. The format for each payload is defined in the following
sections. Table 10 presents the payload types.
Version (1 octet) - Indicates the version of the T-GSAKMP protocol in use.
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Table 10: Payload Types
Next_Payload_Type Value
___________________________________
None 0
Policy Token 1
Key Download Packet 2
Rekey event 3
Identification 4
Authorization 5
Certificate 6
Certificate Request 7
Signature 9
Notification 10
Vendor ID 11
Key Creation 12
Nonce 13
Reserved 14 - 127
Private Use 128 -- 255
Exchange Type (1 octet) - Indicates the type of exchange (also known as
the message type). Table 11 presents the exchange type values.
Sequence ID (4 octets) - Group Management replay protection field.
Sequence ID for group management messages. If not a group management
message, this value is set to zero (0).
Length (4 octets) - Length of total message (header + payloads) in octets.
Encryption can expand the size of a T-GSAKMP message.
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Table 11: Exchange Types
Exchange_Type Value
____________________________________
Request to Join 0
Invitation 1
Invitation Response 2
Key Download 3
Acknowledgement 4
Rekey Event 5
Group Removal/Destruction 6
No Message 7
Light Request to Join 8
Light Key Download 9
Other 10-255
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5.2 Generic Payload Header
Each T-GSAKMP payload defined in the following sections begins with a
generic header, shown in Figure 3, which provides a payload ``chaining``
capability and clearly defines the boundaries of a payload. The Generic
Payload Header fields are 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 3: Generic Payload Header
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in
the message, then this field will be 0. This field provides the
``chaining`` capability.
RESERVED (1 octet) - Unused, set to 0.
Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
5.3 Data Attributes Payload
There are instances within T-GSAKMP where it is necessary to represent
Data Attributes. These Data Attributes are not a T-GSAKMP payload, but
are contained within T-GSAKMP payloads. The format of the Data Attributes
provides the flexibility for representation of many different types of
information. There can be multiple Data Attributes within a payload.
The length of the Data Attributes will either be 4 octets or defined by
the Attribute Length field. This is done using the Attribute Format bit
described in Figure 4.
The Data Attributes fields are defined as follows:
Attribute Type (2 octets) - Unique identifier for each type of attribute.
The most significant bit, or Attribute Format (AF), indicates whether
the data attributes follow the Type/Length/Value (TLV) format or a
shortened Type/Value (TV) format. If the AF bit is a zero (0), then the
Data Attributes are of the Type/Length/Value (TLV) form. If the AF bit
is a one (1), then the Data Attributes are of the Type/Value form.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Attribute Type ! AF=0 Attribute Length !
! ! AF=1 Attribute Value !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! AF=0 Attribute Value ~
! AF=1 Not Transmitted ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 4: Data Attributes Payload
Attribute Length (2 octets) - Length in octets of the Attribute Value.
When the AF bit is a one (1), the Attribute Value is only 2 octets and
the Attribute Length field is not present.
Attribute Value (variable length) - Value of the attribute associated with
the T-GSAKMP-specific Attribute Type. If the AF bit is a zero (0), this
field has a variable length defined by the Attribute Length field. If
the AF bit is a one (1), the Attribute Value has a length of 2 octets.
5.4 Policy Token Payload
The Policy Token Payload contains group specific information that describes
the group security relevant behaviors, access control parameters, and
security mechanisms. This information may contain a digital signature(s) to
prove authority and integrity of the information. Figure 5 shows the format
of the payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! ID Type ! Policy Token Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 5: Policy Token Payload Format
The Policy Token Payload fields are defined as follows:
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Key Download Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 6: Key Download Payload Format
RESERVED (1 octet) - Unused, set to 0.
Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
ID Type (1 octet) - Specifies the type of Policy Token being used.
Table 12 identifies the types of policy tokens.
Table 12: Policy Token Types
ID_Type Value
______________________
Group 0
Auxiliary 1
Reserved 2-63
Unassigned 64-255
Policy Token Data (variable length) - Contains Policy Token information.
The values for this field are group specific and the format is specified
by the ID Type field.
The payload type for the Policy Token Payload is one (1).
5.5 Key Download Payload
The Key Download Payload contains group keys. These key download payloads
can have several security attributes applied to them based upon the security
policy of the group. Figure 6 shows the format of the payload.
If the security policy of the group dictates, the key download payload may
be encrypted with a key exchange key (KEK). The type of encryption used is
specified in the Policy Token. The group members may create the KEK using
the key creation method identified in the Key Creation Payload.
The Key Download Payload fields are defined as follows:
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Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
Key Download Data (variable length) - Contains Key Download information.
Number of Key Packets (2 octets) -- Contains the total number of both
GTEK and Rekey arrays being passed in this data block.
For each Key Packet, the data format is as follows:
Key Download Data (KDD) Type (1 octet) -- Identifier for the Key
Data field of this Key Packet. See Table 13 for the possible
values of this field.
Table 13: Key Download Data Types
Key Download Data Type Value
________________________________
GTEK 0
Rekey 1
Unassigned 2-255
Key Download Length (2 octets) -- Length in octets of the Key
Packet data following this field.
Key Packet Data (variable length) -- Contains Key information.
The format of this field is specific depending on the value of
the Key Download Data field.
5.5.1 GTEK Key Packet
For a Key Download Data value of GTEK, the Key Packet Data field is
formatted as follows:
Key Type (1 octet) -- This is the encryption algorithm for which this key
data is to be used. This value is specified in the Policy Token.
Key Creation Date (4 octets) -- This is the time value of when this key
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data was originally generated.
Key Expiration Date (4 octets) -- This is the time value of when this key
is no longer valid for use.
Key Handle (4 octets) -- This is the randomly generated value to uniquely
identify a key.
Key Data (variable length) -- This is the actual encryption key data,
which is dependent on the Key Type algorithm for its format.
5.5.2 Rekey Key Packet
T-GSAKMP currently uses the Logical Key Hierarchy (LKH) protocol for Rekey
operations. This Key Packet Data is assumed to contain LKH Array data of
the following format:
LKH Version (1 octet) -- Contains the version of the LKH protocol which
the data is formatted in.
Leaf ID (2 octets) -- This is the Leaf Node ID of the LKH sequence
contained in this Key Packet Data block.
Number of LKH Keys (2 octets) -- This value is the number of distinct LKH
keys in this sequence.
For each LKH key in the sequence, the data format is as follows:
LKH ID (2 octets) -- This is the position of this key in the binary
tree structure used by LKH.
Key Type (1 octet) -- This is the encryption algorithm for which this
key data is to be used. This value is specified in the Policy
Token.
Key Creation Date (4 octets) -- This is the time value of when this
key data was originally generated.
Key Expiration Date (4 octets) -- This is the time value of when this
key is no longer valid for use.
Key Handle (4 octets) -- This is the randomly generated value to
uniquely identify a key.
Key Data (variable length) -- This is the actual encryption key data,
which is dependent on the Key Type algorithm for its format.
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The payload type for the Key Download Packet is two (2).
5.6 Rekey Event Payload
The Rekey Event Payload contains multiple keys encrypted in Rekey keys.
These Rekey Event payloads can have several security attributes applied to
them based upon the security policy of the group. Figure 7 shows the format
of the payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! ID Type ! Rekey Event Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 7: Rekey Event Payload Format
The Rekey Event Payload fields are defined as follows:
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
ID Type (1 octet) - Specifies the type of Rekey Event being used.
Table 14 presents the types of Rekey events.
Table 14: Rekey Event Types
ID_Type Value
______________________________
None 0
Group Recovery 1
Individual Recovery 2
Maintenance 3
Delete Group Key 4
Unassigned 5-255
Rekey Event Data (variable length) - Contains Rekey Event information.
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The values for this field are group specific and the format is specified
by the ID Type field. The format for the LKH type of Rekey Event Data
is located in the appendix section.
The Rekey Event payload type is three (3).
5.7 Identification Payload
The Identification Payload contains entity-specific data used to
exchange identification information. This information is used for
determining the identities of negotiating members and may be used for
determining authenticity of information. Figure 8 shows the format of the
Identification Payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! ID Type ! Identification Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 8: Identification Payload Format
The Identification Payload fields are defined as follows:
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
ID Type (1 octet) - Specifies the type of Identification being used.
Table 15 identifies the types of identities.
Identification Data (variable length) - Contains identity information.
The values for this field are group-specific and the format is specified
by the ID Type field.
The payload type for the Identification Payload is four (4).
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Table 15: Identification Types
ID_Type Value
_____________________________________________
Sender Distinguished Name 0
Receiver Distinguished Name 1
Hash of Sender Distinguished Name 2
Hash of Receiver Distinguished Name 3
Unassigned 4-255
5.8 Authorization Payload
The Authorization Payload contains group-specific data used to exchange role
authorization information. This information is used for determining the
authorization of entities within a group. Figure 9 shows the format of the
Authorization Payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Auth Type ! Authorization Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 9: Authorization Payload Format
The Authorization Payload fields are defined as follows:
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
Authorization Type (1 octet) - Specifies the type of role authorization
being used. Table 16 identifies the types of roles.
Authorization Data (variable length) - Contains authorization information.
The values for this field are group-specific and the format is specified
by the Authorization Type field.
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Table 16: Authorization Types
Auth_Type Value
________________________________________________
Group Controller 0
Group and Rekey Controller 1
Rekey Controller 2
Subordinate Group Controller 3
Subordinate Group and Rekey Controller 4
Subordinate Rekey Controller 5
Member ID 6
Unassigned 7-255
The payload type for the Authorization Payload is five (5).
5.9 Certificate Payload
The Certificate Payload provides a means to transport certificates or other
certificate-related information via T-GSAKMP and can appear in any T-GSAKMP
message. Certificate payloads SHOULD be included in an exchange whenever an
appropriate directory service (e.g. Secure DNS [DNSSEC]) is not available
to distribute certificates. The Certificate payload MUST be accepted at
any point during an exchange. Figure 10 shows the format of the Certificate
Payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Cert Encoding ! Certificate Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 10: Certificate Payload Format
The Certificate Payload fields are defined as follows:
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
Payload Length (2 octets) - Length in octets of the current payload,
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including the generic payload header.
Certificate Encoding (1 octet) - This field indicates the type of
certificate or certificate-related information contained in the
Certificate Data field. Table 17 presents the types of certificate
payloads.
Table 17: Certificate Payload Types
Certificate_Type Value
_______________________________________________
None 0
PKCS #7 wrapped X.509 certificate 1
PGP Certificate 2
DNS Signed Key 3
X.509 Certificate -- Signature 4
X.509 Certificate - Key Exchange 5
Kerberos Tokens 6
Certificate Revocation List (CRL) 7
Authority Revocation List (ARL) 8
SPKI Certificate 9
X.509 Certificate -- Attribute 10
Reserved 11 -- 255
Certificate Data (variable length) - Actual encoding of certificate data.
The type of certificate is indicated by the Certificate Encoding field.
The payload type for the Certificate Payload is six (6).
5.10 Certificate Request Payload
The Certificate Request Payload provides a means to request certificates
via T-GSAKMP and can appear in any message. Certificate Request payloads
SHOULD be included in an exchange whenever an appropriate directory service
(e.g., Secure DNS [DNSSEC]) is not available to distribute certificates.
The Certificate Request payload MUST be accepted at any point during the
exchange. The responder to the Certificate Request payload MUST send its
certificate, if certificates are supported, based on the values contained
in the payload. If multiple certificates are required, then multiple
Certificate Request payloads SHOULD be transmitted. Figure 11 shows the
format of the Certificate Request Payload.
The Certificate Payload fields are defined as follows:
Next Payload (1 octet) - Identifier for the payload type of the next
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Cert Type ! Certificate Authority ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 11: Certificate Request Payload Format
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
Certificate Type (1 octet) - Contains an encoding of the type of
certificate requested.
Certificate Authority (variable length) - Contains an encoding of an
acceptable certificate authority for the type of certificate requested.
As an example, for an X.509 certificate this field would contain the
Distinguished Name encoding of the Issuer Name of an X.509 certificate
authority acceptable to the sender of this payload. This would be
included to assist the responder in determining how much of the
certificate chain would need to be sent in response to this request. If
there is no specific certificate authority requested, this field SHOULD
NOT be included.
The payload type for the Certificate Request Payload is seven (7).
5.11 Signature Payload
The Signature Payload contains data generated by the digital signature
function. The digital signature covers the Signature Payload Span and the
Signature Payload up to the Signature Data. The exception to this is if
the signature algorithm used is DSS with ASN.1/DER encoding. Due to the
variable length of a DER encoding, the signature span across the signature
payload itself only extends up to the signature data length field, not the
signature data. Figure 12 shows the format of the Signature Payload.
The Signature Payload fields are defined as follows:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Sig Type ! Signature Payload Span ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
~ ! Sig ID Role ! Signature Timestamp ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
~ ! Signer ID Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
~ Signer ID Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Signature Length ! Signature Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 12: Signature Payload Format
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
Signature Type (1 octet) -- Indicates the type of signature. Table 18
presents the Signature Types.
Table 18: Signature Types
Signature Type Value
_____________________________________
DSS with ASN.1/DER encoding 0
DSS without encoding 1
Other 2-255
Signature Payload Span (4 octets) - Identifies the information included in
the signature. The first two octets define the first signature payload.
The third and fourth octet define the last payload. The payloads in the
message are an ordered sequence beginning at the header, with a value
of 0. If the signature payload itself is not in the signature span, you
must still sign over the signature payload up to the signature data.
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Signature ID Role (1 octet) -- Specifies the type of Authorization (Role)
being used. Refer to Table 16 for the types of authorization (role).
Signature Timestamp (4 octets) -- Date and time that the digital signature
was applied.
Signer ID Length (2 octets) - Length in octets of the Signer' ID.
Signer ID (variable length) -- Data identifying the Signer's ID (e.g.,
DN).
Signature Length (2 octets) -- Length in octets of the Signature Data.
Signature Data (variable length) - Data that results from applying the
digital signature function to the T-GSAKMP message and/or payload.
The payload type for the Signature Payload is nine (9).
5.12 Notification Payload
The Notification Payload can contain both T-GSAKMP and group specific data
and is used to transmit informational data, such as error conditions, to
a T-GSAKMP peer. It is possible to send multiple Notification payloads in
a single T-GSAKMP message. Figure 13 shows the format of the Notification
Payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Notify Message Type ! STATUS TYPE ! ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
~ Notification Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 13: Notification Payload Format
The Notification Payload fields are defined as follows:
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
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Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
Notify Message Type (2 octets) - Specifies the type of notification
message. Table 19 presents the Notify Message Types.
Table 19: Notify Messages Types
Information Value
_______________________________________________
None 0
Invalid-Payload-Type 1
Situation-Not-Supported 2
Invalid-Major-Version 3
Invalid-Version 4
Invalid-Group-ID 5
Invalid-Message-ID 6
Payload-Malformed 7
Invalid-Key-Information 8
Invalid-ID-Information 9
Invalid-Cert-Encoding 10
Invalid-Certificate 11
Cert-Type-Unsupported 12
Invalid-Cert-Authority 13
Authentication-Failed 14
Invalid-Signature 15
Notify-GSA-Lifetime 16
Certificate-Unavailable 17
Unequal-Payload-Lengths 18
Unauthorized Request 19
Unable To Take Requested Role 20
Group Deleted 21
Request To Join 22
Acknowledgement 23
Invitation 24
Invitation-Response 25
Nack 26
Reserved (future use) 27 - 8191
Private Use 8192 -- 16383
Status Type (1 octet) - Specifies the status of group with respect to
originator of notification. Notification information specifies status
data and can be used by a process managing a SA database to communicate
with a peer process. For example, a secure front end or security
gateway may use the Notify message to synchronize SA communication.
Table 20 presents the Notification Message Status Types.
Notification Data (variable length) - Informational or error data
transmitted in addition to the Notify Message Type. Values for this
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Table 20: Notify Messages -- Status Types
Status Value
____________________________________
Not connected 0
Establishing group 1
Connected to group 2
Previously member of group 3
Reserved (future use) 4-255
field are Domain of Interpretation (DOI)-specific.
The payload type for the Notification Payload is ten (10).
5.12.1 Notification Data - Acknowledgement (ACK) Message Type
The data portion of the ACK payload serves either for confirmation of
correct receipt of the Key Download message, or, when needed, can provide
non-repudiation of receipt when included in a signed message. Figure 14
shows the format of the Notification Data - Acknowledge Message Type.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Ack Type ! Acknowledgement Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 14: Notification Data - Acknowledge Message Type Format
The Notification Data - Acknowledgement Message Type data fields are defined
as follows:
Ack Type (1 octet) - Specifies the type of acknowledgement message.
Table 21 presents the Notify Acknowledgement Message Types.
Simple - Data portion null.
MD5 MAC - Data portion contains output of MD5 HMAC function [RFC
2104]. Input to HMAC function is the Nonce_C value appended to the
decrypted portion, sans encryption padding, of the Key Download
payload of the received Key Download Packet.
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Table 21: Acknowledgement Types
ACK_Type Value
____________________
Simple 0
MD5 MAC 1
SHA-1 HMAC 2
Unassigned 3-255
SHA-1 HMAC - Data portion contains output of SHA-1 HMAC function [RFC
2104]. Input to HMAC function is the Nonce_C value appended to the
decrypted portion, sans encryption padding, of the Key Download
payload of the received Key Download Packet.
5.13 Vendor ID Payload
The Vendor ID Payload contains a vendor defined constant. The constant
is used by vendors to identify and recognize remote instances of their
implementations. This mechanism allows a vendor to experiment with new
features while maintaining backwards compatibility. This is not a general
extension facility of T-GSAKMP. Figure 15 shows the format of the Vendor ID
Payload.
The Vendor ID payload is not an announcement from the sender that it
will send private payload types. A vendor sending the Vendor ID MUST
NOT make any assumptions about private payloads that it may send unless
a Vendor ID is received as well. Multiple Vendor ID payloads MAY be
sent. An implementation is NOT REQUIRED to understand any Vendor ID
payloads. An implementation is NOT REQUIRED to send any Vendor ID payload
at all. If a private payload was sent without prior agreement to send it, a
compliant implementation may reject a proposal with a notify message of type
INVALID-PAYLOAD-TYPE.
The vendor defined constant MUST be unique. The choice of hash and text to
hash is left to the vendor to decide. As an example, vendors could generate
their vendor id by taking a plain (non-keyed) hash of a string containing
the product name, and the version of the product.
The Vendor ID Payload fields are defined as follows:
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Vendor ID (VID) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 15: Vendor ID Payload Format
Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
Vendor ID (variable length) - Hash of the vendor string plus version (as
described above).
The payload type for the Vendor ID Payload is eleven (11).
5.14 Key Creation Payload
The Key Creation Payload contains information used to create key encryption
keys. These key creation payloads can have security attributes applied
to them based upon the security policy of the group. Figure 16 shows the
format of the payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! ID Type ! Key Creation Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 16: Key Creation Payload Format
The Key Creation Payload fields are defined as follows:
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
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Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
ID Type (1 octet) - Specifies the type of Key Creation being used.
Table 22 identifies the types of key download information.
Table 22: Types Of Key Creation Information
ID_Type Value
________________________
Reserved 0
Diffie-Hellman 1
other 2-255
Key Creation Data (variable length) - Contains Key Creation information.
The values for this field are group specific and the format is specified
by the ID Type field.
The payload type for the Key Creation Packet is twelve (12).
5.15 Nonce Payload
The Nonce Payload contains random data used to guarantee freshness during an
exchange and protect against replay attacks. Figure 17 shows the format of
the Nonce Payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Nonce Type ! Nonce Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 17: Nonce Payload Format
The Nonce Payload fields are defined as follows:
Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
RESERVED (1 octet) - Unused, set to 0.
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Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
Nonce Type (1 octet) - Specifies the type of Nonce being used. Table 23
identifies the types of nonces.
Table 23: Nonce Types
Nonce_Type Value Definition
__________________________________________________________________________
None 0
Initiator 1
Responder 2
Combined 3 Hash ( Append (Initiator_Value, Responder_Value) )
Unassigned 4-255
Nonce Data (variable length) - Contains the nonce information. The values
for this field are group-specific and the format is specified by the
Nonce Type field. If no group-specific information is provided, the
minimum length for this field is 4 bytes.
The payload type for the Nonce Payload is thirteen (13).
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6 T-GSAKMP State Diagram
Figure 18 presents the states encountered in the use of this protocol.
(1)
! -----------------------------------(17)----------------
! ! !
V V !
( )---------------------(4)---------------->( ) !
(idle) (queued) !
( )<-------------------(5)-----------------( ) !
! ^ !
! ! !
(2) (3) !
V ! !
(Establishing Group) -(10)-> (GSA Established) -(16)->(Destroy GSA)
! ^ ^ ! ^ ^
! ! ! ! ! !----(15)----
! ! ! ! -----(13)- !
(6)! ------(9)----- --(12)-- ! !
!(7) ! ! ! !
V ! ! V ! !
(Establishing Group) (GSA Established) (Destroy GSA) (Destroy GSA)
Figure 18: T-GSAKMP State Diagram
Table 24 defines the transitions.
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Table 24: State Transition Events
____________________________________________________________________
Transition 1 : Request to Join is received from TCP/IP
: GUI Input
_______________:_Application_Input__________________________________
:
_Transition_2__:_Group_SA_Required__________________________________
:
Transition 3 : Failure of Peer SA service
: Protocol Message failure
: Incorrect format
: Signature failed validation
: Certificate on CRL
: Access control invalid
: Authorization invalid
_______________:_Timeout____________________________________________
:
Transition 4 : Session required, but tables full
_______________:_Session_required,_but_processor_busy_______________
:
_Transition_5__:_Timeout____________________________________________
:
Transition 6 : Request Peer SA service
_______________:_Create_Protocol_Messages___________________________
:
_Transition_7__:_Peer_SA_established________________________________
:
_Transition_8__:_N/A________________________________________________
:
_Transition_9__:_Receipt_of_protocol_messages_______________________
:
_Transition_10_:_Group_SA_establishment_complete____________________
:
_Transition_11_:_N/A________________________________________________
:
_Transition_12_:_LKH_event_message_completed________________________
:
_Transition_13_:_Group_SA_send_failure_notification_________________
:
_Transition_14_:_N/A________________________________________________
:
_Transition_15_:_LKH_event_message__________________________________
:
_Transition_16_:_Delete_Request_validated___________________________
:
Transition 17 : Destruction complete
____________________________________________________________________
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7 APPENDIX A -- Rekey Packet data format
This appendix defines the format of the Rekey Event Data in the Rekey Event
Payload, when using Logical Key Hierarchy (LKH) as the rekeying mechanism.
The Rekey Event Data consists of Rekey Event Header and Rekey Event Packet
Data(s). A Packet Data is a complete set of information that an end-user
requires to be Rekeyed. Packet Datas are comprised of new Key Packs of
types GTEK and Rekey.
7.1 Rekey Event Header
The Rekey Event Data Header contains information about the rekey data being
transmitted to the group. Figure 19 shows the format for the header.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Group ID Value ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
~ Group ID Value !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Time/Date Stamp !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Rekey Type ! Algorithm Ver ! # of Rekey Packets !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Rekey Event Packet Data(s) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 19: A.1: Rekey Event Header Format
Group Identification Value (8 octets) - Indicates the name/title of
the group to be rekeyed. This is the same format as the Group
Identification Value in the T-GSAKMP Message Header.
Time/Date Stamp (4 octets) - This is the time value of when the Rekey
Event Data was generated.
Rekey Type (1 octet) - This is the Rekey algorithm being used for this
group. This value is token specific. For this appendix, this value is
LKH, which has a value of one (1).
Algorithm Version (1 octet) - Indicates the version of the Rekey Type
being used. The value at this time is one (1).
# of Rekey Packets (2 octets) - The number of Rekey Packets contained in
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the Rekey Data.
Rekey Event Packet Data(s) (variable length) - Contains the packets of
rekey event information being transmitted.
7.2 Rekey Event Packet Data(s)
As defined in the Rekey Event Header, # of Rekey Packets field, multiple
pieces of information are sent in a Rekey Event Data. Each end user, will
be interested in only one packet of the information sent. Each Packet, will
contain all the Key Packs that a user requires. For each Packet, the data
following the Security Header fields is encrypted with the key identified in
the Security Header. Figure 20 shows the format of each Rekey Event Packet
with respect to LKH.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Packet Length ! Security Header: LKH ID !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Security Header: Key Handle !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! # of Key Packs ! Key Pack Data(s) !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 20: A.2: Rekey Event Packet Data Format
Packet Length (2 octets) - Length in octets of the Rekey Packet, which
consists of the # of Key Packs and the Key Pack Data(s).
Security Header: LKH ID (2 octets) - This is the LKH ID of the Rekey Pack
that is being used for encryption/decryption.
Security Header: Key Handle (4 octets) - This is a randomly generated
value to uniquely identify the key defined by the LKH ID.
# of Key Packs (2 octets) - The number of key packs contained in this
Packet Data.
Key Pack Data(s) (variable length) - Contains all the key pack data for
this packet.
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7.3 Key Pack Data
Each Key Pack contains all the information about the key.
Figure 21 shows the format for each type of key pack.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
! Pack Type ! Pack Length ! Pack Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
Figure 21: A.3: Key Pack Data Format
Pack Type (1 octet) - The type of key in this key pack. Legal values are
GTEK (0) and LKH (1).
Pack Length (2 octets) - The length of the Pack Data.
Pack Data (variable length) - The actual data of the key, defined by the
key type.
7.4 Pack Data Formats
There are 2 legal values for the Pack Type, GTEK and LKH. The formats for
each Pack type are defined in this section.
7.4.1 GTEK Pack Data
This is data for the new GTEK being sent to the Rekeyed group.
Key Type (1 octet) - This is the encryption algorithm for which this key
data is to be used. This value is specified in the Policy Token.
Key Creation Date (4 octets) - This is the time value of when this key
data was originally generated.
Key Expiration Date (4 octets) - This is the time value of when this key
is no longer valid for use.
Key Handle (4 octets) - This is the randomly generated value to uniquely
identify a key.
Key Data (variable length) - This is the actual encryption key data, which
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is dependent on the Key Type algorithm for its format.
7.4.2 LKH Pack Data
This is the data to fix an Group Member Rekey sequence to recover from a
compromise.
LKH ID (2 octets) -- This is the position of this key in the binary tree
structure used by LKH.
Key Type (1 octet) - This is the encryption algorithm for which this key
data is to be used. This value is specified in the Policy Token.
Key Creation Date (4 octets) - This is the time value of when this key
data was originally generated.
Key Expiration Date (4 octets) - This is the time value of when this key
is no longer valid for use.
Key Handle (4 octets) - This is the randomly generated value to uniquely
identify a key.
Key Data (variable length) - This is the actual encryption key data, which
is dependent on the Key Type algorithm for its format.
7.5 Example
This section will give an example of the data. The data to be transmitted
is:
| GroupID | Date/Time | Rekey Type | Algorithm Ver | # of Packets|
{ (GTEK)A, (GTEK, B, E)6, (GTEK, B)F }
This data shows that three packets are being transmitted. Read each
packet as:
a) GTEK wrapped in LKH key A
b) GTEK, LKH keys B & E, all wrapped in LKH key 6
c) GTEK and LKH key B, all wrapped in LKH key F
We will show format for all header data, and packet (b).
Definition of values:
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0xLLLL - length value
0xHHHHHHH# - handle value
0xTTTTTTTC - creation time
0xTTTTTTTE - expiration time
GroupID - 0xAABBCCDD
0x12345678
Date/Time - 0x34574509
Rekey Type - 0x01 (LKH)
Algorithm Vers - 0x01
# of Packets - 0x0003
For Packet (b):
Packet Length - 0xLLLL
Sec HDR:LKH ID - 0x0006
Sec HDR:Key Handle - 0xHHHHHHH1
# of Key Packs - 0x0003
Key Pack 1:
Pack Type - 0x00 (GTEK)
Pack Length - 0xLLLL
Key Type - 0x02 (DES3)
Key Creation Date - 0xTTTTTTTC
Key Expiration Date - 0xTTTTTTTE
Key Handle - 0xHHHHHHH2
Key Data - variable, based on key definition
Key Pack 2:
Pack Type - 0x01 (LKH)
Pack Length - 0xLLLL
LKH ID - 0x000B
Key Type - 0x02 (DES3)
Key Creation Date - 0xTTTTTTTC
Key Expiration Date - 0xTTTTTTTE
Key Handle - 0xHHHHHHH3
Key Data - variable, based on key definition
Key Pack 3:
Pack Type - 0x01 (LKH)
Pack Length - 0xLLLL
LKH ID - 0x000E
Key Type - 0x02 (DES3)
Key Creation Date - 0xTTTTTTTC
Key Expiration Date - 0xTTTTTTTE
Key Handle - 0xHHHHHHH4
Key Data - variable, based on key definition
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8 References and Authors Addresses
8.1 References
The following references were used in the preparation of this document:
Wallner, D., Harder E., and Agee R., ``Key Management for Multicast: Issues
and Architectures'', Internet Draft, Informational, September 1998.
``Multicast Security Management Protocol (MSMP) Requirements and Policy'',
SPARTA, October, 1998.
``Logical Key Hierarchy (LKH) Protocol'', SPARTA, October, 1998.
[RFC 2093] Harney H., Muckenhirn C., and Rivers T., ``Group Key, Management
Protocol Specification'', RFC 2093, Experimental, July 1997.
[RFC 2094] Harney H., Muckenhirn C., and Rivers T., ``Group Key Management
Protocol Architecture'', RFC 2094, Experimental, July 1997.
[RFC 2104] Krawczyk H., Bellare M., and Canetti R., ``HMAC: Keyed-Hashing
for Message Authentication'', RFC 2104, Informational, February 1997.
[RFC 2408] Maughan D., Schertler M., Schneider M., and Turner J., ``Internet
Security Association and Key Management Protocol (ISAKMP)'', RFC 2408,
Proposed Standard, November 1998.
[RFC 2409] Harkins D. and Carrel D., ``The Internet Key Exchange (IKE)'',
RFC 2409, Proposed Standard, November 1998.
[RFC 2412] Orman H. K., ``The OAKLEY Key Determination Protocol'', RFC 2412,
Informational, November 1998.
The Secure Multicast Research Group (SMuG), An Internet Research Task Force
Group formed to discuss issues related to multicast security.
[RFC 2402] Kent S. and Atkinson, R., ``IP Authentication Header'', RFC 2402,
November 1998, Proposed Standard.
[RFC 2401] Kent S. and Atkinson, R., ``Security Architecture for the
Internet Protocol'', RFC 2401, November 1998, Proposed Standard.
[RFC 2406] Kent S. and Atkinson, R., ``IP Encapsulating Security Payload
(ESP)'', RFC 2406, November 1998, Proposed Standard.
Balenson D., McGrew D., Sherman A., ``Key Management for Large Dynamic
Groups: One-Way Function Trees and Amortized Initialization'', Internet
Draft, February 1999.
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Bhattacharya P. and Pereira R., ``IPSec Policy Data Model'', Internet Draft,
February 1998.
8.2 Authors Addresses
Hugh Harney (point-of-contact)
7075 Samuel Morse Drive
Columbia, MD 21046
(410) 872 - 1515 ext 203
FAX (410) 872 - 8079
hh@columbia.sparta.com
Andrea Colegrove
7075 Samuel Morse Drive
Columbia, MD 21046
(410) 872 - 1515 ext 232
FAX (410) 872 - 8079
acc@columbia.sparta.com
Eric J. Harder
R231 NSA
9800 Savage Rd
Suite 6534
Fort Meade, MD 20755
(301) 688-0847
FAX (301) 688-0255
ejharde@tycho.ncsc.mil
Uri Meth
7075 Samuel Morse Drive
Columbia, MD 21046
(410) 872 - 1515 ext 233
FAX (410) 872 - 8079
umeth@columbia.sparta.com
Rod Fleischer
7075 Samuel Morse Drive
Columbia, MD 21046
(410) 872 - 1515 ext 241
FAX (410) 872 - 8079
rodf@columbia.sparta.com
Document expiration: October 31, 2003
Harney/Colegrove/Harder/Meth/Fleischer [Page 52]
