Internet Engineering Task Force
INTERNET-DRAFT A Colegrove (SPARTA)
H Harney (SPARTA)
draft-ietf-msec-policy-token-sec-00.txt SPARTA, Inc.
Expires: December 22, 2004 June 2004
Group Policy Token Version 1 with Application to GSAKMP
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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Abstract
The Policy Token is a structure used to specify the security
policy and configurable parameters for a cryptographic group, such
as a secure multicast group. This document specifies the structure
of such a token in order to securely bind system-level security to
protocols supporting the management of cryptographic groups.
Copyright Notice
Copyright (c) The Internet Society (2004). All Rights Reserved.
INTERNET-DRAFT Group Policy Token Version 1 with Application to GSAKMPJune 2004
Contents
1 Introduction 4
2 Token Creation and Receipt 5
3 The Policy Token 5
3.1 tokenInfo . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2 registration . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3 rekey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.4 data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4 Security Considerations 8
5 IANA Considerations 8
6 References 9
6.1 Normative References . . . . . . . . . . . . . . . . . . . . . . . 9
6.2 Non-Normative References . . . . . . . . . . . . . . . . . . . . . 9
7 Acknowledgements 10
A APPENDIX A -- Core Policy Token ASN.1 Module 11
B APPENDIX B -- GSAKMPv1 Base Policy 12
B.1 GSAKMPv1 Registration Policy . . . . . . . . . . . . . . . . . . . 12
B.1.1Authorization . . . . . . . . . . . . . . . . . . . . . . . . . 12
B.1.2AccessControl . . . . . . . . . . . . . . . . . . . . . . . . . 13
B.1.3JoinMechanisms . . . . . . . . . . . . . . . . . . . . . . . . . 14
B.1.4Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
B.2 GSAKMPv1 Registration ASN.1 Module . . . . . . . . . . . . . . . . 17
B.3 GSAKMPv1 De-Registration Policy . . . . . . . . . . . . . . . . . . 19
B.4 GSAKMPv1 De-Registration ASN.1 Module . . . . . . . . . . . . . . . 20
B.5 GSAKMPv1 Rekey Policy . . . . . . . . . . . . . . . . . . . . . . . 21
B.5.1Rekey Authorization . . . . . . . . . . . . . . . . . . . . . . 21
B.5.2Rekey Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . 21
B.5.3Rekey Event Definition . . . . . . . . . . . . . . . . . . . . . 22
B.5.4Rekey Methods . . . . . . . . . . . . . . . . . . . . . . . . . 22
B.5.4.1Rekey Method NONE . . . . . . . . . . . . . . . . . . . . 23
B.5.4.2Rekey Method GSAKMP LKH . . . . . . . . . . . . . . . . . 23
B.5.5Rekey Interval . . . . . . . . . . . . . . . . . . . . . . . . . 23
B.5.6Rekey Reliability . . . . . . . . . . . . . . . . . . . . . . . 23
B.5.6.1Rekey Reliability Mechanism None . . . . . . . . . . . . . 24
B.5.6.2Rekey Reliability Mechanism Resend . . . . . . . . . . . . 24
B.5.6.3Rekey Reliability Mechanism Post . . . . . . . . . . . . . 24
B.5.7Distributed Operation Policy . . . . . . . . . . . . . . . . . . 25
B.5.7.1No Distributed Operation . . . . . . . . . . . . . . . . . 25
B.5.7.2Autonomous Distributed Mode . . . . . . . . . . . . . . . 25
B.6 GSAKMPv1 LKH Rekey Policy ASN.1 Module . . . . . . . . . . . . . . 26
C APPENDIX C -- Data SA Policy 28
C.1 Secure RTP Data Policy . . . . . . . . . . . . . . . . . . . . . . 28
C.2 Secure RTP Data Policy ASN.1 Module . . . . . . . . . . . . . . . . 30
Authors Addresses 31
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Full Copyright Statement 31
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1 Introduction
The Multicast Group Security Architecture [HW05] defines the security
infrastructure to support secure group communications. The Policy Token
assumes this architecture in its definition. It defines the enforceable
security parameters for a Group Secure Association.
The Policy Token is a verifiable data construct signed by the group
owner, the entity with the authorization to create security policy. The
group controllers in a group will use the policy token to ensure that the
mechanisms used to secure the group are correct and to enforce the access
control rules for joining members. The group members, who may contribute
data to the group or access data from the group, will use the policy token
to ensure that the group is owned by a trusted authority. Also, the members
may want to verify that the access control rules are adequate to protect the
data that member is submitting to the group.
The policy token is specified in ASN.1 with DER encoding. This
specification ability allows the token to easily import group definitions
that span different applications and environments. ASN.1 allows the token
to specify branches that can be used by any multicast security protocol.
Any group can use this policy token structure to specify the use of multiple
protocols in securing the group.
Care was taken in this specification to provide a core level of token
specificity that would allow ease of extensibility and flexibility in
supporting mechanisms. This was done by using the following abstracted
construct:
Mechanism ::= SEQUENCE {
mechanismIdentifier OBJECT IDENTIFIER,
mechanismParameters OCTET STRING
}
This construct will allow the use of group mechanisms specified in other
documents with the Policy Token.
The Policy Token is structured to reflect the MSEC Architecture layers for a
Group Security Association. Each of the architectural layers is identified
and given a branch in the "Core" token. This allows a high degree of
flexibility for future protocol specifications at each architectural layer
without the need to change the "Core" policy token, which can then act as
a single point of reference for defining secure groups using any mix of
protocols for any number of environments.
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2 Token Creation and Receipt
At the time of group creation or whenever the policy of the group is
updated, the Group Owner will create a new policy token.
To ensure authenticity of the specified policy, the Token MUST be signed by
the Group Owner. The signed token MUST be in accordance with the CMS [RFC
3369] SignedData type.
The content of the SignedData is the token itself. It is represented with
the ContentType object identifier of
id-msec-token OBJECT IDENTIFIER ::= {TBD}
The sid of the SignerInfo MUST be that of the Group Owner.
The signedAttrs field MUST be present. In addition to the minimally
required fields of signedAttrs, the signing-time attribute MUST be PRESENT
and MUST be specified as a GeneralizedTime value.
Upon receipt of a policy token, the recipient MUST check that
the Group Owner, as identified by the sid in the SignerInfo, is the
expected entity
the signing-time value is more recent than the signing-time value seen in
a previously received token for that group. If the token is the first
token seen by the recipient for that group, then the signing-time value
MUST be less than or not greater than TBS seconds of the recipient's
local time.
the processing of the signature succeeds in accordance with RFC 3369
the specified security and communication mechanisms (or at least one
mechanism of each choice) are supported and are in compliance with the
recipient's local policy.
3 The Policy Token
The structure of the Policy Token is as follows:
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Token ::= SEQUENCE {
tokenInfo TokenID,
registration SEQUENCE OF Registration,
rekey SEQUENCE OF GroupMngmtProtocol,
data SEQUENCE OF DataProtocol
}
tokenInfo provides information about the instance of the Policy Token.
registration provides a list of acceptable registration and deregistration
policy and mechanisms that may be used to manage member-initiated joins
and departures from a group. A NULL sequence indicates that the group
does not support registration and deregistration of members. A member
MUST be able to support at least one set of Registration mechansims
in order to join the group. When multiple mechanisms are present, a
member MAY use any of the listed methods. The list is ordered in terms
of Group Owner preference. A member SHOULD choose the highest listed
mechanism that local policy supports.
rekey provides the rekey protocols that will be used in managing
the group. The member MUST be able to accept one of the types of
rekey messages listed. The list is ordered in terms of Group Owner
preference. A member SHOULD choose the highest listed mechanism that
local policy supports.
data provides the applications used in the communications between group
members. When multiple applications are provided, the order of the list
implies the order of encapsulation of the data. A member MUST be able
to support all the listed applications and if any choices of mechanisms
are provided per application, the member MUST support at least one of
the mechanisms.
Each data field of the Token is specified further in following sections.
3.1 tokenInfo
tokenInfo explicitly identifies a version of the Policy Token for a
particular group. It is defined as
TokenID ::= OCTET STRING
TokenID is the identifier of the group
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3.2 registration
The registration SA is defined in the MSEC Architecture. During
registration, a prospective group member and the group controller will
interact to give the group member access to the keys and information it
needs to join and participate in the group data SA.
The deregistration piece allows a current group member to notify the GC/KS
that it will no longer be participating in the data layer SA.
Registration ::= SEQUENCE {
register GroupMngmtProtocol,
de-register GroupMngmtProtocol
}
The protocol for registration and de-registration are each specified as
GroupMngmtProtocol ::= Protocol
Protocol ::= SEQUENCE {
protocol OBJECT IDENTIFIER,
protocolInfo OCTET STRING
}
For example, register might be specified as the GSAKMP [HMC] registration
protocol. The OBJECT IDENTIFIER TBS would be followed by the parameters
used in GSAKMP registration as specified in appendix B.1.
3.3 rekey
The Rekey SA is defined in the MSEC Architecture. During Rekey, the
membership of the group can be modified as well as refreshing the group
traffic protection keys and updating the Policy Token.
This field is also specified as a sequence of protocols that will be used by
the GC/KS.
3.4 data
The Data SA is the ultimate consumer of the group keys. The data field
will indicate the keys and mechanisms that are to be used in communications
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between group members. There are several protocols that could make use of
multicast key - IPSec and RTP are the two that are of immediate interest to
the authors. The sequencing of the Data SA mechanisms are from "inside" to
"outside". That is, the first Data SA defined in a policy token must act on
the raw data. Any data SA specified after that will be applied in turn.
DataProtocol ::= Protocol
4 Security Considerations
The document specifies the structure for a Group Policy Token. As such, the
structure as received by a group entity must be verifiably authentic. This
Policy Token uses CMS to apply authentication through digital signatures.
The security of this scheme relies upon a secure CMS implementation, choice
of signature mechanism of appropriate strength for the group using the
Policy Token, and secure, sufficiently strong keys. Additionally, it
relies upon knowledge of a well-known Group Owner as the root of policy
enforcement.
Furthermore, while the Group Owner may list alternate mechanisms for various
functions, the group is only as strong as the weakest accepted mechanisms.
As such, the Group Owner is responsible for providing only acceptable
security mechanisms.
5 IANA Considerations
The following object identifiers should be assigned:
- id-msec-token OBJECT IDENTIFIER ::= TBD
- id-securitySuiteOne OBJECT IDENTIFIER ::= TBD
- id-GSAKMPv1RegistrationProtocol OBJECT IDENTIFIER::= TBD
- id-GSAKMPv1DeRegistrationProtocol OBJECT IDENTIFIER::= TBD
- id-GSAKMPv1Rekey OBJECT IDENTIFIER::= TBD
- id-rekeyNone OBJECT IDENTIFIER ::= TBD
- id-rekeyMethodGSAKMPLKH OBJECT IDENTIFIER ::= TBD
- id-reliabilityNone OBJECT IDENTIFIER ::= TBD
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- id-reliabilityResend OBJECT IDENTIFIER ::= TBD
- id-reliabilityPost OBJECT IDENTIFIER ::= TBD
- id-subGCKSSchemeNone OBJECT IDENTIFIER ::= TBD
- id-subGCKSSchemeAutonomous OBJECT IDENTIFIER ::= TBD
- id-simpleDataSAInfo OBJECT IDENTIFIER ::= TBD
- id-srtpDataSA OBJECT IDENTIFIER ::= TBD
6 References
The following references were used in the preparation of this document.
6.1 Normative References
[HMC] H. Harney, U. Meth, and A. Colegrove, "GSAKMP",
draft-ietf-msec-gsakmp-sec-06.txt, work in progress, May 2004.
[RFC 3280] R. Housley, W. Polk, W. Ford, D. Solo, Internet X.509 Pulbic Key
Infrastructure Certificate and Certificate Revocation List (CRL) Profile,
April 2002.
[RFC 3369] R. Housley, Cryptographic Message Syntax, August 2002.
6.2 Non-Normative References
[HCLM00] H. Harney, A. Colegrove, P. Lough, and U. Meth, "GSAKMP Token
Specification", draft-ietf-msec-tokenspec-sec-00.txt.
[RFC 3711] M. Baugher, D. McGrew, M. Naslund, E. Carrara, and K. Norrman,
"The Secure Real-Time Transport Protocol (SRTP)", March 2004.
[RFC 3740] T. Hardjono and B. Weis, "The Multicast Group Security
Architecture", March 2004.
[HCM01] H. Harney, A. Colegrove, P. McDaniel, "Principles of Policy in
Secure Groups", Proceedings of Network and Distributed Systems Security 2001
Internet Society, San Diego, CA, February 2001
[HHMCD01] , Thomas Hardjono, Hugh Harney, Pat McDaniel, Andrea Colgrove,
Pete Dinsmore, Group Security Policy Token: Definition and Payloads',
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draft-ietf-msec-gspt-00.txt, Work in progress.
7 Acknowledgements
The following individuals deserve recognition and thanks for their
contributions which have greatly improved this specification: Uri Meth, Rod
Fleischer, Peter Lough, Thomas Hardjono, Patrick McDaniel, and Pete Dinsmore
for their work on earlier versions of policy tokens; and George Gross for
the impetus to have a well-specified, extensible policy token.
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A APPENDIX A -- Core Policy Token ASN.1 Module
PolicyToken -- {TBD}
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
Token ::= SEQUENCE {
tokenInfo TokenID,
registration SEQUENCE OF Registration,
rekey SEQUENCE OF GroupMngmtProtocol,
data SEQUENCE OF DataProtocol
}
------------------------------------------------------------
-- Token ID
TokenID ::= OCTET STRING
------------------------------------------------------------
-- Registration
Registration ::= SEQUENCE {
register GroupMngmtProtocol,
de-register GroupMngmtProtocol
}
------------------------------------------------------------
-- GroupMngmtProtocol
GroupMngmtProtocol ::= Protocol
Protocol ::= SEQUENCE {
protocol OBJECT IDENTIFIER,
protocolInfo OCTET STRING
}
------------------------------------------------------------
-- DataProtocol
DataProtocol ::= Protocol
------------------------------------------------------------
END
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B APPENDIX B -- GSAKMPv1 Base Policy
This appendix provides the data structures needed for when GSAKMP exchanges
are used as the GroupMngmtProtocol for the registration, de-registration,
and/or rekey fields in the core Policy Token. This GSAKMP Base Policy
specification assumes familiarity with GSAKMP.
B.1 GSAKMPv1 Registration Policy
The registration policy for GSAKMP provides 1) information on authorizations
for group roles; 2) access control information for group members; 3) the
mechanisms used in the registration process, and 4) information on what
transport the GSAKMP registration exchange will use.
GSAKMPv1RegistrationInfo ::= SEQUENCE {
joinAuthorization JoinAuthorization,
joinAccessControl SEQUENCE OF AccessControl,
joinMechanisms JoinMechanisms,
transport Transport
}
B.1.1 Authorization
joinAuthorization provides information on who is allowed to be a Group
Controller/Key Server (GC/KS) and a sub-GC/KS.
JoinAuthorization ::= SEQUENCE {
gCKS GCKSName,
subGCKS SEQUENCE OF GCKSName OPTIONAL
}
The authorization information is in the form of an access control list
indicating entity name and acceptable certification authority information
for the entities certificate.
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GCKSName ::= SEQUENCE OF UserCAPair
UserCAPair ::= SEQUENCE {
groupEntity GSAKMPID,
cA CertAuth
}
The GSAKMPID is defined by type and value. The types are indicated by
integers that correspond to the GSAKMP Identification types. When a portion
of a defined name type is filled with an "*", this indicates a wildcard,
representing any valid choice for a field. This allows the specification
of an authorization rule that is a set of related names.
GSAKMPID ::= SEQUENCE {
typeValue INTEGER,
typeData OCTET STRING
}
The certificate authority is identified by the X.509 key identifier.
CertAuth ::= KeyIdentifier
B.1.2 AccessControl
joinAccessControl provides information on who is allowed to be a Group
Member. The access control list is augmented by a set of permissions that
the member must also satisfy. Additionally, a list of exclusions to the
list is provided.
AccessControl ::= SEQUENCE {
permissions SEQUENCE OF Permission OPTIONAL,
accessRule SEQUENCE OF UserCAPair,
exclusionsRule SEQUENCE OF UserCAPair OPTIONAL
}
The permissions initially available are an abstract set of numeric levels
that may be interpretted internal to a community.
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Permission ::= CHOICE {
simplePermission [1] SimplePermission
}
SimplePermission ::= ENUMERATED {
one(1),
two(2),
three(3),
four(4),
five(5),
six(6),
seven(7),
eight(8),
nine(9)
}
B.1.3 JoinMechanisms
Allowable GSAKMP mechanism choices for a particular group are specified
in joinMechanisms. Any set of JoinMechanism is acceptable from a policy
perspective.
JoinMechanisms ::= SEQUENCE OF JoinMechanism
Each set of mechanisms used in the GSAKMP Registration may be specified
either as an explicitly defined set or as a pre-defined security suite.
JoinMechanism ::= CHOICE {
alaCarte [0] Mechanisms,
suite [1] SecuritySuite
}
In an explicitly defined -- or alaCarte -- set, a mechanism is defined for
the signature, the key exchange algorithm, the key wrapping algorithm, the
type of acknowledgement data, and configuration data for the setting of
timeouts.
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Mechanisms ::= SEQUENCE {
signatureDef SigDef,
hashAlgorithm INTEGER,
kEAlg KEAlg,
keyWrap KeyWrap,
ackData AckData,
opInfo OpInfo
}
The signature definition requires specification of the signature algorithm
for message signing. The INTEGER that defines the choice corresponds to the
GSAKMP Signature type.
SigDef ::= INTEGER
The key exchange algorithm requires an integer to define the GSAKMP key
creation type and may require additional per type data.
The INTEGER corresponding to hashAlgorithm will map to the GSAKMP Nonce Hash
type values. This algorithm is used in computing the combined nonce.
KEAlg ::= SEQUENCE {
keyExchangeAlgorithmID INTEGER,
keyExchangeAlgorithmData OCTET STRING OPTIONAL
}
The keyWrap is the algorithm that is used to wrap the group key(s) and
the policy token (if included). The integer corresponds to the GSAKMP
encryption type.
KeyWrap ::= INTEGER
Data may potentially be returned in a GSAKMP Key Download ACK/Failure
message. The type of data required by a group is specified by AckData. No
such field is currently supported or required.
AckData ::= CHOICE {
none [0] NULL
}
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OpInfo provides configuration data for the operation of GSAKMP registration.
timeout indicates the elapsed amount of time before a sent message is
considered to be misrouted or lost. It is specified as a time. terse
informs a GC/KS whether the group should be operated in terse (TRUE) or
verbose (FALSE) mode.
OpInfo ::= SEQUENCE {
timeOut LifeDate,
terse BOOLEAN
}
LifeDate ::= CHOICE {
gt [0] GeneralizedTime,
utc [1] UTCTime
}
If the choice of mechanism is a predefined security suite, then it is
identified by OBJECT IDENTIFIER (OID). Other security suites may be defined
elsewhere by specification and registration of an OID.
SecuritySuite ::= OBJECT IDENTIFIER
The OID for security suite 1, as defined within the GSAKMPv1 specification
is
id-securitySuiteOne OBJECT IDENTIFIER ::= {TBD}
B.1.4 Transport
transport indicates what protocol GSAKMP should ride over. The choice of
udpRTJtcpOther indicates that the GSAKMP Request to Join message is carried
by UDP and all other group establishment messages are carried by TCP.
Transport ::= CHOICE {
tcp [0] NULL,
udp [1] NULL,
udpRTJtcpOther [2] NULL
}
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B.2 GSAKMPv1 Registration ASN.1 Module
GSAKMPv1RegistrationSA -- {TBD}
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
EXPORTS
GCKSName;
KeyIdentifier
FROM PKIX1Implicit88 { iso(1) identified-organization(3) dod(6)
internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
id-pkix1-implicit(19) };
-- id-GSAKMPv1RegistrationProtocol OBJECT IDENTIFIER::= {TBD}
GSAKMPv1RegistrationInfo ::= SEQUENCE {
joinAuthorization JoinAuthorization,
joinAccessControl SEQUENCE OF AccessControl,
joinMechanisms JoinMechanisms,
transport Transport
}
JoinAuthorization ::= SEQUENCE {
gCKS GCKSName,
subGCKS SEQUENCE OF GCKSName OPTIONAL
}
GCKSName ::= SEQUENCE OF UserCAPair
AccessControl ::= SEQUENCE {
permissionsi SEQUENCE OF Permission OPTIONAL,
accessRule SEQUENCE OF UserCAPair,
exclusionsRule SEQUENCE OF UserCAPair OPTIONAL
}
UserCAPair ::= SEQUENCE {
groupEntity GSAKMPID,
cA CertAuth
}
Permission ::= CHOICE {
simplePermission [1] SimplePermission
}
SimplePermission ::= ENUMERATED {
one(1),
two(2),
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three(3),
four(4),
five(5),
six(6),
seven(7),
eight(8),
nine(9)
}
GSAKMPID ::= SEQUENCE {
typeValue INTEGER,
typeData OCTET STRING
}
CertAuth ::= KeyIdentifier
JoinMechanisms ::= SEQUENCE OF JoinMechanism
JoinMechanism ::= CHOICE {
alaCarte [0] Mechanisms,
suite [1] SecuritySuite
}
Mechanisms ::= SEQUENCE {
signatureDef SigDef,
hashAlgorithm INTEGER,
kEAlg KEAlg,
keyWrap KeyWrap,
ackData AckData,
opInfo OpInfo
}
SecuritySuite ::= OBJECT IDENTIFIER
-- SECURITY SUITE ONE --
-- id-securitySuiteOne OBJECT IDENTIFIER ::= {TBD}
SigDef ::= INTEGER
KEAlg ::= SEQUENCE {
keyExchangeAlgorithmID INTEGER,
keyExchangeAlgorithmData OCTET STRING OPTIONAL
}
KeyWrap ::= INTEGER
AckData ::= CHOICE {
none [0] NULL
}
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OpInfo ::= SEQUENCE {
timeOut LifeDate,
terse BOOLEAN
}
LifeDate ::= CHOICE {
gt [0] GeneralizedTime,
utc [1] UTCTime
}
Transport ::= CHOICE {
tcp [0] NULL,
udp [1] NULL,
udpRTJtcpOther [2] NULL
}
END
B.3 GSAKMPv1 De-Registration Policy
GSAKMP De-Registration provides a method to notify a (S-)GC/KS that a member
needs to leave a group. The De-Registration policy provides the mechanisms
needed for the De-Registration exchange messages, an indication of whether
the exchange is to done using terse (TRUE) or verbose (FALSE) mode, and the
transport used for the GSAKMP De-registration messages.
GSAKMPv1DeRegistrationInfo ::= SEQUENCE {
leaveMechanisms LeaveMechanisms,
terse BOOLEAN,
transport Transport
}
The policy dictating the mechanisms needed for the De-registration exchange
is defined by leaveMechanisms. This field is specified as
LeaveMechanisms ::= SEQUENCE {
sigAlgorithm INTEGER,
hashAlgorithm INTEGER,
cA KeyIdentifier
}
The INTEGER corresponding to sigAlgorithm will map to the GSAKMP Signature
type values. This algorithm set is to be used for message signing.
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The INTEGER corresponding to hashAlgorithm will map to the GSAKMP Nonce Hash
type values. This algorithm is used in computing the combined nonce.
cA represents a trust point off of which the signer's certificate must
certify. It is identified by the PKIX KeyIdentifier [RFC 3280] type.
transport will provide the expected transport for GSAKMP De-registration
messages. Initially, either UDP or TCP will be the policy for a group.
Transport ::= CHOICE {
tcp [0] NULL,
udp [1] NULL
}
B.4 GSAKMPv1 De-Registration ASN.1 Module
GSAKMPv1DeRegistrationSA -- {TBD}
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
IMPORTS
KeyIdentifier
FROM PKIX1Implicit88 { iso(1) identified-organization(3) dod(6)
internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
id-pkix1-implicit(19) };
-- id-GSAKMPv1DeRegistrationProtocol OBJECT IDENTIFIER::= {TBD}
GSAKMPv1DeRegistrationInfo ::= SEQUENCE {
leaveMechanisms LeaveMechanisms,
terse BOOLEAN,
transport Transport
}
LeaveMechanisms ::= SEQUENCE {
sigAlgorithm INTEGER,
hashAlgorithm INTEGER,
cA KeyIdentifier
}
Transport ::= CHOICE {
tcp [0] NULL,
udp [1] NULL
}
END
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B.5 GSAKMPv1 Rekey Policy
The GSAKMP Rekey Policy provides authorization information, mechanisms for
the GSAKMP Rekey messages, indicators defining rekey event definitions that
define when the GC/KS should send a rekey message, the protocol or method
the rekey event will use, the rekey interval that will allow a member to
recognize a failure in the rekey process, a reliability indicator that
defines the method the rekey will use to increase the likelyhood of a rekey
delivery (if any), and finally an indication of how subordinate-GC/KSs will
handle rekey. This policy also describes the specific Rekey policy methods
"None" and "GSAKMP LKH REKEY".
GSAKMPv1RekeyInfo ::= SEQUENCE {
authorization RekeyAuthorization,
mechanism RekeyMechanisms,
rekeyEventDef RekeyEventDef, -- tells the GCKS when to rekey
rekeyMethod RekeyMethod,
rekeyInterval LifeDate, -- member knows when to rejoin
reliability Reliability, -- what mech will be used to increase
-- the likelihood of rekey delivery
subGCKSInfo SubGCKSInfo -- what subordinate gcks needs
}
B.5.1 Rekey Authorization
RekeyAuthorization ::= GCKSName
B.5.2 Rekey Mechanisms
The policy dictating the mechanisms needed for Rekey message processing is
defined by RekeyMechanisms. This field is specified as
RekeyMechanisms ::= SEQUENCE {
sigAlgorithm INTEGER,
hashAlgorithm INTEGER
}
The INTEGER corresponding to sigAlgorithm will map to the GSAKMP Signature
type values. This algorithm set is to be used for message signing.
The INTEGER corresponding to hashAlgorithm will map to the GSAKMP Nonce Hash
type values. This algorithm is used in computing the combined nonce.
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B.5.3 Rekey Event Definition
Rekey Event Definition provides information to the GC/KS about the system
requirements for sending rekey messages. This allows definition of the
rekey event in time as well as event driven characteristics (a number of
de-registration notifications as an example), or a combination of the two
(e.g., after x de-registrations or 24 hours, which ever comes first).
RekeyEventDef ::= CHOICE {
none [0] NULL, -- never rekey
timeOnly [1] LifeDate, -- rekey every x units
event [2] INTEGER, -- rekey after x events
timeAndEvent [3] TimeAndEvent
}
The LifeDate specifies the maximum time a group should exist between rekeys.
This does not require clock synchronization as this is used with respect to
a local clock.
The INTEGER corresponding to the event is an indicator of the number
of events a group should sustain before a rekey message is sent. This
defines the events between rekeys. An example of a relevant event is
de-registration notificaitons.
The TimeAndEvent is defined as a couple of the LifeDate and Integer
policies.
TimeAndEvent ::= SEQUENCE {
time LifeDate, -- rekey after x units of time OR
event INTEGER -- x events occur
}
B.5.4 Rekey Methods
The policy dictating the rekey method supported by the Rekey message is
defined by RekeyMethod. This field is specified as
RekeyMethod ::= SEQUENCE {
rekeyMethodType OBJECT IDENTIFIER,
rekeyMethodInfo OCTET STRING
}
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The rekeyMethodType will define the rekey method to be used by the group.
The rekeyMethodInfo will supply the GMs with the information they need to
operate in the correct rekey mode.
B.5.4.1 Rekey Method NONE
The group defined to work without a rekey protocols supporting it is
supported by the rekeyMethodType NONE. There is no RekeyMethodNoneInfo
associated with this option.
id-rekeyNone OBJECT IDENTIFIER ::= {TBD}
RekeyMethodNoneInfo ::= NULL
B.5.4.2 Rekey Method GSAKMP LKH
The GSAKMP protocol specification defined an interpretation of the Logical
Key Hierarchy (LKH) protocol as a rekey method. This method is supported by
the following values.
id-rekeyMethodGSAKMPLKH OBJECT IDENTIFIER ::= {TBD}
RekeyMethodGSAKMPLKHInfo ::= INTEGER
The GSAKMP LKH method requires a gsakmp type value for identifying the
cryptographic algorithm used to wrap the keys. This value maps to the
GSAKMP encryption type.
B.5.5 Rekey Interval
Rekey interval defines the maximum delay the GM should see between valid
rekeys. This provides a means to ensure the GM is synchronized, from a
key management perspective, with the rest of the group. It is defined as
a time/date stamp.
B.5.6 Rekey Reliability
The Rekey message in the GSAKMP protocol is a one sided exchange of data.
There are reliability concerns with one sided exchanges. The Reliability
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policy defines the mechanism used to deal with these concerns.
Reliability ::= SEQUENCE {
reliabilityMechanism OBJECT IDENTIFIER,
reliabilityMechContent OCTET STRING
}
The reliability mechanism is defined by an OBJECT IDENTIFIER and
the information needed to operate that mechanism is defined as
reliabilityMechContent and is an OCTET STRING. (as before)
B.5.6.1 Rekey Reliability Mechanism None
In networks with adequate reliability it may not be necessary to use a
mechanism to improve reliability of the Rekey Message. For these networks
the ReliabilityMechanism NONE is appropriate.
id-reliabilityNone OBJECT IDENTIFIER ::= {TBD}
ReliabilityContentNone ::= NULL
B.5.6.2 Rekey Reliability Mechanism Resend
In networks with unknown or questionable reliability it may be necessary
to use a mechanism to improve reliability of the Rekey Message. For these
networks the ReliabilityMechanism RESEND is potentially appropriate. This
mechanism has the GC/KS repeatedly sending out the same message.
id-reliabilityResend OBJECT IDENTIFIER ::= {TBD}
ReliabilityResendInfo ::= INTEGER
The INTEGER value in the ReliabilityResendInfo indicates the number of times
the message should be resent.
B.5.6.3 Rekey Reliability Mechanism Post
Another reliability mechanims is to post the rekey message on some service
that will make it generally available. This is the reliabilityPost method.
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id-reliabilityPost OBJECT IDENTIFIER ::= {TBD}
ReliabilityContentPost ::= IA5String
The IA5String associated with ReliabilityPost is the identifier of the
posting site and rekey message.
B.5.7 Distributed Operation Policy
The policy dictating the relationships between GC/KS and S-GC/KS for
distributed operations is defined as SubGCKSInfo. It is defined as a
couple of a subGCKSScheme and some information relating to that Scheme in
sGCKSContent.
SubGCKSInfo ::= SEQUENCE {
subGCKSScheme OBJECT IDENTIFIER,
sGCKSContent OCTET STRING
}
B.5.7.1 No Distributed Operation
If the group is not to use S-GC/KS then that Scheme would be
SGCKSSchemeNone.
id-subGCKSSchemeNone OBJECT IDENTIFIER ::= {TBD}
SGCKSNoneContent ::= NULL
B.5.7.2 Autonomous Distributed Mode
If the group is to use S-GC/KS as defined in the GSAKMP specification as
Autonomous mode, then that scheme would be SGCKSAutonomous.
id-subGCKSSchemeAutonomous OBJECT IDENTIFIER ::= {TBD}
SGCKSAutonomous ::= SEQUENCE {
authSubs GCKSName,
domain OCTET STRING OPTIONAL
}
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The policy information needed for autonomous mode is a list of authorized
S-GC/KSs and and restrictions on who they may serve. The domain field,
representing these restrictions is NULL for this version.
B.6 GSAKMPv1 LKH Rekey Policy ASN.1 Module
GSAKMPv1RekeySA -- {TBD}
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
IMPORTS
GCKSName
FROM GSAKMPv1RegistrationSA; -- {TBD};
-- id-GSAKMPv1Rekey OBJECT IDENTIFIER::= {TBD}
GSAKMPv1RekeyInfo ::= SEQUENCE {
authorization RekeyAuthorization,
mechanism RekeyMechanisms,
rekeyEventDef RekeyEventDef, -- tells the GCKS when to rekey
rekeyMethod RekeyMethod,
rekeyInterval LifeDate, -- member knows when to rejoin
reliability Reliability, -- what mech will be used to increase
-- the likelyhood of rekey delivery
subGCKSInfo SubGCKSInfo -- what subordinate gcks needs
}
RekeyAuthorization ::= GCKSName
RekeyMechanisms ::= SEQUENCE {
sigAlgorithm INTEGER,
hashAlgorithm INTEGER
}
RekeyEventDef ::= CHOICE {
none [0] NULL, -- never rekey
timeOnly [1] LifeDate, -- rekey every x units
event [2] INTEGER, -- rekey after x events
timeAndEvent [3] TimeAndEvent
}
LifeDate ::= CHOICE {
gt [0] GeneralizedTime,
utc [1] UTCTime
}
TimeAndEvent ::= SEQUENCE {
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time LifeDate, -- rekey after x units of time OR
event INTEGER -- x events occur
}
RekeyMethod ::= SEQUENCE {
rekeyMethodType OBJECT IDENTIFIER,
rekeyMethodInfo OCTET STRING
}
-- REKEY METHOD NONE --
-- id-rekeyNone OBJECT IDENTIFIER ::= {TBD}
RekeyMethodNoneInfo ::= NULL
-- REKEY METHOD GSAKMP LKH --
-- id-rekeyMethodGSAKMPLKH OBJECT IDENTIFIER ::= {TBD}
RekeyMethodGSAKMPLKHInfo ::= INTEGER -- gsakmp type value for
-- wrapping mechanism
Reliability ::= SEQUENCE {
reliabilityMechanism OBJECT IDENTIFIER,
reliabilityMechContent OCTET STRING
}
-- RELIABILITY MECHANISM NONE --
-- id-reliabilityNone OBJECT IDENTIFIER ::= {TBD}
ReliabilityContentNone ::= NULL
-- RELIABILITY MECHANISM RESEND --
-- id-reliabilityResend OBJECT IDENTIFIER ::= {TBD}
ReliabilityResendInfo ::= INTEGER -- #of times rekey message should be resent
-- RELIABILITY MECHANISM POST --
-- id-reliabilityPost OBJECT IDENTIFIER ::= {TBD}
ReliabilityContentPost ::= IA5String
SubGCKSInfo ::= SEQUENCE {
subGCKSScheme OBJECT IDENTIFIER,
sGCKSContent OCTET STRING
}
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-- id-subGCKSSchemeNone OBJECT IDENTIFIER ::= {TBD}
SGCKSNoneContent ::= NULL
-- id-subGCKSSchemeAutonomous OBJECT IDENTIFIER ::= {TBD}
SGCKSAutonomous ::= SEQUENCE {
authSubs GCKSName,
domain OCTET STRING OPTIONAL
}
SGCKSAutonomous ::= NULL
END
C APPENDIX C -- Data SA Policy
The Data SA provides the data structures needed for the protection of the
data exchanged between group members. This appendix defines the specific
data structure needed for one such client of a group security protocol,
Secure Real Time Protocol (SRTP) [RFC 3711].
C.1 Secure RTP Data Policy
The policy parameters for an SRTP security association are
srtpDataSAInfo ::= SEQUENCE {
masterKeyID OCTET STRING (SIZE (4)),
masterSaltKeyID OCTET STRING (SIZE (4)),
encrTransform EncryptionTransform,
authTransform AuthenticationTranform OPTIONAL,
tagLength INTEGER,
prefixLength INTEGER,
pRF PRF,
encrKeyLength INTEGER,
authKeyLength INTEGER,
sessionSaltLength INTEGER,
keyDerivRate INTEGER,
sRTPPacketMax INTEGER,
sRTCPPacketMax INTEGER,
mKI OCTET STRING OPTIONAL,
tOfROM OCTET STRING OPTIONAL
}
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The masterKeyID provides the key management protocol key identifier (e.g.,
GSAKMP KeyID) of the SRTP Master Key. It is not required to be the same as
the mKI field. The masterKey itself is delivered through the key management
protocol.
The masterSaltKeyID provides the key management protocol key identifier of
the SRTP Master Key Salt. It, too, is provided through the key management
protocol.
The encrTransform identifies the encryption transform to be used in an SRTP
encryption session. Its values are enumerated as
EncryptionTransform ::= ENUMERATED {
aesCM (0),
null (1),
aesF8 (2)
}
When policy requires SRTP use authentication, the authTransform field is
PRESENT. Its values are enumerated as
AuthenticationTransform ::= ENUMERATED {
hmacSHA1 (0)
}
Similarly, the key derivation pseudorandomfunction values are enumerated as
PRF ::= ENUMERATED {
aesCM (0)
}
The mKI is the SRTP Master Key Identifier. Both the mKI and the tOfROM
field must not be PRESENT at the same time. Neither is required to be
PRESENT.
The tOfROM indicates the validity field of the mKI.
The remaining fields are INTEGERs setting the numerical parameters of SRTP.
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C.2 Secure RTP Data Policy ASN.1 Module
SRTPDataSA -- {TBD}
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
-- RTP DATA APPLICATION --
-- id-srtpDataSA OBJECT IDENTIFIER ::= {TBD}
srtpDataSAInfo ::= SEQUENCE {
masterKeyID OCTET STRING (SIZE (4)),
masterSaltKeyID OCTET STRING (SIZE (4)),
encrTransform EncryptionTransform,
authTransform AuthenticationTranform OPTIONAL,
tagLength INTEGER,
prefixLength INTEGER,
pRF PRF,
encrKeyLength INTEGER,
authKeyLength INTEGER,
sessionSaltLength INTEGER,
keyDerivRate INTEGER,
sRTPPacketMax INTEGER,
sRTCPPacketMax INTEGER,
mKI OCTET STRING OPTIONAL,
tOfROM OCTET STRING OPTIONAL
}
EncryptionTransform ::= ENUMERATED {
aesCM (0),
null (1),
aesF8 (2)
}
AuthenticationTransform ::= ENUMERATED {
hmacSHA1 (0)
}
PRF ::= ENUMERATED {
aesCM (0)
}
END
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Authors Addresses
Andrea Colegrove
SPARTA, Inc.
7075 Samuel Morse Drive
Columbia, MD 21046
(410) 872-1515 ext 232
FAX (410) 872-8079
acc@sparta.com
Hugh Harney
SPARTA, Inc.
7075 Samuel Morse Drive
Columbia, MD 21046
(410) 872-1515 ext 203
FAX (410) 872-8079
hh@sparta.com
Full Copyright Statement
Copyright (C) The Internet Society (2004). 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 organizations, 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 languages other than English.
The limited permissions granted above are perpetual and will not be revoked
by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an "AS
IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE
DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE.
Document expiration: December 22, 2004
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