Network Working Group Q. Wu, Ed.
Internet-Draft Huawei
Intended status: Standards Track G. Zorn, Ed.
Expires: July 12, 2010 Network Zen
January 8, 2010
Diameter Attribute-Value Pairs for Cryptographic Key Transport
draft-ietf-dime-local-keytran-00
Abstract
Some Authentication, Authorization, and Accounting (AAA) applications
require the transport of cryptographic keying material; this document
specifies a set of Attribute-Value Pairs (AVPs) providing native
Diameter support of cryptographic key delivery.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 3
2.2. Technical Terms and Acronyms . . . . . . . . . . . . . . . 3
3. Attribute-Value Pair Definitions . . . . . . . . . . . . . . . 4
3.1. Key AVP . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1.1. Key-Type AVP . . . . . . . . . . . . . . . . . . . . . 4
3.1.2. Key-Name AVP . . . . . . . . . . . . . . . . . . . . . 5
3.1.3. Keying-Material AVP . . . . . . . . . . . . . . . . . . 5
3.1.4. Key-Lifetime AVP . . . . . . . . . . . . . . . . . . . 5
4. AVP Occurrence Table . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
6.1. AVP Codes . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.2. AVP Values . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
The Diameter EAP application [RFC4072] defines the EAP-Master-
Session-Key and EAP-Key-Name AVPs for the purpose of transporting
cryptographic keying material derived during the execution of certain
EAP [RFC3748] methods (for example, EAP-TLS [RFC5216]). At most one
instance of either of these AVPs is allowed in any Diameter message.
However, recent work [RFC5295] has specified methods to derive other
keys from the keying material created during EAP method execution
that may require transport in addition to the MSK. In addition, ERP
[RFC5296] specifies new keys that may need to be transported between
Diameter nodes.
This note specifies a set of AVPs allowing the transport of multiple
cryptographic keys in a single Diameter message.
2. Terminology
2.1. Standards Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2.2. Technical Terms and Acronyms
DER
Diameter EAP request [RFC4072].
DEA
Diameter EAP Answer [RFC4072].
DSRK
Domain-Specific Root Key [RFC5295].
DSUSRK
Domain-Specific Usage-Specific Root Key. This is a Usage-Specific
Root Key derived from a DSRK [RFC5295].
EAP
Extensible Authentication Protocol [RFC3748].
EMSK
Extended Master Session Key [RFC3748].
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ERP
EAP Re-authentication Protocol [RFC5296].
MSK
Master Session Key [RFC3748].
rMSK
reauthentication MSK [RFC5296]. This is a per-authenticator key,
derived from the rRK (see below).
rRK
reauthentication Root Key, derived from the EMSK or DSRK
[RFC5296].
USRK
Usage-Specific Root Key [RFC5295]
3. Attribute-Value Pair Definitions
This section defines new AVPs for the transport of cryptographic keys
in the Diameter EAP application [RFC4072], as well as other Diameter
applications.
3.1. Key AVP
The Key AVP (AVP Code <AC1>) is of type Grouped [RFC3588] It contains
the name, type and optionally, the usable lifetime of the key, as
well as the keying material itself.
Key ::= < AVP Header: AC1 >
< Key-Type >
{ Keying-Material }
[ Key-Lifetime ]
[ Key-Name ]
* [ AVP ]
3.1.1. Key-Type AVP
The Key-Type AVP (AVP Code <AC2>) is of type Enumerated and signifies
the type of the key being sent. The Key-Type AVP MAY be included in
a DER command as a signal that a certain type of key is required in
the response (e.g., to support ERP). The following values are
defined in this document:
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MSK (0)
The EAP Master Session Key [RFC3748]
DSRK (1)
A Domain-Specific Root Key [RFC5295].
USRK (2)
A Usage Specific Root Key [RFC5295].
rRK (3)
A reauthentication Root Key [RFC5296].
rMSK (4)
A reauthentication Master Session Key [RFC5296].
DSUSRK (5) A Domain-Specific Usage-Specific Root Key [RFC5295].
If additional values are needed, they are to be assigned by IANA
according to the policy stated in Section 6.2
3.1.2. Key-Name AVP
The Key-Name AVP is of type OctetString. It contains an opaque key
identifier. Exactly how this name is generated and used depends on
the key type and link layer in question, and is beyond the scope of
this document (see [RFC5247] and [RFC5295] for discussions of key
name generation in the context of EAP).
3.1.3. Keying-Material AVP
The Keying-Material AVP (AVP Code <AC3>) is of type OctetString. The
exact usage of this keying material depends upon several factors,
including the link layer in use and the type of the key; it is beyond
the scope of this document.
3.1.4. Key-Lifetime AVP
The Key-Lifetime AVP (AVP Code <AC4>) is of type Integer64 [RFC3588]
and represents the period of time (in seconds) for which the contents
of the Keying-Material AVP Section 3.1.3 is valid.
NOTE:
Applications using this value SHOULD consider the beginning of the
lifetime to be the point in time when the keying material is first
used.
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4. AVP Occurrence Table
The following table lists the AVPs that MAY be present in the DER and
DEA commands [RFC4072].
+---------------+
| Command-Code |
+-+-----+-----+-+
AVP Name | DER | DEA |
-------------------------------|-----+-----+
Key | 0 | 0+ |
Key-Type | 0+ | 0 |
Key-Name | 0-1 | 0-1 |
+-----+-----+
DER and DEA Commands AVP Table
5. Security Considerations
The security considerations applicable to the Diameter Base Protocol
[RFC3588] are also applicable to this document.
6. IANA Considerations
Upon publication of this memo as an RFC, IANA is requested to assign
values as described in the following sections.
6.1. AVP Codes
Codes must be assigned for the following AVPs using the policy
specified in RFC 3588, Section 11.1.1:
o Key (<AC1>, Section 3.1)
o Key-Type (<AC2>, Section 3.1.1)
o Keying-Material (<AC3>, Section 3.1.3
o Key-Lifetime (<AC4>, Section 3.1.4
6.2. AVP Values
New values may be assigned for the Key-Type AVP (Section 3.1.1) using
the "First Come First Served" policy [RFC5226].
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7. Acknowledgements
Thanks to Semyon Mizikovsky and Sebastien Decugis for useful
comments.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
Arkko, "Diameter Base Protocol", RFC 3588, September 2003.
[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Levkowetz, "Extensible Authentication Protocol (EAP)",
RFC 3748, June 2004.
[RFC4072] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible
Authentication Protocol (EAP) Application", RFC 4072,
August 2005.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
8.2. Informative References
[RFC5216] Simon, D., Aboba, B., and R. Hurst, "The EAP-TLS
Authentication Protocol", RFC 5216, March 2008.
[RFC5247] Aboba, B., Simon, D., and P. Eronen, "Extensible
Authentication Protocol (EAP) Key Management Framework",
RFC 5247, August 2008.
[RFC5295] Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri,
"Specification for the Derivation of Root Keys from an
Extended Master Session Key (EMSK)", RFC 5295,
August 2008.
[RFC5296] Narayanan, V. and L. Dondeti, "EAP Extensions for EAP Re-
authentication Protocol (ERP)", RFC 5296, August 2008.
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Authors' Addresses
Qin Wu (editor)
Huawei Technologies Co., Ltd.
Site B, Floor 12F, Huihong Mansion, No.91 Baixia Rd.
Nanjing, JiangSu 210001
China
Phone: +86-25-84565892
Email: Sunseawq@huawei.com
Glen Zorn (editor)
Network Zen
1463 East Republican Street
#358
Seattle, Washington 98112
USA
Email: gwz@net-zen.net
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