Diameter Attribute-Value Pairs for Cryptographic Key Transport
draft-wu-dime-local-keytran-01

Status of this Memo

This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work in progress.”

The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt.

The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html.

This Internet-Draft will expire on January 8, 2010.

Copyright Notice

Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document.

Abstract

Some 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.

Table of Contents

1.  Introduction
2.  Terminology
    2.1.  Standards Language
    2.2.  Technical Terms and Acronyms
3.  Attribute-Value Pair Definitions
    3.1.  EAP-Key AVP
        3.1.1.  EAP-Key-Type AVP
        3.1.2.  EAP-Key-Name AVP
        3.1.3.  EAP-Keying-Material AVP
        3.1.4.  EAP-Key-Lifetime AVP
4.  AVP Occurrence Table
5.  Security Considerations
6.  IANA Considerations
    6.1.  AVP Codes
    6.2.  AVP Values
7.  References
    7.1.  Normative References
    7.2.  Informative References
§  Authors' Addresses

1.  Introduction

The Diameter EAP application (Eronen, P., Hiller, T., and G. Zorn, “Diameter Extensible Authentication Protocol (EAP) Application,” August 2005.) [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 (Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, “Extensible Authentication Protocol (EAP),” June 2004.) [RFC3748] methods (for example, EAP-TLS (Simon, D., Aboba, B., and R. Hurst, “The EAP-TLS Authentication Protocol,” March 2008.) [RFC5216]). At most one instance of either of these AVPs is allowed in any Diameter message.

However, recent work (Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri, “Specification for the Derivation of Root Keys from an Extended Master Session Key (EMSK),” August 2008.) [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 (Narayanan, V. and L. Dondeti, “EAP Extensions for EAP Re-authentication Protocol (ERP),” August 2008.) [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

The following terms are used in this note.

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 (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.) [RFC2119].

2.2.  Technical Terms and Acronyms

AAA

Authentication, Authorization, and Accounting (see below).

Accounting

The act of collecting information on resource usage for the purpose of trend analysis, auditing, billing, or cost allocation [RFC2989] (Aboba, B., Calhoun, P., Glass, S., Hiller, T., McCann, P., Shiino, H., Zorn, G., Dommety, G., C.Perkins, B.Patil, D.Mitton, S.Manning, M.Beadles, P.Walsh, X.Chen, S.Sivalingham, A.Hameed, M.Munson, S.Jacobs, B.Lim, B.Hirschman, R.Hsu, Y.Xu, E.Campell, S.Baba, and E.Jaques, “Criteria for Evaluating AAA Protocols for Network Access,” November 2000.).

Authentication

The act of verifying a claimed identity, in the form of a pre-existing label from a mutually known name space, as the originator of a message (message authentication) or as the end-point of a channel (entity authentication) [RFC2989] (Aboba, B., Calhoun, P., Glass, S., Hiller, T., McCann, P., Shiino, H., Zorn, G., Dommety, G., C.Perkins, B.Patil, D.Mitton, S.Manning, M.Beadles, P.Walsh, X.Chen, S.Sivalingham, A.Hameed, M.Munson, S.Jacobs, B.Lim, B.Hirschman, R.Hsu, Y.Xu, E.Campell, S.Baba, and E.Jaques, “Criteria for Evaluating AAA Protocols for Network Access,” November 2000.).

Authorization

The act of determining if a particular right, such as access to some resource, can be granted to the presenter of a particular credential [RFC2989] (Aboba, B., Calhoun, P., Glass, S., Hiller, T., McCann, P., Shiino, H., Zorn, G., Dommety, G., C.Perkins, B.Patil, D.Mitton, S.Manning, M.Beadles, P.Walsh, X.Chen, S.Sivalingham, A.Hameed, M.Munson, S.Jacobs, B.Lim, B.Hirschman, R.Hsu, Y.Xu, E.Campell, S.Baba, and E.Jaques, “Criteria for Evaluating AAA Protocols for Network Access,” November 2000.).

DER

Diameter EAP request. (Eronen, P., Hiller, T., and G. Zorn, “Diameter Extensible Authentication Protocol (EAP) Application,” August 2005.) [RFC4072]

DEA

Diameter EAP Answer. (Eronen, P., Hiller, T., and G. Zorn, “Diameter Extensible Authentication Protocol (EAP) Application,” August 2005.) [RFC4072]

DSRK

Domain Specific Root Key (Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri, “Specification for the Derivation of Root Keys from an Extended Master Session Key (EMSK),” August 2008.) [RFC5295].

EAP

Extensible Authentication Protocol [RFC3748] (Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, “Extensible Authentication Protocol (EAP),” June 2004.).

EMSK

Extended Master Session Key (Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, “Extensible Authentication Protocol (EAP),” June 2004.) [RFC3748].

ERP

EAP Re-authentication Protocol (Narayanan, V. and L. Dondeti, “EAP Extensions for EAP Re-authentication Protocol (ERP),” August 2008.) [RFC5296].

MSK

Master Session Key (Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, “Extensible Authentication Protocol (EAP),” June 2004.) [RFC3748].

rMSK

re-authentication MSK (Narayanan, V. and L. Dondeti, “EAP Extensions for EAP Re-authentication Protocol (ERP),” August 2008.) [RFC5296]. This is a per-authenticator key, derived from the rRK.

rRK

re-authentication Root Key, derived from the EMSK or DSRK (Narayanan, V. and L. Dondeti, “EAP Extensions for EAP Re-authentication Protocol (ERP),” August 2008.) [RFC5296].

USRK

Usage Specific Root Key (Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri, “Specification for the Derivation of Root Keys from an Extended Master Session Key (EMSK),” August 2008.) [RFC5295].

3.  Attribute-Value Pair Definitions

This section defines new AVPs for the transport of cryptographic keys in the Diameter EAP application (Eronen, P., Hiller, T., and G. Zorn, “Diameter Extensible Authentication Protocol (EAP) Application,” August 2005.) [RFC4072], as well as other Diameter applications.

3.1.  EAP-Key AVP

The EAP-Key AVP (AVP Code <AC1>) is of type Grouped (Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko, “Diameter Base Protocol,” September 2003.) [RFC3588]. It contains the name, type and optionally, the usable lifetime of the key, as well as the keying material itself.

  EAP-Key ::= < AVP Header: AC1 >
                                { EAP-Key-Type }
                                { EAP-Keying-Material }
                                [ EAP-Key-Lifetime ]
                                [ EAP-Key-Name ]
                              * [ AVP ]

3.1.1.  EAP-Key-Type AVP

The EAP-Key-Type AVP (AVP Code <AC2>) is of type Enumerated and signifies the type of the key being sent. The EAP-Key-Type 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:

MSK (0)

The EAP Master Session Key. (Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, “Extensible Authentication Protocol (EAP),” June 2004.) [RFC3748]

DSRK (1)

A Domain Specific Root Key. (Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri, “Specification for the Derivation of Root Keys from an Extended Master Session Key (EMSK),” August 2008.) [RFC5295]

USRK (2)

A Usage Specific Root Key. (Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri, “Specification for the Derivation of Root Keys from an Extended Master Session Key (EMSK),” August 2008.) [RFC5295]

rRK (4)

A reauthentication Root Key. (Narayanan, V. and L. Dondeti, “EAP Extensions for EAP Re-authentication Protocol (ERP),” August 2008.) [RFC5296]

rMSK (5)

A reauthentication Master Session Key. (Narayanan, V. and L. Dondeti, “EAP Extensions for EAP Re-authentication Protocol (ERP),” August 2008.) [RFC5296]

If additional values are needed, they are to be assigned by IANA according to the policy stated in Section 6.2 (AVP Values).

3.1.2.  EAP-Key-Name AVP

The syntax and semantics of the EAP-Key-Name AVP are specified in Section 4.1.4 of RFC 4072.

3.1.3.  EAP-Keying-Material AVP

The EAP-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.  EAP-Key-Lifetime AVP

The EAP-Key-Lifetime AVP (AVP Code <AC4>) is of type Integer64 [RFC3588] (Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko, “Diameter Base Protocol,” September 2003.) representing the period of time (in seconds) for which the keying material 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.

4.  AVP Occurrence Table

The following table lists the AVPs that MAY be present in the DER and DEA commands [RFC4072] (Eronen, P., Hiller, T., and G. Zorn, “Diameter Extensible Authentication Protocol (EAP) Application,” August 2005.).

                              +---------------+
                              |  Command-Code |
                              +-+-----+-----+-+
 AVP Name                       | DER | DEA |
 -------------------------------|-----+-----+
 EAP-Key                        |  0  |  0+ |
 EAP-Key-Type                   |  0+ |  0  |
 EAP-Key-Name                   | 0-1 | 0-1 |
                                +-----+-----+

          DER and DEA Commands AVP Table

5.  Security Considerations

The security considerations discussed in [RFC3588] (Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko, “Diameter Base Protocol,” September 2003.) are 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:

• EAP-Key (<AC1>, Section 3.1 (EAP-Key AVP))
• EAP-Key-Type (<AC2>, Section 3.1.1 (EAP-Key-Type AVP))
• EAP-Keying-Material (<AC3>, Section 3.1.3 (EAP-Keying-Material AVP))
• EAP-Key-Lifetime (<AC4>, Section 3.1.4 (EAP-Key-Lifetime AVP))

6.2.  AVP Values

New values may be assigned for the EAP-Key-Type AVP (Section 3.1.1 (EAP-Key-Type AVP)) using the "First Come, First Served" policy [RFC5226] (Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” May 2008.).

7.  References

7.1. Normative References

7.2. Informative References

Authors' Addresses