A Lightweight Approach to Node-to-Node Security in Diameter
draft-zorn-dime-n2n-sec-lite-00

Abstract

This document describes a lightweight method for cryptographically protecting a portion of the contents of a Diameter message in transit between an arbitrary pair of Diameter nodes. The scheme assumes that the destination node possesses an X.509 certificate containing an RSA public key and that that certificate is retrievable by the node originating the message through a DNS query.

In addition to describing the operation of the protocol, this note specifies an Attribute-Value Pair (AVP) for the encapsulation of encrypted AVPs.

Status of this Memo

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Table of Contents

1.  Introduction
2.  Terminology
3.  Protocol Operation
    3.1.  Client Operation
        3.1.1.  Key Establishment
        3.1.2.  Protected Data Transfer
    3.2.  Server Operation
        3.2.1.  Key Establishment
        3.2.2.  Protected Data Transfer
4.  Attribute-Value Pair Definitions
5.  Security Considerations
6.  IANA Considerations
7.  References
    7.1.  Normative References
    7.2.  Informative References
§  Authors' Addresses

1.  Introduction

Historically, Authentication, Authorization and Accounting (AAA) network traffic has been secured on a hop-by-hop basis: messages between AAA entities (such as Diameter clients, agents and servers) have been protected on the wire but those entities have had unfettered access to the message contents. This has not typically been considered to be a concern when all of the entities in question were within the same sphere of administrative control, but may be problematic if the messages pass through an outside system (for example, an agent residing in an intermediate domain in a roaming situation). This document describes a lightweight method for cryptographically protecting a portion of the contents of a Diameter message while in transit between an arbitrary pair of Diameter nodes.

2.  Terminology

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].

3.  Protocol Operation

The following sections describe the operation of the proposed end-to-end security scheme. Although key establishment and data transfer are discussed separately, both will usually take place in the same message.

3.1.  Client Operation

3.1.1.  Key Establishment

TBC.

3.1.2.  Protected Data Transfer

TBC.

3.2.  Server Operation

3.2.1.  Key Establishment

TBC.

3.2.2.  Protected Data Transfer

TBC.

4.  Attribute-Value Pair Definitions

This section defines a container AVP for the transport of encrypted AVPs in Diameter applications.

5.  Security Considerations

The security considerations applicable to the Diameter Base Protocol [RFC3588] (Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko, “Diameter Base Protocol,” September 2003.) are also applicable to this document.

6.  IANA Considerations

TBC.

7.  References

7.1. Normative References

7.2. Informative References

Authors' Addresses