Network Working Group S. Hartman
Internet-Draft M. Wasserman
Intended status: Informational Painless Security
Expires: September 15, 2013 D. Zhang
Huawei
March 14, 2013
EAP Mutual Cryptographic Binding
draft-ietf-emu-crypto-bind-03.txt
Abstract
As the Extensible Authentication Protocol (EAP) evolves, EAP peers
rely increasingly on information received from the EAP server. EAP
extensions such as channel binding or network posture information are
often carried in tunnel methods; peers are likely to rely on this
information. [RFC 3748] is a facility that protects tunnel methods
against man-in-the-middle attacks. However, cryptographic binding
focuses on protecting the server rather than the peer. This memo
explores attacks possible when the peer is not protected from man-in-
the-middle attacks and recommends mutual cryptographic binding, a new
form of cryptographic binding that protects both peer and server
along with other mitigations.
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Keywords for Requirement Levels
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 [RFC2119].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on September 15, 2013.
Copyright Notice
Copyright (c) 2013 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. An Example Problem . . . . . . . . . . . . . . . . . . . . . . 6
3. The Server insertion Attack . . . . . . . . . . . . . . . . . 8
3.1. Conditions for the Attack . . . . . . . . . . . . . . . . 8
3.2. Mitigation Strategies . . . . . . . . . . . . . . . . . . 9
3.2.1. Server Authentication . . . . . . . . . . . . . . . . 9
3.2.2. Server Policy . . . . . . . . . . . . . . . . . . . . 10
3.2.3. Existing Cryptographic Binding . . . . . . . . . . . . 13
3.2.4. IntroducingEMSK-based Cryptographic Binding . . . . . 14
3.2.5. Mix Key into Long-Term Credentials . . . . . . . . . . 15
3.3. Intended Intermediates . . . . . . . . . . . . . . . . . . 15
4. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 17
4.1. Mutual Cryptographic Binding . . . . . . . . . . . . . . . 17
4.2. State Tracking . . . . . . . . . . . . . . . . . . . . . . 17
4.3. Certificate Naming . . . . . . . . . . . . . . . . . . . . 18
4.4. Inner Mixing . . . . . . . . . . . . . . . . . . . . . . . 18
5. Survey of Tunnel Methods . . . . . . . . . . . . . . . . . . . 19
5.1. Tunneled Eap Method (TEAP) . . . . . . . . . . . . . . . . 19
5.2. Flexible Authentication through Secure Tunneling (FAST) . 19
5.3. Tunneled Transport Layer Security (EAP-TTLS) . . . . . . . 19
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