One document matched: draft-cam-winget-eap-fast-potp-provisioning-02.txt
Differences from draft-cam-winget-eap-fast-potp-provisioning-01.txt
Network Working Group D. Mitton
Internet Draft RSA Security Divison of EMC
Category: Informational N. Cam-Winget
Expires: August 2008 Cisco Systems
February 25, 2008
Using the Protected One-Time Password Protocol for
EAP-FAST Provisioning
draft-cam-winget-eap-fast-potp-provisioning-02.txt
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Copyright (C) The IETF Trust (2008).
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Internet-Draft Using POTP for EAP-FAST Provisioning February 2008
Abstract
EAP-FAST is an extensible EAP method that enables the provisioning of
credentials or other information by using the Transport Layer
Security (TLS) to establish a mutually authenticated tunnel. As the
tunnel may be unauthenticated, EAP-FAST further enables the use of
inner EAP methods to establish mutual authentication prior to
provisioning. This document describes how EAP-POTP may be used as
the EAP-FAST inner method for credential provisioning.
Conventions used in this document
In examples, "C:" and "S:" indicate lines sent by the client and
server respectively.
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].
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Table of Contents
1. Introduction...................................................4
2. Authenticating with EAP-POTP in EAP-FAST for provisioning......4
3. Cryptographic Calculations.....................................4
4. Security Considerations........................................5
5. IANA Considerations............................................5
6. Acknowledgments................................................6
7. References.....................................................6
7.1. Normative References......................................6
7.2. Informative References....................................6
8. Author's Addresses.............................................7
APPENDIX A: Example of a successful Tunnel PAC provisioning using
EAP-POTP mutual authentication....................................8
Intellectual Property Statement..................................11
Disclaimer of Validity...........................................11
Copyright Statement..............................................11
Acknowledgment...................................................11
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1. Introduction
EAP-FAST [EAP-FAST] is an extensible EAP method [RFC3748] that can be
used to mutually authenticate peer and server as well as provisioning
information such as user credentials. [FAST-PROVISION] defines how
EAP-FAST is used to enable dynamic or in-band provisioning and
demonstrates how other EAP authentication methods may be used inside
the protected tunnel to ensure mutual authentication prior to
provisioning.
As EAP-FAST enables any inner EAP method to be used, this document
describes how EAP Protected-OTP [EAP-POTP] may be employed within
EAP-FAST Provisioning to ensure mutual authentication during in-band
provisioning.
2. Authenticating with EAP-POTP in EAP-FAST for provisioning
Once a protected tunnel is established as defined in [FAST-
PROVISION], the peer must authenticate itself to the server before
the server can provision the peer. Use of EAP-POTP is negotiated
between the server and the peer. After the peer responds with a EAP
Payload TLV containing the EAP Identity Response, the server MAY
request the use of EAP-POTP as the inner EAP authentication method.
EAP-POTP allows a protected authentication based on a pre-shared
secret provisioned into a one-time password generating token.
Possession of the token and an optional PIN value, provides a
portable strong authenticator. The EAP-POTP method is an end-to-end
authentication method that requires both parties to know the one-time
password generated by the token based on that shared secret. This
information allows a method of secure provisioning that does not
require a user-memorized or static password. Details of the EAP-POTP
method can be found in [EAP-POTP].
The server MAY use EAP-POTP as the inner EAP authentication in either
Server-Authenticated or Server-Unauthenticated provisioning modes.
3. Cryptographic Calculations
The Key derivations for establishing the tunnel are as defined in
[EAP-FAST] Section 5. The Intermediate Compound Key Derivation
following a successful EAP-POTP authentication within EAP-FAST for
provisioning is defined in [FAST-PROVISION] Section 5.2 using the
resulting MSK as described in [EAP-POTP] Section 4.5.
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4. Security Considerations
Though EAP-POTP, like EAP-MSCHAPv2 is a username and password based
authentication mechanism, it provides several features that
strengthen its security:
* The current one-time password is not exchanged, but instead,
authentication is based on values derived from the password, nonces
from each side and inputs including the session instance information.
* The authentication processes can be configured for various sizes of
hash and iteration inputs, to slow active attacks.
* The method is resistant to man-in-the-middle attacks because of
cryptographic bindings to the network messages.
* The method requires mutual authentication of the derived values.
EAP-POTP derives its session keys using a multi-state hashing
function (PBKDF2) [PKCS5] whose input is based on the token code, PIN
input, a random or pre-shared secret, an iteration count and
information about the server, and derives an authentication value for
transmittal.
It also keeps a hash of the running EAP request and response
messages, using an SHA256 function. The hash values are combined with
the generated keys, to cryptographically bind the authentication to
the current message stream and mutually authenticate.
When using EAP-POTP as the inner method, the server can only validate
this value by knowing all of the same inputs. Any man-in-the-middle
change would affect the derived value and cause a failure.
When using EAP-POTP during dynamic EAP-FAST provisioning, session
resumption credentials MUST NOT be used for authentication.
Due to the mutual authentication and key establishment provided by
EAP-POTP, Server-Unauthenticated Provisioning Mode MAY be used when
EAP-POTP is used for PAC provisioning
5. IANA Considerations
This specification requires no new IANA values to be assigned. [RFC
2434]
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6. Acknowledgments
Thanks to Hao Zhou, Magnus Nystrom, and Dmitri Pal for their valuable
input.
This document was prepared using 2-Word-v2.0.template.dot.
7. References
7.1. Normative References
[EAP-FAST] Cam-Winget, N., et al., "The Flexible Authentication via
Secure Tunneling Extensible Authentication Protocol (EAP-
FAST)", RFC 4851, May 2007.
[FAST-PROVISION] Cam-Winget, N. et al., "Dynamic Provisioning via
Secure Tunneling Extensible Authentication Protocol (EAP-
FAST)", draft-cam-winget-eap-fast-provisioning-06 (work in
progress), February 2008.
[EAP-POTP] Nystrom M., "The EAP Protected One-Time Password Protocol
(EAP-POTP)", RFC 4793, February 2007.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative References
[RFC3748] Blunk, L., Vollbrecht, J., Aboba, B., Carlson, J., and
H.Levkowetz, Ed., "Extensible Authentication Protocol
(EAP)", RFC 3748, June 2004.
[PKCS5] RSA Laboratories, "Password-Based Cryptography Standard",
PKCS #5 v2.0, March 1999.
[RFC3979] Bradner, S., "Intellectual Property Rights in IETF
Technology", RFC 3979, March 2005.
[RFC3978] Bradner, S., "IETF Rights in Contributions", RFC 3978,
March 2005.
[RFC2434] Narten, T., and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 2434, October
1998.
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8. Author's Addresses
Nancy Cam-Winget
Cisco Systems Inc.
3625 Cisco Way
San Jose, CA 95134
Email: ncamwing@cisco.com
David Mitton
RSA Security Division of EMC
174 Middlesex Turnpike
Bedford, MA 01730
Email: dmitton@rsasecurity.com
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APPENDIX A: Example of a successful Tunnel PAC provisioning using EAP-
POTP mutual authentication
The following exchanges show anonymous DH with a successful EAP-POTP
exchange within Phase 2 to provision a Tunnel PAC, the conversation
will appear as follows:
Authenticating Peer Authenticator
------------------- -------------
<- EAP-Request/
Identity
EAP-Response/
Identity (MyID1) ->
<- EAP-Request/
EAP-Type=EAP-FAST, V=1
(EAP-FAST Start, S bit set, A-ID)
EAP-Response/
EAP-Type=EAP-FAST, V=1
(TLS client_hello without
PAC-Opaque extension)->
<- EAP-Request/
EAP-Type=EAP-FAST, V=1
(TLS server_hello,
TLS Server Key Exchange
TLS Server Hello Done)
EAP-Response/
EAP-Type=EAP-FAST, V=1 ->
(TLS Client Key Exchange
TLS change_cipher_spec,
TLS finished)
<- EAP-Request/
EAP-Type=EAP-FAST, V=1
(TLS change_cipher_spec
TLS finished)
EAP-Response/
EAP-Type=EAP-FAST, V=1 ->
(Acknowledgement)
TLS channel established
(messages sent within the TLS channel)
<- EAP Payload TLV,
EAP-Request/
EAP Identity Request
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EAP Payload TLV, EAP-Response/
EAP Identity Response ->
<- EAP Payload TLV,
EAP-Request,
OTP-X,
Version TLV:
Highest=0, Lowest=0
Server-Info TLV: N=0
Session Identifier=V1
Session Identifier=V2
Nonce=V3
OTP TLV:
P=1,C=0,N=0,T=0,E=0,R=0
Pepper Length=0
Iteration Count=V4
EAP Payload TLV, ->
EAP-Response,
OTP-X,
Version TLV:
Highest=0
OTP TLV:
P=1,C=0,N=0,T=0,E=0,R=0
Iteration Count=V4
Authentication Data=V5
User Identifier TLV:
User Identifier=V6
Token Key Identifier TLV:
Token Key Identifier=V7
<- EAP Payload TLV,
EAP-Request,
OTP-X,
Confirm TLV:
C=0
Authentication Data=V8
Pepper Identifier=V9
Encrypted Pepper=V10
EAP Payload TLV, ->
EAP-Response,
OTP-X,
Confirm TLV:
(no data)
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<- Intermediate Result TLV (Success)
Crypto-Binding-TLV(Version=1,
EAP-FAST Version=1, SNonce,
CompoundMAC)
Intermediate Result TLV (Success)
Crypto-Binding-TLV(Version=1,
EAP-FAST Version=1,
CNonce, CompoundMAC),
PAC TLV (PAC-Type=User Authorization PAC)->
<- Result TLV (Success)
PAC TLV
Result TLV (Success)
PAC Acknowledgment ->
TLS channel torn down
(messages sent in cleartext)
<- EAP-Success
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