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rfc:rfc5422

Network Working Group N. Cam-Winget Request for Comments: 5422 D. McGrew Category: Informational J. Salowey

                                                               H. Zhou
                                                         Cisco Systems
                                                            March 2009
      Dynamic Provisioning Using Flexible Authentication via
   Secure Tunneling Extensible Authentication Protocol (EAP-FAST)

Status of This Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

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.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified
 outside the IETF Standards Process, and derivative works of it may
 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

IESG Note

 EAP-FAST has been implemented by many vendors and it is used in the
 Internet.  Publication of this specification is intended to promote
 interoperability by documenting current use of existing EAP methods
 within EAP-FAST.

Cam-Winget, et al. Informational [Page 1] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 The EAP method EAP-FAST-MSCHAPv2 reuses the EAP type code assigned to
 EAP-MSCHAPv2 (26) for authentication within an anonymous TLS tunnel.
 In order to minimize the risk associated with an anonymous tunnel,
 changes to the method were made that are not interoperable with EAP-
 MSCHAPv2.  Since EAP-MSCHAPv2 does not support method-specific
 version negotiation, the use of EAP-FAST-MSCHAPv2 is implied by the
 use of an anonymous EAP-FAST tunnel.  This behavior may cause
 problems in implementations where the use of unaltered EAP-MSCHAPv2
 is needed inside an anonymous EAP-FAST tunnel.  Since such support
 requires special case execution of a method within a tunnel, it also
 complicates implementations that use the same method code both within
 and outside of the tunnel method.  If EAP-FAST were to be designed
 today, these difficulties could be avoided by utilization of unique
 EAP Type codes.  Given these issues, assigned method types must not
 be re-used with different meaning inside tunneled methods in the
 future.

Abstract

 The Flexible Authentication via Secure Tunneling Extensible
 Authentication Protocol (EAP-FAST) method enables secure
 communication between a peer and a server by using Transport Layer
 Security (TLS) to establish a mutually authenticated tunnel.  EAP-
 FAST also enables the provisioning credentials or other information
 through this protected tunnel.  This document describes the use of
 EAP-FAST for dynamic provisioning.

Table of Contents

 1. Introduction ....................................................4
    1.1. Specification Requirements .................................4
    1.2. Terminology ................................................4
 2. EAP-FAST Provisioning Modes .....................................5
 3. Dynamic Provisioning Using EAP-FAST Conversation ................6
    3.1. Phase 1 TLS Tunnel .........................................7
         3.1.1. Server-Authenticated Tunnel .........................7
         3.1.2. Server-Unauthenticated Tunnel .......................7
    3.2. Phase 2 - Tunneled Authentication and Provisioning .........7
         3.2.1. Server-Authenticated Tunneled Authentication ........8
         3.2.2. Server-Unauthenticated Tunneled Authentication ......8
         3.2.3. Authenticating Using EAP-FAST-MSCHAPv2 ..............8
         3.2.4. Use of Other Inner EAP Methods for EAP-FAST
                Provisioning ........................................9
    3.3. Key Derivations Used in the EAP-FAST Provisioning
         Exchange ..................................................10
    3.4. Peer-Id, Server-Id, and Session-Id ........................11
    3.5. Network Access after EAP-FAST Provisioning ................11
 4. Information Provisioned in EAP-FAST ............................12

Cam-Winget, et al. Informational [Page 2] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

    4.1. Protected Access Credential ...............................12
         4.1.1. Tunnel PAC .........................................13
         4.1.2. Machine Authentication PAC .........................13
         4.1.3. User Authorization PAC .............................13
         4.1.4. PAC Provisioning ...................................14
    4.2. PAC TLV Format ............................................15
         4.2.1. Formats for PAC Attributes .........................16
         4.2.2. PAC-Key ............................................16
         4.2.3. PAC-Opaque .........................................17
         4.2.4. PAC-Info ...........................................18
         4.2.5. PAC-Acknowledgement TLV ............................20
         4.2.6. PAC-Type TLV .......................................21
    4.3. Trusted Server Root Certificate ...........................21
         4.3.1. Server-Trusted-Root TLV ............................22
         4.3.2. PKCS#7 TLV .........................................23
 5. IANA Considerations ............................................24
 6. Security Considerations ........................................25
    6.1. Provisioning Modes and Man-in-the-Middle Attacks ..........25
         6.1.1. Server-Authenticated Provisioning Mode and
                Man-in-the-Middle Attacks ..........................26
         6.1.2. Server-Unauthenticated Provisioning Mode
                and Man-in-the-Middle Attacks ......................26
    6.2. Dictionary Attacks ........................................27
    6.3. Considerations in Selecting a Provisioning Mode ...........28
    6.4. Diffie-Hellman Groups .....................................28
    6.5. Tunnel PAC Usage ..........................................28
    6.6. Machine Authentication PAC Usage ..........................29
    6.7. User Authorization PAC Usage ..............................29
    6.8. PAC Storage Considerations ................................29
    6.9. Security Claims ...........................................31
 7. Acknowledgements ...............................................31
 8. References .....................................................31
    8.1. Normative References ......................................31
    8.2. Informative References ....................................32
 Appendix A.  Examples .............................................33
   A.1.  Example 1: Successful Tunnel PAC Provisioning .............33
   A.2.  Example 2: Failed Provisioning ............................35
   A.3.  Example 3: Provisioning an Authentication Server's
         Trusted Root Certificate ..................................37

Cam-Winget, et al. Informational [Page 3] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

1. Introduction

 EAP-FAST [RFC4851] is an EAP method that can be used to mutually
 authenticate the peer and server.  Credentials such as a pre-shared
 key, certificate trust anchor, or a Protected Access Credential (PAC)
 must be provisioned to the peer before it can establish mutual
 authentication with the server.  In many cases, the provisioning of
 such information presents deployment hurdles.  Through the use of the
 protected TLS [RFC5246] tunnel, EAP-FAST can enable dynamic in-band
 provisioning to address such deployment obstacles.

1.1. Specification Requirements

 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].

1.2. Terminology

 Much of the terminology used in this document comes from [RFC3748].
 The terms "peer" and "server" are used interchangeably with the terms
 "EAP peer" and "EAP server", respectively.  Additional terms are
 defined below:
 Man in the Middle (MITM)
    An adversary that can successfully inject itself between a peer
    and EAP server.  The MITM succeeds by impersonating a valid peer
    or server.
 Provisioning
    Providing a peer with a trust anchor, shared secret, or other
    appropriate information needed to establish a security
    association.
 Protected Access Credential (PAC)
    Credentials distributed to a peer for future optimized network
    authentication.  The PAC consists of at most three components: a
    shared secret, an opaque element, and optional information.  The
    shared secret part contains the secret key shared between the peer
    and server.  The opaque part contains the shared secret encrypted
    by a private key only known to the server.  It is provided to the
    peer and is presented back to the server when the peer wishes to
    obtain access to network resources.  Finally, a PAC may optionally
    include other information that may be useful to the peer.

Cam-Winget, et al. Informational [Page 4] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 Tunnel PAC
    A set of credentials stored by the peer and consumed by both the
    peer and the server to establish a TLS tunnel.
 User Authorization PAC
    A User Authorization PAC is server-encrypted data containing
    authorization information associated with a previously
    authenticated user.  The User Authorization PAC does not contain a
    key, but rather it is generally bound to a Tunnel PAC, which is
    used with the User Authorization PAC.
 Machine Authentication PAC
    A Machine Authentication PAC contains server-encrypted data
    containing authorization information associated with a device.  A
    Machine Authentication PAC may be used instead of a Tunnel PAC to
    establish the TLS tunnel to provide machine authentication and
    authorization information.  The Machine Authentication PAC is
    useful in cases where the machine needs to be authenticated and
    authorized to access a network before a user has logged in.

2. EAP-FAST Provisioning Modes

 EAP-FAST supports two modes for provisioning:
 1.  Server-Authenticated Provisioning Mode - Provisioning inside a
     TLS tunnel that provides server-side authentication.
 2.  Server-Unauthenticated Provisioning Mode - Provisioning inside an
     anonymous TLS tunnel.
 The EAP-FAST provisioning modes use EAP-FAST phase 2 inside a secure
 TLS tunnel established during phase 1.  [RFC4851] describes the EAP-
 FAST phases in greater detail.
 In the Server-Authenticated Provisioning Mode, the peer has
 successfully authenticated the EAP server as part of EAP-FAST phase 1
 (i.e., TLS tunnel establishment).  Additional exchanges MAY occur
 inside the tunnel to allow the EAP server to authenticate the EAP
 peer before provisioning any information.
 In the Server-Unauthenticated Provisioning Mode, an unauthenticated
 TLS tunnel is established in the EAP-FAST phase 1.  The peer MUST
 negotiate a TLS anonymous Diffie-Hellman-based ciphersuite to signal

Cam-Winget, et al. Informational [Page 5] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 that it wishes to use Server-Unauthenticateded Provisioning Mode.
 This provisioning mode enables the bootstrapping of peers where the
 peer lacks strong credentials usable for mutual authentication with
 the server.
 Since the server is not authenticated in the Server-Unauthenticated
 Provisioning Mode, it is possible that an attacker may intercept the
 TLS tunnel.  If an anonymous tunnel is used, then the peer and server
 MUST negotiate and successfully complete an EAP method supporting
 mutual authentication and key derivation as described in Section 6.
 The peer then uses the Crypto-Binding TLV to validate the integrity
 of the TLS tunnel, thereby verifying that the exchange was not
 subject to a man-in-the-middle attack.
 Server-Authenticated Provisioning Mode protects against the man-in-
 the-middle attack; however, it requires provisioning the peer with
 the credentials necessary to authenticate the server.  Environments
 willing to trade off the security risk of a man-in-the-middle attack
 for ease of deployment can choose to use the Server-Unauthenticated
 Provisioning Mode.
 Assuming that an inner EAP method and Crypto-Binding TLV exchange is
 successful, the server will subsequently provide credential
 information, such as a shared key using a PAC TLV or the trusted
 certificate root(s) of the server using a Server-Trusted-Root TLV.
 Once the EAP-FAST Provisioning conversation completes, the peer is
 expected to use the provisioned credentials in subsequent EAP-FAST
 authentications.

3. Dynamic Provisioning Using EAP-FAST Conversation

 The provisioning occurs in the following steps, which are detailed in
 the subsequent sections and in RFC 4851.  First, the EAP-FAST phase 1
 TLS tunnel is established.  During this process, extra material is
 extracted from the TLS key derivation for use as challenges in the
 subsequent authentication exchange.  Next, an inner EAP method, such
 as EAP-FAST-MSCHAPv2 (Microsoft Challenge Handshake Authentication
 Protocol version 2), is executed within the EAP-FAST phase 2 TLS
 tunnel to authenticate the client using the challenges derived from
 the phase 1 TLS exchange.  Following successful authentication and
 Crypto-Binding TLV exchange, the server provisions the peer with PAC
 information including the secret PAC-Key and the PAC-Opaque.
 Finally, the EAP-FAST conversation completes with Result TLV
 exchanges defined in RFC 4851.  The exported EAP Master Session Key
 (MSK) and Extended MSK (EMSK) are derived from a combination of the
 tunnel key material and key material from the inner EAP method
 exchange.

Cam-Winget, et al. Informational [Page 6] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

3.1. Phase 1 TLS Tunnel

3.1.1. Server-Authenticated Tunnel

 The provisioning EAP-FAST exchange uses the same sequence as the EAP-
 FAST authentication phase 1 to establish a protected TLS tunnel.
 Implementations supporting this version of the Sever-Authenticated
 Provisioning Mode MUST support the following TLS ciphersuites defined
 in [RFC5246]:
       TLS_RSA_WITH_RC4_128_SHA
       TLS_RSA_WITH_AES_128_CBC_SHA
       TLS_DHE_RSA_WITH_AES_128_CBC_SHA
 Other TLS ciphersuites that provide server authentication and
 encryption MAY be supported.  The server MAY authenticate the peer
 during the TLS handshake in Server-Authenticated Provisioning Mode.
 To adhere to best security practices, the peer MUST validate the
 server's certificate chain when performing server-side authentication
 to obtain the full security benefits of Server-Authenticated
 provisioning.

3.1.2. Server-Unauthenticated Tunnel

 Implementations supporting this version of the Sever-Unauthenticated
 Provisioning Mode MUST support the following TLS ciphersuite defined
 in [RFC5246]:
    TLS_DH_anon_WITH_AES_128_CBC_SHA
 Anonymous ciphersuites SHOULD NOT be allowed outside of EAP-FAST
 Server-Unauthenticated Provisioning Mode.  Any ciphersuites that are
 used for Server-Unauthenticated Provisioning Mode MUST provide a key
 agreement contributed by both parties.  Therefore, ciphersuites based
 on RSA key transport MUST NOT be used for this mode.  Ciphersuites
 that are used for provisioning MUST provide encryption.

3.2. Phase 2 - Tunneled Authentication and Provisioning

 Once a protected tunnel is established and the server is
 unauthenticated, the peer and server MUST execute additional
 authentication and perform integrity checks of the TLS tunnel.  Even
 if both parties are authenticated during TLS tunnel establishment,
 the peer and server MAY wish to perform additional authentication
 within the tunnel.  As defined in [RFC4851], the authentication
 exchange will be followed by an Intermediate-Result TLV and a Crypto-
 Binding TLV, if the EAP method succeeded.  The Crypto-Binding TLV

Cam-Winget, et al. Informational [Page 7] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 provides a check on the integrity of the tunnel with respect to the
 endpoints of the EAP method.  If the preceding is successful, then a
 provisioning exchange MAY take place.  The provisioning exchange will
 use a PAC TLV exchange if a PAC is being provisioned and a Server-
 Trusted-Root TLV if a trusted root certificate is being provisioned.
 The provisioning MAY be solicited by the peer or it MAY be
 unsolicited.  The PAC TLV exchange consists of the server
 distributing the PAC in a corresponding PAC TLV to the peer and the
 peer confirming its receipt in a final PAC TLV Acknowledgement
 message.  The peer may also use the PAC TLV to request that the
 server send a PAC.  The provisioning TLVs MAY be piggybacked onto the
 Result TLV.  Many implementations process TLVs in the order they are
 received; thus, for proper provisioning to occur, the Result TLV MUST
 precede the TLVs to be provisioned (e.g., Tunnel PAC, Machine
 Authentication PAC, and User Authorization PAC).  A PAC TLV MUST NOT
 be accepted if it is not encapsulated in an encrypted TLS tunnel.
 A fresh PAC MAY be distributed if the server detects that the PAC is
 expiring soon.  In-band PAC refreshing is through the PAC TLV
 mechanism.  The decision of whether or not to refresh the PAC is
 determined by the server.  Based on the PAC-Opaque information, the
 server MAY determine not to refresh a peer's PAC, even if the PAC-Key
 has expired.

3.2.1. Server-Authenticated Tunneled Authentication

 If Server-Authenticated Provisioning Mode is in use, then any EAP
 method may be used within the TLS tunnel to authenticate the peer
 that is allowed by the peer's policy.

3.2.2. Server-Unauthenticated Tunneled Authentication

 If Server-Unauthenticated Provisioning Mode is in use, then peer
 authenticates the server and the server authenticates the peer within
 the tunnel.  The only method for performing authentication defined in
 this version of EAP-FAST is EAP-FAST-MSCHAPv2 (in a special way as
 described in the following section).  It is possible for other
 methods to be defined to perform this authentication in the future.

3.2.3. Authenticating Using EAP-FAST-MSCHAPv2

 EAP-FAST-MSCHAPv2 is a specific instantiation of EAP-MSCHAPv2
 [EAP-MSCHAPv2] defined for use within EAP-FAST.  The 256-bit inner
 session key (ISK) is generated from EAP-FAST-MSCHAPv2 by combining
 the 128-bit master keys derived according to RFC 3079 [RFC3079], with
 the MasterSendKey taking the first 16 octets and MasterReceiveKey
 taking the last 16 octets.

Cam-Winget, et al. Informational [Page 8] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 Implementations of this version of the EAP-FAST Server-
 Unauthenticated Provisioning Mode MUST support EAP-FAST-MSCHAPv2 as
 the inner authentication method.  While other authentication methods
 exist, EAP-FAST-MSCHAPv2 was chosen for several reasons:
 o  It provides the ability to slow an active attack by using a hash-
    based challenge-response protocol.
 o  Its use of a challenge-response protocol, such as MSCHAPv2,
    provides some ability to detect a man-in-the-middle attack during
    Server-Unauthenticated Provisioning Mode.
 o  It is already supported by a large deployed base.
 o  It allows support for password change during the EAP-FAST
    provisioning modes.
 When using an anonymous Diffie-Hellman (DH) key agreement, the
 challenges MUST be generated as defined in Section 3.3.  This forms a
 binding between the tunnel and the EAP-FAST-MSCHAPv2 exchanges by
 using keying material generated during the EAP-FAST tunnel
 establishment as the EAP-FAST-MSCHAPv2 challenges instead of using
 the challenges exchanged within the protocol itself.  The exchanged
 challenges are zeroed upon transmission, ignored upon reception, and
 the challenges derived from the TLS key exchange are used in the
 calculations.  When EAP-FAST-MSCHAPv2 is used within a tunnel
 established using a ciphersuite other than one that provides
 anonymous key agreement, the randomly generated EAP-FAST-MSCHAPv2
 challenges MUST be exchanged and used.
 The EAP-FAST-MSCHAPv2 exchange forces the server to provide a valid
 ServerChallengeResponse, which must be a function of the server
 challenge, peer challenge, and password as part of its response.
 This reduces the window of vulnerability of a man-in-the-middle
 attack spoofing the server by requiring the attacker to successfully
 break the password within the peer's challenge-response time limit.

3.2.4. Use of Other Inner EAP Methods for EAP-FAST Provisioning

 Once a protected tunnel is established, typically the peer
 authenticates itself to the server before the server can provision
 the peer.  If the authentication mechanism does not support mutual
 authentication and protection from man-in-the-middle attacks, then
 Server-Authenticated Provisioning Mode MUST be used.  Within a server
 side, authenticated tunnel authentication mechanisms such as EAP-
 FAST-GTC (Generic Token Card) [RFC5421] MAY be used.  This will
 enable peers using other authentication mechanisms such as password
 database and one-time passwords to be provisioned in-band as well.

Cam-Winget, et al. Informational [Page 9] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 This version of the EAP-FAST provisioning mode implementation MUST
 support both EAP-FAST-GTC and EAP-FAST-MSCHAPv2 within the tunnel in
 Server-Authenticated Provisioning Mode.
 It should be noted that Server-Authenticated Provisioning Mode
 provides significant security advantages over Server-Unauthenticated
 Provisioning Mode even when EAP-FAST-MSCHAPv2 is being used as the
 inner method.  It protects the EAP-FAST-MSCHAPv2 exchanges from
 potential active MITM attacks by verifying the server's authenticity
 before executing EAP-FAST-MSCHAPv2.  Server-Authenticated
 Provisioning Mode is the recommended provisioning mode.  The EAP-FAST
 peer MUST use the Server- Authenticated Provisioning Mode whenever it
 is configured with a valid trust root for a particular server.

3.3. Key Derivations Used in the EAP-FAST Provisioning Exchange

 The TLS tunnel key is calculated according to the TLS version with an
 extra 72 octets of key material derived from the end of the
 key_block.  Portions of the extra 72 octets are used for the EAP-FAST
 provisioning exchange session key seed and as the random challenges
 in the EAP-FAST-MSCHAPv2 exchange.
 To generate the key material, compute:
              key_block = PRF(master_secret,
                             "key expansion",
                             server_random +
                             client_random);
 until enough output has been generated.
 For example, the key_block for TLS 1.0 [RFC2246] is partitioned as
 follows:
              client_write_MAC_secret[hash_size]
              server_write_MAC_secret[hash_size]
              client_write_key[Key_material_length]
              server_write_key[key_material_length]
              client_write_IV[IV_size]
              server_write_IV[IV_size]
              session_key_seed[40]
              ServerChallenge[16]
              ClientChallenge[16]

Cam-Winget, et al. Informational [Page 10] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 and the key_block for subsequent versions is partitioned as follows:
              client_write_MAC_secret[hash_size]
              server_write_MAC_secret[hash_size]
              client_write_key[Key_material_length]
              server_write_key[key_material_length]
              session_key_seed[40]
              ServerChallenge[16]
              ClientChallenge[16]
 In the extra key material, session_key_seed is used for the EAP-FAST
 Crypto-Binding TLV exchange while the ServerChallenge and
 ClientChallenge correspond to the authentication server's EAP-FAST-
 MSCHAPv2 challenge and the peer's EAP-FAST-MSCHAPv2 challenge,
 respectively.  The ServerChallenge and ClientChallenge are only used
 for the EAP-FAST-MSCHAPv2 exchange when Diffie-Hellman anonymous key
 agreement is used in the EAP-FAST tunnel establishment.

3.4. Peer-Id, Server-Id, and Session-Id

 The provisioning modes of EAP-FAST do not change the general EAP-
 FAST protocol and thus how the Peer-Id, Server-Id, and Session-Id are
 determined is based on the [RFC4851] techniques.
 Section 3.4 of [RFC4851] describes how the Peer-Id and Server-Id are
 determined; Section 3.5 describes how the Session-Id is generated.

3.5. Network Access after EAP-FAST Provisioning

 After successful provisioning, network access MAY be granted or
 denied depending upon the server policy.  For example, in the Server-
 Authenticated Provisioning Mode, access can be granted after the EAP
 server has authenticated the peer and provisioned it with a Tunnel
 PAC (i.e., a PAC used to mutually authenticate and establish the EAP-
 FAST tunnel).  Additionally, peer policy MAY instruct the peer to
 disconnect the current provisioning connection and initiate a new
 EAP-FAST exchange for authentication utilizing the newly provisioned
 information.  At the end of the Server-Unauthenticated Provisioning
 Mode, network access SHOULD NOT be granted as this conversation is
 intended for provisioning only and thus no network access is
 authorized.  The server MAY grant access at the end of a successful
 Server-Authenticated provisioning exchange.
 If after successful provisioning access to the network is denied, the
 EAP Server SHOULD conclude with an EAP Failure.  The EAP server SHALL
 NOT grant network access or distribute any session keys to the
 Network Access Server (NAS) if this exchange is not intended to
 provide network access.  Even though the provisioning mode completes

Cam-Winget, et al. Informational [Page 11] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 with a successful inner termination (e.g., a successful Result TLV),
 the server policy defines whether or not the peer gains network
 access.  Thus, it is feasible that the server, while providing a
 successful Result TLV, may conclude that its authentication policy
 was not satisfied and terminate the conversation with an EAP Failure.
 Denying network access after EAP-FAST Provisioning may cause
 disruption in scenarios such as wireless devices (e.g., in IEEE
 802.11 devices, an EAP Failure may trigger a full 802.11
 disassociation).  While a full EAP restart can be performed, a smooth
 transition to the subsequent EAP-FAST authentications to enable
 network access can be achieved by the peer or server initiating TLS
 renegotiation, where the newly provisioned credentials can be used to
 establish a server-authenticated or mutually authenticated TLS tunnel
 for authentication.  Either the peer or server may reject the request
 for TLS renegotiation.  Upon completion of the TLS negotiation and
 subsequent authentication, normal network access policy on EAP-FAST
 authentication can be applied.

4. Information Provisioned in EAP-FAST

 Multiple types of credentials MAY be provisioned within EAP-FAST.
 The most common credential is the Tunnel PAC that is used to
 establish the EAP-FAST phase 1 tunnel.  In addition to the Tunnel
 PAC, other types of credentials and information can also be
 provisioned through EAP-FAST.  They may include trusted root
 certificates, PACs for specific purposes, and user identities, to
 name a few.  Typically, provisioning is invoked after both the peer
 and server authenticate each other and after a successful Crypto-
 Binding TLV exchange.  However, depending on the information being
 provisioned, mutual authentication MAY not be needed.
 At a minimum, either the peer or server must prove authenticity
 before credentials are provisioned to ensure that information is not
 freely provisioned to or by adversaries.  For example, the EAP server
 may not need to authenticate the peer to provision it with trusted
 root certificates.  However, the peer SHOULD authenticate the server
 before it can accept a trusted server root certificate.

4.1. Protected Access Credential

 A Protected Access Credential (PAC) is a security credential
 generated by the server that holds information specific to a peer.
 The server distributes all PAC information through the use of a PAC
 TLV.  Different types of PAC information are identified through the
 PAC Type and other PAC attributes defined in this section.  This
 document defines three types of PACs: a Tunnel PAC, a Machine
 Authentication PAC, and a User Authorization PAC.

Cam-Winget, et al. Informational [Page 12] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

4.1.1. Tunnel PAC

 The server distributes the Tunnel PAC to the peer, which uses it in
 subsequent attempts to establish a secure EAP-FAST TLS tunnel with
 the server.  The Tunnel PAC includes a secret key (PAC-Key), data
 that is opaque to the peer (PAC-Opaque), and other information (PAC-
 Info) that the peer can interpret.  The opaque data is generated by
 the server and cryptographically protected so it cannot be modified
 or interpreted by the peer.  The Tunnel PAC conveys the server policy
 of what must and can occur in the protected phase 2 tunnel.  It is up
 to the server policy to include what is necessary in a PAC-Opaque to
 enforce the policy in subsequent TLS handshakes.  For example, user
 identity, I-ID, can be included as the part of the server policy.
 This I-ID information limits the inner EAP methods to be carried only
 on the specified user identity.  Other types of information can also
 be included, such as which EAP method(s) and which TLS ciphersuites
 are allowed.  If the server policy is not included in a PAC-Opaque,
 then there is no limitation imposed by the PAC on the usage of the
 inner EAP methods or user identities inside the tunnel established by
 the use of that PAC.

4.1.2. Machine Authentication PAC

 The Machine Authentication PAC contains information in the PAC-Opaque
 that identifies the machine.  It is meant to be used by a machine
 when network access is required and no user is logged in.  Typically,
 a server will only grant the minimal amount of access required for a
 machine without a user present based on the Machine Authentication
 PAC.  The Machine Authentication PAC MAY be provisioned during the
 authentication of a user.  It SHOULD be stored by the peer in a
 location that is only accessible to the machine.  This type of PAC
 typically persists across sessions.
 The peer can use the Machine Authentication PAC as the Tunnel PAC to
 establish the TLS tunnel.  The EAP server MAY have a policy to bypass
 additional inner EAP method and grant limited network access based on
 information in the Machine Authentication PAC.  The server MAY
 request additional exchanges to validate machine's other
 authorization criteria, such as posture information etc., before
 granting network access.

4.1.3. User Authorization PAC

 The User Authorization PAC contains information in the PAC-Opaque
 that identifies a user and provides authorization information.  This
 type of PAC does not contain a PAC-Key.  The PAC-Opaque portion of
 the User Authorization PAC is presented within the protected EAP-FAST
 TLS tunnel to provide user information during stateless session

Cam-Winget, et al. Informational [Page 13] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 resume so user authentication MAY be skipped.  The User Authorization
 PAC MAY be provisioned after user authentication.  It is meant to be
 short lived and not persisted across logon sessions.  The User
 Authorization PAC SHOULD only be available to the user for which it
 is provisioned.  The User Authorization PAC SHOULD be deleted from
 the peer when the local authorization state of a user's session
 changes, such as upon the user logs out.
 Once the EAP-FAST phase 1 TLS tunnel is established, the peer MAY
 present a User Authorization PAC to the server in a PAC TLV.  This is
 sent as TLS application data, but it MAY be included in the same
 message as the Finished Handshake message sent by the peer.  The User
 Authorization PAC MUST only be sent within the protection of an
 encrypted tunnel to an authenticated entity.  The server will decrypt
 the PAC and evaluate the contents.  If the contents are valid and the
 server policy allows the session to be resumed based on this
 information, then the server will complete the session resumption and
 grant access to the peer without requiring an inner authentication
 method.  This is called stateless session resume in EAP-FAST.  In
 this case, the server sends the Result TLV indicating success without
 the Crypto-Binding TLV and the peer sends back a Result TLV
 indicating success.  If the User Authorization PAC fails the server
 validation or the server policy, the server MAY either reject the
 request or continue with performing full user authentication within
 the tunnel.

4.1.4. PAC Provisioning

 To request provisioning of a PAC, a peer sends a PAC TLV containing a
 PAC attribute of PAC Type set to the appropriate value.  For a Tunnel
 PAC, the value is '1'; for a Machine Authentication PAC, the value is
 '2'; and for a User Authorization PAC, the value is '3'.  The request
 MAY be issued after the peer has determined that it has successfully
 authenticated the EAP server and validated the Crypto-Binding TLV to
 ensure that the TLS tunnel's integrity is intact.  Since anonymous DH
 ciphersuites are only allowed for provisioning a Tunnel PAC, if an
 anonymous ciphersuite is negotiated, the Tunnel PAC MAY be
 provisioned automatically by the server.  The peer MUST send separate
 PAC TLVs for each type of PAC it wants to provision.  Multiple PAC
 TLVs can be sent in the same packet or different packets.  When
 requesting the Machine Authentication PAC, the peer SHOULD include an
 I-ID TLV containing the machine name prefixed by "host/".  The EAP
 server will send the PACs after its internal policy has been
 satisfied, or it MAY ignore the request or request additional
 authentications if its policy dictates.  If a peer receives a PAC
 with an unknown type, it MUST ignore it.

Cam-Winget, et al. Informational [Page 14] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 A PAC-TLV containing PAC-Acknowledge attribute MUST be sent by the
 peer to acknowledge the receipt of the Tunnel PAC.  A PAC-Acknowledge
 TLV MUST NOT be used by the peer to acknowledge the receipt of other
 types of PACs.
 Please see Appendix A.1 for an example of packet exchanges to
 provision a Tunnel PAC.

4.2. PAC TLV Format

 The PAC TLV provides support for provisioning the Protected Access
 Credential (PAC) defined within [RFC4851].  The PAC TLV carries the
 PAC and related information within PAC attribute fields.
 Additionally, the PAC TLV MAY be used by the peer to request
 provisioning of a PAC of the type specified in the PAC Type PAC
 attribute.  The PAC TLV MUST only be used in a protected tunnel
 providing encryption and integrity protection.  A general PAC TLV
 format is defined as follows:
 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |M|R|         TLV Type          |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                        PAC Attributes...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      M
           0 - Non-mandatory TLV
           1 - Mandatory TLV
      R
           Reserved, set to zero (0)
      TLV Type
                11 - PAC TLV
      Length
              Two octets containing the length of the PAC attributes
              field in octets.
      PAC Attributes
                      A list of PAC attributes in the TLV format.

Cam-Winget, et al. Informational [Page 15] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

4.2.1. Formats for PAC Attributes

 Each PAC attribute in a PAC TLV is formatted as a TLV defined as
 follows:
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Type               |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                              Value...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      Type
           The Type field is two octets, denoting the attribute type.
           Allocated Types include:
                   1 - PAC-Key
                   2 - PAC-Opaque
                   3 - PAC-Lifetime
                   4 - A-ID
                   5 - I-ID
                   6 - Reserved
                   7 - A-ID-Info
                   8 - PAC-Acknowledgement
                   9 - PAC-Info
                   10 - PAC-Type
      Length
              Two octets containing the length of the Value field in
              octets.
      Value
             The value of the PAC attribute.

4.2.2. PAC-Key

 The PAC-Key is a secret key distributed in a PAC attribute of type
 PAC-Key.  The PAC-Key attribute is included within the PAC TLV
 whenever the server wishes to issue or renew a PAC that is bound to a
 key such as a Tunnel PAC.  The key is a randomly generated octet
 string, which is 32 octets in length.  The generator of this key is
 the issuer of the credential, which is identified by the Authority
 Identifier (A-ID).

Cam-Winget, et al. Informational [Page 16] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Type               |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 ~                              Key                              ~
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Type
       1 - PAC-Key
    Length
       2-octet length indicating a 32-octet key
    Key
       The value of the PAC-Key.

4.2.3. PAC-Opaque

 The PAC-Opaque attribute is included within the PAC TLV whenever the
 server wishes to issue or renew a PAC or the client wishes to present
 a User Authorization PAC to the server.
 The PAC-Opaque is opaque to the peer and thus the peer MUST NOT
 attempt to interpret it.  A peer that has been issued a PAC-Opaque by
 a server stores that data and presents it back to the server
 according to its PAC Type.  The Tunnel PAC is used in the ClientHello
 SessionTicket extension field defined in [RFC5077].  If a peer has
 opaque data issued to it by multiple servers, then it stores the data
 issued by each server separately according to the A-ID.  This
 requirement allows the peer to maintain and use each opaque datum as
 an independent PAC pairing, with a PAC-Key mapping to a PAC-Opaque
 identified by the A-ID.  As there is a one-to-one correspondence
 between the PAC-Key and PAC-Opaque, the peer determines the PAC-Key
 and corresponding PAC-Opaque based on the A-ID provided in the EAP-
 FAST/Start message and the A-ID provided in the PAC-Info when it was
 provisioned with a PAC-Opaque.
 The PAC-Opaque attribute format is summarized as follows:

Cam-Winget, et al. Informational [Page 17] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Type               |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                              Value ...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Type
       2 - PAC-Opaque
    Length
       The Length filed is two octets, which contains the length of
       the Value field in octets.
    Value
       The Value field contains the actual data for the PAC-Opaque.
       It is specific to the server implementation.

4.2.4. PAC-Info

 The PAC-Info is comprised of a set of PAC attributes as defined in
 Section 4.2.1.  The PAC-Info attribute MUST contain the A-ID, A-ID-
 Info, and PAC-Type attributes.  Other attributes MAY be included in
 the PAC-Info to provide more information to the peer.  The PAC-Info
 attribute MUST NOT contain the PAC-Key, PAC-Acknowledgement, PAC-
 Info, or PAC-Opaque attributes.  The PAC-Info attribute is included
 within the PAC TLV whenever the server wishes to issue or renew a
 PAC.
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Type               |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                           Attributes...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Type
       9 - PAC-Info

Cam-Winget, et al. Informational [Page 18] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

    Length
       2-octet Length field containing the length of the attributes
       field in octets.
    Attributes
       The attributes field contains a list of PAC attributes.  Each
       mandatory and optional field type is defined as follows:
       3 - PAC-LIFETIME
          This is a 4-octet quantity representing the expiration time
          of the credential expressed as the number of seconds,
          excluding leap seconds, after midnight UTC, January 1, 1970.
          This attribute MAY be provided to the peer as part of the
          PAC-Info.
       4 - A-ID
          The A-ID is the identity of the authority that issued the
          PAC.  The A-ID is intended to be unique across all issuing
          servers to avoid namespace collisions.  The A-ID is used by
          the peer to determine which PAC to employ.  The A-ID is
          treated as an opaque octet string.  This attribute MUST be
          included in the PAC-Info attribute.  The A-ID MUST match the
          A-ID the server used to establish the tunnel.  Since many
          existing implementations expect the A-ID to be 16 octets in
          length, it is RECOMMENDED that the length of an A-ID be 16
          octets for maximum interoperability.  One method for
          generating the A-ID is to use a high-quality random number
          generator to generate a 16-octet random number.  An
          alternate method would be to take the hash of the public key
          or public key certificate belonging a server represented by
          the A-ID.
       5 - I-ID
          Initiator identifier (I-ID) is the peer identity associated
          with the credential.  This identity is derived from the
          inner EAP exchange or from the client-side authentication
          during tunnel establishment if inner EAP method
          authentication is not used.  The server employs the I-ID in
          the EAP-FAST phase 2 conversation to validate that the same
          peer identity used to execute EAP-FAST phase 1 is also used
          in at minimum one inner EAP method in EAP-FAST phase 2.  If
          the server is enforcing the I-ID validation on the inner EAP
          method, then the I-ID MUST be included in the PAC-Info, to

Cam-Winget, et al. Informational [Page 19] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

          enable the peer to also enforce a unique PAC for each unique
          user.  If the I-ID is missing from the PAC-Info, it is
          assumed that the Tunnel PAC can be used for multiple users
          and the peer will not enforce the unique-Tunnel-PAC-per-user
          policy.
       7 - A-ID-Info
          Authority Identifier Information is intended to provide a
          user-friendly name for the A-ID.  It may contain the
          enterprise name and server name in a human-readable format.
          This TLV serves as an aid to the peer to better inform the
          end-user about the A-ID.  The name is encoded in UTF-8
          [RFC3629] format.  This attribute MUST be included in the
          PAC-Info.
       10 - PAC-type
          The PAC-Type is intended to provide the type of PAC.  This
          attribute SHOULD be included in the PAC-Info.  If the PAC-
          Type is not present, then it defaults to a Tunnel PAC (Type
          1).

4.2.5. PAC-Acknowledgement TLV

 The PAC-Acknowledgement is used to acknowledge the receipt of the
 Tunnel PAC by the peer.  The peer includes the PAC-Acknowledgement
 TLV in a PAC-TLV sent to the server to indicate the result of the
 processing and storing of a newly provisioned Tunnel PAC.  This TLV
 is only used when Tunnel PAC is provisioned.
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Type               |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Result             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Type
       8 - PAC-Acknowledgement
    Length
       The length of this field is two octets containing a value of 2.

Cam-Winget, et al. Informational [Page 20] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

    Result
       The resulting value MUST be one of the following:
             1 - Success
             2 - Failure

4.2.6. PAC-Type TLV

 The PAC-Type TLV is a TLV intended to specify the PAC type.  It is
 included in a PAC-TLV sent by the peer to request PAC provisioning
 from the server.  Its format is described below:
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Type               |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |         PAC Type              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Type
       10 - PAC-Type
    Length
       2-octet Length field with a value of 2
    PAC Type
       This 2-octet field defines the type of PAC being requested or
       provisioned.  The following values are defined:
             1 - Tunnel PAC
             2 - Machine Authentication PAC
             3 - User Authorization PAC

4.3. Trusted Server Root Certificate

 Server-Trusted-Root TLV facilitates the request and delivery of a
 trusted server root certificate.  The Server-Trusted-Root TLV can be
 exchanged in regular EAP-FAST authentication mode or provisioning
 mode.  The Server-Trusted-Root TLV is always marked as optional, and

Cam-Winget, et al. Informational [Page 21] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 cannot be responded to with a Negative Acknowledgement (NAK) TLV.
 The Server-Trusted-Root TLV MUST only be sent as an inner TLV (inside
 the protection of the tunnel).
 After the peer has determined that it has successfully authenticated
 the EAP server and validated the Crypto-Binding TLV, it MAY send one
 or more Server-Trusted-Root TLVs (marked as optional) to request the
 trusted server root certificates from the EAP server.  The EAP server
 MAY send one or more root certificates with a Public Key
 Cryptographic System #7 (PKCS#7) TLV inside Server-Trusted-Root TLV.
 The EAP server MAY also choose not to honor the request.  Please see
 Appendix A.3 for an example of a server provisioning a server trusted
 root certificate.

4.3.1. Server-Trusted-Root TLV

 The Server-Trusted-Root TLV allows the peer to send a request to the
 EAP server for a list of trusted roots.  The server may respond with
 one or more root certificates in PKCS#7 [RFC2315] format.
 If the EAP server sets the credential format to PKCS#7-Server-
 Certificate-Root, then the Server-Trusted-Root TLV should contain the
 root of the certificate chain of the certificate issued to the EAP
 server packaged in a PKCS#7 TLV.  If the Server certificate is a
 self-signed certificate, then the root is the self-signed
 certificate.
 If the Server-Trusted-Root TLV credential format contains a value
 unknown to the peer, then the EAP peer should ignore the TLV.
 The Server-Trusted-Root TLV is defined as follows:
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |M|R|         TLV Type          |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |           Credential-Format   |     Cred TLVs...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
      M
           0 - Non-mandatory TLV
      R
           Reserved, set to zero (0)

Cam-Winget, et al. Informational [Page 22] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

      TLV Type
                18 - Server-Trusted-Root TLV [RFC4851]
      Length
              >=2 octets
      Credential-Format
                         The Credential-Format field is two octets.
                         Values include:
           1 - PKCS#7-Server-Certificate-Root
      Cred TLVs
                 This field is of indefinite length.  It contains TLVs
                 associated with the credential format.  The peer may
                 leave this field empty when using this TLV to request
                 server trust roots.

4.3.2. PKCS#7 TLV

 The PKCS#7 TLV is sent by the EAP server to the peer inside the
 Server-Trusted-Root TLV.  It contains PKCS#7-wrapped [RFC2315] X.509
 certificates.  The format consists of a certificate or certificate
 chain in a Certificates-Only PKCS#7 SignedData message as defined in
 [RFC2311].
 The PKCS#7 TLV is always marked as optional, which cannot be
 responded to with a NAK TLV.  EAP-FAST server implementations that
 claim to support the dynamic provisioning defined in this document
 SHOULD support this TLV.  EAP-FAST peer implementations MAY support
 this TLV.
 If the PKCS#7 TLV contains a certificate or certificate chain that is
 not acceptable to the peer, then the peer MUST ignore the TLV.
 The PKCS#7 TLV is defined as follows:
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |M|R|         TLV Type          |            Length             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |           PKCS #7 Data...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

Cam-Winget, et al. Informational [Page 23] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

    M
       0 - Optional TLV
    R
       Reserved, set to zero (0)
    TLV Type
       20 - PKCS#7 TLV [RFC4851]
    Length
       The length of the PKCS #7 Data field.
    PKCS #7 Data
       This field contains the X.509 certificate or certificate chain
       in a Certificates-Only PKCS#7 SignedData message.

5. IANA Considerations

 This section explains the criteria to be used by the IANA for
 assignment of Type value in the PAC attribute, the PAC Type value in
 the PAC- Type TLV, and the Credential-Format value in the Server-
 Trusted-Root TLV.  The "Specification Required" policy is used here
 with the meaning defined in BCP 26 [RFC5226].
 A registry of values, named "EAP-FAST PAC Attribute Types", has been
 created for the PAC attribute types.  The initial values that
 populate the registry are:
       1 - PAC-Key
       2 - PAC-Opaque
       3 - PAC-Lifetime
       4 - A-ID
       5 - I-ID
       6 - Reserved
       7 - A-ID-Info
       8 - PAC-Acknowledgement
       9 - PAC-Info
      10 - PAC-Type
 Values from 11 to 63 are allocated for management by Cisco.  Values
 64 to 255 are assigned with a "Specification Required" policy.

Cam-Winget, et al. Informational [Page 24] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 A registry of values, named "EAP-FAST PAC Types", has been created
 for PAC-Type values used in the PAC-Type TLV.  The initial values
 that populate the registry are:
       1 - Tunnel PAC
       2 - Machine Authentication PAC
       3 - User Authorization PAC
 Values from 4 to 63 are allocated for management by Cisco.  Values 64
 to 255 are assigned with a "Specification Required" policy.
 A registry of values, named "EAP-FAST Server-Trusted-Root Credential
 Format Types", has been created for Credential-Format values used in
 the Server-Trusted-Root TLV.  The initial values that populate the
 registry are:
       1 - PKCS#7-Server-Certificate-Root
 Values from 2 to 63 are allocated for management by Cisco.  Values 64
 to 255 are assigned with a "Specification Required" policy.

6. Security Considerations

 The Dynamic Provisioning EAP-FAST protocol shares the same security
 considerations outlined in [RFC4851].  Additionally, it also has its
 unique security considerations described below:

6.1. Provisioning Modes and Man-in-the-Middle Attacks

 EAP-FAST can be invoked in two different provisioning modes: Server-
 Authenticated Provisioning Mode and Server-Unauthenticated
 Provisioning Mode.  Each mode provides different levels of resistance
 to man-in-the-middle attacks.  The following list identifies some of
 the problems associated with a man-in-the-middle attack:
 o  Disclosure of secret information such as keys, identities, and
    credentials to an attacker
 o  Spoofing of a valid server to a peer and the distribution of false
    credentials
 o  Spoofing of a valid peer and receiving credentials generated for
    that peer
 o  Denial of service

Cam-Winget, et al. Informational [Page 25] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

6.1.1. Server-Authenticated Provisioning Mode and Man-in-the-Middle

      Attacks
 In Server-Authenticated Provisioning Mode, the TLS handshake assures
 protected communications with the server because the peer must have
 been securely pre-provisioned with the trust roots and/or other
 authentication information necessary to authenticate the server
 during the handshake.  This pre-provisioning step prevents an
 attacker from inserting themselves as a man-in-the-middle of the
 communications.  Unfortunately, secure pre-provisioning can be
 difficult to achieve in many environments.
 Cryptographic binding of inner authentication mechanisms to the TLS
 tunnel provides additional protection from man-in-the-middle attacks
 resulting from the tunneling of authentication mechanisms.
 Server-Authenticated Provisioning Mode provides a high degree of
 protection from man-in-the-middle attacks.

6.1.2. Server-Unauthenticated Provisioning Mode and Man-in-the-Middle

      Attacks
 In Server-Unauthenticated Provisioning Mode, the TLS handshake does
 not assure protected communications with the server because either an
 anonymous handshake is negotiated or the peer lacks the necessary
 information to complete the authentication of the server.  This
 allows an attacker to insert itself in the middle of the TLS
 communications.
 EAP-FAST Server-Unauthenticated Provisioning Mode mitigates the man-
 in-the-middle attack through the following techniques:
 o  Binding the phase 2 authentication method to secret values derived
    from the phase 1 TLS exchange:
    In the case of EAP-FAST-MSCHAPv2 used with an anonymous Diffie-
    Hellman ciphersuite, the challenges for the EAP-FAST-MSCHAPv2
    exchange are derived from the TLS handshake and are not
    transmitted within the EAP-FAST-MSCHAPv2 exchange.  Since the man-
    in-the-middle attack does not know these challenges, it cannot
    successfully impersonate the server without cracking the EAP-FAST-
    MSCHAPv2 message from the peer before the peer times out.
 o  Cryptographic binding of secret values derived from the phase 2
    authentication exchange with secret values derived from the phase
    1 TLS exchange:

Cam-Winget, et al. Informational [Page 26] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

    This makes use of the cryptographic binding exchange defined
    within EAP-FAST to discover the presence of a man-in-the-middle
    attack by binding secret information obtained from the phase 2
    EAP-FAST-MSCHAPv2 exchange with secret information from the phase
    1 TLS exchange.
 While it would be sufficient to only support the cryptographic
 binding to mitigate the MITM, the binding of the EAP-FAST-MSCHAPv2
 random challenge derivations to the TLS key agreement protocol
 enables early detection of a man-in-the-middle attack.  This guards
 against adversaries who may otherwise relay the inner EAP
 authentication messages between the true peer and server, and it
 enforces that the adversary successfully respond with a valid
 challenge response.
 The ciphersuite used to establish phase 1 of the Server-
 Unauthenticated Provisioning Mode MUST be one in which both the peer
 and server provide contribution to the derived TLS master key.
 Ciphersuites that use RSA key transport do not meet this requirement.
 The authenticated and anonymous ephemeral Diffie-Hellman ciphersuites
 provide this type of key agreement.
 This document specifies EAP-FAST-MSCHAPv2 as the inner authentication
 exchange; however, it is possible that other inner authentication
 mechanisms to authenticate the tunnel may be developed in the future.
 Since the strength of the man-in-the-middle protection is directly
 dependent on the strength of the inner method, it is RECOMMENDED that
 any inner method used provide at least as much resistance to attack
 as EAP-FAST-MSCHAPv2.  Cleartext passwords MUST NOT be used in
 Server-Unauthenticated Provisioning Mode.  Note that an active man-
 in-the-middle attack may observe phase 2 authentication method
 exchange until the point that the peer determines that authentication
 mechanism fails or is aborted.  This allows for the disclosure of
 sensitive information such as identity or authentication protocol
 exchanges to the man-in-the-middle attack.

6.2. Dictionary Attacks

 It is often the case that phase 2 authentication mechanisms are based
 on password credentials.  These exchanges may be vulnerable to both
 online and off-line dictionary attacks.  The two provisioning modes
 provide various degrees of protection from these attacks.
 In online dictionary attacks, the attacker attempts to discover the
 password by repeated attempts at authentication using a guessed
 password.  Neither mode prevents this type of attack by itself.
 Implementations should provide controls that limit how often an
 attacker can execute authentication attempts.

Cam-Winget, et al. Informational [Page 27] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 In off-line dictionary attacks, the attacker captures information
 that can be processed off-line to recover the password.  Server-
 Authenticated Provisioning Mode provides effecting mitigation because
 the peer will not engage in phase 2 authentication without first
 authenticating the server during phase 1.  Server-Unauthenticated
 Provisioning Mode is vulnerable to this type of attack.  If, during
 phase 2 authentication, a peer receives no response or an invalid
 response from the server, then there is a possibility there is a man-
 in-the-middle attack in progress.  Implementations SHOULD log these
 events and, if possible, provide warnings to the user.
 Implementations are also encouraged to provide controls, which are
 appropriate to their environment, that limit how and where Server-
 Unauthenticated Provisioning Mode can be performed.  For example, an
 implementation may limit this mode to be used only on certain
 interfaces or require user intervention before allowing this mode if
 provisioning has succeeded in the past.
 Another mitigation technique that should not be overlooked is the
 choice of good passwords that have sufficient complexity and length
 and a password-changing policy that requires regular password
 changes.

6.3. Considerations in Selecting a Provisioning Mode

 Since Server-Authenticated Provisioning Mode provides much better
 protection from attacks than Server-Unauthenticated Provisioning
 Mode, Server-Authenticated Provisioning Mode SHOULD be used whenever
 possible.  The Server-Unauthenticated Provisioning Mode provides a
 viable option as there may be deployments that can physically confine
 devices during the provisioning or are willing to accept the risk of
 an active dictionary attack.  Further, it is the only option that
 enables zero-touch provisioning and facilitates simpler deployments
 requiring little to no peer configuration.  The peer MAY choose to
 use alternative secure out-of-band mechanisms for PAC provisioning
 that afford better security than the Server Unauthenticated
 Provisioning Mode.

6.4. Diffie-Hellman Groups

 To encourage interoperability implementations of EAP-FAST, anonymous
 provisioning modes MUST support the 2048-bit group "14" in [RFC3526].

6.5. Tunnel PAC Usage

 The basic usage of the Tunnel PAC is to establish the TLS tunnel.  In
 this operation, it does not have to provide user authentication as
 user authentication is expected to be carried out in phase 2 of EAP-
 FAST.  The EAP-FAST Tunnel PAC MAY contain information about the

Cam-Winget, et al. Informational [Page 28] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 identity of a peer to prevent a particular Tunnel PAC from being used
 to establish a tunnel that can perform phase 2 authentication other
 peers.  While it is possible for the server to accept the Tunnel PAC
 as authentication for the peer, many current implementations do not
 do this.  The ability to use PAC to authenticate peers and provide
 authorizations will be the subject of a future document.  [RFC5077]
 gives an example PAC-Opaque format in the Recommended Ticket
 Construction section.

6.6. Machine Authentication PAC Usage

 In general, the Machine Authorization PAC is expected to provide the
 minimum access required by a machine without a user.  This will
 typically be a subset of the privilege a registered user has.  The
 server provisioning the PAC should include information necessary to
 validate it at a later point in time.  This would include expiration
 information.  The Machine Authentication PAC includes a key so it can
 be used as a Tunnel PAC.  The PAC-Key MUST be kept secret by the
 peer.

6.7. User Authorization PAC Usage

 The User Authorization PAC provides the privilege associated with a
 user.  The server provisioning the PAC should include the information
 necessary to validate it at a later point in time.  This includes
 expiration and other information associated with the PAC.  The User
 Authorization PAC is a bearer credential such that it does not have a
 key that used to authenticate its ownership.  For this reason, this
 type of PAC MUST NOT be sent in the clear.  For additional
 protection, the PAC MAY be bound to a Tunnel PAC used to establish
 the TLS tunnel.  On the peer, the User Authorization PAC SHOULD only
 be accessible by the user for which it is provisioned.

6.8. PAC Storage Considerations

 The main goal of EAP-FAST is to protect the authentication stream
 over the media link.  However, host security is still an issue.  Some
 care should be taken to protect the PAC on both the peer and server.
 The peer must securely store both the PAC-Key and PAC-Opaque, while
 the server must secure storage of its security association context
 used to consume the PAC-Opaque.  Additionally, if alternate
 provisioning is employed, the transportation mechanism used to
 distribute the PAC must also be secured.

Cam-Winget, et al. Informational [Page 29] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 Most of the attacks described here would require some level of effort
 to execute: conceivably greater than their value.  The main focus
 therefore, should be to ensure that proper protections are used on
 both the peer and server.  There are a number of potential attacks
 that can be considered against secure key storage such as:
 o  Weak Passphrases
    On the peer side, keys are usually protected by a passphrase.  In
    some environments, this passphrase may be associated with the
    user's password.  In either case, if an attacker can obtain the
    encrypted key for a range of users, he may be able to successfully
    attack a weak passphrase.  The tools are already in place today to
    enable an attacker to easily attack all users in an enterprise
    environment through the use of email viruses and other techniques.
 o  Key Finding Attacks
    Key finding attacks are usually mentioned in reference to web
    servers where the private Secure Socket Layer (SSL) key may be
    stored securely, but at some point, it must be decrypted and
    stored in system memory.  An attacker with access to system memory
    can actually find the key by identifying their mathematical
    properties.  To date, this attack appears to be purely theoretical
    and primarily acts to argue strongly for secure access controls on
    the server itself to prevent such unauthorized code from
    executing.
 o  Key duplication, Key substitution, Key modification
    Once keys are accessible to an attacker on either the peer or
    server, they fall under three forms of attack: key duplication,
    key substitution, and key modification.  The first option would be
    the most common, allowing the attacker to masquerade as the user
    in question.  The second option could have some use if an attacker
    could implement it on the server.  Alternatively, an attacker
    could use one of the latter two attacks on either the peer or
    server to force a PAC re-key, and take advantage of the potential
    MITM/dictionary attack vulnerability of the EAP-FAST Server-
    Unauthenticated Provisioning Mode.
 Another consideration is the use of secure mechanisms afforded by the
 particular device.  For instance, some laptops enable secure key
 storage through a special chip.  It would be worthwhile for
 implementations to explore the use of such a mechanism.

Cam-Winget, et al. Informational [Page 30] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

6.9. Security Claims

 The [RFC3748] security claims for EAP-FAST are given in Section 7.8
 of [RFC4851].  When using anonymous provisioning mode, there is a
 greater risk of off-line dictionary attack since it is possible for a
 man-in-the-middle attack to capture the beginning of the inner EAP-
 FAST-MSCHAPv2 conversation.  However, as noted previously, it is
 possible to detect the man-in-the-middle attack.

7. Acknowledgements

 The EAP-FAST design and protocol specification is based on the ideas
 and contributions from Pad Jakkahalli, Mark Krischer, Doug Smith,
 Ilan Frenkel, Max Pritikin, Jan Vilhuber, and Jeremy Steiglitz.  The
 authors would also like to thank Jouni Malinen, Pasi Eronen, Jari
 Arkko, Chris Newman, Ran Canetti, and Vijay Gurbani for reviewing
 this document.

8. References

8.1. Normative References

 [EAP-MSCHAPv2]  Microsoft Corporation, "MS-CHAP: Extensible
                 Authentication Protocol Method for Microsoft
                 Challenge Handshake Authentication Protocol (CHAP)
                 Specification", January 2009.
                 http://msdn2.microsoft.com/
                 en-us/library/cc224612.aspx
 [RFC2119]       Bradner, S., "Key words for use in RFCs to Indicate
                 Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2246]       Dierks, T. and C. Allen, "The TLS Protocol Version
                 1.0", RFC 2246, January 1999.
 [RFC2311]       Dusse, S., Hoffman, P., Ramsdell, B., Lundblade, L.,
                 and L. Repka, "S/MIME Version 2 Message
                 Specification", RFC 2311, March 1998.
 [RFC2315]       Kaliski, B., "PKCS #7: Cryptographic Message Syntax
                 Version 1.5", RFC 2315, March 1998.
 [RFC3079]       Zorn, G., "Deriving Keys for use with Microsoft
                 Point-to-Point Encryption (MPPE)", RFC 3079,
                 March 2001.

Cam-Winget, et al. Informational [Page 31] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

 [RFC3526]       Kivinen, T. and M. Kojo, "More Modular Exponential
                 (MODP) Diffie-Hellman groups for Internet Key
                 Exchange (IKE)", RFC 3526, May 2003.
 [RFC3629]       Yergeau, F., "UTF-8, a transformation format of ISO
                 10646", STD 63, RFC 3629, November 2003.
 [RFC3748]       Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J.,
                 and H. Levkowetz, "Extensible Authentication Protocol
                 (EAP)", RFC 3748, June 2004.
 [RFC4851]       Cam-Winget, N., McGrew, D., Salowey, J., and H. Zhou,
                 "The Flexible Authentication via Secure Tunneling
                 Extensible Authentication Protocol Method (EAP-
                 FAST)", RFC 4851, May 2007.
 [RFC5077]       Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,
                 "Transport Layer Security (TLS) Session Resumption
                 without Server-Side State", RFC 5077, January 2008.
 [RFC5246]       Dierks, T. and E. Rescorla, "The Transport Layer
                 Security (TLS) Protocol Version 1.2", RFC 5246,
                 August 2008.
 [RFC5421]       Cam-Winget, N. and H. Zhou, "Basic Password Exchange
                 within the Flexible Authentication via Secure
                 Tunneling Extensible Authentication Protocol (EAP-
                 FAST)", RFC 5421, March 2009.

8.2. Informative References

 [RFC5226]       Narten, T. and H. Alvestrand, "Guidelines for Writing
                 an IANA Considerations Section in RFCs", BCP 26,
                 RFC 5226, May 2008.

Cam-Winget, et al. Informational [Page 32] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

Appendix A. Examples

A.1. Example 1: Successful Tunnel PAC Provisioning

 The following exchanges show anonymous DH with a successful EAP-FAST-
 MSCHAPv2 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-FAST,
                               (S=1, A-ID)
        EAP-Response/EAP-FAST
        (TLS Client Hello without
        PAC-Opaque in SessionTicket extension)->
                                <- EAP-Request/EAP-FAST
                                  (TLS Server Hello,
                                   TLS Server Key Exchange
                                 TLS Server Hello Done)
        EAP-Response/EAP-FAST
        (TLS Client Key Exchange
         TLS Change Cipher Spec
         TLS Finished)   ->
                                <- EAP-Request/EAP-FAST
                               ( TLS change_cipher_spec,
                                TLS finished,
                               EAP-Payload-TLV
                               (EAP-Request/Identity))
       // TLS channel established
          (Subsequent messages sent within the TLS channel,
                                   encapsulated within EAP-FAST)
       // First EAP Payload TLV is piggybacked on the TLS Finished as
          Application Data and protected by the TLS tunnel

Cam-Winget, et al. Informational [Page 33] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

        EAP Payload TLV
        (EAP-Response/Identity) ->
                               <-  EAP Payload TLV
                                   (EAP-Request/EAP-FAST-MSCHAPv2
                                    (Challenge))
        EAP Payload TLV
        (EAP-Response/EAP-FAST-MSCHAPv2
         (Response)) ->
                               <-  EAP Payload TLV
                                   (EAP-Request/EAP-FAST-MSCHAPv2)
                                   (Success))
        EAP Payload TLV
        (EAP-Response/EAP-FAST-MSCHAPv2
         (Success)) ->
                                <- Intermediate Result TLV(Success)
                                   Crypto-Binding-TLV (Version=1,
                                   EAP-FAST Version=1, Nonce,
                                   CompoundMAC)
        Intermediate Result TLV (Success)
        Crypto-Binding-TLV (Version=1,
        EAP-FAST Version=1, Nonce,
        CompoundMAC)
        PAC-TLV (Type=1)
                                <- Result TLV (Success)
                                   PAC TLV
        Result TLV (Success)
        PAC Acknowledgment ->
        TLS channel torn down
        (messages sent in cleartext)
                                <- EAP-Failure

Cam-Winget, et al. Informational [Page 34] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

A.2. Example 2: Failed Provisioning

 The following exchanges show a failed EAP-FAST-MSCHAPv2 exchange
 within phase 2, where the peer failed to authenticate the server.
 The conversation will appear as follows:
      Authenticating Peer     Authenticator
      -------------------     -------------
                              <- EAP-Request/Identity
      EAP-Response/
      Identity (MyID1) ->
                              <- EAP-Request/EAP-FAST
                                 (s=1, A-ID)
      EAP-Response/EAP-FAST
      (TLS Client Hello without
      SessionTicket extension)->
                              <- EAP-Request/EAP-FAST
                              (TLS Server Hello
                              TLS Server Key Exchange
                              TLS Server Hello Done)
      EAP-Response/EAP-FAST
      (TLS Client Key Exchange
       TLS Change Cipher Spec,
       TLS Finished)   ->
                                               <- EAP-Request/EAP-FAST
                             ( TLS change_cipher_spec,
                              TLS finished,
                             EAP-Payload-TLV
                             (EAP-Request/Identity))
     // TLS channel established
        (Subsequent messages sent within the TLS channel,
                                 encapsulated within EAP-FAST)
     // First EAP Payload TLV is piggybacked on the TLS Finished as
        Application Data and protected by the TLS tunnel
      EAP Payload TLV
      (EAP-Response/Identity)->
                             <-  EAP Payload TLV
                                (EAP-Request/EAP-FAST-MSCHAPv2
                                  (Challenge))

Cam-Winget, et al. Informational [Page 35] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

      EAP Payload TLV
      (EAP-Response/EAP-FAST-MSCHAPv2
       (Response)) ->
                             <-  EAP Payload TLV
                                 (EAP-Request EAP-FAST-MSCHAPv2
                                  (Success))
      // peer failed to verify server MSCHAPv2 response
      EAP Payload TLV
      (EAP-Response/EAP-FAST-MSCHAPv2
       (Failure)) ->
                             <-  Result TLV (Failure)
      Result TLV (Failure) ->
      TLS channel torn down
      (messages sent in cleartext)
                              <- EAP-Failure

Cam-Winget, et al. Informational [Page 36] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

A.3. Example 3: Provisioning an Authentication Server's Trusted Root

    Certificate
 The following exchanges show a successful provisioning of a server
 trusted root certificate using anonymous DH and EAP-FAST-MSCHAPv2
 exchange within phase 2.  The conversation will appear as follows:
    Authenticating Peer     Authenticator
    -------------------     -------------
                            <- EAP-Request/
                            Identity
    EAP-Response/
    Identity (MyID1) ->
                            <- EAP-Requese/EAP-FAST
                            (s=1, A-ID)
    EAP-Response/EAP-FAST
    (TLS Client Hello without
    SessionTicket extension)->
                            <- EAP-Request/EAP-FAST
                            (TLS Server Hello,
                            (TLS Server Key Exchange
                             TLS Server Hello Done)
    EAP-Response/EAP-FAST
    (TLS Client Key Exchange
     TLS Change Cipher Spec,
     TLS Finished)  ->
                            <- EAP-Request/EAP-FAST
                            (TLS Change Cipher Spec
                             TLS Finished)
                             (EAP-Payload-TLV(
                             EAP-Request/Identity))
    // TLS channel established
       (messages sent within the TLS channel)
    // First EAP Payload TLV is piggybacked on the TLS Finished as
       Application Data and protected by the TLS tunnel
    EAP-Payload TLV
    (EAP-Response/Identity) ->
                            <- EAP Payload TLV
                               (EAP-Request/EAP-FAST-MSCHAPv2
                               (Challenge))

Cam-Winget, et al. Informational [Page 37] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

    EAP Payload TLV
    (EAP-Response/EAP-FAST-MSCHAPv2
     (Response)) ->
                           <-  EAP Payload TLV
                               (EAP-Request/EAP-FAST-MSCHAPv2
                                (success))
    EAP Payload TLV
    (EAP-Response/EAP-FAST-MSCHAPv2
     (Success) ->
                            <- Intermediate Result TLV(Success)
                               Crypto-Binding TLV (Version=1,
                               EAP-FAST Version=1, Nonce,
                               CompoundMAC),
    Intermediate Result TLV(Success)
    Crypto-Binding TLV (Version=1
    EAP-FAST Version=1, Nonce,
    CompoundMAC)
    Server-Trusted-Root TLV
    (Type = PKCS#7) ->
                            <- Result TLV (Success)
                               Server-Trusted-Root TLV
                               (PKCS#7 TLV)
    Result TLV (Success) ->
    // TLS channel torn down
       (messages sent in cleartext)
                            <- EAP-Failure

Cam-Winget, et al. Informational [Page 38] RFC 5422 Dynamic Provisioning Using EAP-FAST March 2009

Authors' Addresses

 Nancy Cam-Winget
 Cisco Systems
 3625 Cisco Way
 San Jose, CA  95134
 US
 EMail: ncamwing@cisco.com
 David McGrew
 Cisco Systems
 3625 Cisco Way
 San Jose, CA  95134
 US
 EMail: mcgrew@cisco.com
 Joseph Salowey
 Cisco Systems
 2901 3rd Ave
 Seattle, WA  98121
 US
 EMail: jsalowey@cisco.com
 Hao Zhou
 Cisco Systems
 4125 Highlander Parkway
 Richfield, OH  44286
 US
 EMail: hzhou@cisco.com

Cam-Winget, et al. Informational [Page 39]

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