rfc9427.original   rfc9427.txt 
Network Working Group DeKok, Alan Internet Engineering Task Force (IETF) A. DeKok
INTERNET-DRAFT FreeRADIUS Request for Comments: 9427 FreeRADIUS
Updates: 4851, 5281, 7170 16 February 2023 Updates: 4851, 5281, 7170 June 2023
Category: Standards Track Category: Standards Track
Expires: August 16, 2023 ISSN: 2070-1721
TLS-based EAP types and TLS 1.3 TLS-Based Extensible Authentication Protocol (EAP) Types for Use with
draft-ietf-emu-tls-eap-types-13.txt TLS 1.3
Abstract Abstract
EAP-TLS (RFC 5216) has been updated for TLS 1.3 in RFC 9190. Many The Extensible Authentication Protocol-TLS (EAP-TLS) (RFC 5216) has
other EAP types also depend on TLS, such as EAP-FAST (RFC 4851), EAP- been updated for TLS 1.3 in RFC 9190. Many other EAP Types also
TTLS (RFC 5281), TEAP (RFC 7170), and possibly many vendor specific depend on TLS, such as EAP-Flexible Authentication via Secure
EAP methods. This document updates those methods in order to use the Tunneling (EAP-FAST) (RFC 4851), EAP-Tunneled TLS (EAP-TTLS) (RFC
5281), the Tunnel Extensible Authentication Protocol (TEAP) (RFC
7170). It is possible that many vendor-specific EAP methods, such as
the Protected Extensible Authentication Protocol (PEAP), depend on
TLS as well. This document updates those methods in order to use the
new key derivation methods available in TLS 1.3. Additional changes new key derivation methods available in TLS 1.3. Additional changes
necessitated by TLS 1.3 are also discussed. necessitated by TLS 1.3 are also discussed.
Status of this Memo Status of This Memo
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Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on January 29, 2021. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9427.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction ............................................. 4 1. Introduction
1.1. Requirements Language ............................... 4 1.1. Requirements Language
2. Using TLS-based EAP methods with TLS 1.3 ................. 5 2. Using TLS-Based EAP Methods with TLS 1.3
2.1. Key Derivation ...................................... 5 2.1. Key Derivation
2.2. TEAP ................................................ 6 2.2. TEAP
2.2.1. Client Certificates ............................ 8 2.2.1. Client Certificates
2.3. EAP-FAST ............................................ 8 2.3. EAP-FAST
2.3.1. Client Certificates ............................ 9 2.3.1. Client Certificates
2.4. EAP-TTLS ............................................ 9 2.4. EAP-TTLS
2.4.1. Client Certificates ............................ 10 2.4.1. Client Certificates
2.5. PEAP ................................................ 10 2.5. PEAP
2.5.1. Client Certificates ............................ 11 2.5.1. Client Certificates
3. Application Data ......................................... 11 3. Application Data
3.1. Identities .......................................... 13 3.1. Identities
4. Resumption ............................................... 16 4. Resumption
5. Implementation Status .................................... 17 5. Security Considerations
6. Security Considerations .................................. 17 5.1. Handling of TLS NewSessionTicket Messages
6.1. Handling of TLS NewSessionTicket Messages ........... 17 5.2. Protected Success and Failure Indications
6.2. Protected Success and Failure indications ........... 19 6. IANA Considerations
7. IANA Considerations ...................................... 20 7. References
8. References ............................................... 21 7.1. Normative References
8.1. Normative References ................................ 21 7.2. Informative References
8.2. Informative References .............................. 22 Acknowledgments
Author's Address
1. Introduction 1. Introduction
EAP-TLS has been updated for TLS 1.3 in [RFC9190]. Many other EAP EAP-TLS has been updated for TLS 1.3 in [RFC9190]. Many other EAP
types also depend on TLS, such as EAP-FAST [RFC4851], EAP-TTLS Types also depend on TLS, such as EAP-FAST [RFC4851], EAP-TTLS
[RFC5281], TEAP [RFC7170], and possibly many vendor specific EAP [RFC5281], and TEAP [RFC7170]. It is possible that many vendor-
methods such as PEAP [PEAP]. All of these methods use key derivation specific EAP methods, such as PEAP [PEAP], depend on TLS as well.
functions which are no longer applicable to TLS 1.3. As such, all of All of these methods use key derivation functions that are no longer
those methods are incompatible with TLS 1.3. applicable to TLS 1.3; thus, these methods are incompatible with TLS
1.3.
This document updates those methods in order to be used with TLS 1.3. This document updates these methods in order to be used with TLS 1.3.
These changes involve defining new key derivation functions. We also These changes involve defining new key derivation functions. We also
discuss implementation issues in order to highlight differences discuss implementation issues in order to highlight differences
between TLS 1.3 and earlier versions of TLS. between TLS 1.3 and earlier versions of TLS.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Using TLS-based EAP methods with TLS 1.3 2. Using TLS-Based EAP Methods with TLS 1.3
In general, all of the requirements of [RFC9190] apply to other EAP In general, all of the requirements in [RFC9190] apply to other EAP
methods that wish to use TLS 1.3. Unless otherwise required herein, methods that wish to use TLS 1.3. Unless otherwise required herein,
implementations of EAP methods that wish to use TLS 1.3 MUST follow implementations of EAP methods that wish to use TLS 1.3 MUST follow
the guidelines in [RFC9190]. the guidelines in [RFC9190].
There remain some differences between EAP-TLS and other TLS-based EAP There remain some differences between EAP-TLS and other TLS-based EAP
methods which are addressed by this document. The main difference is methods that are addressed by this document. The main difference is
that [RFC9190] uses the EAP-TLS Type (value 0x0D) in a number of that [RFC9190] uses the EAP-TLS Type (value 0x0D) in a number of
calculations, whereas other method types will use their own Type calculations, whereas other method types will use their own Type
value instead of the EAP-TLS Type value. This topic is discussed value instead of the EAP-TLS Type value. This topic is discussed
further below in Section 2.1. further in Section 2.1.
An additional difference is that [RFC9190] Section 2.5 requires that An additional difference is that [RFC9190], Section 2.5 requires the
once the EAP-TLS handshake has completed, the EAP server sends a EAP server to send a protected success result indication once the
protected success result indication. This indication is composed of EAP-TLS handshake has completed. This indication is composed of one
one octet (0x00) of application data. Other TLS-based EAP methods octet (0x00) of application data. Other TLS-based EAP methods also
also use this result indication, but only during resumption. When use this result indication, but only during resumption. When other
other TLS-based EAP methods use full authentication, the result TLS-based EAP methods use full authentication, the result indication
indication is not needed, and is not used. This topic is explained is not needed or used. This topic is explained in more detail in
in more detail below, in Section 3 and Section 4. Sections 3 and 4.
Finally, the document includes clarifications on how various TLS- Finally, this document includes clarifications on how various TLS-
based parameters are calculated when using TLS 1.3. These parameters based parameters are calculated when using TLS 1.3. These parameters
are different for each EAP method, so they are discussed separately. are different for each EAP method, so they are discussed separately.
2.1. Key Derivation 2.1. Key Derivation
The key derivation for TLS-based EAP methods depends on the value of The key derivation for TLS-based EAP methods depends on the value of
the EAP Type as defined by [IANA] in the Extensible Authentication the EAP Type as defined by [IANA] in the "Extensible Authentication
Protocol (EAP) Registry. The most important definition is of the Protocol (EAP) Registry". The most important definition is of the
Type field, as first defined in [RFC3748] Section 2: Type field, as first defined in [RFC3748], Section 2:
Type = value of the EAP Method type Type = value of the EAP Method type
For the purposes of this specification, when we refer to logical For the purposes of this specification, when we refer to logical
Type, we mean that the logical Type is defined to be 1 octet for Type, we mean that the logical Type is defined as one octet for
values smaller than 254 (the value for the Expanded Type), and when values smaller than 254 (the value for the Expanded Type). When
Expanded EAP Types are used, the logical Type is defined to be the Expanded EAP Types are used, the logical Type is defined as the
concatenation of the fields required to define the Expanded Type, concatenation of the fields required to define the Expanded Type,
including the Type with value 0xfe, Vendor-Id (in network byte order) including the Type with value 0xfe, Vendor-Id (in network byte
and Vendor-Type fields (in network byte order) defined in [RFC3748] order), and Vendor-Type fields (in network byte order) defined in
Section 5.7, as given below: [RFC3748], Section 5.7, as given below:
Type = 0xFE || Vendor-Id || Vendor-Type Type = 0xFE || Vendor-Id || Vendor-Type
This definition does not alter the meaning of Type in [RFC3748], or This definition does not alter the meaning of Type in [RFC3748] or
change the structure of EAP packets. Instead, this definition allows change the structure of EAP packets. Instead, this definition allows
us to simplify references to EAP Types, by using a logical "Type" us to simplify references to EAP Types by using a logical "Type"
instead of referring to "the Type field or the Type field with value instead of referring to "the Type field or the Type field with value
0xfe, plus the Vendor-ID and Vendor-Type". For example, the value of 0xfe, plus the Vendor-ID and Vendor-Type". For example, the value of
Type for PEAP is simply 0x19. Type for PEAP is simply 0x19.
Note that unlike TLS 1.2 and earlier, the calculation of TLS-Exporter Note that unlike TLS 1.2 and earlier, the calculation of the TLS-
depends on the length passed to it. Implementations therefore MUST Exporter function depends on the length passed to it. Therefore,
pass the correct length instead of passing a large length and implementations MUST pass the correct length instead of passing a
truncating the output. Any output calculated using a larger length large length and truncating the output. Any output calculated using
value, and which is then truncated, will be different from the output a larger length value, which is then truncated, will be different
which was calculated using the correct length. from the output that was calculated using the correct length.
Unless otherwise discussed below, the key derivation functions for Unless otherwise discussed below, the key derivation functions for
all TLS-based EAP Types are defined in [RFC9190] Section 2.3, and all TLS-based EAP Types are defined in [RFC9190], Section 2.3 and
reproduced here for clarity. These definitions include ones for the reproduced here for clarity. These definitions include ones for the
Master Session Key (MSK) and the Extended Master Session Key (EMSK): Master Session Key (MSK) and the Extended Master Session Key (EMSK):
Key_Material = TLS-Exporter("EXPORTER_EAP_TLS_Key_Material", Key_Material = TLS-Exporter("EXPORTER_EAP_TLS_Key_Material",
Type, 128) Type, 128)
Method-Id = TLS-Exporter("EXPORTER_EAP_TLS_Method-Id", Method-Id = TLS-Exporter("EXPORTER_EAP_TLS_Method-Id",
Type, 64) Type, 64)
Session-Id = Type || Method-Id Session-Id = Type || Method-Id
MSK = Key_Material(0, 63) MSK = Key_Material(0, 63)
EMSK = Key_Material(64, 127) EMSK = Key_Material(64, 127)
We note that these definitions re-use the EAP-TLS exporter labels, We note that these definitions reuse the EAP-TLS exporter labels and
and change the derivation only by adding a dependency on the logical change the derivation only by adding a dependency on the logical
Type. The reason for this change is simplicity. The inclusion of Type. The reason for this change is simplicity. The inclusion of
the EAP type makes the derivation method-specific. There is no need the EAP Type makes the derivation method specific. There is no need
to use different labels for different EAP types, as was done earlier. to use different labels for different EAP Types as was done earlier.
These definitions apply in their entirety to EAP-TTLS [RFC5281] and These definitions apply in their entirety to EAP-TTLS [RFC5281] and
PEAP as defined in [PEAP] and [MSPEAP]. Some definitions apply to PEAP as defined in [PEAP] and [MSPEAP]. Some definitions apply to
EAP-FAST and TEAP, with exceptions as noted below. EAP-FAST and TEAP with exceptions as noted below.
It is RECOMMENDED that vendor-defined TLS-based EAP methods use the It is RECOMMENDED that vendor-defined and TLS-based EAP methods use
above definitions for TLS 1.3. There is no compelling reason to use the above definitions for TLS 1.3. There is no compelling reason to
different definitions. use different definitions.
2.2. TEAP 2.2. TEAP
TEAP previously used a Protected Access Credential (PAC), which is TEAP previously used a Protected Access Credential (PAC), which is
functionally equivalent to session tickets provided by TLS 1.3 which functionally equivalent to session tickets provided by TLS 1.3 that
contain a pre-shared key (PSK) along with other data. As such, the contain a pre-shared key (PSK) along with other data. As such, the
use of a PAC is deprecated for TEAP in TLS 1.3. PAC provisioning as use of a PAC is deprecated for TEAP in TLS 1.3. PAC provisioning, as
defined in [RFC7170] Section 3.8.1 is also no longer part of TEAP defined in [RFC7170], Section 3.8.1, is also no longer part of TEAP
when TLS 1.3 is used. when TLS 1.3 is used.
[RFC7170] Section 5.2 gives a definition for the Inner Method Session [RFC7170], Section 5.2 gives a definition for the Inner Method
Key (IMSK), which depends on the TLS-PRF. When the j'th inner method Session Key (IMSK), which depends on the TLS Pseudorandom Function
generates an EMSK, we update that definition for TLS 1.3 as: (PRF) (also known as TLS-PRF). When the j'th inner method generates
an EMSK, we update that definition for TLS 1.3 as:
IMSK[j] = TLS-Exporter("TEAPbindkey@ietf.org", secret, 32) IMSK[j] = TLS-Exporter("TEAPbindkey@ietf.org", secret, 32)
The secret is the EMSK or MSK from the j'th inner method. When an The secret is the EMSK or MSK from the j'th inner method. When an
inner method does not provide an EMSK or MSK, IMSK[j] is 32 octets of inner method does not provide an EMSK or MSK, IMSK[j] is 32 octets of
zero. zero.
The other key derivations for TEAP are given here. All derivations The other key derivations for TEAP are given here. All derivations
not given here are the same as given above in the previous section. not given here are the same as given above in the previous section.
These derivations are also used for EAP-FAST, but using the EAP-FAST These derivations are also used for EAP-FAST, but using the EAP-FAST
Type. Type.
The derivation of the Inner Method Session Keys (IMSK), Inner Method The derivation of the IMSKs, Inner Method Compound Keys (IMCKs), and
Compound Keys (IMCK), and Compound Session Keys (CMK) is given below. Compound Session Keys (CMKs) is given below.
session_key_seed = TLS-Exporter("EXPORTER: teap session key seed", session_key_seed = TLS-Exporter("EXPORTER: teap session key seed",
Type, 40) Type, 40)
S-IMCK[0] = session_key_seed S-IMCK[0] = session_key_seed
For j = 1 to n-1 do For j = 1 to n-1 do
IMCK[j] = TLS-Exporter("EXPORTER: Inner Methods Compound Keys", IMCK[j] = TLS-Exporter("EXPORTER: Inner Methods Compound Keys",
S-IMCK[j-1] || IMSK[j], 60) S-IMCK[j-1] || IMSK[j], 60)
S-IMCK[j] = first 40 octets of IMCK[j] S-IMCK[j] = first 40 octets of IMCK[j]
CMK[j] = last 20 octets of IMCK[j] CMK[j] = last 20 octets of IMCK[j]
In these definitions, || denotes concatenation. Note: In these definitions, || denotes concatenation.
In TLS 1.3, the derivation of IMCK[j] uses both a different label, In TLS 1.3, the derivation of IMCK[j] uses both a different label and
and a different order of concatenating fields, than was used by TEAP a different order of concatenating fields than what was used by TEAP
with TLS 1.2. Similarly, the session_key_seed in TLS 1.3 uses the with TLS 1.2. Similarly, the session_key_seed in TLS 1.3 uses the
Type as the context, where in TLS 1.2 the context was a zero-length Type as the context. In TLS 1.2, the context was a zero-length
field. field.
The outer MSK and EMSK are then derived from the final ("n"th) inner The outer MSK and EMSK are then derived from the final ("n"th) inner
method, as follows: method, as follows:
MSK = TLS-Exporter("EXPORTER: Session Key Generating Function", MSK = TLS-Exporter(
S-IMCK[n], 64) "EXPORTER: Session Key Generating Function",
S-IMCK[n], 64)
EMSK = TLS-Exporter("EXPORTER: Extended Session Key Generating Function", EMSK = TLS-Exporter(
S-IMCK[n], 64) "EXPORTER: Extended Session Key Generating Function",
S-IMCK[n], 64)
The TEAP Compound MAC defined in [RFC7170] Section 5.3 remains the The TEAP Compound Message Authentication Code (MAC) defined in
same, but the message authentication code (MAC) for TLS 1.3 is [RFC7170], Section 5.3 remains the same, but the MAC for TLS 1.3 is
computed with the HMAC algorithm negotiated for HKDF in the key computed with the Hashed Message Authentication Code (HMAC) algorithm
schedule, as per section 7.1 of RFC 8446. That is, the MAC used is negotiated for the HMAC-based Key Derivation Function (HKDF) in the
the MAC derived from the TLS handshake. key schedule, as per [RFC8446], Section 7.1. That is, the MAC used
is the MAC derived from the TLS handshake:
Compound-MAC = MAC( CMK[n], BUFFER ) Compound-MAC = MAC( CMK[n], BUFFER )
Where we define CMK[n] as the CMK taken from the final ("n"th) inner where we define CMK[n] as the CMK taken from the final ("n"th) inner
method. method.
For TLS 1.3, the message authentication code (MAC) is computed with For TLS 1.3, the MAC is computed with the HMAC algorithm negotiated
the HMAC algorithm negotiated for HKDF in the key schedule, as per for HKDF in the key schedule, as per [RFC8446], Section 7.1. That
section 7.1 of RFC 8446. That is, the MAC used is the MAC derived is, the MAC used is the MAC derived from the TLS handshake.
from the TLS handshake.
The definition of BUFFER is unchanged from [RFC7170] Section 5.3. The definition of BUFFER is unchanged from [RFC7170], Section 5.3.
2.2.1. Client Certificates 2.2.1. Client Certificates
The use of client certificates is still permitted when using TEAP The use of client certificates is still permitted when using TEAP
with TLS 1.3. However, if the client certificate is accepted, then with TLS 1.3. However, if the client certificate is accepted, then
the EAP peer MUST proceed with additional authentication of Phase 2, the EAP peer MUST proceed with additional authentication of Phase 2,
as per [RFC7170] Section 7.6. If there is no Phase 2 data, then the as per [RFC7170], Section 7.6. If there is no Phase 2 data, then the
EAP server MUST reject the session. EAP server MUST reject the session.
That is, while [RFC7170] Section 7.6 permits "Authentication of the While [RFC5281], Section 7.6 permits "authentication of the client
client via client certificate during phase 1, with no additional via client certificate during phase 1, with no additional
authentication or information exchange required.", this practice is authentication or information exchange required," this practice is
forbidden when TEAP is used with TLS 1.3. If there is a requirement forbidden when TEAP is used with TLS 1.3. If there is a requirement
to use client certificates with no inner tunnel methods, then EAP-TLS to use client certificates with no inner tunnel methods, then EAP-TLS
should be used instead of TEAP. should be used instead of TEAP.
[RFC7170] Section 7.4.1 suggest that client certificates should be [RFC7170], Section 7.4.1 suggests that client certificates should be
sent in Phase 2 of the TEAP exchange, "since TLS client certificates sent in Phase 2 of the TEAP exchange "since TLS client certificates
are sent in the clear". While TLS 1.3 no longer sends client are sent in the clear". While TLS 1.3 no longer sends client
certificates in the clear, TEAP implementations need to distinguish certificates in the clear, TEAP implementations need to distinguish
identities for both User and Machine using the Identity-Type TLV identities for both User and Machine using the Identity-Type TLV
(with values 1 and 2, respectively). When a client certificate is (with values 1 and 2, respectively). When a client certificate is
sent outside of the TLS tunnel, it MUST include Identity-Type as an sent outside of the TLS tunnel, it MUST include Identity-Type as an
outer TLV, in order to signal the type of identity which that client outer TLV in order to signal the type of identity which that client
certificate is for. certificate is for.
2.3. EAP-FAST 2.3. EAP-FAST
For EAP-FAST, the session_key_seed is also part of the key_block, as For EAP-FAST, the session_key_seed is also part of the key_block as
defined in [RFC4851] Section 5.1. defined in [RFC4851], Section 5.1.
The definition of S-IMCK[n], MSK, and EMSK are the same as given The definitions of S-IMCK[n], MSK, and EMSK are the same as given
above for TEAP. We reiterate that the EAP-FAST Type must be used above for TEAP. We reiterate that the EAP-FAST Type must be used
when deriving the session_key_seed, and not the TEAP Type. when deriving the session_key_seed and not the TEAP Type.
Unlike [RFC4851] Section 5.2, the definition of IMCK[j] places the Unlike [RFC4851], Section 5.2, the definition of IMCK[j] places the
reference to S-IMCK after the textual label, and the concatenates the reference to S-IMCK after the textual label and then concatenates the
IMSK instead of MSK. IMSK instead of the MSK.
EAP-FAST previously used a PAC, which is functionally equivalent to EAP-FAST previously used a PAC that is functionally equivalent to
session tickets provided by TLS 1.3 which contain a pre-shared key session tickets provided by TLS 1.3, which contain a PSK along with
(PSK) along with other data. As such, the use of a PAC is deprecated other data. As such, the use of a PAC is deprecated for EAP-FAST in
for EAP-FAST in TLS 1.3. PAC provisioning [RFC5422] is also no longer TLS 1.3. PAC provisioning [RFC5422] is also no longer part of EAP-
part of EAP-FAST when TLS 1.3 is used. FAST when TLS 1.3 is used.
The T-PRF given in [RFC4851] Section 5.5 is not used for TLS 1.3. The T-PRF given in [RFC4851], Section 5.5 is not used for TLS 1.3.
Instead, it is replaced with the TLS 1.3 TLS-Exporter function. Instead, it is replaced with the TLS 1.3 TLS-Exporter function.
2.3.1. Client Certificates 2.3.1. Client Certificates
The use of client certificates is still permitted when using EAP-FAST The use of client certificates is still permitted when using EAP-FAST
with TLS 1.3. However, if the client certificate is accepted, then with TLS 1.3. However, if the client certificate is accepted, then
the EAP peer MUST proceed with additional authentication of Phase 2, the EAP peer MUST proceed with additional authentication of Phase 2,
as per [RFC4851] Section 7.4.1. If there is no Phase 2 data, then as per [RFC4851], Section 7.4.1. If there is no Phase 2 data, then
the EAP server MUST reject the session. the EAP server MUST reject the session.
That is, while [RFC4851] implicitly permits the use of client While [RFC4851] implicitly permits the use of client certificates
certificates without proceeding to Phase 2, this practice is without proceeding to Phase 2, this practice is forbidden when EAP-
forbidden when EAP-FAST is used with TLS 1.3. If there is a FAST is used with TLS 1.3. If there is a requirement to use client
requirement to use client certificates with no inner tunnel methods, certificates with no inner tunnel methods, then EAP-TLS should be
then EAP-TLS should be used instead of EAP-FAST. used instead of EAP-FAST.
2.4. EAP-TTLS 2.4. EAP-TTLS
[RFC5281] Section 11.1 defines an implicit challenge when the inner [RFC5281], Section 11.1 defines an implicit challenge when the inner
methods of CHAP [RFC1994], MS-CHAP [RFC2433], or MS-CHAPv2 [RFC2759] methods of the Challenge Handshake Authentication Protocol (CHAP)
are used. The derivation for TLS 1.3 is instead given as [RFC1994], Microsoft CHAP (MS-CHAP) [RFC2433], or MS-CHAPv2 [RFC2759]
are used. The derivation for TLS 1.3 is instead given as:
EAP-TTLS_challenge = TLS-Exporter("ttls challenge",, n) EAP-TTLS_challenge = TLS-Exporter("ttls challenge",, n)
There is no "context_value" ([RFC8446] Section 7.5) passed to the There is no "context_value" ([RFC8446], Section 7.5) passed to the
TLS-Exporter function. The value "n" given here is the length of the TLS-Exporter function. The value "n" given here is the length of the
data required, which [RFC5281] requires it to be 17 octets for CHAP data required; [RFC5281] requires it to be 17 octets for CHAP
(Section 11.2.2) and MS-CHAPv2 (Section 11.2.4), and to be 9 octets ([RFC5281], Section 11.2.2) and MS-CHAPv2 ([RFC5281],
for MS-CHAP (Section 11.2.3). Section 11.2.4), and 9 octets for MS-CHAP ([RFC5281],
Section 11.2.3).
When PAP, CHAP, or MS-CHAPv1 are used as inner authentication When the Password Authentication Protocol (PAP), CHAP, or MS-CHAPv1
methods, there is no opportunity for the EAP server to send a are used as inner authentication methods, there is no opportunity for
protected success indication, as is done in [RFC9190] Section 2.5. the EAP server to send a protected success indication, as is done in
Instead, when TLS session tickets are disabled, the response from the [RFC9190], Section 2.5. Instead, when TLS session tickets are
EAP server MUST be either EAP-Success or EAP-Failure. These disabled, the response from the EAP server MUST be either EAP-Success
responses are unprotected, and can be forged by a skilled attacker. or EAP-Failure. These responses are unprotected and can be forged by
a skilled attacker.
Where TLS session tickets are enabled, the response from the EAP Where TLS session tickets are enabled, the response from the EAP
server may also continue TLS negotiation with a TLS NewSessionTicket server may also continue TLS negotiation with a TLS NewSessionTicket
message. Since this message is protected by TLS, it can serve as the message. Since this message is protected by TLS, it can serve as the
protected success indication. protected success indication.
It is therefore RECOMMENDED that EAP servers always send a TLS Therefore, it is RECOMMENDED that EAP servers always send a TLS
NewSessionTicket message, even if resumption is not configured. When NewSessionTicket message, even if resumption is not configured. When
the EAP peer attempts to use the ticket, the EAP server can instead the EAP peer attempts to use the ticket, the EAP server can instead
request a full authentication. As noted earlier, implementations request a full authentication. As noted earlier, implementations
SHOULD NOT send TLS NewSessionTicket messages until the "inner SHOULD NOT send TLS NewSessionTicket messages until the "inner
tunnel" authentication has completed, in order to take full advantage tunnel" authentication has completed in order to take full advantage
of the message as a protected success indication. of the message as a protected success indication.
When resumption is not used, the TLS NewSessionTicket message is not When resumption is not used, the TLS NewSessionTicket message is not
available, and some authentication methods will not have a protected available and some authentication methods will not have a protected
success indication. While we would like to always have a protected success indication. While we would like to always have a protected
success indication, limitations of the underlying protocols, success indication, limitations of the underlying protocols,
implementations, and deployment requirements make that impossible. implementations, and deployment requirements make that impossible.
EAP peers MUST continue running their EAP state machine until they EAP peers MUST continue running their EAP state machine until they
receive either an EAP-Success, or an EAP-Failure. Receiving a TLS receive either an EAP-Success or an EAP-Failure. Receiving a TLS
NewSessionTicket message in response to inner method PAP, CHAP, or NewSessionTicket message in response to inner method PAP, CHAP, or
MS-CHAP authentication is normal, and MUST NOT be treated as a MS-CHAP authentication is normal and MUST NOT be treated as a
failure. failure.
2.4.1. Client Certificates 2.4.1. Client Certificates
[RFC5281] Section 7.6 permits "Authentication of the client via [RFC5281], Section 7.6 permits "authentication of the client via
client certificate during phase 1, with no additional authentication client certificate during phase 1, with no additional authentication
or information exchange required.". This practice is forbidden when or information exchange required." This practice is forbidden when
EAP-TTLS is used with TLS 1.3. If there is a requirement to use EAP-TTLS is used with TLS 1.3. If there is a requirement to use
client certificates with no inner tunnel methods, then EAP-TLS should client certificates with no inner tunnel methods, then EAP-TLS should
be used instead of EAP-TTLS. be used instead of EAP-TTLS.
The use of client certificates is still permitted when using EAP-TTLS The use of client certificates is still permitted when using EAP-TTLS
with TLS 1.3. However, if the client certificate is accepted, then with TLS 1.3. However, if the client certificate is accepted, then
the EAP peer MUST proceed with additional authentication of Phase 2, the EAP peer MUST proceed with additional authentication of Phase 2,
as per [RFC5281] Section 7.2 and following. If there is no Phase 2 as per [RFC5281], Section 7.2. If there is no Phase 2 data, then the
data, then the EAP server MUST reject the session. EAP server MUST reject the session.
2.5. PEAP 2.5. PEAP
When PEAP uses crypto binding, it uses a different key calculation When PEAP uses crypto binding, it uses a different key calculation
defined in [PEAP-MPPE] which consumes inner EAP method keying defined in [PEAP-MPPE] that consumes inner EAP method keying
material. The pseudo-random function (PRF+) used in [PEAP-MPPE] is material. The PRF+ function used in [PEAP-MPPE] is not taken from
not taken from the TLS exporter, but is instead calculated via a the TLS exporter but is instead calculated via a different method
different method which is given in [PEAP-PRF]. That derivation that is given in [PEAP-PRF]. That derivation remains unchanged in
remains unchanged in this specification. this specification.
Note that the above derivation uses SHA-1, which may be formally Note that the above derivation uses SHA-1, which may be formally
deprecated in the near future. deprecated in the near future.
However, the pseudo-random function (PRF+) calculation uses a PEAP However, the PRF+ calculation uses a PEAP Tunnel Key (TK), which is
Tunnel Key which is defined in [PEAP-PRF] as: defined in [PEAP-TK] as:
... the TK is the first 60 octets of the Key_Material, as | ... the TK is the first 60 octets of the Key_Material, as
specified in [RFC5216]: TLS-PRF-128 (master secret, "client EAP | specified in [RFC5216]: TLS-PRF-128 (master secret, "client EAP
encryption", client.random || server.random). | encryption", client.random || server.random).
We note that the text in [PEAP-PRF] does not define Key_Material. We note that the text in [PEAP-PRF] does not define Key_Material.
Instead, it defines TK as the first octets of Key_Material, and gives Instead, it defines TK as the first octets of Key_Material and gives
a definition of Key_Material which is appropriate for TLS versions a definition of Key_Material that is appropriate for TLS versions
before TLS 1.3. before TLS 1.3.
For TLS 1.3, the TK should be derived from the Key_Material defined For TLS 1.3, the TK should be derived from the Key_Material defined
here in Section 2.1, instead of using the TLS-PRF-128 derivation here in Section 2.1 instead of using the TLS-PRF-128 derivation given
given in [PEAP-PRF]. The method defined in [PEAP-TK] MUST NOT be in [PEAP-PRF]. The method defined in [PEAP-TK] MUST NOT be used.
used.
2.5.1. Client Certificates 2.5.1. Client Certificates
As with EAP-TTLS, [PEAP] permits the use of client certificates in As with EAP-TTLS, [PEAP] permits the use of client certificates in
addition to inner tunnel methods. The practice of using client addition to inner tunnel methods. The practice of using client
certificates with no "inner method" is forbidden when PEAP is used certificates with no "inner method" is forbidden when PEAP is used
with TLS 1.3. If there is a requirement to use client certificates with TLS 1.3. If there is a requirement to use client certificates
with no inner tunnel methods, then EAP-TLS should be used instead of with no inner tunnel methods, then EAP-TLS should be used instead of
PEAP. PEAP.
The use of client certificates is still permitted when using PEAP The use of client certificates is still permitted when using PEAP
with TLS 1.3. However, if the client certificate is accepted, then with TLS 1.3. However, if the client certificate is accepted, then
the EAP peer MUST proceed with additional authentication of the inner the EAP peer MUST proceed with additional authentication of the inner
tunnel. If there is no inner tunnel authentication data, then the tunnel. If there is no inner tunnel authentication data, then the
EAP server MUST reject the session. EAP server MUST reject the session.
3. Application Data 3. Application Data
Unlike previous TLS versions, TLS 1.3 can continue negotiation after Unlike previous TLS versions, TLS 1.3 can continue negotiation after
the initial TLS handshake has been completed, which TLS 1.3 calls the the initial TLS handshake has been completed; TLS 1.3 calls this the
"CONNECTED" state. Some implementations use receipt of a Finished "CONNECTED" state. Some implementations use receipt of a Finished
message as an indication that TLS negotiation has completed, and that message as an indication that TLS negotiation has completed and that
an "inner tunnel" session can now be negotiated. This assumption is an "inner tunnel" session can now be negotiated. This assumption is
not always correct with TLS 1.3. not always correct with TLS 1.3.
Earlier TLS versions did not send application data along with the Earlier TLS versions did not send application data along with the
Finished message. It was then possible for implementations to assume Finished message. It was then possible for implementations to assume
that a receipt of a Finished message also meant that there was no that a receipt of a Finished message also meant that there was no
application data available, and that another round trip was required. application data available and that another round trip was required.
This assumption is not true with TLS 1.3, and applications relying on This assumption is not true with TLS 1.3, and applications relying on
that behavior will not operate correctly with TLS 1.3. that behavior will not operate correctly with TLS 1.3.
As a result, implementations MUST check for application data once the As a result, implementations MUST check for application data once the
TLS session has been established. This check MUST be performed TLS session has been established. This check MUST be performed
before proceeding with another round trip of TLS negotiation. TLS- before proceeding with another round trip of TLS negotiation. TLS-
based EAP methods such as EAP-TTLS, PEAP, and EAP-FAST each have based EAP methods, such as EAP-TTLS, PEAP, and EAP-FAST, each have
method-specific application data which MUST be processed according to method-specific application data that MUST be processed according to
the EAP type. the EAP Type.
TLS 1.3 in [RFC8446] Section 4.6.1 also permits NewSessionTicket TLS 1.3 in [RFC8446], Section 4.6.1 also permits NewSessionTicket
messages to be sent after the server has received the client Finished messages to be sent after the server has received the client Finished
message, which is a change from earlier TLS versions. This change message, which is a change from earlier TLS versions. This change
can cause implementations to fail in a number of different ways, due can cause implementations to fail in a number of different ways due
to a reliance on implicit behavior seen in earlier TLS versions. to a reliance on implicit behavior seen in earlier TLS versions.
In order to correct this failure, we require that if the underlying In order to correct this failure, we require that implementations
TLS connection is still performing negotiation, then implementations MUST NOT send or expect to receive application data in the TLS
MUST NOT send, or expect to receive application data in the TLS session if the underlying TLS connection is still performing
session. Implementations MUST delay processing of application data negotiation. Implementations MUST delay processing of application
until such time as the TLS negotiation has finished. If the TLS data until such time as the TLS negotiation has finished. If the TLS
negotiation is successful, then the application data can be examined. negotiation is successful, then the application data can be examined.
If the TLS negotiation is unsuccessful, then the application data is If the TLS negotiation is unsuccessful, then the application data is
untrusted, and therefore MUST be discarded without being examined. untrusted; therefore, it MUST be discarded without being examined.
The default for many TLS library implementations is to send a The default for many TLS library implementations is to send a
NewSessionTicket message immediately after, or along with, the NewSessionTicket message immediately after or along with the Finished
Finished message. This ticket could be used for resumption, even if message. This ticket could be used for resumption, even if the
the "inner tunnel" authentication has not been completed. If the "inner tunnel" authentication has not been completed. If the ticket
ticket could be used, then it could allow a malicious EAP peer to could be used, then it could allow a malicious EAP peer to completely
completely bypass the "inner tunnel" authentication. bypass the "inner tunnel" authentication.
Therefore, the EAP server MUST NOT permit any session ticket to Therefore, the EAP server MUST NOT permit any session ticket to
successfully resume authentication, unless the inner tunnel successfully resume authentication unless the inner tunnel
authentication has completed successfully. The alternative would authentication has completed successfully. The alternative would
allow an attacker to bypass authentication by obtaining a session allow an attacker to bypass authentication by obtaining a session
ticket, and then immediately closing the current session, and ticket, immediately closing the current session, and "resuming" using
"resuming" using the session ticket. the session ticket.
To protect against that attack, implementations SHOULD NOT send To protect against that attack, implementations SHOULD NOT send
NewSessionTicket messages until the "inner tunnel" authentication has NewSessionTicket messages until the "inner tunnel" authentication has
completed. There is no reason to send session tickets which will completed. There is no reason to send session tickets that will
later be invalidated or ignored. However, we recognize that this later be invalidated or ignored. However, we recognize that this
suggestion may not always be possible to implement with some suggestion may not always be possible to implement with some
available TLS libraries. As such, EAP servers MUST take care to available TLS libraries. As such, EAP servers MUST take care to
either invalidate or discard session tickets which are associated either invalidate or discard session tickets that are associated with
with sessions that terminate in EAP Failure. sessions that terminate in EAP Failure.
The NewSessionTicket message SHOULD also be sent along with other The NewSessionTicket message SHOULD also be sent along with other
application data, if possible. Sending that message alone prolongs application data, if possible. Sending that message alone prolongs
the packet exchange to no benefit. In addition to prolonging the the packet exchange to no benefit. In addition to prolonging the
packet exchange, using a separate NewSessionTicket message can lead packet exchange, using a separate NewSessionTicket message can lead
to non-interoperable implementations. to non-interoperable implementations.
[RFC9190] Section 2.5 requires a protected result indication which [RFC9190], Section 2.5 requires a protected result indication, which
indicates that TLS negotiation has finished. Methods which use indicates that TLS negotiation has finished. Methods that use "inner
"inner tunnel" methods MUST instead begin their "inner tunnel" tunnel" methods MUST instead begin their "inner tunnel" negotiation
negotiation by sending Type-specific application data. by sending Type-specific application data.
3.1. Identities 3.1. Identities
For EAP-TLS, [RFC9190] Sections 2.1.3 and 2.1.7 recommend the use of For EAP-TLS, Sections 2.1.3 and 2.1.7 of [RFC9190] recommend the use
anonymous Network Access Identifiers (NAIs) [RFC7542] in the EAP of anonymous Network Access Identifiers (NAIs) [RFC7542] in the EAP
Response/Identity packet. However, as EAP-TLS does not send Response/Identity packet. However, as EAP-TLS does not send
application data inside of the TLS tunnel, that specification does application data inside of the TLS tunnel, that specification does
not address the subject of "inner" identities in tunneled EAP not address the subject of "inner" identities in tunneled EAP
methods. This subject must, however, be addressed for the tunneled methods. However, this subject must be addressed for the tunneled
methods. methods.
Using an anonymous NAI for the outer identity as per [RFC7542] Using an anonymous NAI for the outer identity as per [RFC7542],
Section 2.4 has a few benefits. An NAI allows the EAP session to be Section 2.4 has a few benefits. An NAI allows the EAP session to be
routed in an AAA framework as described in [RFC7542] Section 3. routed in a AAA framework as described in [RFC7542], Section 3.
Using an anonymous realm also ensures that user identifiers are kept Using an anonymous realm also ensures that user identifiers are kept
private. private.
As for the inner identity, we define it generically as the As for the inner identity, we define it generically as the
identification information carried inside of the TLS tunnel. For identification information carried inside of the TLS tunnel. For
PEAP, that identity may be an EAP Response/Identity. For EAP-TTLS, PEAP, that identity may be an EAP Response/Identity. For EAP-TTLS,
it may be the User-Name attribute. Vendor-specific EAP methods which it may be the User-Name attribute. Vendor-specific EAP methods that
use TLS will generally also have an inner identity. This identity is use TLS will generally also have an inner identity. This identity is
carried inside of the TLS tunnel, and is therefore both routed to the carried inside of the TLS tunnel and is therefore both routed to the
correct destination by the outer identity, and kept private by the correct destination by the outer identity and kept private by the use
use of TLS. of TLS.
In other words, we can view the outer TLS layer of tunneled EAP In other words, we can view the outer TLS layer of tunneled EAP
methods as a secure transport layer which is responsible for getting methods as a secure transport layer that is responsible for getting
the actual (inner) authentication credentials securely from the EAP the actual (inner) authentication credentials securely from the EAP
peer to the EAP server. The EAP server then uses the inner identity peer to the EAP server. The EAP server then uses the inner identity
and inner authentication data to identify and authenticate a and inner authentication data to identify and authenticate a
particular user. particular user.
As the authentication data is routed to the correct destination, As the authentication data is routed to the correct destination,
there is little reason for the inner identity to also contain a there is little reason for the inner identity to also contain a
realm. We therefore have a few recommendations on the inner and realm. Therefore, we have a few recommendations on the inner and
outer identities, along with their relationship to each other. outer identities, along with their relationship to each other.
The outer identity SHOULD use an anonymous NAI realm, which allows The outer identity SHOULD use an anonymous NAI realm that allows for
for both user privacy, and for the EAP session to be routed in an AAA both user privacy and for the EAP session to be routed in a AAA
framework as described in [RFC7542] Section 3. Where NAI realms are framework as described in [RFC7542], Section 3. Where NAI realms are
not used, packets will not be routable outside of the local not used, packets will not be routable outside of the local
organization. organization.
The inner identity MUST NOT use an anonymous NAI realm. If anonymous The inner identity MUST NOT use an anonymous NAI realm. If anonymous
network access is desired, EAP peers MUST use EAP-TLS without peer network access is desired, EAP peers MUST use EAP-TLS without peer
authentication, as per [RFC9190] section 2.1.5. EAP servers MUST authentication, as per [RFC9190], Section 2.1.5. EAP servers MUST
cause authentication to fail if an EAP peer uses an anonymous "inner" cause authentication to fail if an EAP peer uses an anonymous "inner"
identity for any TLS-based EAP method. identity for any TLS-based EAP method.
Implementations SHOULD NOT use inner identities which contain an NAI Implementations SHOULD NOT use inner identities that contain an NAI
realm. Many organizations typically use only one realm for all user realm. Many organizations typically use only one realm for all user
accounts. accounts.
However, there are situations where it is useful for an inner However, there are situations where it is useful for an inner
identity to contain a realm. For example, an organization may have identity to contain a realm. For example, an organization may have
multiple independent sub-organizations, each with a different and multiple independent sub-organizations, each with a different and
unique realm. These realms may be independent of one another, or the unique realm. These realms may be independent of one another, or the
realms may be a subdomain (or subdomains) of the public outer realm. realms may be a subdomain (or subdomains) of the public outer realm.
In that case, an organization can configure one public "routing" In that case, an organization can configure one public "routing"
realm, and multiple separate "inner" realms. This separation of realm and multiple separate "inner" realms. This separation of
realms also allows an organization to split users into logical groups realms also allows an organization to split users into logical groups
by realm, where the "user" portion of the NAI may otherwise conflict. by realm, where the "user" portion of the NAI may otherwise conflict.
For example, "user@example.com" and "user@example.org" are different For example, "user@example.com" and "user@example.org" are different
NAIs which can both be used as inner identities. NAIs that can both be used as inner identities.
Using only one public realm both keeps internal information private, Using only one public realm both keeps internal information private
and also simplifies realm management for external entities by and simplifies realm management for external entities by minimizing
minimizing the number of realms which have to be tracked by them. the number of realms that have to be tracked by them.
In most situations, routing identifiers should be associated with the In most situations, routing identifiers should be associated with the
authentication data that they are routing. For example, if a user authentication data that they are routing. For example, if a user
has an inner identity of "user@example.com", then it generally makes has an inner identity of "user@example.com", then it generally makes
little sense to have an outer identity of "@example.org". The little sense to have an outer identity of "@example.org". The
authentication request would then be routed to the "example.org" authentication request would then be routed to the "example.org"
domain, which may have no idea what to do with the credentials for domain, which may have no idea what to do with the credentials for
"user@example.com". At best, the authentication request would be "user@example.com". At best, the authentication request would be
discarded. At worst, the "example.org" domain could harvest user discarded. At worst, the "example.org" domain could harvest user
credentials for later use in attacks on "example.com". credentials for later use in attacks on "example.com".
Where an EAP server receives an inner identity for a realm which it When an EAP server receives an inner identity for a realm which it is
is not authoritative, it MUST reject the authentication. There is no not authoritative, it MUST reject the authentication. There is no
reason for one organization to authentication users from a different reason for one organization to authenticate users from a different
(and independent) organization. (and independent) organization.
In addition, associating inner/outer identities from different In addition, associating inner/outer identities from different
organizations in the same EAP authentication session means that organizations in the same EAP authentication session means that
otherwise unrelated realms are tied together, which can make networks otherwise unrelated realms are tied together, which can make networks
more fragile. more fragile.
For example, an organization which uses a "hosted" AAA provider may For example, an organization that uses a "hosted" AAA provider may
choose to use the realm of the AAA provider as the outer identity for choose to use the realm of the AAA provider as the outer identity for
user authentication. The inner identity can then be fully-qualified: user authentication. The inner identity can then be fully qualified:
user name plus realm of the organization. This practice may result username plus realm of the organization. This practice may result in
in successful authentications, but it has practical difficulties. successful authentications, but it has practical difficulties.
For example, an organization may host their own AAA servers, but use Additionally, an organization may host their own AAA servers but use
a "cloud" identity provider to hold user accounts. In that a "cloud" identity provider to hold user accounts. In that
situation, the organizations could see try to use their own realm as situation, the organizations could try to use their own realm as the
the outer (routing) identity, then use an identity from the "cloud" outer (routing) identity and then use an identity from the "cloud"
provider as the inner identity. provider as the inner identity.
This practice is NOT RECOMMENDED. User accounts for an organization This practice is NOT RECOMMENDED. User accounts for an organization
should be qualified as belonging to that organization, and not to an should be qualified as belonging to that organization and not to an
unrelated third party. There is no reason to tie the configuration unrelated third party. There is no reason to tie the configuration
of user systems to public realm routing, that configuration more of user systems to public realm routing; that configuration more
properly belongs in the network. properly belongs in the network.
Both of these practices mean that changing "cloud" providers is Both of these practices mean that changing "cloud" providers is
difficult. When such a change happens, each individual EAP peer must difficult. When such a change happens, each individual EAP peer must
be updated with a different outer identity which points to the new be updated with a different outer identity that points to the new
"cloud" provider. This process can be expensive, and some EAP peers "cloud" provider. This process can be expensive, and some EAP peers
may not be online when this changeover happens. The result could be may not be online when this changeover happens. The result could be
devices or users who are unable to obtain network access, even if all devices or users who are unable to obtain network access, even if all
relevant network systems are online and functional. relevant network systems are online and functional.
Further, standards such as [RFC7585] allow for dynamic discovery of Further, standards such as [RFC7585] allow for dynamic discovery of
home servers for authentication. That specification has been widely home servers for authentication. This specification has been widely
deployed, and means that there is minimal cost to routing deployed and means that there is minimal cost to routing
authentication to a particular domain. The authentication can also authentication to a particular domain. The authentication can also
be routed to a particular identity provider, and changed at will, be routed to a particular identity provider and changed at will with
with no loss of functionality. That specification is also scalable, no loss of functionality. That specification is also scalable since
in that it does not require changes to many systems when a domain it does not require changes to many systems when a domain updates its
updates its configuration. Instead, only one thing has to change: configuration. Instead, only one thing has to change: the
the configuration of that domain. Everything else is discovered configuration of that domain. Everything else is discovered
dynamically. dynamically.
That is, changing the configuration for one domain is significantly That is, changing the configuration for one domain is significantly
simpler and more scalable than changing the configuration for simpler and more scalable than changing the configuration for
potentially millions of end-user devices. potentially millions of end-user devices.
We recognize that there may be existing use-cases where the inner and We recognize that there may be existing use cases where the inner and
outer identities use different realms. As such, we cannot forbid outer identities use different realms. As such, we cannot forbid
that practice. We hope that the discussion above shows not only why that practice. We hope that the discussion above shows not only why
such practices are problematic, but also that it shows how such practices are problematic, but how alternative methods are more
alternative methods are more flexible, more scalable, and are easier flexible, more scalable, and are easier to manage.
to manage.
4. Resumption 4. Resumption
[RFC9190] Section 2.1.3 defines the process for resumption. This [RFC9190], Section 2.1.3 defines the process for resumption. This
process is the same for all TLS-based EAP types. The only practical process is the same for all TLS-based EAP Types. The only practical
difference is that the value of the Type field is different. The difference is that the value of the Type field is different. The
requirements on identities, etc. remain unchanged from that document. requirements on identities, use of TLS cipher suites, resumption,
etc. remain unchanged from that document.
Note that if resumption is performed, then the EAP server MUST send Note that if resumption is performed, then the EAP server MUST send
the protected success result indication (one octet of 0x00) inside the protected success result indication (one octet of 0x00) inside
the TLS tunnel as per [RFC9190]. The EAP peer MUST in turn check for the TLS tunnel, as per [RFC9190]. The EAP peer MUST in turn check
the existence the protected success result indication (one octet of for the existence of the protected success result indication (one
0x00), and cause authentication to fail if that octet is not octet of 0x00) and cause authentication to fail if that octet is not
received. If either peer or server instead initiates an inner tunnel received. If either the peer or the server initiates an inner tunnel
method, then that method MUST be followed, and inner authentication method instead, then that method MUST be followed, and inner
MUST NOT be skipped. authentication MUST NOT be skipped.
All TLS-based EAP methods support resumption, as it is a property of All TLS-based EAP methods support resumption, as it is a property of
the underlying TLS protocol. All EAP servers and peers MUST support the underlying TLS protocol. All EAP servers and peers MUST support
resumption for all TLS-based EAP methods. We note that EAP servers resumption for all TLS-based EAP methods. We note that EAP servers
and peers can still choose to not resume any particular session. For and peers can still choose to not resume any particular session. For
example, EAP servers may forbid resumption for administrative, or example, EAP servers may forbid resumption for administrative or
other policy reasons. other policy reasons.
It is RECOMMENDED that EAP servers and peers enable resumption, and It is RECOMMENDED that EAP servers and peers enable resumption and
use it where possible. The use of resumption decreases the number of use it where possible. The use of resumption decreases the number of
round trips used for authentication. This decrease leads to lower round trips used for authentication. This decrease leads to lower
latency for authentications, and less load on the EAP server. latency for authentications and less load on the EAP server.
Resumption can also lower load on external systems, such as databases Resumption can also lower load on external systems, such as databases
which contain user credentials. that contain user credentials.
As the packet flows for resumption are essentially identical across As the packet flows for resumption are essentially identical across
all TLS-based EAP types, it is technically possible to authenticate all TLS-based EAP Types, it is technically possible to authenticate
using EAP-TLS (Type 13), and then perform resumption using another using EAP-TLS (Type 13) and then perform resumption using another EAP
EAP type, such as with EAP-TTLS (Type 21). However, there is no Type, such as with EAP-TTLS (Type 21). However, there is no
practical benefit to doing so. It is also not clear what this practical benefit to doing so. It is also not clear what this
behavior would mean, or what (if any) security issues there may be behavior would mean or what (if any) security issues there may be
with it. As a result, this behavior is forbidden. with it. As a result, this behavior is forbidden.
EAP servers therefore MUST NOT resume sessions across different EAP EAP servers therefore MUST NOT resume sessions across different EAP
Types, and EAP servers MUST reject resumptions in which the EAP Type Types, and EAP servers MUST reject resumptions in which the EAP Type
value is different from the original authentication. value is different from the original authentication.
5. Implementation Status 5. Security Considerations
RFC Editor: Please remove this section before publication.
EAP-TTLS and PEAP are implemented and tested to be interoperable with
wpa_supplicant 2.10 and Windows 11 as EAP peers, and FreeRADIUS
3.0.26 and Radiator as RADIUS / EAP servers.
The wpa_supplicant implementation requires that a configuration flag
be set "tls_disable_tlsv1_3=0", and describes the flag as "enable
TLSv1.3 (experimental - disabled by default)". However,
interoperability testing shows that PEAP and EAP-TTLS both work with
Radiator and FreeRADIUS.
Implementors have demonstrated significant interest in getting PEAP
and EAP-TTLS working for TLS 1.3, but less interest in EAP-FAST and
TEAP. As such, there is no implementation experience with EAP-FAST
or TEAP. However, we believe that the definitions described above
are correct, and are workable.
6. Security Considerations
[RFC9190] Section 5 is included here by reference. [RFC9190], Section 5 is included here by reference.
Updating the above EAP methods to use TLS 1.3 is of high importance Updating the above EAP methods to use TLS 1.3 is of high importance
for the Internet Community. Using the most recent security protocols for the Internet community. Using the most recent security protocols
can significantly improve security and privacy of a network. can significantly improve security and privacy of a network.
For PEAP, some derivations use HMAC-SHA1 [PEAP-MPPE]. In the For PEAP, some derivations use HMAC-SHA1 [PEAP-MPPE]. In the
interests of interoperability and minimal changes, we do not change interests of interoperability and minimal changes, we do not change
that derivation, as there are no known security issues with HMAC- that derivation, as there are no known security issues with HMAC-
SHA1. Further, the data derived from the HMAC-SHA1 calculations is SHA1. Further, the data derived from the HMAC-SHA1 calculations is
exchanged inside of the TLS tunnel, and is visible only to users who exchanged inside of the TLS tunnel and is visible only to users who
have already successfully authenticated. As such, the security risks have already successfully authenticated. As such, the security risks
are minimal. are minimal.
6.1. Handling of TLS NewSessionTicket Messages 5.1. Handling of TLS NewSessionTicket Messages
In some cases, client certificates are not used for TLS-based EAP In some cases, client certificates are not used for TLS-based EAP
methods. In those cases, the user is authenticated only after methods. In those cases, the user is authenticated only after
successful completion of the inner tunnel authentication. However, successful completion of the inner tunnel authentication. However,
[RFC84346] Section 4.6.1 allows that "At any time after the server [RFC8446], Section 4.6.1 states that "at any time after the server
has received the client Finished message, it MAY send a has received the client Finished message, it MAY send a
NewSessionTicket message." This message is sent by the server before NewSessionTicket message." This message is sent by the server before
the inner authentication method has been run, and therefore before the inner authentication method has been run and therefore before the
the user has been authenticated. user has been authenticated.
This separation of data allows for a "time of use, time of check" This separation of data allows for a "time of use, time of check"
security issue. Malicious clients can begin a session and receive a security issue. Malicious clients can begin a session and receive a
NewSessionTicket message. The malicious client can then abort the NewSessionTicket message. The malicious client can then abort the
authentication session, and use the obtained NewSessionTicket to authentication session and use the obtained NewSessionTicket to
"resume" the previous session. If the server allows the session to "resume" the previous session. If the server allows the session to
resume without verifying that the user had first been authenticated, resume without verifying that the user had first been authenticated,
the malicious client can then obtain network access without ever the malicious client can then obtain network access without ever
being authenticated network access without ever being authenticated. being authenticated.
As a result, EAP servers MUST NOT assume that a user has been As a result, EAP servers MUST NOT assume that a user has been
authenticated simply because a TLS session is being resumed. Even if authenticated simply because a TLS session is being resumed. Even if
a session is being resumed, an EAP server MAY have policies which a session is being resumed, an EAP server MAY have policies that
still force the inner authentication methods to be run. For example, still force the inner authentication methods to be run. For example,
the users password may have expired in the time interval between the user's password may have expired in the time interval between
first authenticaction, and session resumption. first authentication and session resumption.
The guidelines given here therefore describe situations where an EAP Therefore, the guidelines given here describe situations where an EAP
server is permitted to allow session resumption, not where it is server is permitted to allow session resumption rather than where an
required to allow session resumption. An EAP server could simply EAP server is required to allow session resumption. An EAP server
refuse to issue session tickets, or could run the full inner could simply refuse to issue session tickets or could run the full
authentication even if a session was resumed. inner authentication, even if a session was resumed.
Where session tickets are used, the EAP server SHOULD track the Where session tickets are used, the EAP server SHOULD track the
successful completion of an inner authentication, and associate that successful completion of an inner authentication and associate that
status with any session tickets issued for that session. This status with any session tickets issued for that session. This
requirement can be met in a number of different ways. requirement can be met in a number of different ways.
One way is for the EAP server to simply not send any TLS One way is for the EAP server to simply not send any TLS
NewSessionTicket messages until the inner authentication has NewSessionTicket messages until the inner authentication has
completed successfully. The EAP server then knows that the existence completed successfully. The EAP server then knows that the existence
of a session ticket is proof that a user was authenticated, and the of a session ticket is proof that a user was authenticated, and the
session can be resumed. session can be resumed.
Another way is for the EAP server to simple discard or invalidate any Another way is for the EAP server to simply discard or invalidate any
session tickets until after the inner authentication has completed session tickets until after the inner authentication has completed
successfully. When the user is authenticated, a new TLS successfully. When the user is authenticated, a new TLS
NewSessionTicket message can be sent to the client, and the new NewSessionTicket message can be sent to the client, and the new
ticket cached and/or validated. ticket can be cached and/or validated.
Another way is for the EAP server to associate the inner Another way is for the EAP server to associate the inner
authentication status with each session ticket. When a session authentication status with each session ticket. When a session
ticket is used, the authentication status is checked. When a session ticket is used, the authentication status is checked. When a session
ticket shows that the inner authentication did not succeed, the EAP ticket shows that the inner authentication did not succeed, the EAP
server MUST run the inner authentication method(s) in the resumed server MUST run the inner authentication method(s) in the resumed
tunnel, and grant only access based on the success or failure of tunnel and only grant access based on the success or failure of those
those inner methods/ inner methods.
However, the interaction between EAP implementations and any However, the interaction between EAP implementations and any
underlying TLS library may be complex, and the EAP server may not be underlying TLS library may be complex, and the EAP server may not be
able to make the above guarantees. Where the EAP server is unable to able to make the above guarantees. Where the EAP server is unable to
determine the users authentication status from the session ticket, it determine the user's authentication status from the session ticket,
MUST assume that inner authentication has not completed, and it MUST it MUST assume that inner authentication has not completed, and it
run the inner authentication method(s) successfully in the resumed MUST run the inner authentication method(s) successfully in the
tunnel before granting access. resumed tunnel before granting access.
This issue is not relevant for EAP-TLS, which only uses client This issue is not relevant for EAP-TLS, which only uses client
certificates for authentication in the TLS handshake. It is only certificates for authentication in the TLS handshake. It is only
relevant for TLS-based EAP methods which do not use the TLS layer to relevant for TLS-based EAP methods that do not use the TLS layer to
authenticate authenticate.
6.2. Protected Success and Failure indications 5.2. Protected Success and Failure Indications
[RFC9190] provides for protected success and failure indications as [RFC9190] provides for protected success and failure indications as
discussed in Section 4.1.1 of [RFC4137]. These result indications discussed in [RFC4137], Section 4.1.1. These result indications are
are provided for both full authentication, and for resumption. provided for both full authentication and resumption.
Other TLS-based EAP methods provide these result indications only for Other TLS-based EAP methods provide these result indications only for
resumption. resumption.
For full authentication, the other TLS-based EAP methods do not For full authentication, the other TLS-based EAP methods do not
provide for protected success and failure indications as part of the provide for protected success and failure indications as part of the
outer TLS exchange. That is, the protected result indication is not outer TLS exchange. That is, the protected result indication is not
used, and there is no TLS-layer alert sent when the inner used, and there is no TLS-layer alert sent when the inner
authentication fails. Instead, there is simply either an EAP-Success authentication fails. Instead, there is simply either an EAP-Success
or EAP-Failure sent. This behavior is the same as for previous TLS or an EAP-Failure sent. This behavior is the same as for previous
versions, and therefore introduces no new security issues. TLS versions; therefore, it introduces no new security issues.
We note that most TLS-based EAP methods provide for success and We note that most TLS-based EAP methods provide for success and
failure indications as part of the authentication exchange performed failure indications as part of the authentication exchange performed
inside of the TLS tunnel. These result indications are therefore inside of the TLS tunnel. These result indications are therefore
protected, as they cannot be modified or forged. protected, as they cannot be modified or forged.
However, some inner methods do not provide for success or failure However, some inner methods do not provide for success or failure
indications. For example, the use of EAP-TTLS with inner PAP, CHAP, indications. For example, the use of EAP-TTLS with inner PAP, CHAP,
or MS-CHAP. Those methods send authentication credentials to the EAP or MS-CHAP. Those methods send authentication credentials to the EAP
server via the inner tunnel, with no method to signal success or server via the inner tunnel with no method to signal success or
failure inside of the tunnel. failure inside of the tunnel.
There are functionally equivalent authentication methods which can be There are functionally equivalent authentication methods that can be
used to provide protected result indications. PAP can often be used to provide protected result indications. PAP can often be
replaced with EAP-GTC, CHAP with EAP-MD5, and MS-CHAPv1 with MS- replaced with EAP-Generic Token Card (EAP-GTC), CHAP with EAP-MD5,
CHAPv2 or EAP-MSCHAPv2. All of the replacement methods provide for and MS-CHAPv1 with MS-CHAPv2 or EAP-MSCHAPv2. All of the replacement
similar functionality, and have protected success and failure methods provide for similar functionality and have protected success
indication. The main cost to this change is additional round trips. and failure indication. The main cost to this change is additional
round trips.
It is RECOMMENDED that implementations deprecate inner tunnel methods It is RECOMMENDED that implementations deprecate inner tunnel methods
which do not provide protected success and failure indications when that do not provide protected success and failure indications when
TLS session tickets cannot be used. Implementations SHOULD use EAP- TLS session tickets cannot be used. Implementations SHOULD use EAP-
GTC instead of PAP, and EAP-MD5 instead of CHAP. Implementations GTC instead of PAP and EAP-MD5 instead of CHAP. Implementations
SHOULD use MS-CHAPv2 or EAP-MSCHAPv2 instead of MS-CHAPv1. New TLS- SHOULD use MS-CHAPv2 or EAP-MSCHAPv2 instead of MS-CHAPv1. New TLS-
based EAP methods MUST provide protected success and failure based EAP methods MUST provide protected success and failure
indications inside of the TLS tunnel. indications inside of the TLS tunnel.
When the inner authentication protocol indicates that authentication When the inner authentication protocol indicates that authentication
has failed, then implementations MUST fail authentication for the has failed, then implementations MUST fail authentication for the
entire session. There may be additional protocol exchanges in order entire session. There may be additional protocol exchanges in order
to exchange more detailed failure indications, but the final result to exchange more detailed failure indications, but the final result
MUST be a failed authentication. As noted earlier, any session MUST be a failed authentication. As noted earlier, any session
tickets for this failed authentication MUST be either invalidated or tickets for this failed authentication MUST be either invalidated or
discarded. discarded.
Similarly, when the inner authentication protocol indicates that Similarly, when the inner authentication protocol indicates that
authentication has succeeded, then implementations SHOULD cause authentication has succeeded, implementations SHOULD cause
authentication to succeed for the entire session. There MAY be authentication to succeed for the entire session. There MAY be
additional protocol exchanges which could still cause failure, so we additional protocol exchanges that could still cause failure, so we
cannot mandate sending success on successful authentication. cannot mandate sending success on successful authentication.
In both of these cases, the EAP server MUST send an EAP-Failure or In both of these cases, the EAP server MUST send an EAP-Failure or
EAP-Success message, as indicated by Section 2, item 4 of [RFC3748]. EAP-Success message, as indicated by Step 4 in Section 2 of
Even though both parties have already determined the final [RFC3748]. Even though both parties have already determined the
authentication status, the full EAP state machine must still be final authentication status, the full EAP state machine must still be
followed. followed.
7. IANA Considerations 6. IANA Considerations
This section provides guidance to the Internet Assigned Numbers This section provides guidance to the Internet Assigned Numbers
Authority (IANA) regarding registration of values related to the TLS- Authority (IANA) regarding the registration of values related to the
based EAP methods for TLS 1.3 protocol in accordance with [RFC8126]. TLS-based EAP methods for the TLS 1.3 protocol in accordance with
[RFC8126].
This memo requires IANA to add the following labels to the TLS
Exporter Label Registry defined by [RFC5705]. These labels are used
in the derivation of Key_Material and Method-Id as defined above in
Section 2.
The labels below need to be added to the "TLS Exporter Labels" IANA has added the following labels to the "TLS Exporter Label"
registry as "Value", with this specification as "Reference". For all registry defined by [RFC5705]. These labels are used in the
of these labels the "DTLS-OK" field should be "N", and the derivation of Key_Material and Method-Id as defined above in
"Recommended" field should be "Y". Section 2, and they are used only for TEAP.
These labels are used only for TEAP. +============================+=========+=============+===========+
| Value | DTLS-OK | Recommended | Reference |
+============================+=========+=============+===========+
| EXPORTER: teap session key | N | Y | RFC 9427 |
| seed | | | |
+----------------------------+---------+-------------+-----------+
| EXPORTER: Inner Methods | N | Y | RFC 9427 |
| Compound Keys | | | |
+----------------------------+---------+-------------+-----------+
| EXPORTER: Session Key | N | Y | RFC 9427 |
| Generating Function | | | |
+----------------------------+---------+-------------+-----------+
| EXPORTER: Extended Session | N | Y | RFC 9427 |
| Key Generating Function | | | |
+----------------------------+---------+-------------+-----------+
| TEAPbindkey@ietf.org | N | Y | RFC 9427 |
+----------------------------+---------+-------------+-----------+
* EXPORTER: teap session key seed Table 1: TLS Exporter Labels Registry
* EXPORTER: Inner Methods Compound Keys
* EXPORTER: Session Key Generating Function
* EXPORTER: Extended Session Key Generating Function
* TEAPbindkey@ietf.org
8. References 7. References
8.1. Normative References 7.1. Normative References
[RFC2119] [IANA] IANA, "Method Types",
Bradner, S., "Key words for use in RFCs to Indicate Requirement <https://www.iana.org/assignments/eap-numbers/>.
Levels", RFC 2119, March 1997, <http://www.rfc-
editor.org/info/rfc2119>.
[RFC3748] [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Requirement Levels", BCP 14, RFC 2119,
Levkowetz, "Extensible Authentication Protocol (EAP)", RFC 3748, DOI 10.17487/RFC2119, March 1997,
June 2004. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5216] [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Simon, D., Aboba, B., and R. Hurst, "The EAP-TLS Authentication Levkowetz, Ed., "Extensible Authentication Protocol
Protocol", RFC 5216, March 2008 (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004,
<https://www.rfc-editor.org/info/rfc3748>.
[RFC5705] [RFC5216] Simon, D., Aboba, B., and R. Hurst, "The EAP-TLS
Rescorla, E., "Keying Material Exporters for Transport Layer Authentication Protocol", RFC 5216, DOI 10.17487/RFC5216,
Security (TLS)", RFC 5705, March 2010 March 2008, <https://www.rfc-editor.org/info/rfc5216>.
[RFC7170] [RFC5705] Rescorla, E., "Keying Material Exporters for Transport
Zhou, H., et al., "Tunnel Extensible Authentication Protocol (TEAP) Layer Security (TLS)", RFC 5705, DOI 10.17487/RFC5705,
Version 1", RFC 7170, May 2014. March 2010, <https://www.rfc-editor.org/info/rfc5705>.
[RFC8126] [RFC7170] Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna,
Cotton, M., et al., "Guidelines for Writing an IANA Considerations "Tunnel Extensible Authentication Protocol (TEAP) Version
Section in RFCs", RC 8126, June 2017. 1", RFC 7170, DOI 10.17487/RFC7170, May 2014,
<https://www.rfc-editor.org/info/rfc7170>.
[RFC8174] [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Writing an IANA Considerations Section in RFCs", BCP 26,
Words", RFC 8174, May 2017, <http://www.rfc- RFC 8126, DOI 10.17487/RFC8126, June 2017,
editor.org/info/rfc8174>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8446] [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
1.3", RFC 8446, August 2018. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9190] [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Mattsson, J., and Sethi, M., "Using EAP-TLS with TLS 1.3", RFC Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
9190, July 2021. <https://www.rfc-editor.org/info/rfc8446>.
[IANA] [RFC9190] Preuß Mattsson, J. and M. Sethi, "EAP-TLS 1.3: Using the
https://www.iana.org/assignments/eap-numbers/eap-numbers.xhtml#eap- Extensible Authentication Protocol with TLS 1.3",
numbers-4 RFC 9190, DOI 10.17487/RFC9190, February 2022,
<https://www.rfc-editor.org/info/rfc9190>.
8.2. Informative References 7.2. Informative References
[MSPEAP] [MSPEAP] Microsoft Corporation, "[MS-PEAP]: Protected Extensible
https://msdn.microsoft.com/en-us/library/cc238354.aspx Authentication Protocol (PEAP)", Protocol Revision 31.0,
June 2021,
<https://msdn.microsoft.com/en-us/library/cc238354.aspx>.
[PEAP] [PEAP] Palekar, A., Josefsson, S., Simon, D., Zorn, G., Salowey,
Palekar, A. et al., "Protected EAP Protocol (PEAP)", draft- J., and H. Zhou, "Protected EAP Protocol (PEAP) Version
josefsson-pppext-eap-tls-eap-10.txt, October 2004. 2", Work in Progress, Internet-Draft, draft-josefsson-
pppext-eap-tls-eap-10, 15 October 2004,
<https://datatracker.ietf.org/doc/html/draft-josefsson-
pppext-eap-tls-eap-10>.
[PEAP-MPPE] [PEAP-MPPE]
"PEAP Key Management", https ://docs.microsoft.com/en- Microsoft Corporation, "Key Management", Section 3.1.5.7,
us/openspecs/windows_protocols/MS- October 2020, <https://learn.microsoft.com/en-
PEAP/e75b0385-915a-4fc3-a549-fd3d06b995b0 us/openspecs/windows_protocols/ms-peap/e75b0385-915a-
4fc3-a549-fd3d06b995b0>.
[PEAP-PRF] [PEAP-PRF] Microsoft Corporation, "Intermediate PEAP MAC Key (IPMK)
"PEAP Intermediate PEAP MAC Key (IPMK) and Compound MAC Key (CMK)" and Compound MAC Key (CMK)", Section 3.1.5.5.2.2, February
https://docs.microsoft.com/en-us/openspecs/windows_protocols/MS- 2019, <https://docs.microsoft.com/en-
PEAP/0de54161-0bd3-424a-9b1a-854b4040a6df us/openspecs/windows_protocols/MS-PEAP/0de54161-0bd3-424a-
9b1a-854b4040a6df>.
[PEAP-TK] [PEAP-TK] Microsoft Corporation, "PEAP Tunnel Key (TK)",
"PEAP Tunnel Key (TK)" https://docs.microsoft.com/en- Section 3.1.5.5.2.1, April 2021,
us/openspecs/windows_protocols/MS-PEAP/41288c09-3d7d-482f-a57f- <https://docs.microsoft.com/en-
e83691d4d246 us/openspecs/windows_protocols/MS-PEAP/41288c09-3d7d-482f-
a57f-e83691d4d246>.
[RFC1994] [RFC1994] Simpson, W., "PPP Challenge Handshake Authentication
Simpson, W., "PPP Challenge Handshake Authentication Protocol Protocol (CHAP)", RFC 1994, DOI 10.17487/RFC1994, August
(CHAP)", RFC 1994, August 1996. 1996, <https://www.rfc-editor.org/info/rfc1994>.
[RFC2433] [RFC2433] Zorn, G. and S. Cobb, "Microsoft PPP CHAP Extensions",
Zorn, G. and Cobb, S., "Microsoft PPP CHAP Extensions", RFC 2433, RFC 2433, DOI 10.17487/RFC2433, October 1998,
October 1998. <https://www.rfc-editor.org/info/rfc2433>.
[RFC2759] [RFC2759] Zorn, G., "Microsoft PPP CHAP Extensions, Version 2",
Zorn, G., "Microsoft PPP CHAP Extensions, Version 2", RFC 2759, RFC 2759, DOI 10.17487/RFC2759, January 2000,
January 2000. <https://www.rfc-editor.org/info/rfc2759>.
[RFC4137] [RFC4137] Vollbrecht, J., Eronen, P., Petroni, N., and Y. Ohba,
Vollbrecht, J., et al., "State Machines for Extensible "State Machines for Extensible Authentication Protocol
Authentication Protocol (EAP) Peer and Authenticator ", RFC 4137, (EAP) Peer and Authenticator", RFC 4137,
August 2005. DOI 10.17487/RFC4137, August 2005,
<https://www.rfc-editor.org/info/rfc4137>.
[RFC4851] [RFC4851] Cam-Winget, N., McGrew, D., Salowey, J., and H. Zhou, "The
Cam-Winget, N., et al., "The Flexible Authentication via Secure Flexible Authentication via Secure Tunneling Extensible
Tunneling Extensible Authentication Protocol Method (EAP-FAST)", Authentication Protocol Method (EAP-FAST)", RFC 4851,
RFC 4851, May 2007. DOI 10.17487/RFC4851, May 2007,
<https://www.rfc-editor.org/info/rfc4851>.
[RFC5281] [RFC5281] Funk, P. and S. Blake-Wilson, "Extensible Authentication
Funk, P., and Blake-Wilson, S., "Extensible Authentication Protocol Protocol Tunneled Transport Layer Security Authenticated
Tunneled Transport Layer Security Authenticated Protocol Version 0 Protocol Version 0 (EAP-TTLSv0)", RFC 5281,
(EAP-TTLS,v0)", RFC 5281, August 2008. DOI 10.17487/RFC5281, August 2008,
<https://www.rfc-editor.org/info/rfc5281>.
[RFC5422] [RFC5422] Cam-Winget, N., McGrew, D., Salowey, J., and H. Zhou,
Cam-Winget, N., et al., "Dynamic Provisioning Using Flexible "Dynamic Provisioning Using Flexible Authentication via
Authentication via Secure Tunneling Extensible Authentication Secure Tunneling Extensible Authentication Protocol (EAP-
Protocol (EAP-FAST)", RFC 5422, March 2009. FAST)", RFC 5422, DOI 10.17487/RFC5422, March 2009,
<https://www.rfc-editor.org/info/rfc5422>.
[RFC7542] [RFC7542] DeKok, A., "The Network Access Identifier", RFC 7542,
DeKoK, A, "The Network Access Identifier", RFC 7542, May 2015. DOI 10.17487/RFC7542, May 2015,
<https://www.rfc-editor.org/info/rfc7542>.
[RFC7585] [RFC7585] Winter, S. and M. McCauley, "Dynamic Peer Discovery for
Winter, S, and McCauley, M., "Dynamic Peer Discovery for RADIUS/TLS RADIUS/TLS and RADIUS/DTLS Based on the Network Access
and RADIUS/DTLS Based on the Network Access Identifier (NAI)", RFC Identifier (NAI)", RFC 7585, DOI 10.17487/RFC7585, October
7585, October 2015. 2015, <https://www.rfc-editor.org/info/rfc7585>.
Acknowledgments Acknowledgments
Thanks to Jorge Vergara for a detailed review of the requirements for Thanks to Jorge Vergara for a detailed review of the requirements for
various EAP types. various EAP Types.
Thanks to Jorge Vergara, Bruno Periera Vidal, Alexander Clouter, Thanks to Jorge Vergara, Bruno Periera Vidal, Alexander Clouter,
Karri Huhtanen, and Heikki Vatiainen for reviews of this document, Karri Huhtanen, and Heikki Vatiainen for reviews of this document and
and for assistance with interoperability testing. for assistance with interoperability testing.
Authors' Addresses
Alan DeKok Author's Address
The FreeRADIUS Server Project
Email: aland@freeradius.org Alan DeKok
The FreeRADIUS Server Project
Email: aland@freeradius.org
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