Extensible Authentication Protocol (EAP) Session-Id Derivation for EAP Subscriber Identity Module (EAP-SIM), EAP Authentication and Key Agreement (EAP-AKA), and Protected EAP (PEAP)The FreeRADIUS Server Projectaland@freeradius.orgEAPPEAPEAP-AKAEAP-SIMERPFILSSession-IDfast reconnectTLS
RFC 5247 is updated to define and clarify EAP Session-Id derivation
for multiple Extensible Authentication
Protocol (EAP) methods. The derivation of Session-Id was not given
for EAP Subscriber Identity Module (EAP-SIM) or EAP Authentication and Key Agreement (EAP-AKA) when using the fast reconnect exchange instead
of full authentication. The derivation of Session-Id for full
authentication is clarified for both EAP-SIM and EAP-AKA. The
derivation of Session-Id for Protected EAP (PEAP) is also given. The definition for
PEAP follows the definition for other TLS-based EAP methods.Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by
the Internet Engineering Steering Group (IESG). Further
information on Internet Standards is available in Section 2 of
RFC 7841.
Information about the current status of this document, any
errata, and how to provide feedback on it may be obtained at
.
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Table of Contents
. Introduction
. Updates to RFC 5247, Appendix A
. EAP-AKA
. EAP-SIM
. Rationale for EAP-AKA and EAP-SIM Updates
. Session-Id for PEAP
. Security Considerations
. IANA Considerations
. References
. Normative References
. Informative References
Acknowledgments
Author's Address
Introduction
EAP Session-Id derivation has not
been defined for EAP-SIM and EAP-AKA when using the fast reconnect exchange
instead of full authentication.
defines the Session-Id for these EAP methods, but that derivation is only
applicable for the full authentication case. The Session-Id derivation was
not defined for EAP-AKA', but now defines it, along with other updates. As such, the
definition for EAP-AKA' is not included here.
Further, the derivation of Session-Id for full authentication is
clarified, as the text in is
ambiguous.
The IEEE has defined Fast Initial Link Setup (FILS) authentication , which needs the EAP Session-Id in order
for the EAP Re-authentication Protocol (ERP) to work. It is therefore important to address the
existing deficiencies in the definition of EAP Session-Id.
Finally, did not define
Session-Id for PEAP . We correct
these deficiencies here by updating with the Session-Id derivation during fast-reconnect
exchange for EAP-SIM and EAP-AKA; clarifying the Session-Id derivation
during full authentication for EAP-SIM and EAP-AKA; and defining the
Session-Id derivation for PEAP, which is the same for both full
authentication and fast reconnect.Updates to RFC 5247, Appendix A
This section updates to define Session-Id for fast reconnect exchange for EAP-AKA and
EAP-SIM.EAP-AKA
For EAP-AKA, says:
EAP-AKA
EAP-AKA is defined in . The EAP-AKA Session-Id is the concatenation of
the EAP Type Code (0x17) with the contents of the RAND field from
the AT_RAND attribute, followed by the contents of the AUTN field in
the AT_AUTN attribute:
Session-Id = 0x17 || RAND || AUTN
It should say:
EAP-AKA
EAP-AKA is defined in . When using full
authentication, the EAP-AKA Session-Id is the concatenation of the EAP
Type Code (0x17) with the contents of the RAND field from the AT_RAND
attribute, followed by the contents of the AUTN field in the AT_AUTN
attribute:
Session-Id = 0x17 || RAND || AUTN
When using fast reconnect, the EAP-AKA Session-Id is the
concatenation of the EAP Type Code (0x17) with the contents of the
NONCE_S field from the AT_NONCE_S attribute, followed by the contents
of the MAC field from the AT_MAC attribute from
EAP-Request/AKA-Reauthentication:
Session-Id = 0x17 || NONCE_S || MAC
EAP-SIM
Similarly for EAP-SIM, says:
EAP-SIM
EAP-SIM is defined in . The EAP-SIM
Session-Id is the concatenation of the EAP Type Code (0x12) with the
contents of the RAND field from the AT_RAND attribute, followed by the
contents of the NONCE_MT field in the AT_NONCE_MT attribute:
Session-Id = 0x12 || RAND || NONCE_MT
It should say:
EAP-SIM
EAP-SIM is defined in .
When using full authentication, the EAP-SIM Session-Id is the
concatenation of the EAP Type Code (0x12) with the contents of the
RAND field from the AT_RAND attribute, followed by the contents of
the NONCE_MT field in the AT_NONCE_MT attribute.
RFC 4186 says that the EAP server should obtain "n" GSM
triplets where "n=2" or "n=3".For "n=2", the Session-Id is therefore defined as
Session-Id = 0x12 || RAND1 || RAND2 || NONCE_MT
which is 49 octets in length.For "n=3", the Session-Id is therefore defined as
Session-Id = 0x12 || RAND1 || RAND2 || RAND3 || NONCE_MT
which is 65 octets in length.RAND1, RAND2, and RAND3 correspond to the RAND value from the
first, second, and third GSM triplet, respectively.When using fast reconnect, the EAP-SIM Session-Id is the
concatenation of the EAP Type Code (0x12) with the contents of the
NONCE_S field from the AT_NONCE_S attribute, followed by the contents
of the MAC field from the AT_MAC attribute from
EAP-Request/SIM/Reauthentication:
Session-Id = 0x12 || NONCE_S || MAC
which is 33 octets in length.
Rationale for EAP-AKA and EAP-SIM Updates was supposed to define exported parameters for
existing EAP methods. The way Session-Id was defined for
EAP-AKA and EAP-SIM works only for the full authentication case, i.e., it
cannot be used when the optional fast reconnect case is used since the used
parameters (RAND, AUTN, NONCE_MT) are not used in the fast reconnect
case. Based on
and similar text in
, NONCE_S corresponds to RAND and MAC
in EAP-Request/AKA-Reauthentication, and EAP-Request/SIM/Reauthentication
corresponds to AUTN. That would seem to imply that the Session-Id could be
defined using NONCE_S and MAC instead of RAND and AUTN/NONCE_MT.
This derivation is done via a random value created by the server,
along with a secret key and the peer's identity. We believe that
this derivation is secure, though no formal analysis has been done.Session-Id for PEAP did not define Session-Id for Microsoft's
Protected EAP (PEAP). For consistency with the EAP-TLS definition given in
, we define it as:
Session-Id = 0x19 || client.random || server.random
This definition is that same for both full authentication and for fast reconnect.
This definition is already in widespread use in all known PEAP
implementations.
Note that this definition for Session-Id only applies when TLS 1.2 or
earlier is used. A different derivation is defined for TLS 1.3 in
.Security Considerations
This specification defines EAP Session-Ids for ERP with EAP-SIM and
EAP-AKA. It therefore enables ERP key hierarchy establishment using
fast reconnect with EAP-SIM and EAP-AKA.
The Session-Id definitions given here are unique per session, unforgeable, and unguessable by an outside party, as per the
requirements of .
The definitions used here have been widely deployed for years in
all major EAP implementations. However, we acknowledge that very
little security analysis has been done for these definitions. As a
result, any security issues would result in serious issues for the
Internet as a whole.
These updates do not modify the security considerations outlined in
.IANA Considerations
This document has no IANA actions.ReferencesNormative ReferencesIEEE Standard for Information technology--Telecommunications and information exchange between systems - Local and metropolitan area networks--Specific requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications - Amendment 1: Fast Initial Link SetupIEEEExtensible Authentication Protocol (EAP)This document defines the Extensible Authentication Protocol (EAP), an authentication framework which supports multiple authentication methods. EAP typically runs directly over data link layers such as Point-to-Point Protocol (PPP) or IEEE 802, without requiring IP. EAP provides its own support for duplicate elimination and retransmission, but is reliant on lower layer ordering guarantees. Fragmentation is not supported within EAP itself; however, individual EAP methods may support this. This document obsoletes RFC 2284. A summary of the changes between this document and RFC 2284 is available in Appendix A. [STANDARDS-TRACK]The EAP-TLS Authentication ProtocolThe Extensible Authentication Protocol (EAP), defined in RFC 3748, provides support for multiple authentication methods. Transport Layer Security (TLS) provides for mutual authentication, integrity-protected ciphersuite negotiation, and key exchange between two endpoints. This document defines EAP-TLS, which includes support for certificate-based mutual authentication and key derivation.This document obsoletes RFC 2716. A summary of the changes between this document and RFC 2716 is available in Appendix A. [STANDARDS-TRACK]Extensible Authentication Protocol (EAP) Key Management FrameworkThe Extensible Authentication Protocol (EAP), defined in RFC 3748, enables extensible network access authentication. This document specifies the EAP key hierarchy and provides a framework for the transport and usage of keying material and parameters generated by EAP authentication algorithms, known as "methods". It also provides a detailed system-level security analysis, describing the conditions under which the key management guidelines described in RFC 4962 can be satisfied. [STANDARDS-TRACK]Informative ReferencesImproved Extensible Authentication Protocol Method for 3GPP Mobile Network Authentication and Key Agreement (EAP-AKA')EricssonEricssonEricssonIndependent The 3GPP Mobile Network Authentication and Key Agreement (AKA) is the
primary authentication mechanism for devices wishing to access mobile
networks. RFC 4187 (EAP-AKA) made the use of this mechanism possible
within the Extensible Authentication Protocol (EAP) framework. RFC
5448 (EAP-AKA') was an improved version of EAP-AKA.
This memo replaces the specification of EAP-AKA'. EAP-AKA' was
defined in RFC 5448 and updated EAP-AKA RFC 4187. As such this
document obsoletes RFC 5448 and updates RFC 4187.
EAP-AKA' differs from EAP-AKA by providing a key derivation function
that binds the keys derived within the method to the name of the
access network. The key derivation function has been defined in the
3rd Generation Partnership Project (3GPP). EAP-AKA' allows its use
in EAP in an interoperable manner. EAP-AKA' also updates the
algorithm used in hash functions, as it employs SHA-256 / HMAC-
SHA-256 instead of SHA-1 / HMAC-SHA-1 as in EAP-AKA.
This version of EAP-AKA' specification specifies the protocol
behaviour for both 4G and 5G deployments, whereas the previous
version only did this for 4G.
Work in ProgressErratum ID 5011RFC ErrataRFC 5247[MS-PEAP]: Protected Extensible Authentication Protocol (PEAP)MicrosoftProtected EAP Protocol (PEAP) Version 2Microsoft CorporationExtundoMicrosoft CorporationCisco SystemsThe Extensible Authentication Protocol (EAP) provides support for
multiple authentication methods. This document defines the Protected
Extensible Authentication Protocol (PEAP) Version 2, which provides
an encrypted and authenticated tunnel based on transport layer
security (TLS) that encapsulates EAP authentication mechanisms.
PEAPv2 uses TLS to protect against rogue authenticators, protect
against various attacks on the confidentiality and integrity of the
inner EAP method exchange and provide EAP peer identity privacy.
PEAPv2 also provides support for chaining multiple EAP mechanisms,
cryptographic binding between authentications performed by inner EAP
mechanisms and the tunnel, exchange of arbitrary parameters (TLVs),
and fragmentation and reassembly.
Work in ProgressExtensible Authentication Protocol Method for Global System for Mobile Communications (GSM) Subscriber Identity Modules (EAP-SIM)This document specifies an Extensible Authentication Protocol (EAP) mechanism for authentication and session key distribution using the Global System for Mobile Communications (GSM) Subscriber Identity Module (SIM). GSM is a second generation mobile network standard. The EAP-SIM mechanism specifies enhancements to GSM authentication and key agreement whereby multiple authentication triplets can be combined to create authentication responses and session keys of greater strength than the individual GSM triplets. The mechanism also includes network authentication, user anonymity support, result indications, and a fast re-authentication procedure. This memo provides information for the Internet community.Extensible Authentication Protocol Method for 3rd Generation Authentication and Key Agreement (EAP-AKA)This document specifies an Extensible Authentication Protocol (EAP) mechanism for authentication and session key distribution that uses the Authentication and Key Agreement (AKA) mechanism. AKA is used in the 3rd generation mobile networks Universal Mobile Telecommunications System (UMTS) and CDMA2000. AKA is based on symmetric keys, and typically runs in a Subscriber Identity Module, which is a UMTS Subscriber Identity Module, USIM, or a (Removable) User Identity Module, (R)UIM, similar to a smart card.EAP-AKA includes optional identity privacy support, optional result indications, and an optional fast re-authentication procedure. This memo provides information for the Internet community.EAP Extensions for the EAP Re-authentication Protocol (ERP)The Extensible Authentication Protocol (EAP) is a generic framework supporting multiple types of authentication methods. In systems where EAP is used for authentication, it is desirable to avoid repeating the entire EAP exchange with another authenticator. This document specifies extensions to EAP and the EAP keying hierarchy to support an EAP method-independent protocol for efficient re- authentication between the peer and an EAP re-authentication server through any authenticator. The re-authentication server may be in the home network or in the local network to which the peer is connecting. [STANDARDS-TRACK]TLS-based EAP types and TLS 1.3FreeRADIUS EAP-TLS [RFC5216] is being updated for TLS 1.3 in [EAPTLS]. Many
other EAP [RFC3748] and [RFC5247] types also depend on TLS, such as
FAST [RFC4851], TTLS [RFC5281], TEAP [RFC7170], and possibly many
vendor specific EAP methods. This document updates those methods in
order to use the new key derivation methods available in TLS 1.3.
Additional changes necessitated by TLS 1.3 are also discussed.
Work in ProgressAcknowledgments
The issue corrected in this specification was first reported by in a technical erratum for RFC 5247 .
The text in this document follows Jouni's suggestions.
Author's AddressThe FreeRADIUS Server Projectaland@freeradius.org