draft-ietf-emu-rfc5448bis-06.txt   draft-ietf-emu-rfc5448bis.txt 
Network Working Group J. Arkko Network Working Group J. Arkko
Internet-Draft V. Lehtovirta Internet-Draft V. Lehtovirta
Obsoletes: 5448 (if approved) V. Torvinen Updates: 5448,4187 (if approved) V. Torvinen
Updates: 4187 (if approved) Ericsson Intended status: Informational Ericsson
Intended status: Informational P. Eronen Expires: November 11, 2021 P. Eronen
Expires: May 21, 2020 Independent Independent
November 18, 2019 May 10, 2021
Improved Extensible Authentication Protocol Method for 3GPP Mobile Improved Extensible Authentication Protocol Method for 3GPP Mobile
Network Authentication and Key Agreement (EAP-AKA') Network Authentication and Key Agreement (EAP-AKA')
draft-ietf-emu-rfc5448bis-06 draft-ietf-emu-rfc5448bis-10
Abstract Abstract
The 3GPP Mobile Network Authentication and Key Agreement (AKA) is the The 3GPP Mobile Network Authentication and Key Agreement (AKA) is an
primary authentication mechanism for devices wishing to access mobile authentication mechanism for devices wishing to access mobile
networks. RFC 4187 (EAP-AKA) made the use of this mechanism possible networks. RFC 4187 (EAP-AKA) made the use of this mechanism possible
within the Extensible Authentication Protocol (EAP) framework. RFC within the Extensible Authentication Protocol (EAP) framework. RFC
5448 (EAP-AKA') was an improved version of EAP-AKA. 5448 (EAP-AKA') was an improved version of EAP-AKA.
This memo replaces the specification of EAP-AKA'. EAP-AKA' was This document is the most recent specification of EAP-AKA',
defined in RFC 5448 and updated EAP-AKA RFC 4187. As such this including, for instance, details and references about related to
document obsoletes RFC 5448 and updates RFC 4187. operating EAP-AKA' in 5G networks.
EAP-AKA' differs from EAP-AKA by providing a key derivation function 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 that binds the keys derived within the method to the name of the
access network. The key derivation function has been defined in the access network. The key derivation function has been defined in the
3rd Generation Partnership Project (3GPP). EAP-AKA' allows its use 3rd Generation Partnership Project (3GPP). EAP-AKA' allows its use
in EAP in an interoperable manner. EAP-AKA' is also an algorithm in EAP in an interoperable manner. EAP-AKA' also updates the
update, as it employs SHA-256 / HMAC-SHA-256 instead of SHA-1 / HMAC- algorithm used in hash functions, as it employs SHA-256 / HMAC-
SHA-1 as in EAP-AKA. SHA-256 instead of SHA-1 / HMAC-SHA-1 as in EAP-AKA.
This version of EAP-AKA' specification specifies the protocol This version of EAP-AKA' specification specifies the protocol
behaviour for 5G deployments as well. behaviour for both 4G and 5G deployments, whereas the previous
version only did this for 4G.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 21, 2020. This Internet-Draft will expire on November 11, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 2, line 38 skipping to change at page 2, line 41
3. EAP-AKA' . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. EAP-AKA' . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. AT_KDF_INPUT . . . . . . . . . . . . . . . . . . . . . . 8 3.1. AT_KDF_INPUT . . . . . . . . . . . . . . . . . . . . . . 8
3.2. AT_KDF . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2. AT_KDF . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.3. Key Derivation . . . . . . . . . . . . . . . . . . . . . 13 3.3. Key Derivation . . . . . . . . . . . . . . . . . . . . . 13
3.4. Hash Functions . . . . . . . . . . . . . . . . . . . . . 15 3.4. Hash Functions . . . . . . . . . . . . . . . . . . . . . 15
3.4.1. PRF' . . . . . . . . . . . . . . . . . . . . . . . . 15 3.4.1. PRF' . . . . . . . . . . . . . . . . . . . . . . . . 15
3.4.2. AT_MAC . . . . . . . . . . . . . . . . . . . . . . . 15 3.4.2. AT_MAC . . . . . . . . . . . . . . . . . . . . . . . 15
3.4.3. AT_CHECKCODE . . . . . . . . . . . . . . . . . . . . 15 3.4.3. AT_CHECKCODE . . . . . . . . . . . . . . . . . . . . 15
3.5. Summary of Attributes for EAP-AKA' . . . . . . . . . . . 16 3.5. Summary of Attributes for EAP-AKA' . . . . . . . . . . . 16
4. Bidding Down Prevention for EAP-AKA . . . . . . . . . . . . . 18 4. Bidding Down Prevention for EAP-AKA . . . . . . . . . . . . . 18
4.1. Summary of Attributes for EAP-AKA . . . . . . . . . . . . 19 4.1. Summary of Attributes for EAP-AKA . . . . . . . . . . . . 20
5. Peer Identities . . . . . . . . . . . . . . . . . . . . . . . 20 5. Peer Identities . . . . . . . . . . . . . . . . . . . . . . . 20
5.1. Username Types in EAP-AKA' Identities . . . . . . . . . . 20 5.1. Username Types in EAP-AKA' Identities . . . . . . . . . . 20
5.2. Generating Pseudonyms and Fast Re-Authentication 5.2. Generating Pseudonyms and Fast Re-Authentication
Identities . . . . . . . . . . . . . . . . . . . . . . . 21 Identities . . . . . . . . . . . . . . . . . . . . . . . 21
5.3. Identifier Usage in 5G . . . . . . . . . . . . . . . . . 22 5.3. Identifier Usage in 5G . . . . . . . . . . . . . . . . . 22
5.3.1. Key Derivation . . . . . . . . . . . . . . . . . . . 23 5.3.1. Key Derivation . . . . . . . . . . . . . . . . . . . 23
5.3.2. EAP Identity Response and EAP-AKA' AT_IDENTITY 5.3.2. EAP Identity Response and EAP-AKA' AT_IDENTITY
Attribute . . . . . . . . . . . . . . . . . . . . . . 24 Attribute . . . . . . . . . . . . . . . . . . . . . . 24
6. Exported Parameters . . . . . . . . . . . . . . . . . . . . . 25 6. Exported Parameters . . . . . . . . . . . . . . . . . . . . . 24
7. Security Considerations . . . . . . . . . . . . . . . . . . . 26 7. Security Considerations . . . . . . . . . . . . . . . . . . . 25
7.1. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 29 7.1. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 28
7.2. Discovered Vulnerabilities . . . . . . . . . . . . . . . 30 7.2. Discovered Vulnerabilities . . . . . . . . . . . . . . . 30
7.3. Pervasive Monitoring . . . . . . . . . . . . . . . . . . 33 7.3. Pervasive Monitoring . . . . . . . . . . . . . . . . . . 32
7.4. Security Properties of Binding Network Names . . . . . . 33 7.4. Security Properties of Binding Network Names . . . . . . 33
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
8.1. Type Value . . . . . . . . . . . . . . . . . . . . . . . 35 8.1. Type Value . . . . . . . . . . . . . . . . . . . . . . . 34
8.2. Attribute Type Values . . . . . . . . . . . . . . . . . . 35 8.2. Attribute Type Values . . . . . . . . . . . . . . . . . . 34
8.3. Key Derivation Function Namespace . . . . . . . . . . . . 35 8.3. Key Derivation Function Namespace . . . . . . . . . . . . 34
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 35 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 35
9.1. Normative References . . . . . . . . . . . . . . . . . . 35 9.1. Normative References . . . . . . . . . . . . . . . . . . 35
9.2. Informative References . . . . . . . . . . . . . . . . . 37 9.2. Informative References . . . . . . . . . . . . . . . . . 37
Appendix A. Changes from RFC 5448 . . . . . . . . . . . . . . . 41 Appendix A. Changes from RFC 5448 . . . . . . . . . . . . . . . 40
Appendix B. Changes from RFC 4187 to RFC 5448 . . . . . . . . . 41 Appendix B. Changes to RFC 4187 . . . . . . . . . . . . . . . . 41
Appendix C. Changes from Previous Version of This Draft . . . . 41 Appendix C. Changes from Previous Version of This Draft . . . . 41
Appendix D. Importance of Explicit Negotiation . . . . . . . . . 43 Appendix D. Importance of Explicit Negotiation . . . . . . . . . 45
Appendix E. Test Vectors . . . . . . . . . . . . . . . . . . . . 44 Appendix E. Test Vectors . . . . . . . . . . . . . . . . . . . . 46
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 49 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 51
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 49 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51
1. Introduction 1. Introduction
The 3GPP Mobile Network Authentication and Key Agreement (AKA) is the The 3GPP Mobile Network Authentication and Key Agreement (AKA) is an
primary authentication mechanism for devices wishing to access mobile authentication mechanism for devices wishing to access mobile
networks. [RFC4187] (EAP-AKA) made the use of this mechanism networks. [RFC4187] (EAP-AKA) made the use of this mechanism
possible within the Extensible Authentication Protocol (EAP) possible within the Extensible Authentication Protocol (EAP)
framework [RFC3748]. framework [RFC3748].
[RFC5448] (EAP-AKA') was an improved version of EAP-AKA. This memo [RFC5448] (EAP-AKA') was an improved version of EAP-AKA. EAP-AKA'
replaces the specification of EAP-AKA'. EAP-AKA' was defined in RFC was defined in RFC 5448 and updated EAP-AKA RFC 4187.
5448 and updated EAP-AKA RFC 4187. As such this document obsoletes
RFC 5448 and updates RFC 4187. This document is the most recent specification of EAP-AKA',
including, for instance, details and references about related to
operating EAP-AKA' in 5G networks. RFC 5448 is not obsole, but the
most recent and fully backwards compatible specification is in this
document.
EAP-AKA' is commonly implemented in mobile phones and network EAP-AKA' is commonly implemented in mobile phones and network
equipment. It can be used for authentication to gain network access equipment. It can be used for authentication to gain network access
via Wireless LAN networks and, with 5G, also directly to mobile via Wireless LAN networks and, with 5G, also directly to mobile
networks. networks.
EAP-AKA' differs from EAP-AKA by providing a different key derivation EAP-AKA' differs from EAP-AKA by providing a different key derivation
function. This function binds the keys derived within the method to function. This function binds the keys derived within the method to
the name of the access network. This limits the effects of the name of the access network. This limits the effects of
compromised access network nodes and keys. EAP-AKA' is also an compromised access network nodes and keys. EAP-AKA' also updates the
algorithm update for the used hash functions. algorithm used for hash functions.
The EAP-AKA' method employs the derived keys CK' and IK' from the The EAP-AKA' method employs the derived keys CK' and IK' from the
3GPP specification [TS-3GPP.33.402] and updates the used hash 3GPP specification [TS-3GPP.33.402] and updates the used hash
function to SHA-256 [FIPS.180-4] and HMAC to HMAC-SHA-256. function to SHA-256 [FIPS.180-4] and HMAC to HMAC-SHA-256.
Otherwise, EAP-AKA' is equivalent to EAP-AKA. Given that a different Otherwise, EAP-AKA' is equivalent to EAP-AKA. Given that a different
EAP method type value is used for EAP-AKA and EAP-AKA', a mutually EAP method type value is used for EAP-AKA and EAP-AKA', a mutually
supported method may be negotiated using the standard mechanisms in supported method may be negotiated using the standard mechanisms in
EAP [RFC3748]. EAP [RFC3748].
Note that any change of the key derivation must be unambiguous to Note that any change of the key derivation must be unambiguous to
skipping to change at page 4, line 19 skipping to change at page 4, line 27
a proper error message. See Appendix D for further information. a proper error message. See Appendix D for further information.
Note also that choices in authentication protocols should be Note also that choices in authentication protocols should be
secure against bidding down attacks that attempt to force the secure against bidding down attacks that attempt to force the
participants to use the least secure function. See Section 4 for participants to use the least secure function. See Section 4 for
further information. further information.
The changes from RFC 5448 to this specification are as follows: The changes from RFC 5448 to this specification are as follows:
o Update the reference on how the Network Name field is constructed o Update the reference on how the Network Name field is constructed
in the protocol. The update ensures that EAP-AKA' is compatible in the protocol. This update ensures that EAP-AKA' is compatible
with 5G deployments. RFC 5448 referred to the Release 8 version with 5G deployments. RFC 5448 referred to the Release 8 version
of [TS-3GPP.24.302] and this update points to the first 5G of [TS-3GPP.24.302] and this update points to the first 5G
version, Release 15. version, Release 15.
o Specify how EAP and EAP-AKA' use identifiers in 5G. Additional o Specify how EAP and EAP-AKA' use identifiers in 5G. Additional
identifiers are introduced in 5G, and for interoperability, it is identifiers are introduced in 5G, and for interoperability, it is
necessary that the right identifiers are used as inputs in the key necessary that the right identifiers are used as inputs in the key
derivation. In addition, for identity privacy it is important derivation. In addition, for identity privacy it is important
that when privacy-friendly identifiers in 5G are used, no that when privacy-friendly identifiers in 5G are used, no
trackable, permanent identifiers are passed in EAP-AKA' either. trackable, permanent identifiers are passed in EAP-AKA' either.
skipping to change at page 4, line 46 skipping to change at page 5, line 5
o Update the requirements on generating pseudonym usernames and fast o Update the requirements on generating pseudonym usernames and fast
re-authentication identities to ensure identity privacy. re-authentication identities to ensure identity privacy.
o Describe what has been learned about any vulnerabilities in AKA or o Describe what has been learned about any vulnerabilities in AKA or
EAP-AKA'. EAP-AKA'.
o Describe the privacy and pervasive monitoring considerations o Describe the privacy and pervasive monitoring considerations
related to EAP-AKA'. related to EAP-AKA'.
o Summaries of the attributes have been added.
Some of the updates are small. For instance, for the first update, Some of the updates are small. For instance, for the first update,
the reference update does not change the 3GPP specification number, the reference update does not change the 3GPP specification number,
only the version. But this reference is crucial in correct only the version. But this reference is crucial in correct
calculation of the keys resulting from running the EAP-AKA' method, calculation of the keys resulting from running the EAP-AKA' method,
so an update of the RFC with the newest version pointer may be so an update of the RFC with the newest version pointer may be
warranted. warranted.
Note: This specification refers only to the 5G specifications. Note: Any further updates in 3GPP specifications that affect, for
Any further update that affects, for instance, key derivation is instance, key derivation is something that EAP-AKA'
something that EAP-AKA' implementations should take into account. implementations need to take into account. Upon such updates
Upon such updates there will be a need to both update the there will be a need to both update this specification and the
specification and the implementations. implementations.
It is an explicit non-goal of this draft to include any other It is an explicit non-goal of this draft to include any other
technical modifications, addition of new features or other changes. technical modifications, addition of new features or other changes.
The EAP-AKA' base protocol is stable and needs to stay that way. If The EAP-AKA' base protocol is stable and needs to stay that way. If
there are any extensions or variants, those need to be proposed as there are any extensions or variants, those need to be proposed as
standalone extensions or even as different authentication methods. standalone extensions or even as different authentication methods.
The rest of this specification is structured as follows. Section 3 The rest of this specification is structured as follows. Section 3
defines the EAP-AKA' method. Section 4 adds support to EAP-AKA to defines the EAP-AKA' method. Section 4 adds support to EAP-AKA to
prevent bidding down attacks from EAP-AKA'. Section 5 specifies prevent bidding down attacks from EAP-AKA'. Section 5 specifies
requirements regarding the use of peer identities, including how how requirements regarding the use of peer identities, including how 5G
EAP-AKA' identifiers are used in 5G context. Section 6 specifies identifiers are used in the EAP-AKA' context. Section 6 specifies
what parameters EAP-AKA' exports out of the method. Section 7 what parameters EAP-AKA' exports out of the method. Section 7
explains the security differences between EAP-AKA and EAP-AKA'. explains the security differences between EAP-AKA and EAP-AKA'.
Section 8 describes the IANA considerations and Appendix A and Section 8 describes the IANA considerations and Appendix A and
Appendix B explains what updates to RFC 5448 EAP-AKA' and RFC 4187 Appendix B explains what updates to RFC 5448 EAP-AKA' and RFC 4187
EAP-AKA have been made in this specification. Appendix D explains EAP-AKA have been made in this specification. Appendix D explains
some of the design rationale for creating EAP-AKA'. Finally, some of the design rationale for creating EAP-AKA'. Finally,
Appendix E provides test vectors. Appendix E provides test vectors.
Editor's Note: The publication of this RFC depends on its
normative references to 3GPP Technical Specifications reaching a
stable status for Release 15, as indicated by 3GPP. The RFC
Editor should check with the 3GPP liaisons that a stable version
from Release 15 is available and refer to that version. RFC
Editor: Please delete this note upon publication of this
specification as an RFC.
2. Requirements Language 2. 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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. EAP-AKA' 3. EAP-AKA'
skipping to change at page 8, line 9 skipping to change at page 8, line 9
| +--------------------------------------------------+ | +--------------------------------------------------+
| EAP-Success | | EAP-Success |
|<-------------------------------------------------------| |<-------------------------------------------------------|
Figure 1: EAP-AKA' Authentication Process Figure 1: EAP-AKA' Authentication Process
EAP-AKA' can operate on the same credentials as EAP-AKA and employ EAP-AKA' can operate on the same credentials as EAP-AKA and employ
the same identities. However, EAP-AKA' employs different leading the same identities. However, EAP-AKA' employs different leading
characters than EAP-AKA for the conventions given in Section 4.1.1 of characters than EAP-AKA for the conventions given in Section 4.1.1 of
[RFC4187] for International Mobile Subscriber Identifier (IMSI) based [RFC4187] for International Mobile Subscriber Identifier (IMSI) based
usernames. EAP-AKA' MUST use the leading character "6" (ASCII 36 usernames. For 4G networks, EAP-AKA' MUST use the leading character
hexadecimal) instead of "0" for IMSI-based permanent usernames, or "6" (ASCII 36 hexadecimal) instead of "0" for IMSI-based permanent
5G-specific identifiers in 5G networks. Identifier usage in 5G is usernames. For 5G networks, leading character "6" is not used for
specified in Section 5.3. All other usage and processing of the IMSI-based permanent user names. Identifier usage in 5G is specified
leading characters, usernames, and identities is as defined by EAP- in Section 5.3. All other usage and processing of the leading
AKA [RFC4187]. For instance, the pseudonym and fast re- characters, usernames, and identities is as defined by EAP-AKA
authentication usernames need to be constructed so that the server [RFC4187]. For instance, the pseudonym and fast re-authentication
can recognize them. As an example, a pseudonym could begin with a usernames need to be constructed so that the server can recognize
leading "7" character (ASCII 37 hexadecimal) and a fast re- them. As an example, a pseudonym could begin with a leading "7"
authentication username could begin with "8" (ASCII 38 hexadecimal). character (ASCII 37 hexadecimal) and a fast re-authentication
Note that a server that implements only EAP-AKA may not recognize username could begin with "8" (ASCII 38 hexadecimal). Note that a
these leading characters. According to Section 4.1.4 of [RFC4187], server that implements only EAP-AKA may not recognize these leading
such a server will re-request the identity via the EAP- Request/AKA- characters. According to Section 4.1.4 of [RFC4187], such a server
Identity message, making obvious to the peer that EAP-AKA and will re-request the identity via the EAP- Request/AKA-Identity
associated identity are expected. message, making obvious to the peer that EAP-AKA and associated
identity are expected.
3.1. AT_KDF_INPUT 3.1. AT_KDF_INPUT
The format of the AT_KDF_INPUT attribute is shown below. The format of the AT_KDF_INPUT attribute is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AT_KDF_INPUT | Length | Actual Network Name Length | | AT_KDF_INPUT | Length | Actual Network Name Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 9, line 19 skipping to change at page 9, line 22
Network Name Network Name
This field contains the network name of the access network for This field contains the network name of the access network for
which the authentication is being performed. The name does not which the authentication is being performed. The name does not
include any terminating null characters. Because the length of include any terminating null characters. Because the length of
the entire attribute must be a multiple of 4 bytes, the sender the entire attribute must be a multiple of 4 bytes, the sender
pads the name with 1, 2, or 3 bytes of all zero bits when pads the name with 1, 2, or 3 bytes of all zero bits when
necessary. necessary.
Only the server sends the AT_KDF_INPUT attribute. The value is sent Only the server sends the AT_KDF_INPUT attribute. The value is sent
as specified in [TS-3GPP.24.302] for non-3GPP access networks, and as as specified in [TS-3GPP.24.302] for both non-3GPP access networks
specified in [TS-3GPP.33.501] for 5G access networks. Per and for 5G access networks. Per [TS-3GPP.33.402], the server always
[TS-3GPP.33.402], the server always verifies the authorization of a verifies the authorization of a given access network to use a
given access network to use a particular name before sending it to particular name before sending it to the peer over EAP-AKA'. The
the peer over EAP-AKA'. The value of the AT_KDF_INPUT attribute from value of the AT_KDF_INPUT attribute from the server MUST be non-
the server MUST be non-empty. If it is empty, the peer behaves as if empty, with a greater than zero length in the Actual Network Name
AUTN had been incorrect and authentication fails. See Section 3 and Length field. If AT_KDF_INPUT attribute is empty, the peer behaves
Figure 3 of [RFC4187] for an overview of how authentication failures as if AUTN had been incorrect and authentication fails. See
are handled. Section 3 and Figure 3 of [RFC4187] for an overview of how
authentication failures are handled.
Note: Currently, [TS-3GPP.24.302] or [TS-3GPP.33.501] specify
separate values. The former specifies what is called "Access
Network ID" and the latter specifies what is called "Serving
Network Name". However, from an EAP-AKA' perspective both occupy
the same field, and need to be distinguishable from each other.
Currently specified values are distinguishable, but it would be
useful that this be specified explicitly in the 3GPP
specifications.
In addition, the peer MAY check the received value against its own In addition, the peer MAY check the received value against its own
understanding of the network name. Upon detecting a discrepancy, the understanding of the network name. Upon detecting a discrepancy, the
peer either warns the user and continues, or fails the authentication peer either warns the user and continues, or fails the authentication
process. More specifically, the peer SHOULD have a configurable process. More specifically, the peer SHOULD have a configurable
policy that it can follow under these circumstances. If the policy policy that it can follow under these circumstances. If the policy
indicates that it can continue, the peer SHOULD log a warning message indicates that it can continue, the peer SHOULD log a warning message
or display it to the user. If the peer chooses to proceed, it MUST or display it to the user. If the peer chooses to proceed, it MUST
use the network name as received in the AT_KDF_INPUT attribute. If use the network name as received in the AT_KDF_INPUT attribute. If
the policy indicates that the authentication should fail, the peer the policy indicates that the authentication should fail, the peer
skipping to change at page 13, line 44 skipping to change at page 13, line 41
IK' and CK' are derived as specified in [TS-3GPP.33.402]. The IK' and CK' are derived as specified in [TS-3GPP.33.402]. The
functions that derive IK' and CK' take the following parameters: functions that derive IK' and CK' take the following parameters:
CK and IK produced by the AKA algorithm, and value of the Network CK and IK produced by the AKA algorithm, and value of the Network
Name field comes from the AT_KDF_INPUT attribute (without length Name field comes from the AT_KDF_INPUT attribute (without length
or padding). or padding).
The value "EAP-AKA'" is an eight-characters-long ASCII string. It The value "EAP-AKA'" is an eight-characters-long ASCII string. It
is used as is, without any trailing NUL characters. is used as is, without any trailing NUL characters.
Identity is the peer identity as specified in Section 7 of Identity is the peer identity as specified in Section 7 of
[RFC4187]. [RFC4187], and Section 5.3.2 in this document for the 5G cases.
When the server creates an AKA challenge and corresponding AUTN, When the server creates an AKA challenge and corresponding AUTN,
CK, CK', IK, and IK' values, it MUST set the Authentication CK, CK', IK, and IK' values, it MUST set the Authentication
Management Field (AMF) separation bit to 1 in the AKA algorithm Management Field (AMF) separation bit to 1 in the AKA algorithm
[TS-3GPP.33.102]. Similarly, the peer MUST check that the AMF [TS-3GPP.33.102]. Similarly, the peer MUST check that the AMF
separation bit is set to 1. If the bit is not set to 1, the peer separation bit is set to 1. If the bit is not set to 1, the peer
behaves as if the AUTN had been incorrect and fails the behaves as if the AUTN had been incorrect and fails the
authentication. authentication.
On fast re-authentication, the following keys are calculated: On fast re-authentication, the following keys are calculated:
skipping to change at page 15, line 19 skipping to change at page 15, line 15
3.4. Hash Functions 3.4. Hash Functions
EAP-AKA' uses SHA-256 / HMAC-SHA-256, not SHA-1 / HMAC-SHA-1 (see EAP-AKA' uses SHA-256 / HMAC-SHA-256, not SHA-1 / HMAC-SHA-1 (see
[FIPS.180-4] [RFC2104]) as in EAP-AKA. This requires a change to the [FIPS.180-4] [RFC2104]) as in EAP-AKA. This requires a change to the
pseudo-random function (PRF) as well as the AT_MAC and AT_CHECKCODE pseudo-random function (PRF) as well as the AT_MAC and AT_CHECKCODE
attributes. attributes.
3.4.1. PRF' 3.4.1. PRF'
The PRF' construction is the same one IKEv2 uses (see Section 2.13 of The PRF' construction is the same one IKEv2 uses (see Section 2.13 of
[RFC7296]). The function takes two arguments. K is a 256-bit value [RFC7296]; this is the same function as was defined [RFC4306] that
and S is a byte string of arbitrary length. PRF' is defined as RFC 5448 referred to). The function takes two arguments. K is a
follows: 256-bit value and S is a byte string of arbitrary length. PRF' is
defined as follows:
PRF'(K,S) = T1 | T2 | T3 | T4 | ... PRF'(K,S) = T1 | T2 | T3 | T4 | ...
where: where:
T1 = HMAC-SHA-256 (K, S | 0x01) T1 = HMAC-SHA-256 (K, S | 0x01)
T2 = HMAC-SHA-256 (K, T1 | S | 0x02) T2 = HMAC-SHA-256 (K, T1 | S | 0x02)
T3 = HMAC-SHA-256 (K, T2 | S | 0x03) T3 = HMAC-SHA-256 (K, T2 | S | 0x03)
T4 = HMAC-SHA-256 (K, T3 | S | 0x04) T4 = HMAC-SHA-256 (K, T3 | S | 0x04)
... ...
skipping to change at page 16, line 22 skipping to change at page 16, line 22
| | | |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Second, the checkcode is a hash value, calculated with SHA-256 Second, the checkcode is a hash value, calculated with SHA-256
[FIPS.180-4], over the data specified in Section 10.13 of [RFC4187]. [FIPS.180-4], over the data specified in Section 10.13 of [RFC4187].
3.5. Summary of Attributes for EAP-AKA' 3.5. Summary of Attributes for EAP-AKA'
The following table provides a guide to which attributes may be found Table 1 provides a guide to which attributes may be found in which
in which kinds of messages, and in what quantity. kinds of messages, and in what quantity.
Messages are denoted with numbers in parentheses as follows: Messages are denoted with numbers in parentheses as follows:
(1) EAP-Request/AKA-Identity, (1) EAP-Request/AKA-Identity,
(2) EAP-Response/AKA-Identity, (2) EAP-Response/AKA-Identity,
(3) EAP-Request/AKA-Challenge, (3) EAP-Request/AKA-Challenge,
(4) EAP-Response/AKA-Challenge, (4) EAP-Response/AKA-Challenge,
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(9) EAP-Response/AKA-Reauthentication, (9) EAP-Response/AKA-Reauthentication,
(10) EAP-Response/AKA-Authentication-Reject, and (10) EAP-Response/AKA-Authentication-Reject, and
(11) EAP-Response/AKA-Synchronization-Failure. (11) EAP-Response/AKA-Synchronization-Failure.
The column denoted with "E" indicates whether the attribute is a The column denoted with "E" indicates whether the attribute is a
nested attribute that MUST be included within AT_ENCR_DATA. nested attribute that MUST be included within AT_ENCR_DATA.
In addition: In addition,the numbered columns indicate the quantity of the
attribute within the message as follows:
"0" indicates that the attribute MUST NOT be included in the "0" indicates that the attribute MUST NOT be included in the
message, message,
"1" indicates that the attribute MUST be included in the message, "1" indicates that the attribute MUST be included in the message,
"0-1" indicates that the attribute is sometimes included in the "0-1" indicates that the attribute is sometimes included in the
message, message,
"0+" indicates that zero or more copies of the attribute MAY be "0+" indicates that zero or more copies of the attribute MAY be
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AT_RESULT_IND 0 0 0-1 0-1 0 0 0 0-1 0-1 0 0 N AT_RESULT_IND 0 0 0-1 0-1 0 0 0 0-1 0-1 0 0 N
AT_MAC 0 0 1 0-1 0-1 0-1 0 1 1 0 0 N AT_MAC 0 0 1 0-1 0-1 0-1 0 1 1 0 0 N
AT_COUNTER 0 0 0 0 0-1 0-1 0 1 1 0 0 Y AT_COUNTER 0 0 0 0 0-1 0-1 0 1 1 0 0 Y
AT_COUNTER_TOO_SMALL 0 0 0 0 0 0 0 0 0-1 0 0 Y AT_COUNTER_TOO_SMALL 0 0 0 0 0 0 0 0 0-1 0 0 Y
AT_NONCE_S 0 0 0 0 0 0 0 1 0 0 0 Y AT_NONCE_S 0 0 0 0 0 0 0 1 0 0 0 Y
AT_NOTIFICATION 0 0 0 0 1 0 0 0 0 0 0 N AT_NOTIFICATION 0 0 0 0 1 0 0 0 0 0 0 N
AT_CLIENT_ERROR_CODE 0 0 0 0 0 0 1 0 0 0 0 N AT_CLIENT_ERROR_CODE 0 0 0 0 0 0 1 0 0 0 0 N
AT_KDF 0 0 1+ 0+ 0 0 0 0 0 0 1+ N AT_KDF 0 0 1+ 0+ 0 0 0 0 0 0 1+ N
AT_KDF_INPUT 0 0 1 0 0 0 0 0 0 0 0 N AT_KDF_INPUT 0 0 1 0 0 0 0 0 0 0 0 N
Table 1: The attribute table
4. Bidding Down Prevention for EAP-AKA 4. Bidding Down Prevention for EAP-AKA
As discussed in [RFC3748], negotiation of methods within EAP is As discussed in [RFC3748], negotiation of methods within EAP is
insecure. That is, a man-in-the-middle attacker may force the insecure. That is, a man-in-the-middle attacker may force the
endpoints to use a method that is not the strongest that they both endpoints to use a method that is not the strongest that they both
support. This is a problem, as we expect EAP-AKA and EAP-AKA' to be support. This is a problem, as we expect EAP-AKA and EAP-AKA' to be
negotiated via EAP. negotiated via EAP.
In order to prevent such attacks, this RFC specifies a new mechanism In order to prevent such attacks, this RFC specifies a new mechanism
for EAP-AKA that allows the endpoints to securely discover the for EAP-AKA that allows the endpoints to securely discover the
skipping to change at page 19, line 43 skipping to change at page 19, line 45
message. If the peer supports EAP-AKA', it compares the received message. If the peer supports EAP-AKA', it compares the received
value to its own capabilities. If it turns out that both the server value to its own capabilities. If it turns out that both the server
and peer would have been able to use EAP-AKA' and preferred it over and peer would have been able to use EAP-AKA' and preferred it over
EAP-AKA, the peer behaves as if AUTN had been incorrect and fails the EAP-AKA, the peer behaves as if AUTN had been incorrect and fails the
authentication (see Figure 3 of [RFC4187]). A peer not supporting authentication (see Figure 3 of [RFC4187]). A peer not supporting
EAP-AKA' will simply ignore this attribute. In all cases, the EAP-AKA' will simply ignore this attribute. In all cases, the
attribute is protected by the integrity mechanisms of EAP-AKA, so it attribute is protected by the integrity mechanisms of EAP-AKA, so it
cannot be removed by a man-in-the-middle attacker. cannot be removed by a man-in-the-middle attacker.
Note that we assume (Section 7) that EAP-AKA' is always stronger than Note that we assume (Section 7) that EAP-AKA' is always stronger than
EAP-AKA. As a result, there is no need to prevent bidding "down" EAP-AKA. As a result, this specification does not provide protection
attacks in the other direction, i.e., attackers forcing the endpoints against bidding "down" attacks in the other direction, i.e.,
to use EAP-AKA'. attackers forcing the endpoints to use EAP-AKA'.
4.1. Summary of Attributes for EAP-AKA 4.1. Summary of Attributes for EAP-AKA
The appearance of the AT_BIDDING attribute in EAP-AKA exchanges is The appearance of the AT_BIDDING attribute in EAP-AKA exchanges is
shown below, using the notation from Section 3.5: shown below, using the notation from Section 3.5:
Attribute (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)(11) E Attribute (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)(11) E
AT_BIDDING 0 0 1 0 0 0 0 0 0 0 0 N AT_BIDDING 0 0 1 0 0 0 0 0 0 0 0 N
5. Peer Identities 5. Peer Identities
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Temporary Mobile Subscriber Identities (TMSI) that are used on Temporary Mobile Subscriber Identities (TMSI) that are used on
cellular networks. cellular networks.
5.1. Username Types in EAP-AKA' Identities 5.1. Username Types in EAP-AKA' Identities
Section 4.1.1.3 of [RFC4187] specified that there are three types of Section 4.1.1.3 of [RFC4187] specified that there are three types of
usernames: permanent, pseudonym, and fast re-authentication usernames: permanent, pseudonym, and fast re-authentication
usernames. This specification extends this definition as follows. usernames. This specification extends this definition as follows.
There are four types of usernames: There are four types of usernames:
(1) Regular usernames. These are external names given to EAP- (1) Regular usernames. These are external names given to EAP-AKA'
AKA'. The regular usernames are further subdivided into to peers. The regular usernames are further subdivided into to
categories: categories:
(a) Permanent usernames, for instance IMSI-based usernames. (a) Permanent usernames, for instance IMSI-based usernames.
(b) Privacy-friendly temporary usernames, for instance 5G (b) Privacy-friendly temporary usernames, for instance 5G GUTI
privacy identifiers (see Section 5.3.2 and Section 5.3.2.1. (5G Globally Unique Temporary Identifier) or 5G privacy
identifiers (see Section 5.3.2), for instance SUCI
(Subscription Concealed Identifier).
(2) EAP-AKA' pseudonym usernames. For example, (2) EAP-AKA' pseudonym usernames. For example,
2s7ah6n9q@example.com might be a valid pseudonym identity. In 2s7ah6n9q@example.com might be a valid pseudonym identity. In
this example, 2s7ah6n9q is the pseudonym username. this example, 2s7ah6n9q is the pseudonym username.
(3) EAP-AKA' fast re-authentication usernames. For example, (3) EAP-AKA' fast re-authentication usernames. For example,
43953754@example.com might be a valid fast re-authentication 43953754@example.com might be a valid fast re-authentication
identity and 43953754 the fast re-authentication username. identity and 43953754 the fast re-authentication username.
The permanent, privacy-friendly temporary, and pseudonym usernames The permanent, privacy-friendly temporary, and pseudonym usernames
are only used on full authentication, and fast re-authentication are only used on full authentication, and fast re-authentication
usernames only on fast re-authentication. Unlike permanent usernames usernames only on fast re-authentication. Unlike permanent usernames
and pseudonym usernames, privacy friendly temporary usernames and and pseudonym usernames, privacy friendly temporary usernames and
fast re-authentication usernames are one-time identifiers, which are fast re-authentication usernames are one-time identifiers, which are
not re-used across EAP exchanges. not re-used across EAP exchanges.
5.2. Generating Pseudonyms and Fast Re-Authentication Identities 5.2. Generating Pseudonyms and Fast Re-Authentication Identities
This section provides some additional guidance for implementations
for producing secure pseudonyms and fast re-authentication
identities. It does not impact backwards compatibility, because each
server consumes only the identities it itself generates. However,
adherence to the guidance will provide better security.
As specified by [RFC4187] Section 4.1.1.7, pseudonym usernames and As specified by [RFC4187] Section 4.1.1.7, pseudonym usernames and
fast re-authentication identities are generated by the EAP server, in fast re-authentication identities are generated by the EAP server, in
an implementation-dependent manner. RFC 4187 provides some general an implementation-dependent manner. RFC 4187 provides some general
requirements on how these identities are transported, how they map to requirements on how these identities are transported, how they map to
the NAI syntax, how they are distinguished from each other, and so the NAI syntax, how they are distinguished from each other, and so
on. on.
However, to ensure privacy some additional requirements need to be However, to enhance privacy some additional requirements need to be
applied. applied.
The pseudonym usernames and fast re-authentication identities MUST be The pseudonym usernames and fast re-authentication identities MUST be
generated in a cryptographically secure way so that that it is generated in a cryptographically secure way so that that it is
computationally infeasible for at attacker to differentiate two computationally infeasible for an attacker to differentiate two
identities belonging to the same user from two identities belonging identities belonging to the same user from two identities belonging
to different users. This can be achieved, for instance, by using to different users. This can be achieved, for instance, by using
random or pseudo-random identifiers such as random byte strings or random or pseudo-random identifiers such as random byte strings or
ciphertexts. See also [RFC4086] for guidance on random number ciphertexts. See also [RFC4086] for guidance on random number
generation. generation.
Note that the pseudonym and fast re-authentication usernames also Note that the pseudonym and fast re-authentication usernames also
MUST NOT include substrings that can be used to relate the username MUST NOT include substrings that can be used to relate the username
to a particular entity or a particular permanent identity. For to a particular entity or a particular permanent identity. For
instance, the usernames can not include any subscriber-identifying instance, the usernames can not include any subscriber-identifying
skipping to change at page 22, line 16 skipping to change at page 22, line 27
In EAP-AKA', the peer identity may be communicated to the server in In EAP-AKA', the peer identity may be communicated to the server in
one of three ways: one of three ways:
o As a part of link layer establishment procedures, externally to o As a part of link layer establishment procedures, externally to
EAP. EAP.
o With the EAP-Response/Identity message in the beginning of the EAP o With the EAP-Response/Identity message in the beginning of the EAP
exchange, but before the selection of EAP-AKA'. exchange, but before the selection of EAP-AKA'.
o Transmitted from the peer to the server using EAP-AKA messages o Transmitted from the peer to the server using EAP-AKA' messages
instead of EAP-Response/Identity. In this case, the server instead of EAP-Response/Identity. In this case, the server
includes an identity requesting attribute (AT_ANY_ID_REQ, includes an identity requesting attribute (AT_ANY_ID_REQ,
AT_FULLAUTH_ID_REQ or AT_PERMANENT_ID_REQ) in the EAP-Request/AKA- AT_FULLAUTH_ID_REQ or AT_PERMANENT_ID_REQ) in the EAP-Request/AKA-
Identity message; and the peer includes the AT_IDENTITY attribute, Identity message; and the peer includes the AT_IDENTITY attribute,
which contains the peer's identity, in the EAP-Response/AKA- which contains the peer's identity, in the EAP-Response/AKA-
Identity message. Identity message.
The identity carried above may be a permanent identity, privacy The identity carried above may be a permanent identity, privacy
friendly identity, pseudonym identity, or fast re-authentication friendly identity, pseudonym identity, or fast re-authentication
identity as defined in this RFC. identity as defined in Section 5.1.
5G supports the concept of privacy identifiers, and it is important 5G supports the concept of privacy identifiers, and it is important
for interoperability that the right type of identifier is used. for interoperability that the right type of identifier is used.
5G defines the SUbscription Permanent Identifier (SUPI) and 5G defines the SUbscription Permanent Identifier (SUPI) and
SUbscription Concealed Identifier (SUCI) [TS-3GPP.23.501] SUbscription Concealed Identifier (SUCI) [TS-3GPP.23.501]
[TS-3GPP.33.501] [TS-3GPP.23.003]. SUPI is globally unique and [TS-3GPP.33.501] [TS-3GPP.23.003]. SUPI is globally unique and
allocated to each subscriber. However, it is only used internally in allocated to each subscriber. However, it is only used internally in
the 5G network, and is privacy sensitive. The SUCI is a privacy the 5G network, and is privacy sensitive. The SUCI is a privacy
preserving identifier containing the concealed SUPI, using public key preserving identifier containing the concealed SUPI, using public key
skipping to change at page 23, line 15 skipping to change at page 23, line 27
to prepare for many different situations, including sometimes having to prepare for many different situations, including sometimes having
to communicate identities within EAP. to communicate identities within EAP.
The following sections clarify which identifiers are used and how. The following sections clarify which identifiers are used and how.
5.3.1. Key Derivation 5.3.1. Key Derivation
In EAP-AKA', the peer identity is used in the Section 3.3 key In EAP-AKA', the peer identity is used in the Section 3.3 key
derivation formula. derivation formula.
The identity needs to be represented in exact correct format for the
key derivation formula to produce correct results.
If the AT_KDF_INPUT parameter contains the prefix "5G:", the AT_KDF If the AT_KDF_INPUT parameter contains the prefix "5G:", the AT_KDF
parameter has the value 1, and this authentication is not a fast re- parameter has the value 1, and this authentication is not a fast re-
authentication, then the peer identity used in the key derivation authentication, then the peer identity used in the key derivation
MUST be the 5G SUPI for the peer. This rule applies to all full EAP- MUST be as specified in Annex F.3 of [TS-3GPP.33.501] and Clause 2.2
AKA' authentication processes, even if the peer sent some other of [TS-3GPP.23.003]. This is in contrast to [RFC5448], which used
identifier at a lower layer or as a response to an EAP Identity the identity as communicated in EAP and represented as a NAI. Also,
Request or if no identity was sent. in contrast to [RFC5448], in 5G EAP-AKA' does not use the "0" or "6"
prefix in front of the identifier.
The identity MUST also be represented in the exact correct format for For an example of the format of the identity, see Clause 2.2 of
the key derivation formula to produce correct results. In 5G, this [TS-3GPP.23.003].
identifier is the SUPI. The SUPI format is as defined
Section 5.3.1.1.
In all other cases, the following applies: In all other cases, the following applies:
The identity used in the key derivation formula MUST be exactly The identity used in the key derivation formula MUST be exactly
the one sent in EAP-AKA' AT_IDENTITY attribute, if one was sent, the one sent in EAP-AKA' AT_IDENTITY attribute, if one was sent,
regardless of the kind of identity that it may have been. If no regardless of the kind of identity that it may have been. If no
AT_IDENTITY was sent, the identity MUST be the exactly the one AT_IDENTITY was sent, the identity MUST be the exactly the one
sent in the generic EAP Identity exchange, if one was made. sent in the generic EAP Identity exchange, if one was made.
Again, the identity MUST be used exactly as sent.
If no identity was communicated inside EAP, then the identity is If no identity was communicated inside EAP, then the identity is
the one communicated outside EAP in link layer messaging. the one communicated outside EAP in link layer messaging.
In this case, the used identity MUST be the identity most recently In this case, the used identity MUST be the identity most recently
communicated by the peer to the network, again regardless of what communicated by the peer to the network, again regardless of what
type of identity it may have been. type of identity it may have been.
5.3.1.1. Format of the SUPI
A SUPI is either an IMSI or a Network Access Identifier [RFC7542].
When used in EAP-AKA', the format of the SUPI MUST be as specified in
[TS-3GPP.23.003] Section 28.7.2, with the semantics defined in
[TS-3GPP.23.003] Section 2.2A. Also, in contrast to [RFC5448], in 5G
EAP-AKA' does not use the "0" or "6" prefix in front of the entire
IMSI.
For instance, if the IMSI is 234150999999999 (MCC = 234, MNC = 15),
the NAI format for the SUPI takes the form:
234150999999999@nai.5gc.mnc015.mcc234.3gppnetwork.org
5.3.2. EAP Identity Response and EAP-AKA' AT_IDENTITY Attribute 5.3.2. EAP Identity Response and EAP-AKA' AT_IDENTITY Attribute
The EAP authentication option is only available in 5G when the new 5G The EAP authentication option is only available in 5G when the new 5G
core network is also in use. However, in other networks an EAP-AKA' core network is also in use. However, in other networks an EAP-AKA'
peer may be connecting to other types of networks and existing peer may be connecting to other types of networks and existing
equipment. equipment.
When the EAP peer is connecting to a 5G access network and uses the When the EAP server is in a 5G network, the 5G procedures for EAP-
5G Non-Access Stratum (NAS) protocol [TS-3GPP.24.501], the EAP server AKA' apply. When EAP server is defined to be in a 5G network is
is in a 5G network. The EAP identity exchanges are generally not specified in [TS-3GPP.33.501].
used in this case, as the identity is already made available on
previous link layer exchanges.
In this situation, the EAP server SHOULD NOT request an additional
identity from the peer. If the peer for some reason receives EAP-
Request/Identity or EAP-Request/AKA-Identity messages, the peer
behaves as follows.
Receive EAP-Request/Identity
In this case, the peer MUST respond with a EAP-Response/Identity
containing the privacy-friendly 5G identifier, the SUCI. The SUCI
MUST be represented as specified in Section 5.3.2.1.
EAP-Request/AKA-Identity with AT_PERMANENT_REQ
For privacy reasons, the peer MUST follow a "conservative" policy
and terminate the authentication exchange rather than risk
revealing its permanent identity.
The peer MUST respond with EAP-Response/AKA-Client-Error with the
client error code 0, "unable to process packet".
EAP-Request/AKA-Identity with AT_FULLAUTH_REQ
In this case, the peer MUST respond with a EAP-Response/AKA-
Identity containing the SUCI. The SUCI MUST be represented as
specified in Section 5.3.2.1.
EAP-Request/AKA-Identity with AT_ANY_ID_REQ
If the peer supports fast re-authentication and has a fast re-
authentication identity available, the peer SHOULD respond with
EAP-Response/AKA-Identity containing the fast re-authentication
identity. Otherwise the peer MUST respond with a EAP-Response/
AKA-Identity containing the SUCI, and MUST represent the SUCI as
specified in Section 5.3.2.1.
Similarly, if the peer is communicating over a non-3GPP network but Note: Currently, the following conditions are specified: when the
carrying EAP inside 5G NAS protocol, it MUST assume that the EAP EAP peer uses the 5G Non-Access Stratum (NAS) protocol
server is in a 5G network, and again employ the SUCI within EAP. [TS-3GPP.24.501] or when the EAP peer attaches to a network that
advertises 5G connectivity without NAS [TS-3GPP.23.501]. Possible
future conditions may also be specified by 3GPP.
Otherwise, the peer SHOULD employ IMSI, SUPI, or a NAI as it is When the 5G procedures for EAP-AKA' apply, EAP identity exchanges are
configured to use. generally not used as the identity is already made available on
previous link layer exchanges.
5.3.2.1. Format of the SUCI In this situation, the EAP Identity Response and EAP-AKA' AT_IDENTITY
attribute are handled as specified in Annex F.2 of [TS-3GPP.33.501].
When used in EAP-AKA', the format of the SUCI MUST be as specified in When used in EAP-AKA', the format of the SUCI MUST be as specified in
[TS-3GPP.23.003] Section 28.7.3, with the semantics defined in [TS-3GPP.23.003] Section 28.7.3, with the semantics defined in
[TS-3GPP.23.003] Section 2.2B. Also, in contrast to [RFC5448], in 5G [TS-3GPP.23.003] Section 2.2B. Also, in contrast to [RFC5448], in 5G
EAP-AKA' does not use the "0" or "6" prefix in front of the EAP-AKA' does not use the "0" or "6" prefix in front of the
identifier. identifier.
For instance, assuming the IMSI 234150999999999, where MCC=234, For an example of an IMSI in NAI format, see [TS-3GPP.23.003]
MNC=15 and MSISN=0999999999, the Routing Indicator 678, and a Home Section 28.7.3.
Network Public Key Identifier of 27, the NAI format for the SUCI
takes the form:
For the null-scheme:
type0.rid678.schid0.userid0999999999@nai.5gc.mnc015.
mcc234.3gppnetwork.org
For the Profile <A> protection scheme:
type0.rid678.schid1.hnkey27.ecckey<ECC ephemeral public key>. Otherwise, the peer SHOULD employ IMSI, SUPI, or a NAI as it is
cip<encryption of 0999999999>.mac<MAC tag value>@nai.5gc. configured to use.
mnc015.mcc234.3gppnetwork.org
6. Exported Parameters 6. Exported Parameters
The EAP-AKA' Session-Id is the concatenation of the EAP Type Code When not using fast re-authentication, the EAP-AKA' Session-Id is the
(0x32, one byte) with the contents of the RAND field from the AT_RAND concatenation of the EAP Type Code (0x32, one byte) with the contents
attribute, followed by the contents of the AUTN field in the AT_AUTN of the RAND field from the AT_RAND attribute, followed by the
attribute: contents of the AUTN field in the AT_AUTN attribute :
Session-Id = 0x32 || RAND || AUTN Session-Id = 0x32 || RAND || AUTN
When using fast re-authentication, the EAP-AKA' Session-Id is the When using fast re-authentication, the EAP-AKA' Session-Id is the
concatenation of the EAP Type Code (0x32) with the contents of the concatenation of the EAP Type Code (0x32) with the contents of the
NONCE_S field from the AT_NONCE_S attribute, followed by the contents 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- of the MAC field from the AT_MAC attribute from EAP-Request/AKA-
Reauthentication: Reauthentication:
Session-Id = 0x32 || NONCE_S || MAC Session-Id = 0x32 || NONCE_S || MAC
The Peer-Id is the contents of the Identity field from the The Peer-Id is the contents of the Identity field from the
AT_IDENTITY attribute, using only the Actual Identity Length bytes AT_IDENTITY attribute, using only the Actual Identity Length bytes
from the beginning. Note that the contents are used as they are from the beginning. Note that the contents are used as they are
transmitted, regardless of whether the transmitted identity was a transmitted, regardless of whether the transmitted identity was a
permanent, pseudonym, or fast EAP re-authentication identity. If no permanent, pseudonym, or fast EAP re-authentication identity. If no
AT_IDENTITY attribute was exchanged, the exported Peer-Id is the AT_IDENTITY attribute was exchanged, the exported Peer-Id is the
identity provided from the EAP Identity Response packet. If no EAP identity provided from the EAP Identity Response packet. If no EAP
Identity Response was provided either, the exported Peer-Id is null Identity Response was provided either, the exported Peer-Id is the
string (zero length). null string (zero length).
The Server-Id is the null string (zero length). The Server-Id is the null string (zero length).
7. Security Considerations 7. Security Considerations
A summary of the security properties of EAP-AKA' follows. These A summary of the security properties of EAP-AKA' follows. These
properties are very similar to those in EAP-AKA. We assume that HMAC properties are very similar to those in EAP-AKA. We assume that HMAC
SHA-256 is at least as secure as HMAC SHA-1 (see also [RFC6194]. SHA-256 is at least as secure as HMAC SHA-1 (see also [RFC6194].
This is called the SHA-256 assumption in the remainder of this This is called the SHA-256 assumption in the remainder of this
section. Under this assumption, EAP-AKA' is at least as secure as section. Under this assumption, EAP-AKA' is at least as secure as
EAP-AKA. EAP-AKA.
If the AT_KDF attribute has value 1, then the security properties of If the AT_KDF attribute has value 1, then the security properties of
EAP-AKA' are as follows: EAP-AKA' are as follows:
Protected ciphersuite negotiation Protected ciphersuite negotiation
EAP-AKA' has no ciphersuite negotiation mechanisms. It does have EAP-AKA' has no ciphersuite negotiation mechanisms. It does have
a negotiation mechanism for selecting the key derivation a negotiation mechanism for selecting the key derivation
functions. This mechanism is secure against bidding down attacks. functions. This mechanism is secure against bidding down attacks
The negotiation mechanism allows changing the offered key from EAP-AKA' to EAP-AKA. The negotiation mechanism allows
derivation function, but the change is visible in the final EAP- changing the offered key derivation function, but the change is
Request/AKA'-Challenge message that the server sends to the peer. visible in the final EAP-Request/AKA'-Challenge message that the
This message is authenticated via the AT_MAC attribute, and server sends to the peer. This message is authenticated via the
carries both the chosen alternative and the initially offered AT_MAC attribute, and carries both the chosen alternative and the
list. The peer refuses to accept a change it did not initiate. initially offered list. The peer refuses to accept a change it
As a result, both parties are aware that a change is being made did not initiate. As a result, both parties are aware that a
and what the original offer was. change is being made and what the original offer was.
Per assumptions in Section 4, there is no protection against
bidding down attacks from EAP-AKA to EAP-AKA', should EAP-AKA'
somehow be considered less secure some day than EAP-AKA. Such
protection was not provided in RFC 5448 implementations and
consequently neither does this specification provide it. If such
support is needed, it would have to be added as a separate new
feature.
In general, it is expected that the current negotiation
capabilities in EAP-AKA' are sufficient for some types of
extensions, including adding Perfect Forward Secrecy
([I-D.ietf-emu-aka-pfs]) and perhaps others. But as with how EAP-
AKA' itself came about, some larger changes may require a new EAP
method type. One example of such change would be the introduction
of new algorithms.
Mutual authentication Mutual authentication
Under the SHA-256 assumption, the properties of EAP-AKA' are at Under the SHA-256 assumption, the properties of EAP-AKA' are at
least as good as those of EAP-AKA in this respect. Refer to least as good as those of EAP-AKA in this respect. Refer to
[RFC4187], Section 12 for further details. [RFC4187], Section 12 for further details.
Integrity protection Integrity protection
Under the SHA-256 assumption, the properties of EAP-AKA' are at Under the SHA-256 assumption, the properties of EAP-AKA' are at
least as good (most likely better) as those of EAP-AKA in this least as good (most likely better) as those of EAP-AKA in this
respect. Refer to [RFC4187], Section 12 for further details. The respect. Refer to [RFC4187], Section 12 for further details. The
only difference is that a stronger hash algorithm and keyed MAC, only difference is that a stronger hash algorithm and keyed MAC,
skipping to change at page 29, line 18 skipping to change at page 28, line 38
7.1. Privacy 7.1. Privacy
[RFC6973] suggests that the privacy considerations of IETF protocols [RFC6973] suggests that the privacy considerations of IETF protocols
be documented. be documented.
The confidentiality properties of EAP-AKA' itself have been discussed The confidentiality properties of EAP-AKA' itself have been discussed
above under "Confidentiality". above under "Confidentiality".
EAP-AKA' uses several different types of identifiers to identify the EAP-AKA' uses several different types of identifiers to identify the
authenticating peer. It is strongly RECOMMENDED to use the privacy- authenticating peer. It is strongly RECOMMENDED to use the privacy-
friendly temporary or hidden identifiers, i.e., the 5G SUCI, friendly temporary or hidden identifiers, i.e., the 5G GUTI or SUCI,
pseudonym usernames, and fast re-authentication usernames. The use pseudonym usernames, and fast re-authentication usernames. The use
of permanent identifiers such as the IMSI or SUPI may lead to an of permanent identifiers such as the IMSI or SUPI may lead to an
ability to track the peer and/or user associated with the peer. The ability to track the peer and/or user associated with the peer. The
use of permanent identifiers such as the IMSI or SUPI is strongly NOT use of permanent identifiers such as the IMSI or SUPI is strongly NOT
RECOMMENDED. RECOMMENDED.
As discussed in Section 5.3, when authenticating to a 5G network, As discussed in Section 5.3, when authenticating to a 5G network,
only the 5G SUCI identifier should be used. The use of pseudonyms in only the SUCI identifier is normally used. The use of EAP-AKA'
this situation is at best limited. In fact, the re-use of the same pseudonyms in this situation is at best limited, because the SUCI
pseudonym multiple times will result in a tracking opportunity for already provides a stronger mechanism. In fact, the re-use of the
observers that see the pseudonym pass by. To avoid this, the peer same pseudonym multiple times will result in a tracking opportunity
and server need to follow the guidelines given in Section 5.2. for observers that see the pseudonym pass by. To avoid this, the
peer and server need to follow the guidelines given in Section 5.2.
When authenticating to a 5G network, per Section 5.3.1, both the EAP- When authenticating to a 5G network, per Section 5.3.1, both the EAP-
AKA' peer and server need to employ the permanent identifier, SUPI, AKA' peer and server need to employ the permanent identifier, SUPI,
as an input to key derivation. However, this use of the SUPI is only as an input to key derivation. However, this use of the SUPI is only
internal. As such, the SUPI need not be communicated in EAP internal. As such, the SUPI need not be communicated in EAP
messages. Therefore, SUPI MUST NOT be communicated in EAP-AKA' when messages. Therefore, SUPI MUST NOT be communicated in EAP-AKA' when
authenticating to a 5G network. authenticating to a 5G network.
While the use of SUCI in 5G networks generally provides identity While the use of SUCI in 5G networks generally provides identity
privacy, this is not true if the null-scheme encryption is used to privacy, this is not true if the null-scheme encryption is used to
construct the SUCI (see [TS-3GPP.23.501] Annex C). The use of this construct the SUCI (see [TS-3GPP.33.501] Annex C). The use of this
scheme turns the use of SUCI equivalent to the use of SUPI or IMSI. scheme turns the use of SUCI equivalent to the use of SUPI or IMSI.
The use of the null scheme is NOT RECOMMENDED where identity privacy The use of the null scheme is NOT RECOMMENDED where identity privacy
is important. is important.
The use of fast re-authentication identities when authenticating to a The use of fast re-authentication identities when authenticating to a
5G network does not have the same problems as the use of pseudonyms, 5G network does not have the same problems as the use of pseudonyms,
as long as the 5G authentication server generates the fast re- as long as the 5G authentication server generates the fast re-
authentication identifiers in a proper manner specified in authentication identifiers in a proper manner specified in
Section 5.2. Section 5.2.
Outside 5G, there is a full choice to use permanent, pseudonym, or Outside 5G, the peer can freely choose between the use of permanent,
fast re-authentication identifiers: pseudonym, or fast re-authentication identifiers:
o A peer that has not yet performed any EAP-AKA' exchanges does not o A peer that has not yet performed any EAP-AKA' exchanges does not
typically have a pseudonym available. If the peer does not have a typically have a pseudonym available. If the peer does not have a
pseudonym available, then the privacy mechanism cannot be used, pseudonym available, then the privacy mechanism cannot be used,
and the permanent identity will have to be sent in the clear. and the permanent identity will have to be sent in the clear.
The terminal SHOULD store the pseudonym in non-volatile memory so The terminal SHOULD store the pseudonym in non-volatile memory so
that it can be maintained across reboots. An active attacker that that it can be maintained across reboots. An active attacker that
impersonates the network may use the AT_PERMANENT_ID_REQ attribute impersonates the network may use the AT_PERMANENT_ID_REQ attribute
([RFC4187] Section 4.1.2) to learn the subscriber's IMSI. ([RFC4187] Section 4.1.2) to learn the subscriber's IMSI.
skipping to change at page 30, line 28 skipping to change at page 29, line 48
refuse to send the cleartext permanent identity if it believes refuse to send the cleartext permanent identity if it believes
that the network should be able to recognize the pseudonym. that the network should be able to recognize the pseudonym.
o When pseudonyms and fast re-authentication identities are used, o When pseudonyms and fast re-authentication identities are used,
the peer relies on the properly created identifiers by the server. the peer relies on the properly created identifiers by the server.
It is essential that an attacker cannot link a privacy-friendly It is essential that an attacker cannot link a privacy-friendly
identifier to the user in any way or determine that two identifier to the user in any way or determine that two
identifiers belong to the same user as outlined in Section 5.2. identifiers belong to the same user as outlined in Section 5.2.
The pseudonym usernames and fast re-authentication identities MUST The pseudonym usernames and fast re-authentication identities MUST
also not be used for other purposes (e.g. in other protocols). NOT be used for other purposes (e.g., in other protocols).
If the peer and server cannot guarantee that 5G SUCI can be used or If the peer and server cannot guarantee that SUCI can be used or
pseudonyms will available, generated properly, and maintained pseudonyms will be available, generated properly, and maintained
reliably, and identity privacy is required then additional protection reliably, and identity privacy is required then additional protection
from an external security mechanism such as tunneled EAP methods may from an external security mechanism such as tunneled EAP methods such
be used. The benefits and the security considerations of using an as TTLS [RFC5281] or TEAP [RFC7170] may be used. The benefits and
external security mechanism with EAP-AKA are beyond the scope of this the security considerations of using an external security mechanism
document. with EAP-AKA are beyond the scope of this document.
Finally, as with other EAP methods, even when privacy-friendly Finally, as with other EAP methods, even when privacy-friendly
identifiers or EAP tunneling is used, typically the domain part of an identifiers or EAP tunneling is used, typically the domain part of an
identifier (e.g., the home operator) is visible to external parties. identifier (e.g., the home operator) is visible to external parties.
7.2. Discovered Vulnerabilities 7.2. Discovered Vulnerabilities
There have been no published attacks that violate the primary secrecy There have been no published attacks that violate the primary secrecy
or authentication properties defined for Authentication and Key or authentication properties defined for Authentication and Key
Agreement (AKA) under the originally assumed trust model. The same Agreement (AKA) under the originally assumed trust model. The same
is true of EAP-AKA'. is true of EAP-AKA'.
However, there have been attacks when a different trust model is in However, there have been attacks when a different trust model is in
use, with characteristics not originally provided by the design, or use, with characteristics not originally provided by the design, or
when participants in the protocol leak information to outsiders on when participants in the protocol leak information to outsiders on
purpose, and there has been some privacy-related attacks. purpose, and there have been some privacy-related attacks.
For instance, the original AKA protocol does not prevent supplying For instance, the original AKA protocol does not prevent supplying
keys by an insider to a third party as done in, e.g., by Mjolsnes and keys by an insider to a third party as done in, e.g., by Mjolsnes and
Tsay in [MT2012] where a serving network lets an authentication run Tsay in [MT2012] where a serving network lets an authentication run
succeed, but then misuses the session keys to send traffic on the succeed, but then misuses the session keys to send traffic on the
authenticated user's behalf. This particular attack is not different authenticated user's behalf. This particular attack is not different
from any on-path entity (such as a router) pretending to send from any on-path entity (such as a router) pretending to send
traffic, but the general issue of insider attacks can be a problem, traffic, but the general issue of insider attacks can be a problem,
particularly in a large group of collaborating operators. particularly in a large group of collaborating operators.
Another class of attacks is the use of tunneling of traffic from one Another class of attacks is the use of tunneling of traffic from one
place to another, e.g., as done by Zhang and Fang in [ZF2005] to place to another, e.g., as done by Zhang and Fang in [ZF2005] to
leverage security policy differences between different operator leverage security policy differences between different operator
networks, for instance. To gain something in such an attack, the networks, for instance. To gain something in such an attack, the
attacker needs to trick the user into believing it is in another attacker needs to trick the user into believing it is in another
location where, for instance, it is not required to encrypt all location. If policies between different locations differ, for
payload traffic after encryption. As an authentication mechanism, instance, in some location it is not required to encrypt all payload
EAP-AKA' is not directly affected by most such attacks. EAP-AKA' traffic, the attacker may trick the user into opening a
network name binding can also help alleviate some of the attacks. In vulnerability. As an authentication mechanism, EAP-AKA' is not
any case, it is recommended that EAP-AKA' configuration not be directly affected by most such attacks. EAP-AKA' network name
dependent on the location of where a request comes from, unless the binding can also help alleviate some of the attacks. In any case, it
location information can be cryptographically confirmed, e.g., with is recommended that EAP-AKA' configuration not be dependent on the
the network name binding. location of where a request comes from, unless the location
information can be cryptographically confirmed, e.g., with the
network name binding.
Zhang and Fang also looked at Denial-of-Service attacks [ZF2005]. A Zhang and Fang also looked at Denial-of-Service attacks [ZF2005]. A
serving network may request large numbers of authentication runs for serving network may request large numbers of authentication runs for
a particular subscriber from a home network. While resynchronization a particular subscriber from a home network. While resynchronization
process can help recover from this, eventually it is possible to process can help recover from this, eventually it is possible to
exhaust the sequence number space and render the subscriber's card exhaust the sequence number space and render the subscriber's card
unusable. This attack is possible for both native AKA and EAP-AKA'. unusable. This attack is possible for both native AKA and EAP-AKA'.
However, it requires the collaboration of a serving network in an However, it requires the collaboration of a serving network in an
attack. It is recommended that EAP-AKA' implementations provide attack. It is recommended that EAP-AKA' implementations provide
means to track, detect, and limit excessive authentication attempts means to track, detect, and limit excessive authentication attempts
to combat this problem. to combat this problem.
There has also been attacks related to the use of AKA without the There have also been attacks related to the use of AKA without the
generated session keys (e.g., [BT2013]). Some of those attacks generated session keys (e.g., [BT2013]). Some of those attacks
relate to the use of originally man-in-the-middle vulnerable HTTP relate to the use of originally man-in-the-middle vulnerable HTTP
Digest AKAv1 [RFC3310]. This has since then been corrected in Digest AKAv1 [RFC3310]. This has since then been corrected in
[RFC4169]. The EAP-AKA' protocol uses session keys and provides [RFC4169]. The EAP-AKA' protocol uses session keys and provides
channel binding, and as such, is resistant to the above attacks channel binding, and as such, is resistant to the above attacks
except where the protocol participants leak information to outsiders. except where the protocol participants leak information to outsiders.
Basin et al [Basin2018] have performed formal analysis and concluded Basin et al [Basin2018] have performed formal analysis and concluded
that the AKA protocol would have benefited from additional security that the AKA protocol would have benefited from additional security
requirements, such as key confirmation. requirements, such as key confirmation.
skipping to change at page 32, line 26 skipping to change at page 31, line 48
Borgaonkar et al discovered that the AKA resynchronization protocol Borgaonkar et al discovered that the AKA resynchronization protocol
may also be used to predict the authentication frequency of a may also be used to predict the authentication frequency of a
subscribers if non-time-based SQN generation scheme is used subscribers if non-time-based SQN generation scheme is used
[Borgaonkar2018]. The attacker can force the re-use of the keystream [Borgaonkar2018]. The attacker can force the re-use of the keystream
that is used to protect the SQN in the AKA resynchronization that is used to protect the SQN in the AKA resynchronization
protocol. The attacker then guesses the authentication frequency protocol. The attacker then guesses the authentication frequency
based on the lowest bits of two XORed SQNs. The researchers' concern based on the lowest bits of two XORed SQNs. The researchers' concern
was that the authentication frequency would reveal some information was that the authentication frequency would reveal some information
about the phone usage behavior, e.g., number of phone calls made or about the phone usage behavior, e.g., number of phone calls made or
number of SMS messages sent. However, phone calls and SMS messages number of SMS messages sent. There are a number of possible triggers
are just some of the many potential triggers for authentication. For for authentication, so such information leak is not direct, but can
instance, various mobility events and the amount of mobile data sent be a concern. The impact of the attack is also different depending
or received can also trigger authentication. As a result, while some on whether time or non-time-based SQN generation scheme is used.
amount of information may be derived about the activity level on a
particular phone in some cases, the linkage to specific activities is
not direct. The impact of the attack is also different depending on
whether time or non-time-based SQN generation scheme is used.
Similar attacks are possible outside AKA in the cellular paging Similar attacks are possible outside AKA in the cellular paging
protocols where the attacker can simply send application layer data, protocols where the attacker can simply send application layer data,
short messages or make phone calls to the intended victim and observe short messages or make phone calls to the intended victim and observe
the air-interface (e.g., [Kune2012] and [Shaik2016]). Hussain et. the air-interface (e.g., [Kune2012] and [Shaik2016]). Hussain et.
al. demonstrated a slightly more sophisticated version of the attack al. demonstrated a slightly more sophisticated version of the attack
that exploits the fact that 4G paging protocol uses the IMSI to that exploits the fact that 4G paging protocol uses the IMSI to
calculate the paging timeslot [Hussain2019]. As this attack is calculate the paging timeslot [Hussain2019]. As this attack is
outside AKA, it does not impact EAP-AKA'. outside AKA, it does not impact EAP-AKA'.
Finally, bad implementations of EAP-AKA' may not produce pseudonym Finally, bad implementations of EAP-AKA' may not produce pseudonym
usernames or fast re-authentication identities in a manner that is usernames or fast re-authentication identities in a manner that is
sufficiently secure. While it is not a problem with the protocol sufficiently secure. While it is not a problem with the protocol
itself, recommendations from Section 5.2 need to be followed to avoid itself, following the recommendations in Section 5.2 mitigate this
this. concern.
7.3. Pervasive Monitoring 7.3. Pervasive Monitoring
As required by [RFC7258], work on IETF protocols needs to consider As required by [RFC7258], work on IETF protocols needs to consider
the effects of pervasive monitoring and mitigate them when possible. the effects of pervasive monitoring and mitigate them when possible.
As described Section 7.2, after the publication of RFC 5448, new As described in Section 7.2, after the publication of RFC 5448, new
information has come to light regarding the use of pervasive information has come to light regarding the use of pervasive
monitoring techniques against many security technologies, including monitoring techniques against many security technologies, including
AKA-based authentication. AKA-based authentication.
For AKA, these attacks relate to theft of the long-term shared secret For AKA, these attacks relate to theft of the long-term shared secret
key material stored on the cards. Such attacks are conceivable, for key material stored on the cards. Such attacks are conceivable, for
instance, during the manufacturing process of cards, through coercion instance, during the manufacturing process of cards, through coercion
of the card manufacturers, or during the transfer of cards and of the card manufacturers, or during the transfer of cards and
associated information to an operator. Since the publication of associated information to an operator. Since the publication of
reports about such attacks, manufacturing and provisioning processes reports about such attacks, manufacturing and provisioning processes
have gained much scrutiny and have improved. have gained much scrutiny and have improved.
In particular, it is crucial that manufacturers limit access to the In particular, it is crucial that manufacturers limit access to the
secret information and the cards only to necessary systems and secret information and the cards only to necessary systems and
personnel. It is also crucial that secure mechanisms be used to personnel. It is also crucial that secure mechanisms be used to
communicate the secrets between the manufacturer and the operator store and communicate the secrets between the manufacturer and the
that adopts those cards for their customers. operator that adopts those cards for their customers.
Beyond these operational considerations, there are also technical Beyond these operational considerations, there are also technical
means to improve resistance to these attacks. One approach is to means to improve resistance to these attacks. One approach is to
provide Perfect Forwards Secrecy (PFS). This would prevent any provide Perfect Forward Secrecy (PFS). This would prevent any
passive attacks merely based on the long-term secrets and observation passive attacks merely based on the long-term secrets and observation
of traffic. Such a mechanism can be defined as an backwards- of traffic. Such a mechanism can be defined as a backwards-
compatible extension of EAP-AKA', and is pursued separately from this compatible extension of EAP-AKA', and is pursued separately from this
specification [I-D.arkko-eap-aka-pfs]. Alternatively, EAP-AKA' specification [I-D.ietf-emu-aka-pfs]. Alternatively, EAP-AKA'
authentication can be run inside a PFS-capable tunneled authentication can be run inside a PFS-capable tunneled
authentication method. In any case, the use of some PFS-capable authentication method. In any case, the use of some PFS-capable
mechanism is recommended. mechanism is recommended.
7.4. Security Properties of Binding Network Names 7.4. Security Properties of Binding Network Names
The ability of EAP-AKA' to bind the network name into the used keys The ability of EAP-AKA' to bind the network name into the used keys
provides some additional protection against key leakage to provides some additional protection against key leakage to
inappropriate parties. The keys used in the protocol are specific to inappropriate parties. The keys used in the protocol are specific to
a particular network name. If key leakage occurs due to an accident, a particular network name. If key leakage occurs due to an accident,
skipping to change at page 35, line 45 skipping to change at page 35, line 15
Value Description Reference Value Description Reference
--------- ---------------------- ------------------------------- --------- ---------------------- -------------------------------
0 Reserved [RFC Editor: Refer to this RFC] 0 Reserved [RFC Editor: Refer to this RFC]
1 EAP-AKA' with CK'/IK' [RFC Editor: Refer to this RFC] 1 EAP-AKA' with CK'/IK' [RFC Editor: Refer to this RFC]
2-65535 Unassigned 2-65535 Unassigned
9. References 9. References
9.1. Normative References 9.1. Normative References
[Note] Editors, "All 3GPP references should be updated to the
latest Release 15 version before publishing.".
[TS-3GPP.23.003] [TS-3GPP.23.003]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Numbering, Specification Group Core Network and Terminals; Numbering,
addressing and identification (Release 15)", 3GPP Draft addressing and identification (Release 16)",
Technical Specification 23.003, June 2019. 3GPP Technical Specification 23.003 version 16.5.0,
December 2020.
[TS-3GPP.23.501] [TS-3GPP.23.501]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G Specification Group Services and System Aspects; 3G
Security; Security architecture and procedures for 5G Security; Security architecture and procedures for 5G
System; (Release 15)", 3GPP Technical Specification System; (Release 16)", 3GPP Technical Specification 23.501
23.501, June 2019. version 16.7.0, December 2020.
[TS-3GPP.24.302] [TS-3GPP.24.302]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Access to Specification Group Core Network and Terminals; Access to
the 3GPP Evolved Packet Core (EPC) via non-3GPP access the 3GPP Evolved Packet Core (EPC) via non-3GPP access
networks; Stage 3; (Release 15)", 3GPP Draft Technical networks; Stage 3; (Release 16)", 3GPP Technical
Specification 24.302, June 2019. Specification 24.302 version 16.4.0, July 2020.
[TS-3GPP.24.501] [TS-3GPP.24.501]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Access to Specification Group Core Network and Terminals; Access to
the 3GPP Evolved Packet Core (EPC) via non-3GPP access the 3GPP Evolved Packet Core (EPC) via non-3GPP access
networks; Stage 3; (Release 15)", 3GPP Draft Technical networks; Stage 3; (Release 16)", 3GPP Draft Technical
Specification 24.501, June 2019. Specification 24.501 version 16.7.0, December 2020.
[TS-3GPP.33.102] [TS-3GPP.33.102]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G Specification Group Services and System Aspects; 3G
Security; Security architecture (Release 15)", 3GPP Draft Security; Security architecture (Release 16)",
Technical Specification 33.102, December 2018. 3GPP Technical Specification 33.102 version 16.0.0, July
2020.
[TS-3GPP.33.402] [TS-3GPP.33.402]
3GPP, "3GPP System Architecture Evolution (SAE); Security 3GPP, "3GPP System Architecture Evolution (SAE); Security
aspects of non-3GPP accesses (Release 15)", 3GPP Draft aspects of non-3GPP accesses (Release 16)", 3GPP Technical
Technical Specification 33.402, June 2018. Specification 33.402 version 16.0.0, July 2020.
[TS-3GPP.33.501] [TS-3GPP.33.501]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G Specification Group Services and System Aspects; 3G
Security; Security architecture and procedures for 5G Security; Security architecture and procedures for 5G
System (Release 15)", 3GPP Draft Technical Specification System (Release 16)", 3GPP Technical Specification 33.501
33.501, June 2019. version 16.5.0, December 2020.
[FIPS.180-4] [FIPS.180-4]
National Institute of Standards and Technology, "Secure National Institute of Standards and Technology, "Secure
Hash Standard", FIPS PUB 180-4, August 2015, Hash Standard", FIPS PUB 180-4, August 2015,
<https://nvlpubs.nist.gov/nistpubs/FIPS/ <https://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.180-4.pdf>. NIST.FIPS.180-4.pdf>.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997, <https://www.rfc- DOI 10.17487/RFC2104, February 1997, <https://www.rfc-
skipping to change at page 37, line 40 skipping to change at page 37, line 11
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References 9.2. Informative References
[NoteAlso]
Editors, "All 3GPP references should be updated to the
latest Release 15 version before publishing.".
[TS-3GPP.35.208] [TS-3GPP.35.208]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G Specification Group Services and System Aspects; 3G
Security; Specification of the MILENAGE Algorithm Set: An Security; Specification of the MILENAGE Algorithm Set: An
example algorithm set for the 3GPP authentication and key example algorithm set for the 3GPP authentication and key
generation functions f1, f1*, f2, f3, f4, f5 and f5*; generation functions f1, f1*, f2, f3, f4, f5 and f5*;
Document 4: Design Conformance Test Data (Release 14)", Document 4: Design Conformance Test Data (Release 14)",
3GPP Technical Specification 35.208, October 2018. 3GPP Technical Specification 35.208 version 15.0.0,
October 2018.
[FIPS.180-1] [FIPS.180-1]
National Institute of Standards and Technology, "Secure National Institute of Standards and Technology, "Secure
Hash Standard", FIPS PUB 180-1, April 1995, Hash Standard", FIPS PUB 180-1, April 1995,
<http://www.itl.nist.gov/fipspubs/fip180-1.htm>. <http://www.itl.nist.gov/fipspubs/fip180-1.htm>.
[FIPS.180-2] [FIPS.180-2]
National Institute of Standards and Technology, "Secure National Institute of Standards and Technology, "Secure
Hash Standard", FIPS PUB 180-2, August 2002, Hash Standard", FIPS PUB 180-2, August 2002,
<http://csrc.nist.gov/publications/fips/fips180-2/ <http://csrc.nist.gov/publications/fips/fips180-2/
skipping to change at page 38, line 43 skipping to change at page 38, line 10
Authentication Protocol Method for Global System for Authentication Protocol Method for Global System for
Mobile Communications (GSM) Subscriber Identity Modules Mobile Communications (GSM) Subscriber Identity Modules
(EAP-SIM)", RFC 4186, DOI 10.17487/RFC4186, January 2006, (EAP-SIM)", RFC 4186, DOI 10.17487/RFC4186, January 2006,
<https://www.rfc-editor.org/info/rfc4186>. <https://www.rfc-editor.org/info/rfc4186>.
[RFC4284] Adrangi, F., Lortz, V., Bari, F., and P. Eronen, "Identity [RFC4284] Adrangi, F., Lortz, V., Bari, F., and P. Eronen, "Identity
Selection Hints for the Extensible Authentication Protocol Selection Hints for the Extensible Authentication Protocol
(EAP)", RFC 4284, DOI 10.17487/RFC4284, January 2006, (EAP)", RFC 4284, DOI 10.17487/RFC4284, January 2006,
<https://www.rfc-editor.org/info/rfc4284>. <https://www.rfc-editor.org/info/rfc4284>.
[RFC4306] Kaufman, C., Ed., "Internet Key Exchange (IKEv2)
Protocol", RFC 4306, DOI 10.17487/RFC4306, December 2005,
<https://www.rfc-editor.org/info/rfc4306>.
[RFC5113] Arkko, J., Aboba, B., Korhonen, J., Ed., and F. Bari, [RFC5113] Arkko, J., Aboba, B., Korhonen, J., Ed., and F. Bari,
"Network Discovery and Selection Problem", RFC 5113, "Network Discovery and Selection Problem", RFC 5113,
DOI 10.17487/RFC5113, January 2008, <https://www.rfc- DOI 10.17487/RFC5113, January 2008, <https://www.rfc-
editor.org/info/rfc5113>. editor.org/info/rfc5113>.
[RFC5247] Aboba, B., Simon, D., and P. Eronen, "Extensible [RFC5247] Aboba, B., Simon, D., and P. Eronen, "Extensible
Authentication Protocol (EAP) Key Management Framework", Authentication Protocol (EAP) Key Management Framework",
RFC 5247, DOI 10.17487/RFC5247, August 2008, RFC 5247, DOI 10.17487/RFC5247, August 2008,
<https://www.rfc-editor.org/info/rfc5247>. <https://www.rfc-editor.org/info/rfc5247>.
[RFC5281] Funk, P. and S. Blake-Wilson, "Extensible Authentication
Protocol Tunneled Transport Layer Security Authenticated
Protocol Version 0 (EAP-TTLSv0)", RFC 5281,
DOI 10.17487/RFC5281, August 2008, <https://www.rfc-
editor.org/info/rfc5281>.
[RFC5448] Arkko, J., Lehtovirta, V., and P. Eronen, "Improved [RFC5448] Arkko, J., Lehtovirta, V., and P. Eronen, "Improved
Extensible Authentication Protocol Method for 3rd Extensible Authentication Protocol Method for 3rd
Generation Authentication and Key Agreement (EAP-AKA')", Generation Authentication and Key Agreement (EAP-AKA')",
RFC 5448, DOI 10.17487/RFC5448, May 2009, RFC 5448, DOI 10.17487/RFC5448, May 2009,
<https://www.rfc-editor.org/info/rfc5448>. <https://www.rfc-editor.org/info/rfc5448>.
[RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security [RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security
Considerations for the SHA-0 and SHA-1 Message-Digest Considerations for the SHA-0 and SHA-1 Message-Digest
Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011, Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011,
<https://www.rfc-editor.org/info/rfc6194>. <https://www.rfc-editor.org/info/rfc6194>.
[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", RFC 6973, Considerations for Internet Protocols", RFC 6973,
DOI 10.17487/RFC6973, July 2013, <https://www.rfc- DOI 10.17487/RFC6973, July 2013, <https://www.rfc-
editor.org/info/rfc6973>. editor.org/info/rfc6973>.
[RFC7170] Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna,
"Tunnel Extensible Authentication Protocol (TEAP) Version
1", RFC 7170, DOI 10.17487/RFC7170, May 2014,
<https://www.rfc-editor.org/info/rfc7170>.
[RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an [RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
2014, <https://www.rfc-editor.org/info/rfc7258>. 2014, <https://www.rfc-editor.org/info/rfc7258>.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2 Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <https://www.rfc-editor.org/info/rfc7296>. 2014, <https://www.rfc-editor.org/info/rfc7296>.
[I-D.arkko-eap-aka-pfs] [I-D.ietf-emu-aka-pfs]
Arkko, J., Norrman, K., and V. Torvinen, "Perfect-Forward Ericsson, Ericsson, and Ericsson, "Perfect-Forward Secrecy
Secrecy for the Extensible Authentication Protocol Method for the Extensible Authentication Protocol Method for
for Authentication and Key Agreement (EAP-AKA' PFS)", Authentication and Key Agreement (EAP-AKA' PFS)", draft-
draft-arkko-eap-aka-pfs-04 (work in progress), January ietf-emu-aka-pfs-05 (work in progress), October 2020.
2019.
[Heist2015] [Heist2015]
Scahill, J. and J. Begley, "The great SIM heist", February Scahill, J. and J. Begley, "The great SIM heist", February
2015, in https://firstlook.org/theintercept/2015/02/19/ 2015, in https://firstlook.org/theintercept/2015/02/19/
great-sim-heist/ . great-sim-heist/ .
[MT2012] Mjolsnes, S. and J-K. Tsay, "A vulnerability in the UMTS [MT2012] Mjolsnes, S. and J-K. Tsay, "A vulnerability in the UMTS
and LTE authentication and key agreement protocols", and LTE authentication and key agreement protocols",
October 2012, in Proceedings of the 6th international October 2012, in Proceedings of the 6th international
conference on Mathematical Methods, Models and conference on Mathematical Methods, Models and
skipping to change at page 41, line 26 skipping to change at page 40, line 50
Thirdly, exported parameters for EAP-AKA' have been defined in Thirdly, exported parameters for EAP-AKA' have been defined in
Section 6, as required by [RFC5247], including the definition of Section 6, as required by [RFC5247], including the definition of
those parameters for both full authentication and fast re- those parameters for both full authentication and fast re-
authentication. authentication.
The security, privacy, and pervasive monitoring considerations have The security, privacy, and pervasive monitoring considerations have
been updated or added. See Section 7. been updated or added. See Section 7.
The references to [RFC2119], [RFC7542], [RFC7296], [RFC8126], The references to [RFC2119], [RFC7542], [RFC7296], [RFC8126],
[FIPS.180-1] and [FIPS.180-2] have been updated to their most recent [FIPS.180-1] and [FIPS.180-2] have been updated to their most recent
versions and language in this document changed accordingly. versions and language in this document changed accordingly. However,
this is merely an update to a newer RFC but the actual protocol
functions are the same as defined in the earlier RFCs.
Similarly, references to all 3GPP technical specifications have been Similarly, references to all 3GPP technical specifications have been
updated to their 5G (Release 15) versions or otherwise most recent updated to their 5G (Release 16) versions or otherwise most recent
version when there has not been a 5G-related update. version when there has not been a 5G-related update.
Finally, a number of clarifications have been made, including a Finally, a number of clarifications have been made, including a
summary of where attributes may appear. summary of where attributes may appear.
Appendix B. Changes from RFC 4187 to RFC 5448 Appendix B. Changes to RFC 4187
In addition to specifying EAP-AKA', this document mandates also a
change to another EAP method, EAP-AKA that was defined in RFC 4187.
This change was mandated already in RFC 5448 but repeated here to
ensure that the latest EAP-AKA' specification contains the
instructions about the necessary bidding down feature in EAP-AKA as
well.
The changes to RFC 4187 relate only to the bidding down prevention The changes to RFC 4187 relate only to the bidding down prevention
support defined in Section 4. In particular, this document does not support defined in Section 4. In particular, this document does not
change how the Master Key (MK) is calculated in RFC 4187 (it uses CK change how the Master Key (MK) is calculated or any other aspect of
and IK, not CK' and IK'); neither is any processing of the AMF bit EAP-AKA. The provisions in this specification for EAP-AKA' do not
added to RFC 4187. apply to EAP-AKA, outside Section 4.
Appendix C. Changes from Previous Version of This Draft Appendix C. Changes from Previous Version of This Draft
RFC Editor: Please delete this section at the time of publication. RFC Editor: Please delete this section at the time of publication.
The -00 version of the working group draft is merely a republication The -00 version of the working group draft is merely a republication
of an earlier individual draft. of an earlier individual draft.
The -01 version of the working group draft clarifies updates The -01 version of the working group draft clarifies updates
relationship to RFC 4187, clarifies language relating to obsoleting relationship to RFC 4187, clarifies language relating to obsoleting
skipping to change at page 43, line 36 skipping to change at page 43, line 21
o Updated and added several references o Updated and added several references
o Switched to use of hexadecimal for EAP Type Values for consistency o Switched to use of hexadecimal for EAP Type Values for consistency
with other documents. with other documents.
o Made editorial clarifications to a number places in the document. o Made editorial clarifications to a number places in the document.
The version -06 included changes to updates of references to newer The version -06 included changes to updates of references to newer
versions on IANA considerations guidelines, NAIs, and IKEv2. versions on IANA considerations guidelines, NAIs, and IKEv2.
The version -07 includes the following changes, per AD and last call
review comments:
o The use of pseudonyms has been clarified in Section 7.1.
o The document now clarifies that it specifies behaviour both for 4G
and 5G.
o The implications of collisions between "Access Network ID" (4G)
and "Serving Network Name" (5G) have been explained in
Section 3.1.
o The ability of the bidding down protection to protect bidding down
only in the direction from EAP-AKA' to EAP-AKA but the other way
around has been noted in Section 7.
o The implications of the attack described by [Borgaonkar2018] have
been updated.
o Section 3.1 now specifies more clearly that zero-length network
name is not allowed.
o Section 3.1 refers to the network name that is today specified in
[TS-3GPP.24.302] for both 4G (non-3GPP access) and 5G.
o Section 7 now discusses cryptographic agility.
o The document now is clear that any change to key aspects of 3GPP
specifications, such as key derivation for AKA, would affect this
specification and implementations.
o References have been updated to the latest Release 15 versions,
that are now stable.
o Tables have been numbered.
o Adopted a number of other editorial corrections.
The version -08 includes the following changes:
o Alignment of the 3GPP TS Annex and this draft, so that each
individual part of the specification is stated in only one place.
This has lead to this draft referring to bigger parts of the 3GPP
specification, instead of spelling out the details within this
document. Note that this alignment change is a proposal at this
stage, and will be discussed in the upcoming 3GPP meeting.
o Relaxed the language on using only SUCI in 5G. While that is the
mode of operation expected to be used, [TS-3GPP.33.501] does not
prohibit other types of identifiers.
The version -09 includes the following changes:
o Updated the language relating to obsoleting/updating RFC 5448;
there was an interest to ensure that RFC 5448 stays a valid
specification also in the future, owing to existing
implementations.
o Clarified that the leading digit "6" is not used in 5G networks.
o Updated the language relating to when 5G-specific procedures are
in effect, to support new use cases 3GPP has defined.
o Updated the reference in Section 3.3, as the identities are
different in the 5G case.
o Clarified that the use of the newer reference to IKEv2 RFC did not
change the actual PRF' function from RFC 5448.
o Clarified that the Section 5.2 text does not impact backwards
compatibility.
o Corrected the characterization of the attack from [ZF2005].
o Mentioned 5G GUTIs as one possible 5G-identifier in Section 5.1.
o Updated the references to Release 16. These specifications are
stable in 3GPP.
Version -10 is the final version and made changes per IESG and
directorate review comments. These changes were editorial. One
duplicate requirement in Section 5.3.1 was removed, and some
references were added for tunnel methods discussion in Section 7.1.
The language about exported parameters was clarified in Section 6.
Appendix D. Importance of Explicit Negotiation Appendix D. Importance of Explicit Negotiation
Choosing between the traditional and revised AKA key derivation Choosing between the traditional and revised AKA key derivation
functions is easy when their use is unambiguously tied to a functions is easy when their use is unambiguously tied to a
particular radio access network, e.g., Long Term Evolution (LTE) as particular radio access network, e.g., Long Term Evolution (LTE) as
defined by 3GPP or evolved High Rate Packet Data (eHRPD) as defined defined by 3GPP or evolved High Rate Packet Data (eHRPD) as defined
by 3GPP2. There is no possibility for interoperability problems if by 3GPP2. There is no possibility for interoperability problems if
this radio access network is always used in conjunction with new this radio access network is always used in conjunction with new
protocols that cannot be mixed with the old ones; clients will always protocols that cannot be mixed with the old ones; clients will always
know whether they are connecting to the old or new system. know whether they are connecting to the old or new system.
skipping to change at page 49, line 15 skipping to change at page 51, line 15
Jouni Malinen provided suggested text for Section 6. John Mattsson Jouni Malinen provided suggested text for Section 6. John Mattsson
provided much of the text for Section 7.1. Karl Norrman was the provided much of the text for Section 7.1. Karl Norrman was the
source of much of the information in Section 7.2. source of much of the information in Section 7.2.
Acknowledgments Acknowledgments
The authors would like to thank Guenther Horn, Joe Salowey, Mats The authors would like to thank Guenther Horn, Joe Salowey, Mats
Naslund, Adrian Escott, Brian Rosenberg, Laksminath Dondeti, Ahmad Naslund, Adrian Escott, Brian Rosenberg, Laksminath Dondeti, Ahmad
Muhanna, Stefan Rommer, Miguel Garcia, Jan Kall, Ankur Agarwal, Jouni Muhanna, Stefan Rommer, Miguel Garcia, Jan Kall, Ankur Agarwal, Jouni
Malinen, John Mattsson, Jesus De Gregorio, Brian Weis, Russ Housley, Malinen, John Mattsson, Jesus De Gregorio, Brian Weis, Russ Housley,
Alfred Hoenes, Anand Palanigounder, Michael Richardsson, Marcus Wong, Alfred Hoenes, Anand Palanigounder, Michael Richardsson, Roman
Kalle Jarvinen, Daniel Migault, and Mohit Sethi for their in-depth Danyliw, Dan Romascanu, Kyle Rose, Benjamin Kaduk, Alissa Cooper,
reviews and interesting discussions in this problem space. Erik Kline, Murray Kucherawy, Robert Wilton, Warren Kumari, Andreas
Kunz, Marcus Wong, Kalle Jarvinen, Daniel Migault, and Mohit Sethi
for their in-depth reviews and interesting discussions in this
problem space.
Authors' Addresses Authors' Addresses
Jari Arkko Jari Arkko
Ericsson Ericsson
Jorvas 02420 Jorvas 02420
Finland Finland
Email: jari.arkko@piuha.net Email: jari.arkko@piuha.net
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