draft-ietf-emu-rfc5448bis-10.txt   rfc9048.txt 
Network Working Group J. Arkko Internet Engineering Task Force (IETF) J. Arkko
Internet-Draft V. Lehtovirta Request for Comments: 9048 V. Lehtovirta
Updates: 5448,4187 (if approved) V. Torvinen Updates: 4187, 5448 V. Torvinen
Intended status: Informational Ericsson Category: Informational Ericsson
Expires: November 11, 2021 P. Eronen ISSN: 2070-1721 P. Eronen
Independent Independent
May 10, 2021 October 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-10
Abstract Abstract
The 3GPP Mobile Network Authentication and Key Agreement (AKA) is an The 3GPP mobile network Authentication and Key Agreement (AKA) is an
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 document is the most recent specification of EAP-AKA', This document is the most recent specification of EAP-AKA',
including, for instance, details and references about related to including, for instance, details about and references related to
operating EAP-AKA' in 5G networks. 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' also updates the in EAP in an interoperable manner. EAP-AKA' also updates the
algorithm used in hash functions, as it employs SHA-256 / HMAC- algorithm used in hash functions, as it employs SHA-256 / HMAC-
SHA-256 instead of SHA-1 / HMAC-SHA-1 as in EAP-AKA. SHA-256 instead of SHA-1 / HMAC-SHA-1, which is used in EAP-AKA.
This version of EAP-AKA' specification specifies the protocol This version of the EAP-AKA' specification defines the protocol
behaviour for both 4G and 5G deployments, whereas the previous behavior for both 4G and 5G deployments, whereas the previous version
version only did this for 4G. defined protocol behavior for 4G deployments only. While EAP-AKA' as
defined in RFC 5448 is not obsolete, this document defines the most
recent and fully backwards-compatible specification of EAP-AKA'.
This document updates both RFCs 4187 and 5448.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This document is not an Internet Standards Track specification; it is
provisions of BCP 78 and BCP 79. published for informational purposes.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are candidates for any level of Internet
Standard; see Section 2 of RFC 7841.
This Internet-Draft will expire on November 11, 2021. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9048.
Copyright Notice Copyright Notice
Copyright (c) 2021 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.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5 2. Requirements Language
3. EAP-AKA' . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. EAP-AKA'
3.1. AT_KDF_INPUT . . . . . . . . . . . . . . . . . . . . . . 8 3.1. AT_KDF_INPUT
3.2. AT_KDF . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2. AT_KDF
3.3. Key Derivation . . . . . . . . . . . . . . . . . . . . . 13 3.3. Key Derivation
3.4. Hash Functions . . . . . . . . . . . . . . . . . . . . . 15 3.4. Hash Functions
3.4.1. PRF' . . . . . . . . . . . . . . . . . . . . . . . . 15 3.4.1. PRF'
3.4.2. AT_MAC . . . . . . . . . . . . . . . . . . . . . . . 15 3.4.2. AT_MAC
3.4.3. AT_CHECKCODE . . . . . . . . . . . . . . . . . . . . 15 3.4.3. AT_CHECKCODE
3.5. Summary of Attributes for EAP-AKA' . . . . . . . . . . . 16 3.5. Summary of Attributes for EAP-AKA'
4. Bidding Down Prevention for EAP-AKA . . . . . . . . . . . . . 18 4. Bidding Down Prevention for EAP-AKA
4.1. Summary of Attributes for EAP-AKA . . . . . . . . . . . . 20 4.1. Summary of Attributes for EAP-AKA
5. Peer Identities . . . . . . . . . . . . . . . . . . . . . . . 20 5. Peer Identities
5.1. Username Types in EAP-AKA' Identities . . . . . . . . . . 20 5.1. Username Types in EAP-AKA' Identities
5.2. Generating Pseudonyms and Fast Re-Authentication 5.2. Generating Pseudonyms and Fast Re-Authentication Identities
Identities . . . . . . . . . . . . . . . . . . . . . . . 21 5.3. Identifier Usage in 5G
5.3. Identifier Usage in 5G . . . . . . . . . . . . . . . . . 22 5.3.1. Key Derivation
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
6. Exported Parameters . . . . . . . . . . . . . . . . . . . . . 24 6. Exported Parameters
7. Security Considerations . . . . . . . . . . . . . . . . . . . 25 7. Security Considerations
7.1. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 28 7.1. Privacy
7.2. Discovered Vulnerabilities . . . . . . . . . . . . . . . 30 7.2. Discovered Vulnerabilities
7.3. Pervasive Monitoring . . . . . . . . . . . . . . . . . . 32 7.3. Pervasive Monitoring
7.4. Security Properties of Binding Network Names . . . . . . 33 7.4. Security Properties of Binding Network Names
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34 8. IANA Considerations
8.1. Type Value . . . . . . . . . . . . . . . . . . . . . . . 34 8.1. Type Value
8.2. Attribute Type Values . . . . . . . . . . . . . . . . . . 34 8.2. Attribute Type Values
8.3. Key Derivation Function Namespace . . . . . . . . . . . . 34 8.3. Key Derivation Function Namespace
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 35 9. References
9.1. Normative References . . . . . . . . . . . . . . . . . . 35 9.1. Normative References
9.2. Informative References . . . . . . . . . . . . . . . . . 37 9.2. Informative References
Appendix A. Changes from RFC 5448 . . . . . . . . . . . . . . . 40 Appendix A. Changes from RFC 5448
Appendix B. Changes to RFC 4187 . . . . . . . . . . . . . . . . 41 Appendix B. Changes to RFC 4187
Appendix C. Changes from Previous Version of This Draft . . . . 41 Appendix C. Importance of Explicit Negotiation
Appendix D. Importance of Explicit Negotiation . . . . . . . . . 45 Appendix D. Test Vectors
Appendix E. Test Vectors . . . . . . . . . . . . . . . . . . . . 46 Acknowledgments
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Contributors
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 51 Authors' Addresses
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51
1. Introduction 1. Introduction
The 3GPP Mobile Network Authentication and Key Agreement (AKA) is an The 3GPP mobile network Authentication and Key Agreement (AKA) is an
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. EAP-AKA' EAP-AKA' is an improved version of EAP-AKA. EAP-AKA' was defined in
was defined in RFC 5448 and updated EAP-AKA RFC 4187. RFC 5448 [RFC5448], and it updated EAP-AKA [RFC4187].
This document is the most recent specification of EAP-AKA', This document is the most recent specification of EAP-AKA',
including, for instance, details and references about related to including, for instance, details about and references related to
operating EAP-AKA' in 5G networks. RFC 5448 is not obsole, but the operating EAP-AKA' in 5G networks. This document does not obsolete
most recent and fully backwards compatible specification is in this RFC 5448; however, this document is the most recent and fully
document. backwards-compatible specification.
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' also updates the compromised access network nodes and keys. EAP-AKA' also updates the
algorithm used for 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 hash function
function to SHA-256 [FIPS.180-4] and HMAC to HMAC-SHA-256. that is used 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
both sides in the protocol. That is, it must not be possible to to both sides in the protocol. That is, it must not be
accidentally connect old equipment to new equipment and get the possible to accidentally connect old equipment to new equipment
key derivation wrong or attempt to use wrong keys without getting and get the key derivation wrong or to attempt to use incorrect
a proper error message. See Appendix D for further information. keys without getting a proper error message. See Appendix C
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
further information. for further information.
The changes from RFC 5448 to this specification are as follows: This specification makes the following changes from RFC 5448:
o Update the reference on how the Network Name field is constructed * Updates the reference that specifies how the Network Name field is
in the protocol. This update ensures that EAP-AKA' is compatible constructed in the protocol. This update ensures that EAP-AKA' is
with 5G deployments. RFC 5448 referred to the Release 8 version compatible with 5G deployments. RFC 5448 referred to the Release
of [TS-3GPP.24.302] and this update points to the first 5G 8 version of [TS-3GPP.24.302]. This document points to the first
version, Release 15. 5G version, Release 16.
o Specify how EAP and EAP-AKA' use identifiers in 5G. Additional * Specifies 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.
o Specify session identifiers and other exported parameters, as * Specifies session identifiers and other exported parameters, as
those were not specified in [RFC5448] despite requirements set those were not specified in [RFC5448] despite requirements set
forward in [RFC5247] to do so. Also, while [RFC5247] specified forward in [RFC5247] to do so. Also, while [RFC5247] specified
session identifiers for EAP-AKA, it only did so for the full session identifiers for EAP-AKA, it only did so for the full
authentication case, not for the case of fast re-authentication. authentication case, not for the case of fast re-authentication.
o Update the requirements on generating pseudonym usernames and fast * Updates the requirements on generating pseudonym usernames and
re-authentication identities to ensure identity privacy. fast re-authentication identities to ensure identity privacy.
o Describe what has been learned about any vulnerabilities in AKA or * Describes what has been learned about any vulnerabilities in AKA
EAP-AKA'. or EAP-AKA'.
o Describe the privacy and pervasive monitoring considerations * Describes the privacy and pervasive monitoring considerations
related to EAP-AKA'. related to EAP-AKA'.
o Summaries of the attributes have been added. * Adds summaries of the attributes.
Some of the updates are small. For instance, for the first update, Some of the updates are small. For instance, the reference update to
the reference update does not change the 3GPP specification number, [TS-3GPP.24.302] does not change the 3GPP specification number, only
only the version. But this reference is crucial in correct the version. But this reference is crucial for the correct
calculation of the keys resulting from running the EAP-AKA' method, calculation of the keys that result from running the EAP-AKA' method,
so an update of the RFC with the newest version pointer may be so an RFC update pointing to the newest version was warranted.
warranted.
Note: Any further updates in 3GPP specifications that affect, for Note: Any further updates in 3GPP specifications that affect,
instance, key derivation is something that EAP-AKA' for instance, key derivation is something that EAP-AKA'
implementations need to take into account. Upon such updates implementations need to take into account. Upon such updates,
there will be a need to both update this specification and the there will be a need to update both this 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 specification 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 5G requirements regarding the use of peer identities, including how 5G
identifiers are used in the EAP-AKA' 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 which 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 explain the updates to RFC 5448 (EAP-AKA') and RFC 4187
EAP-AKA have been made in this specification. Appendix D explains (EAP-AKA) that have been made in this specification. Appendix C
some of the design rationale for creating EAP-AKA'. Finally, explains some of the design rationale for creating EAP-AKA'.
Appendix E provides test vectors. Finally, Appendix D provides test vectors.
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
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. EAP-AKA' 3. EAP-AKA'
EAP-AKA' is an EAP method that follows the EAP-AKA specification EAP-AKA' is an EAP method that follows the EAP-AKA specification
[RFC4187] in all respects except the following: [RFC4187] in all respects except the following:
o It uses the Type code 0x32, not 0x17 (which is used by EAP-AKA). * It uses the Type code 0x32, not 0x17 (which is used by EAP-AKA).
o It carries the AT_KDF_INPUT attribute, as defined in Section 3.1, * It carries the AT_KDF_INPUT attribute, as defined in Section 3.1,
to ensure that both the peer and server know the name of the to ensure that both the peer and server know the name of the
access network. access network.
o It supports key derivation function negotiation via the AT_KDF * It supports key derivation function negotiation via the AT_KDF
attribute (Section 3.2) to allow for future extensions. attribute (Section 3.2) to allow for future extensions.
o It calculates keys as defined in Section 3.3, not as defined in * It calculates keys as defined in Section 3.3, not as defined in
EAP-AKA. EAP-AKA.
o It employs SHA-256 / HMAC-SHA-256, not SHA-1 / HMAC-SHA-1 * It employs SHA-256 / HMAC-SHA-256 [FIPS.180-4], not SHA-1 / HMAC-
[FIPS.180-4] (Section 3.4 [RFC2104]). SHA-1 [RFC2104] (see Section 3.4).
Figure 1 shows an example of the authentication process. Each Figure 1 shows an example of the authentication process. Each
message AKA'-Challenge and so on represents the corresponding message message AKA'-Challenge and so on represents the corresponding message
from EAP-AKA, but with EAP-AKA' Type code. The definition of these from EAP-AKA, but with the EAP-AKA' Type code. The definition of
messages, along with the definition of attributes AT_RAND, AT_AUTN, these messages, along with the definition of attributes AT_RAND,
AT_MAC, and AT_RES can be found in [RFC4187]. AT_AUTN, AT_MAC, and AT_RES can be found in [RFC4187].
Peer Server Peer Server
| EAP-Request/Identity | | EAP-Request/Identity |
|<-------------------------------------------------------| |<-------------------------------------------------------|
| | | |
| EAP-Response/Identity | | EAP-Response/Identity |
| (Includes user's Network Access Identifier, NAI) | | (Includes user's Network Access Identifier, NAI) |
|------------------------------------------------------->| |------------------------------------------------------->|
| +--------------------------------------------------+ | +--------------------------------------------------+
| | Server determines the network name and ensures | | | Server determines the network name and ensures |
skipping to change at page 7, line 52 skipping to change at line 306
| (AT_RES, AT_MAC) | | (AT_RES, AT_MAC) |
|------------------------------------------------------->| |------------------------------------------------------->|
| +--------------------------------------------------+ | +--------------------------------------------------+
| | Server checks the RES and MAC values received | | | Server checks the RES and MAC values received |
| | in AT_RES and AT_MAC, respectively. Success | | | in AT_RES and AT_MAC, respectively. Success |
| | requires both to be found correct. | | | requires both to be found correct. |
| +--------------------------------------------------+ | +--------------------------------------------------+
| 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 usernames based on International Mobile Subscriber
usernames. For 4G networks, EAP-AKA' MUST use the leading character Identifier (IMSI). For 4G networks, EAP-AKA' MUST use the leading
"6" (ASCII 36 hexadecimal) instead of "0" for IMSI-based permanent character "6" (ASCII 36 hexadecimal) instead of "0" for IMSI-based
usernames. For 5G networks, leading character "6" is not used for permanent usernames. For 5G networks, the leading character "6" is
IMSI-based permanent user names. Identifier usage in 5G is specified not used for IMSI-based permanent usernames. Identifier usage in 5G
in Section 5.3. All other usage and processing of the leading is specified in Section 5.3. All other usage and processing of the
characters, usernames, and identities is as defined by EAP-AKA leading characters, usernames, and identities is as defined by EAP-
[RFC4187]. For instance, the pseudonym and fast re-authentication AKA [RFC4187]. For instance, the pseudonym and fast re-
usernames need to be constructed so that the server can recognize authentication usernames need to be constructed so that the server
them. As an example, a pseudonym could begin with a leading "7" can recognize them. As an example, a pseudonym could begin with a
character (ASCII 37 hexadecimal) and a fast re-authentication leading "7" character (ASCII 37 hexadecimal) and a fast re-
username could begin with "8" (ASCII 38 hexadecimal). Note that a authentication username could begin with "8" (ASCII 38 hexadecimal).
server that implements only EAP-AKA may not recognize these leading Note that a server that implements only EAP-AKA may not recognize
characters. According to Section 4.1.4 of [RFC4187], such a server these leading characters. According to Section 4.1.4 of [RFC4187],
will re-request the identity via the EAP- Request/AKA-Identity such a server will re-request the identity via the EAP-Request/AKA-
message, making obvious to the peer that EAP-AKA and associated Identity message, making obvious to the peer that EAP-AKA and
identity are expected. 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 8, line 44 skipping to change at line 347
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Network Name . . Network Name .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are as follows: The fields are as follows:
AT_KDF_INPUT AT_KDF_INPUT
This is set to 23. This is set to 23.
Length Length
The length of the attribute, calculated as defined in [RFC4187], The length of the attribute, calculated as defined in [RFC4187],
Section 8.1. Section 8.1.
Actual Network Name Length Actual Network Name Length
This is a 2-byte actual length field, needed due to the
This is a 2 byte actual length field, needed due to the
requirement that the previous field is expressed in multiples of 4 requirement that the previous field is expressed in multiples of 4
bytes per the usual EAP-AKA rules. The Actual Network Name Length bytes per the usual EAP-AKA rules. The Actual Network Name Length
field provides the length of the network name in bytes. field provides the length of the network name in bytes.
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 both non-3GPP access networks as specified in [TS-3GPP.24.302] for both non-3GPP access networks
and for 5G access networks. Per [TS-3GPP.33.402], the server always and for 5G access networks. Per [TS-3GPP.33.402], the server always
skipping to change at page 9, line 28 skipping to change at line 374
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 both non-3GPP access networks as specified in [TS-3GPP.24.302] for both non-3GPP access networks
and for 5G access networks. Per [TS-3GPP.33.402], the server always and for 5G access networks. Per [TS-3GPP.33.402], the server always
verifies the authorization of a given access network to use a verifies the authorization of a given access network to use a
particular name before sending it to the peer over EAP-AKA'. The particular name before sending it to the peer over EAP-AKA'. The
value of the AT_KDF_INPUT attribute from the server MUST be non- value of the AT_KDF_INPUT attribute from the server MUST be non-
empty, with a greater than zero length in the Actual Network Name empty, with a greater than zero length in the Actual Network Name
Length field. If AT_KDF_INPUT attribute is empty, the peer behaves Length field. If the AT_KDF_INPUT attribute is empty, the peer
as if AUTN had been incorrect and authentication fails. See behaves as if AUTN had been incorrect and authentication fails. See
Section 3 and Figure 3 of [RFC4187] for an overview of how Section 3 and Figure 3 of [RFC4187] for an overview of how
authentication failures are handled. authentication failures are handled.
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
skipping to change at page 10, line 8 skipping to change at line 403
(:). The algorithms and mechanisms to construct the identity string (:). The algorithms and mechanisms to construct the identity string
depend on the used access technology. depend on the used access technology.
On the network side, the network name construction is a configuration On the network side, the network name construction is a configuration
issue in an access network and an authorization check in the issue in an access network and an authorization check in the
authentication server. On the peer, the network name is constructed authentication server. On the peer, the network name is constructed
based on the local observations. For instance, the peer knows which based on the local observations. For instance, the peer knows which
access technology it is using on the link, it can see information in access technology it is using on the link, it can see information in
a link-layer beacon, and so on. The construction rules specify how a link-layer beacon, and so on. The construction rules specify how
this information maps to an access network name. Typically, the this information maps to an access network name. Typically, the
network name consists of the name of the access technology, or the network name consists of the name of the access technology or the
name of the access technology followed by some operator identifier name of the access technology followed by some operator identifier
that was advertised in a link-layer beacon. In all cases, that was advertised in a link-layer beacon. In all cases,
[TS-3GPP.24.302] is the normative specification for the construction [TS-3GPP.24.302] is the normative specification for the construction
in both the network and peer side. If the peer policy allows running in both the network and peer side. If the peer policy allows running
EAP-AKA' over an access technology for which that specification does EAP-AKA' over an access technology for which that specification does
not provide network name construction rules, the peer SHOULD rely not provide network name construction rules, the peer SHOULD rely
only on the information from the AT_KDF_INPUT attribute and not only on the information from the AT_KDF_INPUT attribute and not
perform a comparison. perform a comparison.
If a comparison of the locally determined network name and the one If a comparison of the locally determined network name and the one
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processing the received EAP-Request/AKA'-Challenge as specified in processing the received EAP-Request/AKA'-Challenge as specified in
[RFC4187] and Section 3.1 of this document. If not, it behaves as if [RFC4187] and Section 3.1 of this document. If not, it behaves as if
AT_MAC had been incorrect and fails the authentication. If the peer AT_MAC had been incorrect and fails the authentication. If the peer
receives multiple EAP-Request/AKA'-Challenge messages with differing receives multiple EAP-Request/AKA'-Challenge messages with differing
AT_KDF attributes without having requested negotiation, the peer MUST AT_KDF attributes without having requested negotiation, the peer MUST
behave as if AT_MAC had been incorrect and fail the authentication. behave as if AT_MAC had been incorrect and fail the authentication.
Note that the peer may also request sequence number resynchronization Note that the peer may also request sequence number resynchronization
[RFC4187]. This happens after AT_KDF negotiation has already [RFC4187]. This happens after AT_KDF negotiation has already
completed. That is, the EAP-Request/AKA'-Challenge and, possibly, completed. That is, the EAP-Request/AKA'-Challenge and, possibly,
the EAP-Response/AKA'-Challenge message are exchanged first to come the EAP-Response/AKA'-Challenge messages are exchanged first to
up with a mutually acceptable key derivation function, and only then determine a mutually acceptable key derivation function, and only
the possible AKA'-Synchronization-Failure message is sent. The AKA'- then is the possible AKA'-Synchronization-Failure message sent. The
Synchronization-Failure message is sent as a response to the newly AKA'-Synchronization-Failure message is sent as a response to the
received EAP-Request/AKA'-Challenge which is the last message of the newly received EAP-Request/AKA'-Challenge, which is the last message
AT_KDF negotiation. Note that if the first proposed KDF is of the AT_KDF negotiation. Note that if the first proposed KDF is
acceptable, then last message is at the same time the first EAP- acceptable, then the first EAP-Request/AKA'-Challenge message is also
Request/AKA'-Challenge message. The AKA'-Synchronization-Failure the last message. The AKA'-Synchronization-Failure message MUST
message MUST contain the AUTS parameter as specified in [RFC4187] and contain the AUTS parameter as specified in [RFC4187] and a copy the
a copy the AT_KDF attributes as they appeared in the last message of AT_KDF attributes as they appeared in the last message of the AT_KDF
the AT_KDF negotiation. If the AT_KDF attributes are found to differ negotiation. If the AT_KDF attributes are found to differ from their
from their earlier values, the peer and server MUST behave as if earlier values, the peer and server MUST behave as if AT_MAC had been
AT_MAC had been incorrect and fail the authentication. incorrect and fail the authentication.
3.3. Key Derivation 3.3. Key Derivation
Both the peer and server MUST derive the keys as follows. Both the peer and server MUST derive the keys as follows.
AT_KDF parameter has the value 1 AT_KDF parameter has the value 1
In this case, MK is derived and used as follows: In this case, MK is derived and used as follows:
MK = PRF'(IK'|CK',"EAP-AKA'"|Identity) MK = PRF'(IK'|CK',"EAP-AKA'"|Identity)
K_encr = MK[0..127] K_encr = MK[0..127]
K_aut = MK[128..383] K_aut = MK[128..383]
K_re = MK[384..639] K_re = MK[384..639]
MSK = MK[640..1151] MSK = MK[640..1151]
EMSK = MK[1152..1663] EMSK = MK[1152..1663]
Here [n..m] denotes the substring from bit n to m, including bits Here [n..m] denotes the substring from bit n to m, including bits
n and m. PRF' is a new pseudo-random function specified in n and m. PRF' is a new pseudorandom function specified in
Section 3.4. The first 1664 bits from its output are used for Section 3.4. The first 1664 bits from its output are used for
K_encr (encryption key, 128 bits), K_aut (authentication key, 256 K_encr (encryption key, 128 bits), K_aut (authentication key, 256
bits), K_re (re-authentication key, 256 bits), MSK (Master Session bits), K_re (re-authentication key, 256 bits), MSK (Master Session
Key, 512 bits), and EMSK (Extended Master Session Key, 512 bits). Key, 512 bits), and EMSK (Extended Master Session Key, 512 bits).
These keys are used by the subsequent EAP-AKA' process. K_encr is These keys are used by the subsequent EAP-AKA' process. K_encr is
used by the AT_ENCR_DATA attribute, and K_aut by the AT_MAC used by the AT_ENCR_DATA attribute, and K_aut by the AT_MAC
attribute. K_re is used later in this section. MSK and EMSK are attribute. K_re is used later in this section. MSK and EMSK are
outputs from a successful EAP method run [RFC3748]. outputs from a successful EAP method run [RFC3748].
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], and Section 5.3.2 in this document for the 5G cases. [RFC4187] and in Section 5.3.2 of 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:
MK = PRF'(K_re,"EAP-AKA' re-auth"|Identity|counter|NONCE_S) MK = PRF'(K_re,"EAP-AKA' re-auth"|Identity|counter|NONCE_S)
MSK = MK[0..511] MSK = MK[0..511]
EMSK = MK[512..1023] EMSK = MK[512..1023]
MSK and EMSK are the resulting 512-bit keys, taking the first 1024 MSK and EMSK are the resulting 512-bit keys, taking the first 1024
bits from the result of PRF'. Note that K_encr and K_aut are not bits from the result of PRF'. Note that K_encr and K_aut are not
re-derived on fast re-authentication. K_re is the re- re-derived on fast re-authentication. K_re is the re-
authentication key from the preceding full authentication and authentication key from the preceding full authentication and
stays unchanged over any fast re-authentication(s) that may happen stays unchanged over any fast re-authentication(s) that may happen
based on it. The value "EAP-AKA' re-auth" is a sixteen- based on it. The value "EAP-AKA' re-auth" is a sixteen-
characters-long ASCII string, again represented without any characters-long ASCII string, again represented without any
trailing NUL characters. Identity is the fast re-authentication trailing NUL characters. Identity is the fast re-authentication
identity, counter is the value from the AT_COUNTER attribute, identity, counter is the value from the AT_COUNTER attribute,
skipping to change at page 15, line 8 skipping to change at line 630
The peer behaves as if the AUTN had been incorrect and MUST fail The peer behaves as if the AUTN had been incorrect and MUST fail
the authentication. the authentication.
If the peer supports a given key derivation function but is unwilling If the peer supports a given key derivation function but is unwilling
to perform it for policy reasons, it refuses to calculate the keys to perform it for policy reasons, it refuses to calculate the keys
and behaves as explained in Section 3.2. and behaves as explained in Section 3.2.
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] and [RFC2104]) as in EAP-AKA. This requires a change to
pseudo-random function (PRF) as well as the AT_MAC and AT_CHECKCODE the pseudorandom function (PRF) as well as the AT_MAC and
attributes. AT_CHECKCODE 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]; this is the same function as was defined [RFC4306] that [RFC7296]; the definition of this function has not changed since
RFC 5448 referred to). The function takes two arguments. K is a [RFC4306], which was referenced by [RFC5448]). The function takes
256-bit value and S is a byte string of arbitrary length. PRF' is two arguments. K is a 256-bit value and S is a byte string of
defined as follows: 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 line 688
| | | |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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'
Table 1 provides a guide to which attributes may be found in which Table 1 identifies which attributes may be found in which kinds of
kinds of messages, and in what quantity. messages, and in what quantity.
Messages are denoted with numbers in parentheses as follows: Messages are denoted with numbers 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
(5) EAP-Request/AKA-Notification, 5 EAP-Request/AKA-Notification
(6) EAP-Response/AKA-Notification, 6 EAP-Response/AKA-Notification
(7) EAP-Response/AKA-Client-Error 7 EAP-Response/AKA-Client-Error
(8) EAP-Request/AKA-Reauthentication, 8 EAP-Request/AKA-Reauthentication
(9) EAP-Response/AKA-Reauthentication, 9 EAP-Response/AKA-Reauthentication
(10) EAP-Response/AKA-Authentication-Reject, and 10 EAP-Response/AKA-Authentication-Reject
(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,the numbered columns indicate the quantity of the In addition, the numbered columns indicate the quantity of the
attribute within the message as follows: 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
included in the message, included in the message.
"1+" indicates that there MUST be at least one attribute in the "1+" Indicates that there MUST be at least one attribute in the
message but more than one MAY be included in the message, and message but more than one MAY be included in the message.
"0*" indicates that the attribute is not included in the message "0*" Indicates that the attribute is not included in the message
in cases specified in this document, but MAY be included in the in cases specified in this document, but MAY be included in
future versions of the protocol. the future versions of the protocol.
The attribute table is shown below. The table is largely the same as The attribute table is shown below. The table is largely the same as
in the EAP-AKA attribute table ([RFC4187] Section 10.1), but changes in the EAP-AKA attribute table ([RFC4187], Section 10.1), but changes
how many times AT_MAC may appear in EAP-Response/AKA'-Challenge how many times AT_MAC may appear in an EAP-Response/AKA'-Challenge
message as it does not appear there when AT_KDF has to be sent from message as it does not appear there when AT_KDF has to be sent from
the peer to the server. The table also adds the AT_KDF and the peer to the server. The table also adds the AT_KDF and
AT_KDF_INPUT attributes. AT_KDF_INPUT attributes.
Attribute (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)(11) E +======================+===+===+===+===+===+===+=+====+=====+==+==+=+
AT_PERMANENT_ID_REQ 0-1 0 0 0 0 0 0 0 0 0 0 N | Attribute |1 |2 |3 |4 |5 |6 |7|8 | 9 |10|11|E|
AT_ANY_ID_REQ 0-1 0 0 0 0 0 0 0 0 0 0 N +======================+===+===+===+===+===+===+=+====+=====+==+==+=+
AT_FULLAUTH_ID_REQ 0-1 0 0 0 0 0 0 0 0 0 0 N | AT_PERMANENT_ID_REQ |0-1|0 |0 |0 |0 |0 |0|0 | 0 |0 |0 |N|
AT_IDENTITY 0 0-1 0 0 0 0 0 0 0 0 0 N +----------------------+---+---+---+---+---+---+-+----+-----+--+--+-+
AT_RAND 0 0 1 0 0 0 0 0 0 0 0 N | AT_ANY_ID_REQ |0-1|0 |0 |0 |0 |0 |0|0 | 0 |0 |0 |N|
AT_AUTN 0 0 1 0 0 0 0 0 0 0 0 N +----------------------+---+---+---+---+---+---+-+----+-----+--+--+-+
AT_RES 0 0 0 1 0 0 0 0 0 0 0 N | AT_FULLAUTH_ID_REQ |0-1|0 |0 |0 |0 |0 |0|0 | 0 |0 |0 |N|
AT_AUTS 0 0 0 0 0 0 0 0 0 0 1 N +----------------------+---+---+---+---+---+---+-+----+-----+--+--+-+
AT_NEXT_PSEUDONYM 0 0 0-1 0 0 0 0 0 0 0 0 Y | AT_IDENTITY |0 |0-1|0 |0 |0 |0 |0|0 | 0 |0 |0 |N|
AT_NEXT_REAUTH_ID 0 0 0-1 0 0 0 0 0-1 0 0 0 Y +----------------------+---+---+---+---+---+---+-+----+-----+--+--+-+
AT_IV 0 0 0-1 0* 0-1 0-1 0 1 1 0 0 N | AT_RAND |0 |0 |1 |0 |0 |0 |0|0 | 0 |0 |0 |N|
AT_ENCR_DATA 0 0 0-1 0* 0-1 0-1 0 1 1 0 0 N +----------------------+---+---+---+---+---+---+-+----+-----+--+--+-+
AT_PADDING 0 0 0-1 0* 0-1 0-1 0 0-1 0-1 0 0 Y | AT_AUTN |0 |0 |1 |0 |0 |0 |0|0 | 0 |0 |0 |N|
AT_CHECKCODE 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_RES |0 |0 |0 |1 |0 |0 |0|0 | 0 |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_AUTS |0 |0 |0 |0 |0 |0 |0|0 | 0 |0 |1 |N|
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_NEXT_PSEUDONYM |0 |0 |0-1|0 |0 |0 |0|0 | 0 |0 |0 |Y|
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_NEXT_REAUTH_ID |0 |0 |0-1|0 |0 |0 |0|0-1 | 0 |0 |0 |Y|
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_IV |0 |0 |0-1|0* |0-1|0-1|0|1 | 1 |0 |0 |N|
+----------------------+---+---+---+---+---+---+-+----+-----+--+--+-+
| AT_ENCR_DATA |0 |0 |0-1|0* |0-1|0-1|0|1 | 1 |0 |0 |N|
+----------------------+---+---+---+---+---+---+-+----+-----+--+--+-+
| AT_PADDING |0 |0 |0-1|0* |0-1|0-1|0|0-1 | 0-1 |0 |0 |Y|
+----------------------+---+---+---+---+---+---+-+----+-----+--+--+-+
| AT_CHECKCODE |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_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_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_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_INPUT |0 |0 |1 |0 |0 |0 |0|0 | 0 |0 |0 |N|
+----------------------+---+---+---+---+---+---+-+----+-----+--+--+-+
Table 1: The attribute table 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 mechanism for
for EAP-AKA that allows the endpoints to securely discover the EAP-AKA that allows the endpoints to securely discover the
capabilities of each other. This mechanism comes in the form of the capabilities of each other. This mechanism comes in the form of the
AT_BIDDING attribute. This allows both endpoints to communicate AT_BIDDING attribute. This allows both endpoints to communicate
their desire and support for EAP-AKA' when exchanging EAP-AKA their desire and support for EAP-AKA' when exchanging EAP-AKA
messages. This attribute is not included in EAP-AKA' messages. It messages. This attribute is not included in EAP-AKA' messages. It
is only included in EAP-AKA messages. (Those messages are protected is only included in EAP-AKA messages, which are protected with the
with the AT_MAC attribute.) This approach is based on the assumption AT_MAC attribute. This approach is based on the assumption that EAP-
that EAP-AKA' is always preferable (see Section 7). If during the AKA' is always preferable (see Section 7). If during the EAP-AKA
EAP-AKA authentication process it is discovered that both endpoints authentication process it is discovered that both endpoints would
would have been able to use EAP-AKA', the authentication process have been able to use EAP-AKA', the authentication process SHOULD be
SHOULD be aborted, as a bidding down attack may have happened. aborted, as a bidding down attack may have happened.
The format of the AT_BIDDING attribute is shown below. The format of the AT_BIDDING 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_BIDDING | Length |D| Reserved | | AT_BIDDING | Length |D| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are as follows: The fields are as follows:
skipping to change at page 20, line 10 skipping to change at line 864
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, this specification does not provide protection EAP-AKA. As a result, this specification does not provide protection
against bidding "down" attacks in the other direction, i.e., against bidding "down" attacks in the other direction, i.e.,
attackers forcing the endpoints 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 +============+===+===+===+===+===+===+===+===+===+====+====+===+
AT_BIDDING 0 0 1 0 0 0 0 0 0 0 0 N | 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 |
+------------+---+---+---+---+---+---+---+---+---+----+----+---+
Table 2: AT_BIDDING Attribute Appearance
5. Peer Identities 5. Peer Identities
EAP-AKA' peer identities are as specified in [RFC4187] Section 4.1, EAP-AKA' peer identities are as specified in [RFC4187], Section 4.1,
with the addition of some requirements specified in this section. with the addition of some requirements specified in this section.
EAP-AKA' includes optional identity privacy support that can be used EAP-AKA' includes optional identity privacy support that can be used
to hide the cleartext permanent identity and thereby make the to hide the cleartext permanent identity and thereby make the
subscriber's EAP exchanges untraceable to eavesdroppers. EAP-AKA' subscriber's EAP exchanges untraceable to eavesdroppers. EAP-AKA'
can also use the privacy friendly identifiers specified for 5G can also use the privacy-friendly identifiers specified for 5G
networks. networks.
The permanent identity is usually based on the IMSI. Exposing the The permanent identity is usually based on the IMSI. Exposing the
IMSI is undesirable, because as a permanent identity it is easily IMSI is undesirable because, as a permanent identity, it is easily
trackable. In addition, since IMSIs may be used in other contexts as trackable. In addition, since IMSIs may be used in other contexts as
well, there would be additional opportunities for such tracking. well, there would be additional opportunities for such tracking.
In EAP-AKA', identity privacy is based on temporary usernames, or In EAP-AKA', identity privacy is based on temporary usernames or
pseudonym usernames. These are similar to but separate from the pseudonym usernames. These are similar to, but separate from, the
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] specifies 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-AKA' (1) Regular usernames. These are external names given to EAP-AKA'
peers. 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 GUTI (b) Privacy-friendly temporary usernames, for instance, 5G GUTI
(5G Globally Unique Temporary Identifier) or 5G privacy (5G Globally Unique Temporary Identifier) or 5G privacy
identifiers (see Section 5.3.2), for instance SUCI identifiers (see Section 5.3.2) such as SUCI (Subscription
(Subscription Concealed Identifier). 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 with full authentication, and fast re-authentication
usernames only on fast re-authentication. Unlike permanent usernames usernames only with fast re-authentication. Unlike permanent
and pseudonym usernames, privacy friendly temporary usernames and usernames and pseudonym usernames, privacy-friendly temporary
fast re-authentication usernames are one-time identifiers, which are usernames and fast re-authentication usernames are one-time
not re-used across EAP exchanges. identifiers, which are not reused 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 This section provides some additional guidance to implementations for
for producing secure pseudonyms and fast re-authentication producing secure pseudonyms and fast re-authentication identities.
identities. It does not impact backwards compatibility, because each It does not impact backwards compatibility because each server
server consumes only the identities it itself generates. However, consumes only the identities that it generates itself. However,
adherence to the guidance will provide better security. 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 enhance 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 it is
computationally infeasible for an 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 pseudorandom 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 cannot include any subscriber-identifying
part of an IMSI or other permanent identifier. Similarly, no part of part of an IMSI or other permanent identifier. Similarly, no part of
the username can be formed by a fixed mapping that stays the same the username can be formed by a fixed mapping that stays the same
across multiple different pseudonyms or fast re-authentication across multiple different pseudonyms or fast re-authentication
identities for the same subscriber. identities for the same subscriber.
When the identifier used to identify a subscriber in an EAP-AKA' When the identifier used to identify a subscriber in an EAP-AKA'
authentication exchange is a privacy-friendly identifier that is used authentication exchange is a privacy-friendly identifier that is used
only once, the EAP-AKA' peer MUST NOT use a pseudonym provided in only once, the EAP-AKA' peer MUST NOT use a pseudonym provided in
that authentication exchange in subsequent exchanges more than once. that authentication exchange in subsequent exchanges more than once.
To ensure that this does not happen, EAP-AKA' server MAY decline to To ensure that this does not happen, the EAP-AKA' server MAY decline
provide a pseudonym in such authentication exchanges. An important to provide a pseudonym in such authentication exchanges. An
case where such privacy-friendly identifiers are used is in 5G important case where such privacy-friendly identifiers are used is in
networks (see Section 5.3). 5G networks (see Section 5.3).
5.3. Identifier Usage in 5G 5.3. Identifier Usage in 5G
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 * 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 * 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 * 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/
Identity message; and the peer includes the AT_IDENTITY attribute, AKA-Identity message, and the peer includes the AT_IDENTITY
which contains the peer's identity, in the EAP-Response/AKA- attribute, which contains the peer's identity, in the EAP-
Identity message. Response/AKA-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 Section 5.1. 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
cryptography to encrypt the SUPI. cryptography to encrypt the SUPI.
Given the choice between these two types of identifiers, EAP-AKA' Given the choice between these two types of identifiers, EAP-AKA'
ensures interoperability as follows: ensures interoperability as follows:
o Where identifiers are used within EAP-AKA' -- such as key * Where identifiers are used within EAP-AKA' (such as key
derivation -- specify what values exactly should be used, to avoid derivation) determine the exact values of the identity to be used,
ambiguity (see Section 5.3.1). to avoid ambiguity (see Section 5.3.1).
o Where identifiers are carried within EAP-AKA' packets -- such as * Where identifiers are carried within EAP-AKA' packets (such as in
in the AT_IDENTITY attribute -- specify which identifiers should the AT_IDENTITY attribute) determine which identifiers should be
be filled in (see Section 5.3.2). filled in (see Section 5.3.2).
In 5G, the normal mode of operation is that identifiers are only In 5G, the normal mode of operation is that identifiers are only
transmitted outside EAP. However, in a system involving terminals transmitted outside EAP. However, in a system involving terminals
from many generations and several connectivity options via 5G and from many generations and several connectivity options via 5G and
other mechanisms, implementations and the EAP-AKA' specification need other mechanisms, implementations and the EAP-AKA' specification need
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 key derivation formula
derivation formula. found in Section 3.3.
The identity needs to be represented in exact correct format for the The identity needs to be represented in exactly the correct format
key derivation formula to produce correct results. 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 as specified in Annex F.3 of [TS-3GPP.33.501] and Clause 2.2 MUST be as specified in Annex F.3 of [TS-3GPP.33.501] and Clause 2.2
of [TS-3GPP.23.003]. This is in contrast to [RFC5448], which used of [TS-3GPP.23.003]. This is in contrast to [RFC5448], which uses
the identity as communicated in EAP and represented as a NAI. Also, the identity as communicated in EAP and represented as a NAI. Also,
in contrast to [RFC5448], in 5G EAP-AKA' does not use the "0" or "6" in contrast to [RFC5448], in 5G EAP-AKA' does not use the "0" nor the
prefix in front of the identifier. "6" prefix in front of the identifier.
For an example of the format of the identity, see Clause 2.2 of For an example of the format of the identity, see Clause 2.2 of
[TS-3GPP.23.003]. [TS-3GPP.23.003].
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 the EAP-AKA' AT_IDENTITY attribute, if one was
regardless of the kind of identity that it may have been. If no sent, regardless of the kind of identity that it may have been.
AT_IDENTITY was sent, the identity MUST be the exactly the one If no AT_IDENTITY was sent, the identity MUST be exactly the
sent in the generic EAP Identity exchange, if one was made. one sent in the generic EAP Identity exchange, if one was made.
If no identity was communicated inside EAP, then the identity is If no identity was communicated inside EAP, then the identity
the one communicated outside EAP in link layer messaging. is 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
communicated by the peer to the network, again regardless of what recently communicated by the peer to the network, again
type of identity it may have been. regardless of what type of identity it may have been.
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 server is in a 5G network, the 5G procedures for EAP- When the EAP server is in a 5G network, the 5G procedures for EAP-
AKA' apply. When EAP server is defined to be in a 5G network is AKA' apply. [TS-3GPP.33.501] specifies when the EAP server is in a
specified in [TS-3GPP.33.501]. 5G network.
Note: Currently, the following conditions are specified: when the Note: Currently, the following conditions are specified: when
EAP peer uses the 5G Non-Access Stratum (NAS) protocol the EAP peer uses the 5G Non-Access Stratum (NAS) protocol
[TS-3GPP.24.501] or when the EAP peer attaches to a network that [TS-3GPP.24.501] or when the EAP peer attaches to a network
advertises 5G connectivity without NAS [TS-3GPP.23.501]. Possible that advertises 5G connectivity without NAS [TS-3GPP.23.501].
future conditions may also be specified by 3GPP. Possible future conditions may also be specified by 3GPP.
When the 5G procedures for EAP-AKA' apply, EAP identity exchanges are When the 5G procedures for EAP-AKA' apply, EAP identity exchanges are
generally not used as the identity is already made available on generally not used as the identity is already made available on
previous link layer exchanges. previous link-layer exchanges.
In this situation, the EAP Identity Response and EAP-AKA' AT_IDENTITY 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]. 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
EAP-AKA' does not use the "0" or "6" prefix in front of the 5G EAP-AKA' does not use the "0" nor the "6" prefix in front of the
identifier. identifier.
For an example of an IMSI in NAI format, see [TS-3GPP.23.003] For an example of an IMSI in NAI format, see [TS-3GPP.23.003],
Section 28.7.3. Section 28.7.3.
Otherwise, the peer SHOULD employ IMSI, SUPI, or a NAI as it is Otherwise, the peer SHOULD employ an IMSI, SUPI, or NAI [RFC7542] as
configured to use. it is configured to use.
6. Exported Parameters 6. Exported Parameters
When not using fast re-authentication, the EAP-AKA' Session-Id is the When not using fast re-authentication, the EAP-AKA' Session-Id is the
concatenation of the EAP Type Code (0x32, one byte) with the contents concatenation of the EAP-AKA' Type value (0x32, one byte) with the
of the RAND field from the AT_RAND attribute, followed by the contents of the RAND field from the AT_RAND attribute followed by the
contents of the AUTN field in the AT_AUTN 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-AKA' Type value (0x32) with the contents of
NONCE_S field from the AT_NONCE_S attribute, followed by the contents the NONCE_S field from the AT_NONCE_S attribute followed by the
of the MAC field from the AT_MAC attribute from EAP-Request/AKA- contents of the MAC field from the AT_MAC attribute from the EAP-
Reauthentication: Request/AKA-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 the Identity Response was provided either, the exported Peer-Id is the
null 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
from EAP-AKA' to EAP-AKA. The negotiation mechanism allows from EAP-AKA' to EAP-AKA. The negotiation mechanism allows
changing the offered key derivation function, but the change is changing the offered key derivation function, but the change is
visible in the final EAP-Request/AKA'-Challenge message that the visible in the final EAP-Request/AKA'-Challenge message that the
server sends to the peer. This message is authenticated via the server sends to the peer. This message is authenticated via the
AT_MAC attribute, and carries both the chosen alternative and the AT_MAC attribute, and carries both the chosen alternative and the
initially offered list. The peer refuses to accept a change it initially offered list. The peer refuses to accept a change it
did not initiate. As a result, both parties are aware that a did not initiate. As a result, both parties are aware that a
skipping to change at page 25, line 52 skipping to change at line 1151
from EAP-AKA' to EAP-AKA. The negotiation mechanism allows from EAP-AKA' to EAP-AKA. The negotiation mechanism allows
changing the offered key derivation function, but the change is changing the offered key derivation function, but the change is
visible in the final EAP-Request/AKA'-Challenge message that the visible in the final EAP-Request/AKA'-Challenge message that the
server sends to the peer. This message is authenticated via the server sends to the peer. This message is authenticated via the
AT_MAC attribute, and carries both the chosen alternative and the AT_MAC attribute, and carries both the chosen alternative and the
initially offered list. The peer refuses to accept a change it initially offered list. The peer refuses to accept a change it
did not initiate. As a result, both parties are aware that a did not initiate. As a result, both parties are aware that a
change is being made 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 Per assumptions in Section 4, there is no protection against
bidding down attacks from EAP-AKA to EAP-AKA', should EAP-AKA' bidding down attacks from EAP-AKA to EAP-AKA' should EAP-AKA'
somehow be considered less secure some day than EAP-AKA. Such somehow be considered less secure some day than EAP-AKA. Such
protection was not provided in RFC 5448 implementations and protection was not provided in RFC 5448 implementations and
consequently neither does this specification provide it. If such consequently neither does this specification provide it. If such
support is needed, it would have to be added as a separate new support is needed, it would have to be added as a separate new
feature. feature.
In general, it is expected that the current negotiation In general, it is expected that the current negotiation
capabilities in EAP-AKA' are sufficient for some types of capabilities in EAP-AKA' are sufficient for some types of
extensions, including adding Perfect Forward Secrecy extensions, including adding Perfect Forward Secrecy [EMU-AKA-PFS]
([I-D.ietf-emu-aka-pfs]) and perhaps others. But as with how EAP- and perhaps others. However, some larger changes may require a
AKA' itself came about, some larger changes may require a new EAP new EAP method type, which is how EAP-AKA' itself happened. One
method type. One example of such change would be the introduction example of such change would be the introduction of new
of new algorithms. 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.
only difference is that a stronger hash algorithm and keyed MAC, The only difference is that a stronger hash algorithm and keyed
SHA-256 / HMAC-SHA-256, is used instead of SHA-1 / HMAC-SHA-1. MAC, SHA-256 / HMAC-SHA-256, is used instead of SHA-1 / HMAC-SHA-
1.
Replay protection Replay 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 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.
Confidentiality Confidentiality
The properties of EAP-AKA' are exactly the same as those of EAP- The properties of EAP-AKA' are exactly the same as those of EAP-
AKA in this respect. Refer to [RFC4187], Section 12 for further AKA in this respect. Refer to [RFC4187], Section 12, for further
details. details.
Key derivation Key derivation
EAP-AKA' supports key derivation with an effective key strength EAP-AKA' supports key derivation with an effective key strength
against brute force attacks equal to the minimum of the length of against brute-force attacks equal to the minimum of the length of
the derived keys and the length of the AKA base key, i.e., 128 the derived keys and the length of the AKA base key, i.e., 128
bits or more. The key hierarchy is specified in Section 3.3. bits or more. The key hierarchy is specified in Section 3.3.
The Transient EAP Keys used to protect EAP-AKA packets (K_encr, The Transient EAP Keys used to protect EAP-AKA packets (K_encr,
K_aut, K_re), the MSK, and the EMSK are cryptographically K_aut, K_re), the MSK, and the EMSK are cryptographically
separate. If we make the assumption that SHA-256 behaves as a separate. If we make the assumption that SHA-256 behaves as a
pseudo-random function, an attacker is incapable of deriving any pseudorandom function, an attacker is incapable of deriving any
non-trivial information about any of these keys based on the other non-trivial information about any of these keys based on the other
keys. An attacker also cannot calculate the pre-shared secret keys. An attacker also cannot calculate the pre-shared secret
from IK, CK, IK', CK', K_encr, K_aut, K_re, MSK, or EMSK by any from IK, CK, IK', CK', K_encr, K_aut, K_re, MSK, or EMSK by any
practically feasible means. practically feasible means.
EAP-AKA' adds an additional layer of key derivation functions EAP-AKA' adds an additional layer of key derivation functions
within itself to protect against the use of compromised keys. within itself to protect against the use of compromised keys.
This is discussed further in Section 7.4. This is discussed further in Section 7.4.
EAP-AKA' uses a pseudo-random function modeled after the one used EAP-AKA' uses a pseudorandom function modeled after the one used
in IKEv2 [RFC7296] together with SHA-256. in IKEv2 [RFC7296] together with SHA-256.
Key strength Key strength
See above. See above.
Dictionary attack resistance Dictionary attack resistance
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.
Fast reconnect Fast reconnect
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. Note that [RFC4187], Section 12, for further details. Note that
implementations MUST prevent performing a fast reconnect across implementations MUST prevent performing a fast reconnect across
method types. method types.
Cryptographic binding Cryptographic binding
Note that this term refers to a very specific form of binding, Note that this term refers to a very specific form of binding,
something that is performed between two layers of authentication. something that is performed between two layers of authentication.
It is not the same as the binding to a particular network name. It is not the same as the binding to a particular network name.
The properties of EAP-AKA' are exactly the same as those of EAP- The properties of EAP-AKA' are exactly the same as those of EAP-
AKA in this respect, i.e., as it is not a tunnel method, this AKA in this respect, i.e., as it is not a tunnel method, this
property is not applicable to it. Refer to [RFC4187], Section 12 property is not applicable to it. Refer to [RFC4187], Section 12,
for further details. for further details.
Session independence Session independence
The properties of EAP-AKA' are exactly the same as those of EAP- The properties of EAP-AKA' are exactly the same as those of EAP-
AKA in this respect. Refer to [RFC4187], Section 12 for further AKA in this respect. Refer to [RFC4187], Section 12, for further
details. details.
Fragmentation Fragmentation
The properties of EAP-AKA' are exactly the same as those of EAP- The properties of EAP-AKA' are exactly the same as those of EAP-
AKA in this respect. Refer to [RFC4187], Section 12 for further AKA in this respect. Refer to [RFC4187], Section 12, for further
details. details.
Channel binding Channel binding
EAP-AKA', like EAP-AKA, does not provide channel bindings as EAP-AKA', like EAP-AKA, does not provide channel bindings as
they're defined in [RFC3748] and [RFC5247]. New skippable they're defined in [RFC3748] and [RFC5247]. New skippable
attributes can be used to add channel binding support in the attributes can be used to add channel binding support in the
future, if required. future, if required.
However, including the Network Name field in the AKA' algorithms However, including the Network Name field in the AKA' algorithms
(which are also used for other purposes than EAP-AKA') provides a (which are also used for other purposes than EAP-AKA') provides a
form of cryptographic separation between different network names, form of cryptographic separation between different network names,
which resembles channel bindings. However, the network name does which resembles channel bindings. However, the network name does
not typically identify the EAP (pass-through) authenticator. See not typically identify the EAP (pass-through) authenticator. See
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which resembles channel bindings. However, the network name does which resembles channel bindings. However, the network name does
not typically identify the EAP (pass-through) authenticator. See not typically identify the EAP (pass-through) authenticator. See
Section 7.4 for more discussion. Section 7.4 for more discussion.
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" (Section 7).
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 GUTI or 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 SUCI identifier is normally used. The use of EAP-AKA' only the SUCI identifier is normally used. The use of EAP-AKA'
pseudonyms in this situation is at best limited, because the SUCI pseudonyms in this situation is at best limited because the SUCI
already provides a stronger mechanism. In fact, the re-use of the already provides a stronger mechanism. In fact, reusing the same
same pseudonym multiple times will result in a tracking opportunity pseudonym multiple times will result in a tracking opportunity for
for observers that see the pseudonym pass by. To avoid this, the observers that see the pseudonym pass by. To avoid this, the peer
peer and server need to follow the guidelines given in Section 5.2. 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
as an input to key derivation. However, this use of the SUPI is only 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.33.501] 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 makes 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, the peer can freely choose between the use of permanent, Outside 5G, the peer can freely choose between the use of permanent,
pseudonym, or fast re-authentication identifiers: pseudonym, or fast re-authentication identifiers:
o A peer that has not yet performed any EAP-AKA' exchanges does not * 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 nonvolatile 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.
However, as discussed in [RFC4187] Section 4.1.2, the terminal can However, as discussed in [RFC4187], Section 4.1.2, the terminal
refuse to send the cleartext permanent identity if it believes can 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, * 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
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 SUCI can be used or If the peer and server cannot guarantee that SUCI can be used or that
pseudonyms will be 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
from an external security mechanism such as tunneled EAP methods such protection from an external security mechanism such as tunneled EAP
as TTLS [RFC5281] or TEAP [RFC7170] may be used. The benefits and methods like Tunneled Transport Layer Security (TTLS) [RFC5281] or
the security considerations of using an external security mechanism Tunnel Extensible Authentication Protocol (TEAP) [RFC7170] may be
with EAP-AKA are beyond the scope of this document. used. The benefits and the security considerations of using an
external security mechanism 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 have 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 an insider
keys by an insider to a third party as done in, e.g., by Mjolsnes and supplying keys to a third party, e.g., as described by Mjølsnes 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 it 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. If policies between different locations differ, for location. If policies between locations differ, for instance, if
instance, in some location it is not required to encrypt all payload payload traffic is not required to be encrypted in some location, the
traffic, the attacker may trick the user into opening a attacker may trick the user into opening a vulnerability. As an
vulnerability. As an authentication mechanism, EAP-AKA' is not authentication mechanism, EAP-AKA' is not directly affected by most
directly affected by most such attacks. EAP-AKA' network name of these attacks. EAP-AKA' network name binding can also help
binding can also help alleviate some of the attacks. In any case, it alleviate some of the attacks. In any case, it is recommended that
is recommended that EAP-AKA' configuration not be dependent on the EAP-AKA' configuration not be dependent on the location of request
location of where a request comes from, unless the location origin, unless the location information can be cryptographically
information can be cryptographically confirmed, e.g., with the confirmed, e.g., with the network name binding.
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 the
process can help recover from this, eventually it is possible to resynchronization process can help recover from this, eventually it
exhaust the sequence number space and render the subscriber's card is possible to exhaust the sequence number space and render the
unusable. This attack is possible for both native AKA and EAP-AKA'. subscriber's card unusable. This attack is possible for both
However, it requires the collaboration of a serving network in an original AKA and EAP-AKA'. However, it requires the collaboration of
attack. It is recommended that EAP-AKA' implementations provide a serving network in an attack. It is recommended that EAP-AKA'
means to track, detect, and limit excessive authentication attempts implementations provide the means to track, detect, and limit
to combat this problem. excessive authentication attempts to combat this problem.
There have 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 HTTP Digest AKAv1 [RFC3310], which was
Digest AKAv1 [RFC3310]. This has since then been corrected in originally vulnerable to man-in-the-middle attacks. This has since
[RFC4169]. The EAP-AKA' protocol uses session keys and provides been corrected in [RFC4169]. The EAP-AKA' protocol uses session keys
channel binding, and as such, is resistant to the above attacks and provides channel binding, and as such, it is resistant to the
except where the protocol participants leak information to outsiders. above attacks 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
that the AKA protocol would have benefited from additional security concluded that the AKA protocol would have benefited from additional
requirements, such as key confirmation. security requirements such as key confirmation.
In the context of pervasive monitoring revelations, there were also In the context of pervasive monitoring revelations, there were also
reports of compromised long term pre-shared keys used in SIM and AKA reports of compromised long-term pre-shared keys used in SIM and AKA
[Heist2015]. While no protocol can survive the theft of key material [Heist2015]. While no protocol can survive the theft of key material
associated with its credentials, there are some things that alleviate associated with its credentials, there are some things that alleviate
the impacts in such situations. These are discussed further in the impacts in such situations. These are discussed further in
Section 7.3. Section 7.3.
Arapinis et al ([Arapinis2012]) describe an attack that uses the AKA Arapinis, et al. [Arapinis2012] describe an attack that uses the AKA
resynchronization protocol to attempt to detect whether a particular resynchronization protocol to attempt to detect whether a particular
subscriber is on a given area. This attack depends on the ability of subscriber is in a given area. This attack depends on the attacker
the attacker to have a false base station on the given area, and the setting up a false base station in the given area and on the
subscriber performing at least one authentication between the time subscriber performing at least one authentication between the time
the attack is set up and run. the attack is set up and run.
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 subscriber if a non-time-based sequence number (SQN) generation
[Borgaonkar2018]. The attacker can force the re-use of the keystream scheme is used [Borgaonkar2018]. The attacker can force the reuse of
that is used to protect the SQN in the AKA resynchronization the keystream that is used to protect the SQN in the AKA
protocol. The attacker then guesses the authentication frequency resynchronization protocol. The attacker then guesses the
based on the lowest bits of two XORed SQNs. The researchers' concern authentication frequency based on the lowest bits of two XORed SQNs.
was that the authentication frequency would reveal some information The researchers' concern was that the authentication frequency would
about the phone usage behavior, e.g., number of phone calls made or reveal some information about the phone usage behavior, e.g., number
number of SMS messages sent. There are a number of possible triggers of phone calls made or number of SMS messages sent. There are a
for authentication, so such information leak is not direct, but can number of possible triggers for authentication, so such an
be a concern. The impact of the attack is also different depending information leak is not direct, but it can be a concern. The impact
on whether time or non-time-based SQN generation scheme is used. of the attack differs depending on whether the SQN generation scheme
that is used is time-based or not.
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 send short messages, or make phone calls to the intended victim and
the air-interface (e.g., [Kune2012] and [Shaik2016]). Hussain et. observe the air interface (e.g., [Kune2012] and [Shaik2016]).
al. demonstrated a slightly more sophisticated version of the attack Hussain, et al. demonstrated a slightly more sophisticated version of
that exploits the fact that 4G paging protocol uses the IMSI to the attack that exploits the fact that the 4G paging protocol uses
calculate the paging timeslot [Hussain2019]. As this attack is the IMSI to calculate the paging timeslot [Hussain2019]. As this
outside AKA, it does not impact EAP-AKA'. attack is 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, following the recommendations in Section 5.2 mitigate this itself, following the recommendations in Section 5.2 can mitigate
concern. 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 in 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-
key material stored on the cards. Such attacks are conceivable, for secret key material stored on the cards. Such attacks are
instance, during the manufacturing process of cards, through coercion conceivable, for instance, during the manufacturing process of cards,
of the card manufacturers, or during the transfer of cards and through coercion of the card manufacturers, or during the transfer of
associated information to an operator. Since the publication of cards and associated information to an operator. Since the
reports about such attacks, manufacturing and provisioning processes publication of reports about such attacks, manufacturing and
have gained much scrutiny and have improved. provisioning processes 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
store and communicate the secrets between the manufacturer and the store and communicate the secrets between the manufacturer and the
operator 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 Forward 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 a 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.ietf-emu-aka-pfs]. Alternatively, EAP-AKA' specification [EMU-AKA-PFS]. Alternatively, EAP-AKA' authentication
authentication can be run inside a PFS-capable tunneled can be run inside a PFS-capable, tunneled authentication method. In
authentication method. In any case, the use of some PFS-capable 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,
access node compromise, or another attack, the leaked keys are only access node compromise, or another attack, the leaked keys are only
useful when providing access with that name. For instance, a useful when providing access with that name. For instance, a
malicious access point cannot claim to be network Y if it has stolen malicious access point cannot claim to be network Y if it has stolen
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attacks; however, the binding to a particular name limits the attacks; however, the binding to a particular name limits the
attacker's choices, allows better tracking of attacks, makes it attacker's choices, allows better tracking of attacks, makes it
possible to identify compromised networks, and applies good possible to identify compromised networks, and applies good
cryptographic hygiene. cryptographic hygiene.
The server receives the EAP transaction from a given access network, The server receives the EAP transaction from a given access network,
and verifies that the claim from the access network corresponds to and verifies that the claim from the access network corresponds to
the name that this access network should be using. It becomes the name that this access network should be using. It becomes
impossible for an access network to claim over AAA that it is another impossible for an access network to claim over AAA that it is another
access network. In addition, if the peer checks that the information access network. In addition, if the peer checks that the information
it has received locally over the network-access link layer matches it has received locally over the network-access link-layer matches
with the information the server has given it via EAP-AKA', it becomes with the information the server has given it via EAP-AKA', it becomes
impossible for the access network to tell one story to the AAA impossible for the access network to tell one story to the AAA
network and another one to the peer. These checks prevent some network and another one to the peer. These checks prevent some
"lying NAS" (Network Access Server) attacks. For instance, a roaming "lying NAS" (Network Access Server) attacks. For instance, a roaming
partner, R, might claim that it is the home network H in an effort to partner, R, might claim that it is the home network H in an effort to
lure peers to connect to itself. Such an attack would be beneficial lure peers to connect to itself. Such an attack would be beneficial
for the roaming partner if it can attract more users, and damaging for the roaming partner if it can attract more users, and damaging
for the users if their access costs in R are higher than those in for the users if their access costs in R are higher than those in
other alternative networks, such as H. other alternative networks, such as H.
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Ideally, the names allow separating each different access technology, Ideally, the names allow separating each different access technology,
each different access network, and each different NAS within a each different access network, and each different NAS within a
domain. If this is not possible, the full benefits may not be domain. If this is not possible, the full benefits may not be
achieved. For instance, if the names identify just an access achieved. For instance, if the names identify just an access
technology, use of compromised keys in a different technology can be technology, use of compromised keys in a different technology can be
prevented, but it is not possible to prevent their use by other prevented, but it is not possible to prevent their use by other
domains or devices using the same technology. domains or devices using the same technology.
8. IANA Considerations 8. IANA Considerations
IANA should update the Extensible Authentication Protocol (EAP) IANA has updated the "Extensible Authentication Protocol (EAP)
Registry and the EAP-AKA and EAP-SIM Parameters so that entries Registry" and the "EAP-AKA and EAP-SIM Parameters" registry so that
pointing to RFC 5448 will point to this RFC instead. entries that pointed to RFC 5448 now point to this RFC instead.
8.1. Type Value 8.1. Type Value
EAP-AKA' has the EAP Type value 0x32 in the Extensible Authentication IANA has updated the reference for EAP-AKA' (0x32) in the "Method
Protocol (EAP) Registry under Method Types. Per Section 6.2 of Types" subregistry under the "Extensible Authentication Protocol
[RFC3748], this allocation can be made with Designated Expert and (EAP) Registry" to point to this document. Per Section 6.2 of
Specification Required. [RFC3748], this allocation can be made with Specification Required
[RFC8126].
8.2. Attribute Type Values 8.2. Attribute Type Values
EAP-AKA' shares its attribute space and subtypes with EAP-SIM EAP-AKA' shares its attribute space and subtypes with EAP-SIM
[RFC4186] and EAP-AKA [RFC4187]. No new registries are needed. [RFC4186] and EAP-AKA [RFC4187]. No new registries are needed.
However, a new Attribute Type value (23) in the non-skippable range IANA has updated the reference for AT_KDF_INPUT (23) and AT_KDF (24)
has been assigned for AT_KDF_INPUT (Section 3.1) in the EAP-AKA and in the "Attribute Types (Non-Skippable Attributes 0-127)" subregistry
EAP-SIM Parameters registry under Attribute Types. under the "EAP-AKA and EAP-SIM Parameters" registry to point to this
document. AT_KDF_INPUT and AT_KDF are defined in Sections 3.1 and
Also, a new Attribute Type value (24) in the non-skippable range has 3.2, respectively, of this document.
been assigned for AT_KDF (Section 3.2).
Finally, a new Attribute Type value (136) in the skippable range has IANA has also updated the reference for AT_BIDDING (136) in the
been assigned for AT_BIDDING (Section 4). "Attribute Types (Skippable Attributes 128-255)" subregistry of the
"EAP-AKA and EAP-SIM Parameters" registry to point to this document.
AT_BIDDING is defined in Section 4.
8.3. Key Derivation Function Namespace 8.3. Key Derivation Function Namespace
IANA has also created a new namespace for EAP-AKA' AT_KDF Key IANA has updated the reference for the "EAP-AKA' AT_KDF Key
Derivation Function Values. This namespace exists under the EAP-AKA Derivation Function Values" subregistry to point to this document.
and EAP-SIM Parameters registry. The initial contents of this This subregistry appears under the "EAP-AKA and EAP-SIM Parameters"
namespace are given below; new values can be created through the registry. The references for following entries have also been
Specification Required policy [RFC8126]. updated to point to this document. New values can be created through
the Specification Required policy [RFC8126].
Value Description Reference +=======+=======================+===========+
--------- ---------------------- ------------------------------- | Value | Description | Reference |
0 Reserved [RFC Editor: Refer to this RFC] +=======+=======================+===========+
1 EAP-AKA' with CK'/IK' [RFC Editor: Refer to this RFC] | 0 | Reserved | RFC 9048 |
2-65535 Unassigned +-------+-----------------------+-----------+
| 1 | EAP-AKA' with CK'/IK' | RFC 9048 |
+-------+-----------------------+-----------+
Table 3: EAP-AKA' AT_KDF Key Derivation
Function Values
9. References 9. References
9.1. Normative References 9.1. Normative References
[TS-3GPP.23.003]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Numbering,
addressing and identification (Release 16)",
3GPP Technical Specification 23.003 version 16.5.0,
December 2020.
[TS-3GPP.23.501]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G
Security; Security architecture and procedures for 5G
System; (Release 16)", 3GPP Technical Specification 23.501
version 16.7.0, December 2020.
[TS-3GPP.24.302]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Access to
the 3GPP Evolved Packet Core (EPC) via non-3GPP access
networks; Stage 3; (Release 16)", 3GPP Technical
Specification 24.302 version 16.4.0, July 2020.
[TS-3GPP.24.501]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Access to
the 3GPP Evolved Packet Core (EPC) via non-3GPP access
networks; Stage 3; (Release 16)", 3GPP Draft Technical
Specification 24.501 version 16.7.0, December 2020.
[TS-3GPP.33.102]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G
Security; Security architecture (Release 16)",
3GPP Technical Specification 33.102 version 16.0.0, July
2020.
[TS-3GPP.33.402]
3GPP, "3GPP System Architecture Evolution (SAE); Security
aspects of non-3GPP accesses (Release 16)", 3GPP Technical
Specification 33.402 version 16.0.0, July 2020.
[TS-3GPP.33.501]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G
Security; Security architecture and procedures for 5G
System (Release 16)", 3GPP Technical Specification 33.501
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,
DOI 10.6028/NIST.FIPS.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,
editor.org/info/rfc2104>. <https://www.rfc-editor.org/info/rfc2104>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <https://www.rfc- DOI 10.17487/RFC2119, March 1997,
editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Levkowetz, Ed., "Extensible Authentication Protocol Levkowetz, Ed., "Extensible Authentication Protocol
(EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004, (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004,
<https://www.rfc-editor.org/info/rfc3748>. <https://www.rfc-editor.org/info/rfc3748>.
[RFC4187] Arkko, J. and H. Haverinen, "Extensible Authentication [RFC4187] Arkko, J. and H. Haverinen, "Extensible Authentication
Protocol Method for 3rd Generation Authentication and Key Protocol Method for 3rd Generation Authentication and Key
Agreement (EAP-AKA)", RFC 4187, DOI 10.17487/RFC4187, Agreement (EAP-AKA)", RFC 4187, DOI 10.17487/RFC4187,
January 2006, <https://www.rfc-editor.org/info/rfc4187>. January 2006, <https://www.rfc-editor.org/info/rfc4187>.
[RFC7542] DeKok, A., "The Network Access Identifier", RFC 7542, [RFC7542] DeKok, A., "The Network Access Identifier", RFC 7542,
DOI 10.17487/RFC7542, May 2015, <https://www.rfc- DOI 10.17487/RFC7542, May 2015,
editor.org/info/rfc7542>. <https://www.rfc-editor.org/info/rfc7542>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
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 [TS-3GPP.23.003]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Numbering,
addressing and identification (Release 16)", Version
16.7.0, 3GPP Technical Specification 23.003, June 2021.
[TS-3GPP.35.208] [TS-3GPP.23.501]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; System
architecture for the 5G System (5GS); (Release 16)",
Version 16.9.0, 3GPP Technical Specification 23.501, June
2021.
[TS-3GPP.24.302]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Access to
the 3GPP Evolved Packet Core (EPC) via non-3GPP access
networks; Stage 3; (Release 16)", Version 16.4.0, 3GPP
Technical Specification 24.302, July 2020.
[TS-3GPP.24.501]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Non-
Access-Stratum (NAS) protocol for 5G System (5GS); Stage
3; (Release 16)", Version 16.9.0, 3GPP Draft Technical
Specification 24.501, June 2021.
[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; Specification of the MILENAGE Algorithm Set: An Security; Security architecture (Release 16)", Version
example algorithm set for the 3GPP authentication and key 16.0.0, 3GPP Technical Specification 33.102, July 2020.
generation functions f1, f1*, f2, f3, f4, f5 and f5*;
Document 4: Design Conformance Test Data (Release 14)", [TS-3GPP.33.402]
3GPP Technical Specification 35.208 version 15.0.0, 3GPP, "3GPP System Architecture Evolution (SAE); Security
October 2018. aspects of non-3GPP accesses (Release 16)", Version
16.0.0, 3GPP Technical Specification 33.402, July 2020.
[TS-3GPP.33.501]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G
Security; Security architecture and procedures for 5G
System (Release 16)", Version 16.7.1, 3GPP Technical
Specification 33.501, July 2021.
9.2. Informative References
[Arapinis2012]
Arapinis, M., Mancini, L., Ritter, E., Ryan, M., Golde,
N., Redon, R., and R. Borgaonkar, "New Privacy Issues in
Mobile Telephony: Fix and Verification", in CCS '12:
Proceedings of the 2012 ACM Conference on Computer and
Communications Security, Raleigh, North Carolina, USA,
DOI 10.1145/2382196.2382221, October 2012,
<https://doi.org/10.1145/2382196.2382221>.
[Basin2018]
Basin, D., Dreier, J., Hirschi, L., Radomirović, S.,
Sasse, R., and V. Stettler, "A Formal Analysis of 5G
Authentication", arXiv:1806.10360,
DOI 10.1145/3243734.3243846, August 2018,
<https://doi.org/10.1145/3243734.3243846>.
[Borgaonkar2018]
Borgaonkar, R., Hirschi, L., Park, S., and A. Shaik, "New
Privacy Threat on 3G, 4G, and Upcoming 5G AKA Protocols",
in IACR Cryptology ePrint Archive, 2018.
[BT2013] Beekman, J. G. and C. Thompson, "Breaking Cell Phone
Authentication: Vulnerabilities in AKA, IMS and Android",
in 7th USENIX Workshop on Offensive Technologies, WOOT
'13, August 2013.
[EMU-AKA-PFS]
Arkko, J., Norrman, K., and V. Torvinen, "Perfect-Forward
Secrecy for the Extensible Authentication Protocol Method
for Authentication and Key Agreement (EAP-AKA' PFS)", Work
in Progress, Internet-Draft, draft-ietf-emu-aka-pfs-05, 30
October 2020, <https://datatracker.ietf.org/doc/html/
draft-ietf-emu-aka-pfs-05>.
[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,
<http://www.itl.nist.gov/fipspubs/fip180-1.htm>. DOI 10.6028/NIST.FIPS.180-1, April 1995,
<https://csrc.nist.gov/publications/detail/fips/180/1/
archive/1995-04-17>.
[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/ <https://csrc.nist.gov/publications/detail/fips/180/2/
fips180-2.pdf>. archive/2002-08-01>.
[Heist2015]
Scahill, J. and J. Begley, "How Spies Stole the Keys to
the Encryption Castle", February 2015,
<https://firstlook.org/theintercept/2015/02/19/great-sim-
heist/>.
[Hussain2019]
Hussain, S., Echeverria, M., Chowdhury, O., Li, N., and E.
Bertino, "Privacy Attacks to the 4G and 5G Cellular Paging
Protocols Using Side Channel Information", in the
proceedings of NDSS '19, held 24-27 February, 2019, San
Diego, California, 2019.
[Kune2012] Kune, D., Koelndorfer, J., Hopper, N., and Y. Kim,
"Location Leaks on the GSM Air Interface", in the
proceedings of NDSS '12, held 5-8 February, 2012, San
Diego, California, 2012.
[MT2012] Mjølsnes, S. F. and J-K. Tsay, "A Vulnerability in the
UMTS and LTE Authentication and Key Agreement Protocols",
in Computer Network Security, Proceedings of the 6th
International Conference on Mathematical Methods, Models
and Architectures for Computer Network Security, Lecture
Notes in Computer Science, Vol. 7531, pp. 65-76,
DOI 10.1007/978-3-642-33704-8_6, October 2012,
<https://doi.org/10.1007/978-3-642-33704-8_6>.
[RFC3310] Niemi, A., Arkko, J., and V. Torvinen, "Hypertext Transfer [RFC3310] Niemi, A., Arkko, J., and V. Torvinen, "Hypertext Transfer
Protocol (HTTP) Digest Authentication Using Authentication Protocol (HTTP) Digest Authentication Using Authentication
and Key Agreement (AKA)", RFC 3310, DOI 10.17487/RFC3310, and Key Agreement (AKA)", RFC 3310, DOI 10.17487/RFC3310,
September 2002, <https://www.rfc-editor.org/info/rfc3310>. September 2002, <https://www.rfc-editor.org/info/rfc3310>.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086, "Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005, <https://www.rfc- DOI 10.17487/RFC4086, June 2005,
editor.org/info/rfc4086>. <https://www.rfc-editor.org/info/rfc4086>.
[RFC4169] Torvinen, V., Arkko, J., and M. Naslund, "Hypertext [RFC4169] Torvinen, V., Arkko, J., and M. Naslund, "Hypertext
Transfer Protocol (HTTP) Digest Authentication Using Transfer Protocol (HTTP) Digest Authentication Using
Authentication and Key Agreement (AKA) Version-2", Authentication and Key Agreement (AKA) Version-2",
RFC 4169, DOI 10.17487/RFC4169, November 2005, RFC 4169, DOI 10.17487/RFC4169, November 2005,
<https://www.rfc-editor.org/info/rfc4169>. <https://www.rfc-editor.org/info/rfc4169>.
[RFC4186] Haverinen, H., Ed. and J. Salowey, Ed., "Extensible [RFC4186] Haverinen, H., Ed. and J. Salowey, Ed., "Extensible
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
skipping to change at page 38, line 16 skipping to change at line 1783
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) [RFC4306] Kaufman, C., Ed., "Internet Key Exchange (IKEv2)
Protocol", RFC 4306, DOI 10.17487/RFC4306, December 2005, Protocol", RFC 4306, DOI 10.17487/RFC4306, December 2005,
<https://www.rfc-editor.org/info/rfc4306>. <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,
editor.org/info/rfc5113>. <https://www.rfc-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 [RFC5281] Funk, P. and S. Blake-Wilson, "Extensible Authentication
Protocol Tunneled Transport Layer Security Authenticated Protocol Tunneled Transport Layer Security Authenticated
Protocol Version 0 (EAP-TTLSv0)", RFC 5281, Protocol Version 0 (EAP-TTLSv0)", RFC 5281,
DOI 10.17487/RFC5281, August 2008, <https://www.rfc- DOI 10.17487/RFC5281, August 2008,
editor.org/info/rfc5281>. <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,
editor.org/info/rfc6973>. <https://www.rfc-editor.org/info/rfc6973>.
[RFC7170] Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna, [RFC7170] Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna,
"Tunnel Extensible Authentication Protocol (TEAP) Version "Tunnel Extensible Authentication Protocol (TEAP) Version
1", RFC 7170, DOI 10.17487/RFC7170, May 2014, 1", RFC 7170, DOI 10.17487/RFC7170, May 2014,
<https://www.rfc-editor.org/info/rfc7170>. <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.ietf-emu-aka-pfs]
Arkko, J., Norrman, K., and V. Torvinen,"Perfect-Forward Secrecy
for the Extensible Authentication Protocol Method for
Authentication and Key Agreement (EAP-AKA' PFS)", draft-
ietf-emu-aka-pfs-05 (work in progress), October 2020.
[Heist2015]
Scahill, J. and J. Begley, "The great SIM heist", February
2015, in https://firstlook.org/theintercept/2015/02/19/
great-sim-heist/ .
[MT2012] Mjolsnes, S. and J-K. Tsay, "A vulnerability in the UMTS
and LTE authentication and key agreement protocols",
October 2012, in Proceedings of the 6th international
conference on Mathematical Methods, Models and
Architectures for Computer Network Security: computer
network security.
[BT2013] Beekman, J. and C. Thompson, "Breaking Cell Phone
Authentication: Vulnerabilities in AKA, IMS and Android",
August 2013, in 7th USENIX Workshop on Offensive
Technologies, WOOT '13.
[ZF2005] Zhang, M. and Y. Fang, "Breaking Cell Phone
Authentication: Vulnerabilities in AKA, IMS and Android",
March 2005, IEEE Transactions on Wireless Communications,
Vol. 4, No. 2.
[Basin2018]
Basin, D., Dreier, J., Hirsch, L., Radomirovic, S., Sasse,
R., and V. Stettle, "A Formal Analysis of 5G
Authentication", August 2018, arXiv:1806.10360.
[Arapinis2012]
Arapinis, M., Mancini, L., Ritter, E., Ryan, M., Golde,
N., and R. Borgaonkar, "New Privacy Issues in Mobile
Telephony: Fix and Verification", October 2012, CCS'12,
Raleigh, North Carolina, USA.
[Borgaonkar2018]
Borgaonkar, R., Hirschi, L., Park, S., and A. Shaik, "New
Privacy Threat on 3G, 4G, and Upcoming 5G AKA Protocols",
2018 in IACR Cryptology ePrint Archive.
[Kune2012]
Kune, D., Koelndorfer, J., and Y. Kim, "Location leaks on
the GSM air interface", 2012 in the proceedings of NDSS
'12 held 5-8 February, 2012 in San Diego, California.
[Shaik2016] [Shaik2016]
Shaik, A., Seifert, J., Borgaonkar, R., Asokan, N., and V. Shaik, A., Seifert, J., Borgaonkar, R., Asokan, N., and V.
Niemi, "Practical attacks against privacy and availability Niemi, "Practical attacks against Privacy and Availability
in 4G/LTE mobile communication systems", 2012 in the in 4G/LTE Mobile Communication Systems", in the
proceedings of NDSS '16 held 21-24 February, 2016 in San proceedings of NDSS '16 held 21-24 February, 2016, San
Diego, California. Diego, California, 2012.
[Hussain2019] [TS-3GPP.35.208]
Hussain, S., Echeverria, M., Chowdhury, O., Li, N., and E. 3GPP, "3rd Generation Partnership Project; Technical
Bertino, "Privacy Attacks to the 4G and 5G Cellular Paging Specification Group Services and System Aspects; 3G
Protocols Using Side Channel Information", in the Security; Specification of the MILENAGE Algorithm Set: An
Proceedings of NDSS '19, held 24-27 February, 2019, in San example algorithm set for the 3GPP authentication and key
Diego, California. generation functions f1, f1*, f2, f3, f4, f5 and f5*;
Document 4: Design Conformance Test Data (Release 14)",
Version 16.0.0, 3GPP Technical Specification 35.208, July
2020.
[ZF2005] Zhang, M. and Y. Fang, "Security analysis and enhancements
of 3GPP authentication and key agreement protocol", IEEE
Transactions on Wireless Communications, Vol. 4, No. 2,
DOI 10.1109/TWC.2004.842941, March 2005,
<https://doi.org/10.1109/TWC.2004.842941>.
Appendix A. Changes from RFC 5448 Appendix A. Changes from RFC 5448
The changes consist first of all, referring to a newer version of The change from RFC 5448 was to refer to a newer version of
[TS-3GPP.24.302]. The new version includes an updated definition of [TS-3GPP.24.302]. This RFC includes an updated definition of the
the Network Name field, to include 5G. Network Name field to include 5G.
Secondly, identifier usage for 5G has been specified in Section 5.3. Identifier usage for 5G has been specified in Section 5.3. Also, the
Also, the requirements on generating pseudonym usernames and fast re- requirements for generating pseudonym usernames and fast re-
authentication identities have been updated from the original authentication identities have been updated from the original
definition in RFC 5448, which referenced RFC 4187. See Section 5. definition in RFC 5448, which referenced RFC 4187. See Section 5.
Thirdly, exported parameters for EAP-AKA' have been defined in Exported parameters for EAP-AKA' have been defined in Section 6, as
Section 6, as required by [RFC5247], including the definition of required by [RFC5247], including the definition of those parameters
those parameters for both full authentication and fast re- 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], [RFC4306], [RFC7296], [FIPS.180-1] and
[FIPS.180-1] and [FIPS.180-2] have been updated to their most recent [FIPS.180-2] have been updated to their most recent versions, and
versions and language in this document changed accordingly. However, language in this document has been changed accordingly. However,
this is merely an update to a newer RFC but the actual protocol these are merely reference updates to newer specifications; the
functions are the same as defined in the earlier RFCs. 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 16) versions or otherwise most recent updated to their 5G versions (Release 16) 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 to RFC 4187 Appendix B. Changes to RFC 4187
In addition to specifying EAP-AKA', this document mandates also a In addition to specifying EAP-AKA', this document also mandates a
change to another EAP method, EAP-AKA that was defined in RFC 4187. 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 This change was already mandated in RFC 5448 but repeated here to
ensure that the latest EAP-AKA' specification contains the ensure that the latest EAP-AKA' specification contains the
instructions about the necessary bidding down feature in EAP-AKA as instructions about the necessary bidding down prevention feature in
well. 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 or any other aspect of change how the Master Key (MK) is calculated or any other aspect of
EAP-AKA. The provisions in this specification for EAP-AKA' do not EAP-AKA. The provisions in this specification for EAP-AKA' do not
apply to EAP-AKA, outside Section 4. apply to EAP-AKA, outside of Section 4.
Appendix C. Changes from Previous Version of This Draft
RFC Editor: Please delete this section at the time of publication.
The -00 version of the working group draft is merely a republication
of an earlier individual draft.
The -01 version of the working group draft clarifies updates
relationship to RFC 4187, clarifies language relating to obsoleting
RFC 5448, clarifies when the 3GPP references are expected to be
stable, updates several past references to their more recently
published versions, specifies what identifiers should be used in key
derivation formula for 5G, specifies how to construct the network
name in manner that is compatible with both 5G and previous versions,
and has some minor editorial changes.
The -02 version of the working group draft added specification of
peer identity usage in EAP-AKA', added requirements on the generation
of pseudonym and fast re-authentication identifiers, specified the
format of 5G-identifiers when they are used within EAP-AKA', defined
privacy and pervasive surveillance considerations, clarified when 5G-
related procedures apply, specified what Peer-Id value is exported
when no AT_IDENTITY is exchanged within EAP-AKA', and made a number
of other clarifications and editorial improvements. The security
considerations section also includes a summary of vulnerabilities
brought up in the context of AKA or EAP-AKA', and discusses their
applicability and impacts in EAP-AKA'.
The -03 version of the working group draft corrected some typos,
referred to the 3GPP specifications for the SUPI and SUCI formats,
updated some of the references to newer versions, and reduced the
strength of some of the recommendations in the security
considerations section from keyword level to normal language (as they
are just deployment recommendations).
The -04 version of the working group draft rewrote the abstract and
some of the introduction, corrected some typos, added sentence to the
abstract about obsoleting RFC 5448, clarified the use of the language
when referring to AT_KDF values vs. AT_KDF attribute number, provided
guidance on random number generation, clarified the dangers relating
to the use of permanent user identities such as IMSIs, aligned the
key derivation function/mechanism terminology, aligned the key
derivation/generation terminology, aligned the octet/byte
terminology, clarified the text regarding strength of SHA-256, added
some cross references between sections, instructed IANA to change
registries to point to this RFC rather than RFC 5448, and changed
Pasi's listed affiliation.
The -05 version of the draft corrected the Section 7.1 statement that
SUCI must not be communicated in EAP-AKA'; this statement was meant
to say SUPI must not be communicated. That was a major bug, but
hopefully one that previous readers understood was a mistake!
The -05 version also changed keyword strengths for identifier
requests in different cases in a 5G network, to match the 3GPP
specifications (see Section 5.3.2.
Tables of where attributes may appear has been added to the -05
version of the document, see Section 3.5 and Section 4.1. The tables
are based on the original table in RFC 4187.
Other changes in the -05 version included the following:
o The attribute appearance table entry for AT_MAC in EAP-Response/
AKA-Challenge has been specified to be 0-1 because it does not
appear when AT_KDF has to be sent; this was based on implementor
feedback.
o Added information about attacks against the re-synchronization
protocol and other attacks recently discussed in academic
conferences.
o Clarified length field calculations and the AT_KDF negotiation
procedure.
o The treatment of AT_KDF attribute copy in the EAP-Response/AKA'-
Synchronization-Failure message was clarified in Section 3.2.
o Updated and added several references
o Switched to use of hexadecimal for EAP Type Values for consistency
with other documents.
o Made editorial clarifications to a number places in the document.
The version -06 included changes to updates of references to newer
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 C. 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 46, line 5 skipping to change at line 1938
requests, or server configuration does not match expectations. It requests, or server configuration does not match expectations. It
also does not help to assume that the EAP client and server are also does not help to assume that the EAP client and server are
running a particular release of 3GPP network specifications. Network running a particular release of 3GPP network specifications. Network
vendors often provide features from future releases early or do not vendors often provide features from future releases early or do not
provide all features of the current release. And obviously, there provide all features of the current release. And obviously, there
are many EAP and even some EAP-AKA implementations that are not are many EAP and even some EAP-AKA implementations that are not
bundled with the 3GPP network offerings. In general, these bundled with the 3GPP network offerings. In general, these
approaches are expected to lead to hard-to-diagnose problems and approaches are expected to lead to hard-to-diagnose problems and
increased support calls. increased support calls.
Appendix E. Test Vectors Appendix D. Test Vectors
Test vectors are provided below for four different cases. The test Test vectors are provided below for four different cases. The test
vectors may be useful for testing implementations. In the first two vectors may be useful for testing implementations. In the first two
cases, we employ the MILENAGE algorithm and the algorithm cases, we employ the MILENAGE algorithm and the algorithm
configuration parameters (the subscriber key K and operator algorithm configuration parameters (the subscriber key K and operator algorithm
variant configuration value OP) from test set 19 in [TS-3GPP.35.208]. variant configuration value OP) from test set 19 in [TS-3GPP.35.208].
The last two cases use artificial values as the output of AKA, and is The last two cases use artificial values as the output of AKA, which
useful only for testing the computation of values within EAP-AKA', are useful only for testing the computation of values within EAP-
not AKA itself. AKA', not AKA itself.
Case 1 Case 1
The parameters for the AKA run are as follows: The parameters for the AKA run are as follows:
Identity: "0555444333222111" Identity: "0555444333222111"
Network name: "WLAN" Network name: "WLAN"
RAND: 81e9 2b6c 0ee0 e12e bceb a8d9 2a99 dfa5 RAND: 81e9 2b6c 0ee0 e12e bceb a8d9 2a99 dfa5
skipping to change at page 50, line 47 skipping to change at line 2118
MSK: c6d3 a6e0 ceea 951e b20d 74f3 2c30 61d0 MSK: c6d3 a6e0 ceea 951e b20d 74f3 2c30 61d0
680a 04b0 b086 ee87 00ac e3e0 b95f a026 680a 04b0 b086 ee87 00ac e3e0 b95f a026
83c2 87be ee44 4322 94ff 98af 26d2 cc78 83c2 87be ee44 4322 94ff 98af 26d2 cc78
3bac e75c 4b0a f7fd feb5 511b a8e4 cbd0 3bac e75c 4b0a f7fd feb5 511b a8e4 cbd0
EMSK: 7fb5 6813 838a dafa 99d1 40c2 f198 f6da EMSK: 7fb5 6813 838a dafa 99d1 40c2 f198 f6da
cebf b6af ee44 4961 1054 02b5 08c7 f363 cebf b6af ee44 4961 1054 02b5 08c7 f363
352c b291 9644 b504 63e6 a693 5415 0147 352c b291 9644 b504 63e6 a693 5415 0147
ae09 cbc5 4b8a 651d 8787 a689 3ed8 536d ae09 cbc5 4b8a 651d 8787 a689 3ed8 536d
Contributors
The test vectors in Appendix C were provided by Yogendra Pal and
Jouni Malinen, based on two independent implementations of this
specification.
Jouni Malinen provided suggested text for Section 6. John Mattsson
provided much of the text for Section 7.1. Karl Norrman was the
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, Roman Alfred Hoenes, Anand Palanigounder, Michael Richardson, Roman
Danyliw, Dan Romascanu, Kyle Rose, Benjamin Kaduk, Alissa Cooper, Danyliw, Dan Romascanu, Kyle Rose, Benjamin Kaduk, Alissa Cooper,
Erik Kline, Murray Kucherawy, Robert Wilton, Warren Kumari, Andreas Erik Kline, Murray Kucherawy, Robert Wilton, Warren Kumari, Andreas
Kunz, Marcus Wong, Kalle Jarvinen, Daniel Migault, and Mohit Sethi Kunz, Marcus Wong, Kalle Jarvinen, Daniel Migault, and Mohit Sethi
for their in-depth reviews and interesting discussions in this for their in-depth reviews and interesting discussions in this
problem space. problem space.
Contributors
The test vectors in Appendix D were provided by Yogendra Pal and
Jouni Malinen, based on two independent implementations of this
specification.
Jouni Malinen provided suggested text for Section 6. John Mattsson
provided much of the text for Section 7.1. Karl Norrman was the
source of much of the information in Section 7.2.
Authors' Addresses Authors' Addresses
Jari Arkko Jari Arkko
Ericsson Ericsson
Jorvas 02420 FI-02420 Jorvas
Finland Finland
Email: jari.arkko@piuha.net Email: jari.arkko@piuha.net
Vesa Lehtovirta Vesa Lehtovirta
Ericsson Ericsson
Jorvas 02420 FI-02420 Jorvas
Finland Finland
Email: vesa.lehtovirta@ericsson.com Email: vesa.lehtovirta@ericsson.com
Vesa Torvinen Vesa Torvinen
Ericsson Ericsson
Jorvas 02420 FI-02420 Jorvas
Finland Finland
Email: vesa.torvinen@ericsson.com Email: vesa.torvinen@ericsson.com
Pasi Eronen Pasi Eronen
Independent Independent
Finland Finland
Email: pe@iki.fi Email: pe@iki.fi
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