draft-ietf-emu-rfc5448bis-06.txt   draft-ietf-emu-rfc5448bis-07.txt 
Network Working Group J. Arkko Network Working Group J. Arkko
Internet-Draft V. Lehtovirta Internet-Draft V. Lehtovirta
Obsoletes: 5448 (if approved) V. Torvinen Obsoletes: 5448 (if approved) V. Torvinen
Updates: 4187 (if approved) Ericsson Updates: 4187 (if approved) Ericsson
Intended status: Informational P. Eronen Intended status: Informational P. Eronen
Expires: May 21, 2020 Independent Expires: September 10, 2020 Independent
November 18, 2019 March 9, 2020
Improved Extensible Authentication Protocol Method for 3GPP Mobile Improved Extensible Authentication Protocol Method for 3GPP Mobile
Network Authentication and Key Agreement (EAP-AKA') Network Authentication and Key Agreement (EAP-AKA')
draft-ietf-emu-rfc5448bis-06 draft-ietf-emu-rfc5448bis-07
Abstract Abstract
The 3GPP Mobile Network Authentication and Key Agreement (AKA) is the The 3GPP Mobile Network Authentication and Key Agreement (AKA) is the
primary authentication mechanism for devices wishing to access mobile primary authentication mechanism for devices wishing to access mobile
networks. RFC 4187 (EAP-AKA) made the use of this mechanism possible networks. RFC 4187 (EAP-AKA) made the use of this mechanism possible
within the Extensible Authentication Protocol (EAP) framework. RFC within the Extensible Authentication Protocol (EAP) framework. RFC
5448 (EAP-AKA') was an improved version of EAP-AKA. 5448 (EAP-AKA') was an improved version of EAP-AKA.
This memo replaces the specification of EAP-AKA'. EAP-AKA' was This memo replaces the specification of EAP-AKA'. EAP-AKA' was
defined in RFC 5448 and updated EAP-AKA RFC 4187. As such this defined in RFC 5448 and updated EAP-AKA RFC 4187. As such this
document obsoletes RFC 5448 and updates RFC 4187. document obsoletes RFC 5448 and updates RFC 4187.
EAP-AKA' differs from EAP-AKA by providing a key derivation function EAP-AKA' differs from EAP-AKA by providing a key derivation function
that binds the keys derived within the method to the name of the that binds the keys derived within the method to the name of the
access network. The key derivation function has been defined in the access network. The key derivation function has been defined in the
3rd Generation Partnership Project (3GPP). EAP-AKA' allows its use 3rd Generation Partnership Project (3GPP). EAP-AKA' allows its use
in EAP in an interoperable manner. EAP-AKA' is also an algorithm in EAP in an interoperable manner. EAP-AKA' also updates the
update, as it employs SHA-256 / HMAC-SHA-256 instead of SHA-1 / HMAC- algorithm used in hash functions, as it employs SHA-256 / HMAC-
SHA-1 as in EAP-AKA. SHA-256 instead of SHA-1 / HMAC-SHA-1 as in EAP-AKA.
This version of EAP-AKA' specification specifies the protocol This version of EAP-AKA' specification specifies the protocol
behaviour for 5G deployments as well. behaviour for both 4G and 5G deployments, whereas the previous
version only did this for 4G.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 21, 2020. This Internet-Draft will expire on September 10, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2020 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 . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5
3. EAP-AKA' . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. EAP-AKA' . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. AT_KDF_INPUT . . . . . . . . . . . . . . . . . . . . . . 8 3.1. AT_KDF_INPUT . . . . . . . . . . . . . . . . . . . . . . 8
3.2. AT_KDF . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2. AT_KDF . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3. Key Derivation . . . . . . . . . . . . . . . . . . . . . 13 3.3. Key Derivation . . . . . . . . . . . . . . . . . . . . . 13
3.4. Hash Functions . . . . . . . . . . . . . . . . . . . . . 15 3.4. Hash Functions . . . . . . . . . . . . . . . . . . . . . 15
3.4.1. PRF' . . . . . . . . . . . . . . . . . . . . . . . . 15 3.4.1. PRF' . . . . . . . . . . . . . . . . . . . . . . . . 15
3.4.2. AT_MAC . . . . . . . . . . . . . . . . . . . . . . . 15 3.4.2. AT_MAC . . . . . . . . . . . . . . . . . . . . . . . 15
3.4.3. AT_CHECKCODE . . . . . . . . . . . . . . . . . . . . 15 3.4.3. AT_CHECKCODE . . . . . . . . . . . . . . . . . . . . 15
3.5. Summary of Attributes for EAP-AKA' . . . . . . . . . . . 16 3.5. Summary of Attributes for EAP-AKA' . . . . . . . . . . . 16
4. Bidding Down Prevention for EAP-AKA . . . . . . . . . . . . . 18 4. Bidding Down Prevention for EAP-AKA . . . . . . . . . . . . . 18
4.1. Summary of Attributes for EAP-AKA . . . . . . . . . . . . 19 4.1. Summary of Attributes for EAP-AKA . . . . . . . . . . . . 20
5. Peer Identities . . . . . . . . . . . . . . . . . . . . . . . 20 5. Peer Identities . . . . . . . . . . . . . . . . . . . . . . . 20
5.1. Username Types in EAP-AKA' Identities . . . . . . . . . . 20 5.1. Username Types in EAP-AKA' Identities . . . . . . . . . . 20
5.2. Generating Pseudonyms and Fast Re-Authentication 5.2. Generating Pseudonyms and Fast Re-Authentication
Identities . . . . . . . . . . . . . . . . . . . . . . . 21 Identities . . . . . . . . . . . . . . . . . . . . . . . 21
5.3. Identifier Usage in 5G . . . . . . . . . . . . . . . . . 22 5.3. Identifier Usage in 5G . . . . . . . . . . . . . . . . . 22
5.3.1. Key Derivation . . . . . . . . . . . . . . . . . . . 23 5.3.1. Key Derivation . . . . . . . . . . . . . . . . . . . 23
5.3.2. EAP Identity Response and EAP-AKA' AT_IDENTITY 5.3.2. EAP Identity Response and EAP-AKA' AT_IDENTITY
Attribute . . . . . . . . . . . . . . . . . . . . . . 24 Attribute . . . . . . . . . . . . . . . . . . . . . . 24
6. Exported Parameters . . . . . . . . . . . . . . . . . . . . . 25 6. Exported Parameters . . . . . . . . . . . . . . . . . . . . . 26
7. Security Considerations . . . . . . . . . . . . . . . . . . . 26 7. Security Considerations . . . . . . . . . . . . . . . . . . . 26
7.1. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 29 7.1. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 29
7.2. Discovered Vulnerabilities . . . . . . . . . . . . . . . 30 7.2. Discovered Vulnerabilities . . . . . . . . . . . . . . . 31
7.3. Pervasive Monitoring . . . . . . . . . . . . . . . . . . 33 7.3. Pervasive Monitoring . . . . . . . . . . . . . . . . . . 33
7.4. Security Properties of Binding Network Names . . . . . . 33 7.4. Security Properties of Binding Network Names . . . . . . 34
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
8.1. Type Value . . . . . . . . . . . . . . . . . . . . . . . 35 8.1. Type Value . . . . . . . . . . . . . . . . . . . . . . . 35
8.2. Attribute Type Values . . . . . . . . . . . . . . . . . . 35 8.2. Attribute Type Values . . . . . . . . . . . . . . . . . . 35
8.3. Key Derivation Function Namespace . . . . . . . . . . . . 35 8.3. Key Derivation Function Namespace . . . . . . . . . . . . 35
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 35 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 36
9.1. Normative References . . . . . . . . . . . . . . . . . . 35 9.1. Normative References . . . . . . . . . . . . . . . . . . 36
9.2. Informative References . . . . . . . . . . . . . . . . . 37 9.2. Informative References . . . . . . . . . . . . . . . . . 38
Appendix A. Changes from RFC 5448 . . . . . . . . . . . . . . . 41 Appendix A. Changes from RFC 5448 . . . . . . . . . . . . . . . 41
Appendix B. Changes from RFC 4187 to RFC 5448 . . . . . . . . . 41 Appendix B. Changes to RFC 4187 . . . . . . . . . . . . . . . . 41
Appendix C. Changes from Previous Version of This Draft . . . . 41 Appendix C. Changes from Previous Version of This Draft . . . . 42
Appendix D. Importance of Explicit Negotiation . . . . . . . . . 43 Appendix D. Importance of Explicit Negotiation . . . . . . . . . 44
Appendix E. Test Vectors . . . . . . . . . . . . . . . . . . . . 44 Appendix E. Test Vectors . . . . . . . . . . . . . . . . . . . . 45
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 49 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 50
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 49 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 50
1. Introduction 1. Introduction
The 3GPP Mobile Network Authentication and Key Agreement (AKA) is the The 3GPP Mobile Network Authentication and Key Agreement (AKA) is the
primary authentication mechanism for devices wishing to access mobile primary authentication mechanism for devices wishing to access mobile
networks. [RFC4187] (EAP-AKA) made the use of this mechanism networks. [RFC4187] (EAP-AKA) made the use of this mechanism
possible within the Extensible Authentication Protocol (EAP) possible within the Extensible Authentication Protocol (EAP)
framework [RFC3748]. framework [RFC3748].
[RFC5448] (EAP-AKA') was an improved version of EAP-AKA. This memo [RFC5448] (EAP-AKA') was an improved version of EAP-AKA. This memo
skipping to change at page 3, line 42 skipping to change at page 3, line 44
RFC 5448 and updates RFC 4187. RFC 5448 and updates RFC 4187.
EAP-AKA' is commonly implemented in mobile phones and network EAP-AKA' is commonly implemented in mobile phones and network
equipment. It can be used for authentication to gain network access equipment. It can be used for authentication to gain network access
via Wireless LAN networks and, with 5G, also directly to mobile via Wireless LAN networks and, with 5G, also directly to mobile
networks. networks.
EAP-AKA' differs from EAP-AKA by providing a different key derivation EAP-AKA' differs from EAP-AKA by providing a different key derivation
function. This function binds the keys derived within the method to function. This function binds the keys derived within the method to
the name of the access network. This limits the effects of the name of the access network. This limits the effects of
compromised access network nodes and keys. EAP-AKA' is also an compromised access network nodes and keys. EAP-AKA' also updates the
algorithm update for the used hash functions. algorithm used for hash functions.
The EAP-AKA' method employs the derived keys CK' and IK' from the The EAP-AKA' method employs the derived keys CK' and IK' from the
3GPP specification [TS-3GPP.33.402] and updates the used hash 3GPP specification [TS-3GPP.33.402] and updates the used hash
function to SHA-256 [FIPS.180-4] and HMAC to HMAC-SHA-256. function to SHA-256 [FIPS.180-4] and HMAC to HMAC-SHA-256.
Otherwise, EAP-AKA' is equivalent to EAP-AKA. Given that a different Otherwise, EAP-AKA' is equivalent to EAP-AKA. Given that a different
EAP method type value is used for EAP-AKA and EAP-AKA', a mutually EAP method type value is used for EAP-AKA and EAP-AKA', a mutually
supported method may be negotiated using the standard mechanisms in supported method may be negotiated using the standard mechanisms in
EAP [RFC3748]. EAP [RFC3748].
Note that any change of the key derivation must be unambiguous to Note that any change of the key derivation must be unambiguous to
skipping to change at page 4, line 19 skipping to change at page 4, line 21
a proper error message. See Appendix D for further information. a proper error message. See Appendix D for further information.
Note also that choices in authentication protocols should be Note also that choices in authentication protocols should be
secure against bidding down attacks that attempt to force the secure against bidding down attacks that attempt to force the
participants to use the least secure function. See Section 4 for participants to use the least secure function. See Section 4 for
further information. further information.
The changes from RFC 5448 to this specification are as follows: The changes from RFC 5448 to this specification are as follows:
o Update the reference on how the Network Name field is constructed o Update the reference on how the Network Name field is constructed
in the protocol. The update ensures that EAP-AKA' is compatible in the protocol. This update ensures that EAP-AKA' is compatible
with 5G deployments. RFC 5448 referred to the Release 8 version with 5G deployments. RFC 5448 referred to the Release 8 version
of [TS-3GPP.24.302] and this update points to the first 5G of [TS-3GPP.24.302] and this update points to the first 5G
version, Release 15. version, Release 15.
o Specify how EAP and EAP-AKA' use identifiers in 5G. Additional o Specify how EAP and EAP-AKA' use identifiers in 5G. Additional
identifiers are introduced in 5G, and for interoperability, it is identifiers are introduced in 5G, and for interoperability, it is
necessary that the right identifiers are used as inputs in the key necessary that the right identifiers are used as inputs in the key
derivation. In addition, for identity privacy it is important derivation. In addition, for identity privacy it is important
that when privacy-friendly identifiers in 5G are used, no that when privacy-friendly identifiers in 5G are used, no
trackable, permanent identifiers are passed in EAP-AKA' either. trackable, permanent identifiers are passed in EAP-AKA' either.
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o Describe the privacy and pervasive monitoring considerations o Describe the privacy and pervasive monitoring considerations
related to EAP-AKA'. related to EAP-AKA'.
Some of the updates are small. For instance, for the first update, Some of the updates are small. For instance, for the first update,
the reference update does not change the 3GPP specification number, the reference update does not change the 3GPP specification number,
only the version. But this reference is crucial in correct only the version. But this reference is crucial in correct
calculation of the keys resulting from running the EAP-AKA' method, calculation of the keys resulting from running the EAP-AKA' method,
so an update of the RFC with the newest version pointer may be so an update of the RFC with the newest version pointer may be
warranted. warranted.
Note: This specification refers only to the 5G specifications. Note: Any further updates in 3GPP specifications that affect, for
Any further update that affects, for instance, key derivation is instance, key derivation is something that EAP-AKA'
something that EAP-AKA' implementations should take into account. implementations need to take into account. Upon such updates
Upon such updates there will be a need to both update the there will be a need to both update this specification and the
specification and the implementations. implementations.
It is an explicit non-goal of this draft to include any other It is an explicit non-goal of this draft to include any other
technical modifications, addition of new features or other changes. technical modifications, addition of new features or other changes.
The EAP-AKA' base protocol is stable and needs to stay that way. If The EAP-AKA' base protocol is stable and needs to stay that way. If
there are any extensions or variants, those need to be proposed as there are any extensions or variants, those need to be proposed as
standalone extensions or even as different authentication methods. standalone extensions or even as different authentication methods.
The rest of this specification is structured as follows. Section 3 The rest of this specification is structured as follows. Section 3
defines the EAP-AKA' method. Section 4 adds support to EAP-AKA to defines the EAP-AKA' method. Section 4 adds support to EAP-AKA to
prevent bidding down attacks from EAP-AKA'. Section 5 specifies prevent bidding down attacks from EAP-AKA'. Section 5 specifies
requirements regarding the use of peer identities, including how how requirements regarding the use of peer identities, including how EAP-
EAP-AKA' identifiers are used in 5G context. Section 6 specifies AKA' identifiers are used in 5G context. Section 6 specifies what
what parameters EAP-AKA' exports out of the method. Section 7 parameters EAP-AKA' exports out of the method. Section 7 explains
explains the security differences between EAP-AKA and EAP-AKA'. the security differences between EAP-AKA and EAP-AKA'. Section 8
Section 8 describes the IANA considerations and Appendix A and describes the IANA considerations and Appendix A and Appendix B
Appendix B explains what updates to RFC 5448 EAP-AKA' and RFC 4187 explains what updates to RFC 5448 EAP-AKA' and RFC 4187 EAP-AKA have
EAP-AKA have been made in this specification. Appendix D explains been made in this specification. Appendix D explains some of the
some of the design rationale for creating EAP-AKA'. Finally, design rationale for creating EAP-AKA'. Finally, Appendix E provides
Appendix E provides test vectors. test vectors.
Editor's Note: The publication of this RFC depends on its Editor's Note: The publication of this RFC depends on its
normative references to 3GPP Technical Specifications reaching a normative references to 3GPP Technical Specifications reaching a
stable status for Release 15, as indicated by 3GPP. The RFC stable status for Release 15, as indicated by 3GPP. The RFC
Editor should check with the 3GPP liaisons that a stable version Editor should check with the 3GPP liaisons that a stable version
from Release 15 is available and refer to that version. RFC from Release 15 is available and refer to that version. RFC
Editor: Please delete this note upon publication of this Editor: Please delete this note upon publication of this
specification as an RFC. specification as an RFC.
2. Requirements Language 2. Requirements Language
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Network Name Network Name
This field contains the network name of the access network for This field contains the network name of the access network for
which the authentication is being performed. The name does not which the authentication is being performed. The name does not
include any terminating null characters. Because the length of include any terminating null characters. Because the length of
the entire attribute must be a multiple of 4 bytes, the sender the entire attribute must be a multiple of 4 bytes, the sender
pads the name with 1, 2, or 3 bytes of all zero bits when pads the name with 1, 2, or 3 bytes of all zero bits when
necessary. necessary.
Only the server sends the AT_KDF_INPUT attribute. The value is sent Only the server sends the AT_KDF_INPUT attribute. The value is sent
as specified in [TS-3GPP.24.302] for non-3GPP access networks, and as as specified in [TS-3GPP.24.302] for both non-3GPP access networks
specified in [TS-3GPP.33.501] for 5G access networks. Per for 5G access networks. Per [TS-3GPP.33.402], the server always
[TS-3GPP.33.402], the server always verifies the authorization of a verifies the authorization of a given access network to use a
given access network to use a particular name before sending it to particular name before sending it to the peer over EAP-AKA'. The
the peer over EAP-AKA'. The value of the AT_KDF_INPUT attribute from value of the AT_KDF_INPUT attribute from the server MUST be non-
the server MUST be non-empty. If it is empty, the peer behaves as if empty, with a greater than zero length in the Actual Network Name
AUTN had been incorrect and authentication fails. See Section 3 and Length field. If AT_KDF_INPUT attribute is empty, the peer behaves
Figure 3 of [RFC4187] for an overview of how authentication failures as if AUTN had been incorrect and authentication fails. See
are handled. Section 3 and Figure 3 of [RFC4187] for an overview of how
authentication failures are handled.
Note: Currently, [TS-3GPP.24.302] or [TS-3GPP.33.501] specify
separate values. The former specifies what is called "Access
Network ID" and the latter specifies what is called "Serving
Network Name". However, from an EAP-AKA' perspective both occupy
the same field, and need to be distinguishable from each other.
Currently specified values are distinguishable, but it would be
useful that this be specified explicitly in the 3GPP
specifications.
In addition, the peer MAY check the received value against its own In addition, the peer MAY check the received value against its own
understanding of the network name. Upon detecting a discrepancy, the understanding of the network name. Upon detecting a discrepancy, the
peer either warns the user and continues, or fails the authentication peer either warns the user and continues, or fails the authentication
process. More specifically, the peer SHOULD have a configurable process. More specifically, the peer SHOULD have a configurable
policy that it can follow under these circumstances. If the policy policy that it can follow under these circumstances. If the policy
indicates that it can continue, the peer SHOULD log a warning message indicates that it can continue, the peer SHOULD log a warning message
or display it to the user. If the peer chooses to proceed, it MUST or display it to the user. If the peer chooses to proceed, it MUST
use the network name as received in the AT_KDF_INPUT attribute. If use the network name as received in the AT_KDF_INPUT attribute. If
the policy indicates that the authentication should fail, the peer the policy indicates that the authentication should fail, the peer
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| | | |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Second, the checkcode is a hash value, calculated with SHA-256 Second, the checkcode is a hash value, calculated with SHA-256
[FIPS.180-4], over the data specified in Section 10.13 of [RFC4187]. [FIPS.180-4], over the data specified in Section 10.13 of [RFC4187].
3.5. Summary of Attributes for EAP-AKA' 3.5. Summary of Attributes for EAP-AKA'
The following table provides a guide to which attributes may be found Table 1 provides a guide to which attributes may be found in which
in which kinds of messages, and in what quantity. kinds of messages, and in what quantity.
Messages are denoted with numbers in parentheses as follows: Messages are denoted with numbers in parentheses as follows:
(1) EAP-Request/AKA-Identity, (1) EAP-Request/AKA-Identity,
(2) EAP-Response/AKA-Identity, (2) EAP-Response/AKA-Identity,
(3) EAP-Request/AKA-Challenge, (3) EAP-Request/AKA-Challenge,
(4) EAP-Response/AKA-Challenge, (4) EAP-Response/AKA-Challenge,
skipping to change at page 18, line 30 skipping to change at page 18, line 30
AT_RESULT_IND 0 0 0-1 0-1 0 0 0 0-1 0-1 0 0 N AT_RESULT_IND 0 0 0-1 0-1 0 0 0 0-1 0-1 0 0 N
AT_MAC 0 0 1 0-1 0-1 0-1 0 1 1 0 0 N AT_MAC 0 0 1 0-1 0-1 0-1 0 1 1 0 0 N
AT_COUNTER 0 0 0 0 0-1 0-1 0 1 1 0 0 Y AT_COUNTER 0 0 0 0 0-1 0-1 0 1 1 0 0 Y
AT_COUNTER_TOO_SMALL 0 0 0 0 0 0 0 0 0-1 0 0 Y AT_COUNTER_TOO_SMALL 0 0 0 0 0 0 0 0 0-1 0 0 Y
AT_NONCE_S 0 0 0 0 0 0 0 1 0 0 0 Y AT_NONCE_S 0 0 0 0 0 0 0 1 0 0 0 Y
AT_NOTIFICATION 0 0 0 0 1 0 0 0 0 0 0 N AT_NOTIFICATION 0 0 0 0 1 0 0 0 0 0 0 N
AT_CLIENT_ERROR_CODE 0 0 0 0 0 0 1 0 0 0 0 N AT_CLIENT_ERROR_CODE 0 0 0 0 0 0 1 0 0 0 0 N
AT_KDF 0 0 1+ 0+ 0 0 0 0 0 0 1+ N AT_KDF 0 0 1+ 0+ 0 0 0 0 0 0 1+ N
AT_KDF_INPUT 0 0 1 0 0 0 0 0 0 0 0 N AT_KDF_INPUT 0 0 1 0 0 0 0 0 0 0 0 N
Table 1: The attribute table
4. Bidding Down Prevention for EAP-AKA 4. Bidding Down Prevention for EAP-AKA
As discussed in [RFC3748], negotiation of methods within EAP is As discussed in [RFC3748], negotiation of methods within EAP is
insecure. That is, a man-in-the-middle attacker may force the insecure. That is, a man-in-the-middle attacker may force the
endpoints to use a method that is not the strongest that they both endpoints to use a method that is not the strongest that they both
support. This is a problem, as we expect EAP-AKA and EAP-AKA' to be support. This is a problem, as we expect EAP-AKA and EAP-AKA' to be
negotiated via EAP. negotiated via EAP.
In order to prevent such attacks, this RFC specifies a new mechanism In order to prevent such attacks, this RFC specifies a new mechanism
for EAP-AKA that allows the endpoints to securely discover the for EAP-AKA that allows the endpoints to securely discover the
skipping to change at page 21, line 21 skipping to change at page 21, line 25
5.2. Generating Pseudonyms and Fast Re-Authentication Identities 5.2. Generating Pseudonyms and Fast Re-Authentication Identities
As specified by [RFC4187] Section 4.1.1.7, pseudonym usernames and As specified by [RFC4187] Section 4.1.1.7, pseudonym usernames and
fast re-authentication identities are generated by the EAP server, in fast re-authentication identities are generated by the EAP server, in
an implementation-dependent manner. RFC 4187 provides some general an implementation-dependent manner. RFC 4187 provides some general
requirements on how these identities are transported, how they map to requirements on how these identities are transported, how they map to
the NAI syntax, how they are distinguished from each other, and so the NAI syntax, how they are distinguished from each other, and so
on. on.
However, to ensure privacy some additional requirements need to be However, to enhance privacy some additional requirements need to be
applied. applied.
The pseudonym usernames and fast re-authentication identities MUST be The pseudonym usernames and fast re-authentication identities MUST be
generated in a cryptographically secure way so that that it is generated in a cryptographically secure way so that that it is
computationally infeasible for at attacker to differentiate two computationally infeasible for an attacker to differentiate two
identities belonging to the same user from two identities belonging identities belonging to the same user from two identities belonging
to different users. This can be achieved, for instance, by using to different users. This can be achieved, for instance, by using
random or pseudo-random identifiers such as random byte strings or random or pseudo-random identifiers such as random byte strings or
ciphertexts. See also [RFC4086] for guidance on random number ciphertexts. See also [RFC4086] for guidance on random number
generation. generation.
Note that the pseudonym and fast re-authentication usernames also Note that the pseudonym and fast re-authentication usernames also
MUST NOT include substrings that can be used to relate the username MUST NOT include substrings that can be used to relate the username
to a particular entity or a particular permanent identity. For to a particular entity or a particular permanent identity. For
instance, the usernames can not include any subscriber-identifying instance, the usernames can not include any subscriber-identifying
skipping to change at page 26, line 41 skipping to change at page 26, line 50
section. Under this assumption, EAP-AKA' is at least as secure as section. Under this assumption, EAP-AKA' is at least as secure as
EAP-AKA. EAP-AKA.
If the AT_KDF attribute has value 1, then the security properties of If the AT_KDF attribute has value 1, then the security properties of
EAP-AKA' are as follows: EAP-AKA' are as follows:
Protected ciphersuite negotiation Protected ciphersuite negotiation
EAP-AKA' has no ciphersuite negotiation mechanisms. It does have EAP-AKA' has no ciphersuite negotiation mechanisms. It does have
a negotiation mechanism for selecting the key derivation a negotiation mechanism for selecting the key derivation
functions. This mechanism is secure against bidding down attacks. functions. This mechanism is secure against bidding down attacks
The negotiation mechanism allows changing the offered key from EAP-AKA' to EAP-AKA. The negotiation mechanism allows
derivation function, but the change is visible in the final EAP- changing the offered key derivation function, but the change is
Request/AKA'-Challenge message that the server sends to the peer. visible in the final EAP-Request/AKA'-Challenge message that the
This message is authenticated via the AT_MAC attribute, and server sends to the peer. This message is authenticated via the
carries both the chosen alternative and the initially offered AT_MAC attribute, and carries both the chosen alternative and the
list. The peer refuses to accept a change it did not initiate. initially offered list. The peer refuses to accept a change it
As a result, both parties are aware that a change is being made did not initiate. As a result, both parties are aware that a
and what the original offer was. change is being made and what the original offer was.
Per assumptions in Section 4, there is no protection against
bidding down attacks from EAP-AKA to EAP-AKA', should EAP-AKA'
somehow be considered less secure some day than EAP-AKA. Such
protection was not provided in RFC 5448 implementations and
consequently neither does this specification provide it. If such
support is needed, it would have to be added as a separate new
feature.
In general, it is expected that the current negotiation
capabilities in EAP-AKA' are sufficient for some types of
extensions and cryptographic agility, including adding Perfect
Forward Secrecy ([I-D.ietf-emu-aka-pfs]) and perhaps others. But
as with how EAP-AKA' itself came about, some larger changes may
require a new EAP method type.
Mutual authentication Mutual authentication
Under the SHA-256 assumption, the properties of EAP-AKA' are at Under the SHA-256 assumption, the properties of EAP-AKA' are at
least as good as those of EAP-AKA in this respect. Refer to least as good as those of EAP-AKA in this respect. Refer to
[RFC4187], Section 12 for further details. [RFC4187], Section 12 for further details.
Integrity protection Integrity protection
Under the SHA-256 assumption, the properties of EAP-AKA' are at Under the SHA-256 assumption, the properties of EAP-AKA' are at
least as good (most likely better) as those of EAP-AKA in this least as good (most likely better) as those of EAP-AKA in this
respect. Refer to [RFC4187], Section 12 for further details. The respect. Refer to [RFC4187], Section 12 for further details. The
only difference is that a stronger hash algorithm and keyed MAC, only difference is that a stronger hash algorithm and keyed MAC,
skipping to change at page 29, line 26 skipping to change at page 29, line 51
EAP-AKA' uses several different types of identifiers to identify the EAP-AKA' uses several different types of identifiers to identify the
authenticating peer. It is strongly RECOMMENDED to use the privacy- authenticating peer. It is strongly RECOMMENDED to use the privacy-
friendly temporary or hidden identifiers, i.e., the 5G SUCI, friendly temporary or hidden identifiers, i.e., the 5G SUCI,
pseudonym usernames, and fast re-authentication usernames. The use pseudonym usernames, and fast re-authentication usernames. The use
of permanent identifiers such as the IMSI or SUPI may lead to an of permanent identifiers such as the IMSI or SUPI may lead to an
ability to track the peer and/or user associated with the peer. The ability to track the peer and/or user associated with the peer. The
use of permanent identifiers such as the IMSI or SUPI is strongly NOT use of permanent identifiers such as the IMSI or SUPI is strongly NOT
RECOMMENDED. RECOMMENDED.
As discussed in Section 5.3, when authenticating to a 5G network, As discussed in Section 5.3, when authenticating to a 5G network,
only the 5G SUCI identifier should be used. The use of pseudonyms in only the 5G SUCI identifier should be used. The use of EAP-AKA'
this situation is at best limited. In fact, the re-use of the same pseudonyms in this situation is at best limited, because the 5G SUCI
pseudonym multiple times will result in a tracking opportunity for already provides a stronger mechanism. In fact, the re-use of the
observers that see the pseudonym pass by. To avoid this, the peer same pseudonym multiple times will result in a tracking opportunity
and server need to follow the guidelines given in Section 5.2. for observers that see the pseudonym pass by. To avoid this, the
peer and server need to follow the guidelines given in Section 5.2.
When authenticating to a 5G network, per Section 5.3.1, both the EAP- When authenticating to a 5G network, per Section 5.3.1, both the EAP-
AKA' peer and server need to employ the permanent identifier, SUPI, AKA' peer and server need to employ the permanent identifier, SUPI,
as an input to key derivation. However, this use of the SUPI is only as an input to key derivation. However, this use of the SUPI is only
internal. As such, the SUPI need not be communicated in EAP internal. As such, the SUPI need not be communicated in EAP
messages. Therefore, SUPI MUST NOT be communicated in EAP-AKA' when messages. Therefore, SUPI MUST NOT be communicated in EAP-AKA' when
authenticating to a 5G network. authenticating to a 5G network.
While the use of SUCI in 5G networks generally provides identity While the use of SUCI in 5G networks generally provides identity
privacy, this is not true if the null-scheme encryption is used to privacy, this is not true if the null-scheme encryption is used to
skipping to change at page 30, line 5 skipping to change at page 30, line 30
scheme turns the use of SUCI equivalent to the use of SUPI or IMSI. scheme turns the use of SUCI equivalent to the use of SUPI or IMSI.
The use of the null scheme is NOT RECOMMENDED where identity privacy The use of the null scheme is NOT RECOMMENDED where identity privacy
is important. is important.
The use of fast re-authentication identities when authenticating to a The use of fast re-authentication identities when authenticating to a
5G network does not have the same problems as the use of pseudonyms, 5G network does not have the same problems as the use of pseudonyms,
as long as the 5G authentication server generates the fast re- as long as the 5G authentication server generates the fast re-
authentication identifiers in a proper manner specified in authentication identifiers in a proper manner specified in
Section 5.2. Section 5.2.
Outside 5G, there is a full choice to use permanent, pseudonym, or Outside 5G, the peer can freely choose between the use of permanent,
fast re-authentication identifiers: pseudonym, or fast re-authentication identifiers:
o A peer that has not yet performed any EAP-AKA' exchanges does not o A peer that has not yet performed any EAP-AKA' exchanges does not
typically have a pseudonym available. If the peer does not have a typically have a pseudonym available. If the peer does not have a
pseudonym available, then the privacy mechanism cannot be used, pseudonym available, then the privacy mechanism cannot be used,
and the permanent identity will have to be sent in the clear. and the permanent identity will have to be sent in the clear.
The terminal SHOULD store the pseudonym in non-volatile memory so The terminal SHOULD store the pseudonym in non-volatile memory so
that it can be maintained across reboots. An active attacker that that it can be maintained across reboots. An active attacker that
impersonates the network may use the AT_PERMANENT_ID_REQ attribute impersonates the network may use the AT_PERMANENT_ID_REQ attribute
([RFC4187] Section 4.1.2) to learn the subscriber's IMSI. ([RFC4187] Section 4.1.2) to learn the subscriber's IMSI.
skipping to change at page 32, line 26 skipping to change at page 33, line 5
Borgaonkar et al discovered that the AKA resynchronization protocol Borgaonkar et al discovered that the AKA resynchronization protocol
may also be used to predict the authentication frequency of a may also be used to predict the authentication frequency of a
subscribers if non-time-based SQN generation scheme is used subscribers if non-time-based SQN generation scheme is used
[Borgaonkar2018]. The attacker can force the re-use of the keystream [Borgaonkar2018]. The attacker can force the re-use of the keystream
that is used to protect the SQN in the AKA resynchronization that is used to protect the SQN in the AKA resynchronization
protocol. The attacker then guesses the authentication frequency protocol. The attacker then guesses the authentication frequency
based on the lowest bits of two XORed SQNs. The researchers' concern based on the lowest bits of two XORed SQNs. The researchers' concern
was that the authentication frequency would reveal some information was that the authentication frequency would reveal some information
about the phone usage behavior, e.g., number of phone calls made or about the phone usage behavior, e.g., number of phone calls made or
number of SMS messages sent. However, phone calls and SMS messages number of SMS messages sent. There are a number of possible triggers
are just some of the many potential triggers for authentication. For for authentication, so such information leak is not direct, but can
instance, various mobility events and the amount of mobile data sent be a concern. The impact of the attack is also different depending
or received can also trigger authentication. As a result, while some on whether time or non-time-based SQN generation scheme is used.
amount of information may be derived about the activity level on a
particular phone in some cases, the linkage to specific activities is
not direct. The impact of the attack is also different depending on
whether time or non-time-based SQN generation scheme is used.
Similar attacks are possible outside AKA in the cellular paging Similar attacks are possible outside AKA in the cellular paging
protocols where the attacker can simply send application layer data, protocols where the attacker can simply send application layer data,
short messages or make phone calls to the intended victim and observe short messages or make phone calls to the intended victim and observe
the air-interface (e.g., [Kune2012] and [Shaik2016]). Hussain et. the air-interface (e.g., [Kune2012] and [Shaik2016]). Hussain et.
al. demonstrated a slightly more sophisticated version of the attack al. demonstrated a slightly more sophisticated version of the attack
that exploits the fact that 4G paging protocol uses the IMSI to that exploits the fact that 4G paging protocol uses the IMSI to
calculate the paging timeslot [Hussain2019]. As this attack is calculate the paging timeslot [Hussain2019]. As this attack is
outside AKA, it does not impact EAP-AKA'. outside AKA, it does not impact EAP-AKA'.
skipping to change at page 33, line 33 skipping to change at page 34, line 5
In particular, it is crucial that manufacturers limit access to the In particular, it is crucial that manufacturers limit access to the
secret information and the cards only to necessary systems and secret information and the cards only to necessary systems and
personnel. It is also crucial that secure mechanisms be used to personnel. It is also crucial that secure mechanisms be used to
communicate the secrets between the manufacturer and the operator communicate the secrets between the manufacturer and the operator
that adopts those cards for their customers. that adopts those cards for their customers.
Beyond these operational considerations, there are also technical Beyond these operational considerations, there are also technical
means to improve resistance to these attacks. One approach is to means to improve resistance to these attacks. One approach is to
provide Perfect Forwards Secrecy (PFS). This would prevent any provide Perfect Forwards Secrecy (PFS). This would prevent any
passive attacks merely based on the long-term secrets and observation passive attacks merely based on the long-term secrets and observation
of traffic. Such a mechanism can be defined as an backwards- of traffic. Such a mechanism can be defined as a backwards-
compatible extension of EAP-AKA', and is pursued separately from this compatible extension of EAP-AKA', and is pursued separately from this
specification [I-D.arkko-eap-aka-pfs]. Alternatively, EAP-AKA' specification [I-D.ietf-emu-aka-pfs]. Alternatively, EAP-AKA'
authentication can be run inside a PFS-capable tunneled authentication can be run inside a PFS-capable tunneled
authentication method. In any case, the use of some PFS-capable authentication method. In any case, the use of some PFS-capable
mechanism is recommended. mechanism is recommended.
7.4. Security Properties of Binding Network Names 7.4. Security Properties of Binding Network Names
The ability of EAP-AKA' to bind the network name into the used keys The ability of EAP-AKA' to bind the network name into the used keys
provides some additional protection against key leakage to provides some additional protection against key leakage to
inappropriate parties. The keys used in the protocol are specific to inappropriate parties. The keys used in the protocol are specific to
a particular network name. If key leakage occurs due to an accident, a particular network name. If key leakage occurs due to an accident,
skipping to change at page 35, line 45 skipping to change at page 36, line 17
Value Description Reference Value Description Reference
--------- ---------------------- ------------------------------- --------- ---------------------- -------------------------------
0 Reserved [RFC Editor: Refer to this RFC] 0 Reserved [RFC Editor: Refer to this RFC]
1 EAP-AKA' with CK'/IK' [RFC Editor: Refer to this RFC] 1 EAP-AKA' with CK'/IK' [RFC Editor: Refer to this RFC]
2-65535 Unassigned 2-65535 Unassigned
9. References 9. References
9.1. Normative References 9.1. Normative References
[Note] Editors, "All 3GPP references should be updated to the
latest Release 15 version before publishing.".
[TS-3GPP.23.003] [TS-3GPP.23.003]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Numbering, Specification Group Core Network and Terminals; Numbering,
addressing and identification (Release 15)", 3GPP Draft addressing and identification (Release 15)",
Technical Specification 23.003, June 2019. 3GPP Technical Specification 23.003 version 15.8.0,
September 2019.
[TS-3GPP.23.501] [TS-3GPP.23.501]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G Specification Group Services and System Aspects; 3G
Security; Security architecture and procedures for 5G Security; Security architecture and procedures for 5G
System; (Release 15)", 3GPP Technical Specification System; (Release 15)", 3GPP Technical Specification 23.501
23.501, June 2019. version 15.8.0, December 2019.
[TS-3GPP.24.302] [TS-3GPP.24.302]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Access to Specification Group Core Network and Terminals; Access to
the 3GPP Evolved Packet Core (EPC) via non-3GPP access the 3GPP Evolved Packet Core (EPC) via non-3GPP access
networks; Stage 3; (Release 15)", 3GPP Draft Technical networks; Stage 3; (Release 15)", 3GPP Technical
Specification 24.302, June 2019. Specification 24.302 version 15.7.0, June 2019.
[TS-3GPP.24.501] [TS-3GPP.24.501]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Access to Specification Group Core Network and Terminals; Access to
the 3GPP Evolved Packet Core (EPC) via non-3GPP access the 3GPP Evolved Packet Core (EPC) via non-3GPP access
networks; Stage 3; (Release 15)", 3GPP Draft Technical networks; Stage 3; (Release 15)", 3GPP Draft Technical
Specification 24.501, June 2019. Specification 24.501 version 15.6.0, December 2019.
[TS-3GPP.33.102] [TS-3GPP.33.102]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G Specification Group Services and System Aspects; 3G
Security; Security architecture (Release 15)", 3GPP Draft Security; Security architecture (Release 15)",
Technical Specification 33.102, December 2018. 3GPP Technical Specification 33.102 version 15.1.0,
December 2018.
[TS-3GPP.33.402] [TS-3GPP.33.402]
3GPP, "3GPP System Architecture Evolution (SAE); Security 3GPP, "3GPP System Architecture Evolution (SAE); Security
aspects of non-3GPP accesses (Release 15)", 3GPP Draft aspects of non-3GPP accesses (Release 15)", 3GPP Technical
Technical Specification 33.402, June 2018. Specification 33.402 version 15.1.0, June 2018.
[TS-3GPP.33.501] [TS-3GPP.33.501]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G Specification Group Services and System Aspects; 3G
Security; Security architecture and procedures for 5G Security; Security architecture and procedures for 5G
System (Release 15)", 3GPP Draft Technical Specification System (Release 15)", 3GPP Technical Specification 33.501
33.501, June 2019. version 15.7.0, December 2019.
[FIPS.180-4] [FIPS.180-4]
National Institute of Standards and Technology, "Secure National Institute of Standards and Technology, "Secure
Hash Standard", FIPS PUB 180-4, August 2015, Hash Standard", FIPS PUB 180-4, August 2015,
<https://nvlpubs.nist.gov/nistpubs/FIPS/ <https://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.180-4.pdf>. NIST.FIPS.180-4.pdf>.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997, <https://www.rfc- DOI 10.17487/RFC2104, February 1997, <https://www.rfc-
skipping to change at page 37, line 40 skipping to change at page 38, line 11
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References 9.2. Informative References
[NoteAlso]
Editors, "All 3GPP references should be updated to the
latest Release 15 version before publishing.".
[TS-3GPP.35.208] [TS-3GPP.35.208]
3GPP, "3rd Generation Partnership Project; Technical 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; 3G Specification Group Services and System Aspects; 3G
Security; Specification of the MILENAGE Algorithm Set: An Security; Specification of the MILENAGE Algorithm Set: An
example algorithm set for the 3GPP authentication and key example algorithm set for the 3GPP authentication and key
generation functions f1, f1*, f2, f3, f4, f5 and f5*; generation functions f1, f1*, f2, f3, f4, f5 and f5*;
Document 4: Design Conformance Test Data (Release 14)", Document 4: Design Conformance Test Data (Release 14)",
3GPP Technical Specification 35.208, October 2018. 3GPP Technical Specification 35.208 version 15.0.0,
October 2018.
[FIPS.180-1] [FIPS.180-1]
National Institute of Standards and Technology, "Secure National Institute of Standards and Technology, "Secure
Hash Standard", FIPS PUB 180-1, April 1995, Hash Standard", FIPS PUB 180-1, April 1995,
<http://www.itl.nist.gov/fipspubs/fip180-1.htm>. <http://www.itl.nist.gov/fipspubs/fip180-1.htm>.
[FIPS.180-2] [FIPS.180-2]
National Institute of Standards and Technology, "Secure National Institute of Standards and Technology, "Secure
Hash Standard", FIPS PUB 180-2, August 2002, Hash Standard", FIPS PUB 180-2, August 2002,
<http://csrc.nist.gov/publications/fips/fips180-2/ <http://csrc.nist.gov/publications/fips/fips180-2/
skipping to change at page 39, line 31 skipping to change at page 39, line 46
[RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an [RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
2014, <https://www.rfc-editor.org/info/rfc7258>. 2014, <https://www.rfc-editor.org/info/rfc7258>.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2 Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <https://www.rfc-editor.org/info/rfc7296>. 2014, <https://www.rfc-editor.org/info/rfc7296>.
[I-D.arkko-eap-aka-pfs] [I-D.ietf-emu-aka-pfs]
Arkko, J., Norrman, K., and V. Torvinen, "Perfect-Forward Arkko, J., Norrman, K., and V. Torvinen, "Perfect-Forward
Secrecy for the Extensible Authentication Protocol Method Secrecy for the Extensible Authentication Protocol Method
for Authentication and Key Agreement (EAP-AKA' PFS)", for Authentication and Key Agreement (EAP-AKA' PFS)",
draft-arkko-eap-aka-pfs-04 (work in progress), January draft-ietf-emu-aka-pfs-02 (work in progress), November
2019. 2019.
[Heist2015] [Heist2015]
Scahill, J. and J. Begley, "The great SIM heist", February Scahill, J. and J. Begley, "The great SIM heist", February
2015, in https://firstlook.org/theintercept/2015/02/19/ 2015, in https://firstlook.org/theintercept/2015/02/19/
great-sim-heist/ . great-sim-heist/ .
[MT2012] Mjolsnes, S. and J-K. Tsay, "A vulnerability in the UMTS [MT2012] Mjolsnes, S. and J-K. Tsay, "A vulnerability in the UMTS
and LTE authentication and key agreement protocols", and LTE authentication and key agreement protocols",
October 2012, in Proceedings of the 6th international October 2012, in Proceedings of the 6th international
skipping to change at page 41, line 34 skipping to change at page 41, line 48
The references to [RFC2119], [RFC7542], [RFC7296], [RFC8126], The references to [RFC2119], [RFC7542], [RFC7296], [RFC8126],
[FIPS.180-1] and [FIPS.180-2] have been updated to their most recent [FIPS.180-1] and [FIPS.180-2] have been updated to their most recent
versions and language in this document changed accordingly. versions and language in this document changed accordingly.
Similarly, references to all 3GPP technical specifications have been Similarly, references to all 3GPP technical specifications have been
updated to their 5G (Release 15) versions or otherwise most recent updated to their 5G (Release 15) versions or otherwise most recent
version when there has not been a 5G-related update. version when there has not been a 5G-related update.
Finally, a number of clarifications have been made, including a Finally, a number of clarifications have been made, including a
summary of where attributes may appear. summary of where attributes may appear.
Appendix B. Changes from RFC 4187 to RFC 5448 Appendix B. Changes to RFC 4187
In addition to specifying EAP-AKA', this document mandates also a
change to another EAP method, EAP-AKA that was defined in RFC 4187.
This change was mandated already in RFC 5448 but repeated here to
ensure that the latest EAP-AKA' specification contains the
instructions about the necessary bidding down feature in EAP-AKA as
well.
The changes to RFC 4187 relate only to the bidding down prevention The changes to RFC 4187 relate only to the bidding down prevention
support defined in Section 4. In particular, this document does not support defined in Section 4. In particular, this document does not
change how the Master Key (MK) is calculated in RFC 4187 (it uses CK change how the Master Key (MK) is calculated or any other aspect of
and IK, not CK' and IK'); neither is any processing of the AMF bit EAP-AKA. The provisions in this specification for EAP-AKA' do not
added to RFC 4187. apply to EAP-AKA, outside Section 4.
Appendix C. Changes from Previous Version of This Draft Appendix C. Changes from Previous Version of This Draft
RFC Editor: Please delete this section at the time of publication. RFC Editor: Please delete this section at the time of publication.
The -00 version of the working group draft is merely a republication The -00 version of the working group draft is merely a republication
of an earlier individual draft. of an earlier individual draft.
The -01 version of the working group draft clarifies updates The -01 version of the working group draft clarifies updates
relationship to RFC 4187, clarifies language relating to obsoleting relationship to RFC 4187, clarifies language relating to obsoleting
skipping to change at page 43, line 36 skipping to change at page 44, line 8
o Updated and added several references o Updated and added several references
o Switched to use of hexadecimal for EAP Type Values for consistency o Switched to use of hexadecimal for EAP Type Values for consistency
with other documents. with other documents.
o Made editorial clarifications to a number places in the document. o Made editorial clarifications to a number places in the document.
The version -06 included changes to updates of references to newer The version -06 included changes to updates of references to newer
versions on IANA considerations guidelines, NAIs, and IKEv2. versions on IANA considerations guidelines, NAIs, and IKEv2.
The version -07 includes the following changes, per AD and last call
review comments:
o The use of pseudonyms has been clarified in Section 7.1.
o The document now clarifies that it specifies behaviour both for 4G
and 5G.
o The implications of collisions between "Access Network ID" (4G)
and "Serving Network Name" (5G) have been explained in
Section 3.1.
o The ability of the bidding down protection to protect bidding down
only in the direction from EAP-AKA' to EAP-AKA but the other way
around has been noted in Section 7.
o The implications of the attack described by [Borgaonkar2018] have
been updated.
o Section 3.1 now specifies more clearly that zero-length network
name is not allowed.
o Section 3.1 refers to the network name that is today specified in
[TS-3GPP.24.302] for both 4G (non-3GPP access) and 5G.
o Section 7 now discusses cryptographic agility.
o The document now is clear that any change to key aspects of 3GPP
specifications, such as key derivation for AKA, would affect this
specification and implementations.
o References have been updated to the latest Release 15 versions,
that are now stable.
o Tables have been numbered.
o Adopted a number of other editorial corrections.
Appendix D. Importance of Explicit Negotiation Appendix D. Importance of Explicit Negotiation
Choosing between the traditional and revised AKA key derivation Choosing between the traditional and revised AKA key derivation
functions is easy when their use is unambiguously tied to a functions is easy when their use is unambiguously tied to a
particular radio access network, e.g., Long Term Evolution (LTE) as particular radio access network, e.g., Long Term Evolution (LTE) as
defined by 3GPP or evolved High Rate Packet Data (eHRPD) as defined defined by 3GPP or evolved High Rate Packet Data (eHRPD) as defined
by 3GPP2. There is no possibility for interoperability problems if by 3GPP2. There is no possibility for interoperability problems if
this radio access network is always used in conjunction with new this radio access network is always used in conjunction with new
protocols that cannot be mixed with the old ones; clients will always protocols that cannot be mixed with the old ones; clients will always
know whether they are connecting to the old or new system. know whether they are connecting to the old or new system.
skipping to change at page 49, line 15 skipping to change at page 50, line 15
Jouni Malinen provided suggested text for Section 6. John Mattsson Jouni Malinen provided suggested text for Section 6. John Mattsson
provided much of the text for Section 7.1. Karl Norrman was the provided much of the text for Section 7.1. Karl Norrman was the
source of much of the information in Section 7.2. source of much of the information in Section 7.2.
Acknowledgments Acknowledgments
The authors would like to thank Guenther Horn, Joe Salowey, Mats The authors would like to thank Guenther Horn, Joe Salowey, Mats
Naslund, Adrian Escott, Brian Rosenberg, Laksminath Dondeti, Ahmad Naslund, Adrian Escott, Brian Rosenberg, Laksminath Dondeti, Ahmad
Muhanna, Stefan Rommer, Miguel Garcia, Jan Kall, Ankur Agarwal, Jouni Muhanna, Stefan Rommer, Miguel Garcia, Jan Kall, Ankur Agarwal, Jouni
Malinen, John Mattsson, Jesus De Gregorio, Brian Weis, Russ Housley, Malinen, John Mattsson, Jesus De Gregorio, Brian Weis, Russ Housley,
Alfred Hoenes, Anand Palanigounder, Michael Richardsson, Marcus Wong, Alfred Hoenes, Anand Palanigounder, Michael Richardsson, Roman
Kalle Jarvinen, Daniel Migault, and Mohit Sethi for their in-depth Danyliw, Dan Romascanu, Kyle Rose, Marcus Wong, Kalle Jarvinen,
reviews and interesting discussions in this problem space. Daniel Migault, and Mohit Sethi for their in-depth reviews and
interesting discussions in this problem space.
Authors' Addresses Authors' Addresses
Jari Arkko Jari Arkko
Ericsson Ericsson
Jorvas 02420 Jorvas 02420
Finland Finland
Email: jari.arkko@piuha.net Email: jari.arkko@piuha.net
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