draft-ietf-tokbind-negotiation-01.txt   draft-ietf-tokbind-negotiation-02.txt 
Internet Engineering Task Force A. Popov, Ed. Internet Engineering Task Force A. Popov, Ed.
Internet-Draft M. Nystroem Internet-Draft M. Nystroem
Intended status: Standards Track Microsoft Corp. Intended status: Standards Track Microsoft Corp.
Expires: April 8, 2016 D. Balfanz Expires: July 11, 2016 D. Balfanz
A. Langley A. Langley
Google Inc. Google Inc.
October 6, 2015 January 8, 2016
Transport Layer Security (TLS) Extension for Token Binding Protocol Transport Layer Security (TLS) Extension for Token Binding Protocol
Negotiation Negotiation
draft-ietf-tokbind-negotiation-01 draft-ietf-tokbind-negotiation-02
Abstract Abstract
This document specifies a Transport Layer Security (TLS) [RFC5246] This document specifies a Transport Layer Security (TLS) [RFC5246]
extension for the negotiation of Token Binding protocol extension for the negotiation of Token Binding protocol
[I-D.ietf-tokbind-protocol] version and key parameters. [I-D.ietf-tokbind-protocol] version and key parameters.
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
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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 April 8, 2016. This Internet-Draft will expire on July 11, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Token Binding Negotiation Client Hello Extension . . . . . . 2 2. Token Binding Negotiation Client Hello Extension . . . . . . 2
3. Token Binding Negotiation Server Hello Extension . . . . . . 3 3. Token Binding Negotiation Server Hello Extension . . . . . . 3
4. Negotiating Token Binding Protocol Version and Key Parameters 4 4. Negotiating Token Binding Protocol Version and Key Parameters 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6.1. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 6 6.1. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 6
6.2. Triple Handshake Vulnerability in TLS . . . . . . . . . . 6 6.2. Triple Handshake Vulnerability in TLS 1.2 and Older TLS
Versions . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 7 8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
In order to use the Token Binding protocol In order to use the Token Binding protocol
[I-D.ietf-tokbind-protocol], the client and server need to agree on [I-D.ietf-tokbind-protocol], the client and server need to agree on
the Token Binding protocol version and the parameters (signature the Token Binding protocol version and the parameters (signature
algorithm, length) of the Token Binding key. This document specifies algorithm, length) of the Token Binding key. This document specifies
a new TLS extension to accomplish this negotiation without a new TLS extension to accomplish this negotiation without
introducing additional network round-trips. introducing additional network round-trips.
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message containing the "token_binding" extension, will include the message containing the "token_binding" extension, will include the
"token_binding" extension in the server hello if all of the following "token_binding" extension in the server hello if all of the following
conditions are satisfied: conditions are satisfied:
1. The server supports the Token Binding protocol version offered by 1. The server supports the Token Binding protocol version offered by
the client or a lower version. the client or a lower version.
2. The server finds acceptable Token Binding key parameters on the 2. The server finds acceptable Token Binding key parameters on the
client's list. client's list.
3. The server is also negotiating Extended Master Secret TLS 3. The server is also negotiating Extended Master Secret [RFC7627]
extension [I-D.ietf-tls-session-hash] (see security and Renegotiation Indication [RFC5746] TLS extensions. This
considerations section below for more details). requirement only applies when TLS 1.2 or an older TLS version is
used (see security considerations section below for more
details).
The server will ignore any key parameters that it does not recognize. The server will ignore any key parameters that it does not recognize.
The "extension_data" field of the "token_binding" extension is The "extension_data" field of the "token_binding" extension is
structured the same as described above for the client structured the same as described above for the client
"extension_data". "extension_data".
"token_binding_version" contains the lower of the Token Binding "token_binding_version" contains the lower of the Token Binding
protocol version offered by the client in the "token_binding" protocol version offered by the client in the "token_binding"
extension and the highest version supported by the server. extension and the highest version supported by the server.
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2. "token_binding_version" is higher than the Token Binding protocol 2. "token_binding_version" is higher than the Token Binding protocol
version advertised by the client. version advertised by the client.
3. "key_parameters_list" includes more than one Token Binding key 3. "key_parameters_list" includes more than one Token Binding key
parameters identifier. parameters identifier.
4. "key_parameters_list" includes an identifier that was not 4. "key_parameters_list" includes an identifier that was not
advertised by the client. advertised by the client.
5. Extended Master Secret [I-D.ietf-tls-session-hash] is not 5. TLS 1.2 or an older TLS version is used, but Extended Master
negotiated (see security considerations section below for more Secret [RFC7627] and Renegotiation Indication [RFC5746] TLS
details). extensions are not negotiated (see security considerations
section below for more details).
If the "token_binding" extension is included in the server hello and If the "token_binding" extension is included in the server hello and
the client supports the Token Binding protocol version selected by the client supports the Token Binding protocol version selected by
the server, it means that the version and key parameters have been the server, it means that the version and key parameters have been
negotiated between the client and the server and SHALL be definitive negotiated between the client and the server and SHALL be definitive
for the TLS connection. In this case, the client MUST use the for the TLS connection. In this case, the client MUST use the
negotiated key parameters in the "provided_token_binding" as negotiated key parameters in the "provided_token_binding" as
described in [I-D.ietf-tokbind-protocol]. described in [I-D.ietf-tokbind-protocol].
If the client does not support the Token Binding protocol version If the client does not support the Token Binding protocol version
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6.1. Downgrade Attacks 6.1. Downgrade Attacks
The Token Binding protocol version and key parameters are negotiated The Token Binding protocol version and key parameters are negotiated
via "token_binding" extension within the TLS handshake. TLS prevents via "token_binding" extension within the TLS handshake. TLS prevents
active attackers from modifying the messages of the TLS handshake, active attackers from modifying the messages of the TLS handshake,
therefore it is not possible for the attacker to remove or modify the therefore it is not possible for the attacker to remove or modify the
"token_binding" extension. The signature algorithm and key length "token_binding" extension. The signature algorithm and key length
used in the TokenBinding of type "provided_token_binding" MUST match used in the TokenBinding of type "provided_token_binding" MUST match
the parameters negotiated via "token_binding" extension. the parameters negotiated via "token_binding" extension.
6.2. Triple Handshake Vulnerability in TLS 6.2. Triple Handshake Vulnerability in TLS 1.2 and Older TLS Versions
The Token Binding protocol relies on the TLS Exporters [RFC5705] to The Token Binding protocol relies on the TLS Exporters [RFC5705] to
associate a TLS connection with a Token Binding. The triple associate a TLS connection with a Token Binding. The triple
handshake attack [TRIPLE-HS] is a known TLS protocol vulnerability handshake attack [TRIPLE-HS] is a known TLS protocol vulnerability
allowing the attacker to synchronize exported keying material between allowing the attacker to synchronize exported keying material between
TLS connections. The attacker can then successfully replay bound TLS connections. The attacker can then successfully replay bound
tokens. For this reason, the Token Binding protocol MUST NOT be tokens. For this reason, the Token Binding protocol MUST NOT be
negotiated unless the Extended Master Secret TLS extension negotiated with these TLS versions, unless the Extended Master Secret
[I-D.ietf-tls-session-hash] has also been negotiated. [RFC7627] and Renegotiation Indication [RFC5746] TLS extensions have
also been negotiated.
7. Acknowledgements 7. Acknowledgements
This document incorporates comments and suggestions offered by Eric This document incorporates comments and suggestions offered by Eric
Rescorla, Gabriel Montenegro, Martin Thomson, Vinod Anupam, Bill Cox, Rescorla, Gabriel Montenegro, Martin Thomson, Vinod Anupam, Bill Cox,
Nick Harper and others. Nick Harper and others.
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-tokbind-protocol] [I-D.ietf-tokbind-protocol]
Popov, A., Nystrom, M., Balfanz, D., and A. Langley, "The Popov, A., Nystrom, M., Balfanz, D., and A. Langley, "The
Token Binding Protocol Version 1.0", draft-ietf-tokbind- Token Binding Protocol Version 1.0", draft-ietf-tokbind-
protocol-02 (work in progress), September 2015. protocol-03 (work in progress), October 2015.
[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, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. <http://www.rfc-editor.org/info/rfc5226>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, (TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008, DOI 10.17487/RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>. <http://www.rfc-editor.org/info/rfc5246>.
[RFC5705] Rescorla, E., "Keying Material Exporters for Transport [RFC5705] Rescorla, E., "Keying Material Exporters for Transport
Layer Security (TLS)", RFC 5705, DOI 10.17487/RFC5705, Layer Security (TLS)", RFC 5705, DOI 10.17487/RFC5705,
March 2010, <http://www.rfc-editor.org/info/rfc5705>. March 2010, <http://www.rfc-editor.org/info/rfc5705>.
8.2. Informative References [RFC5746] Rescorla, E., Ray, M., Dispensa, S., and N. Oskov,
"Transport Layer Security (TLS) Renegotiation Indication
Extension", RFC 5746, DOI 10.17487/RFC5746, February 2010,
<http://www.rfc-editor.org/info/rfc5746>.
[I-D.ietf-tls-session-hash] [RFC7627] Bhargavan, K., Ed., Delignat-Lavaud, A., Pironti, A.,
Bhargavan, K., Delignat-Lavaud, A., Pironti, A., Langley, Langley, A., and M. Ray, "Transport Layer Security (TLS)
A., and M. Ray, "Transport Layer Security (TLS) Session Session Hash and Extended Master Secret Extension",
Hash and Extended Master Secret Extension", draft-ietf- RFC 7627, DOI 10.17487/RFC7627, September 2015,
tls-session-hash-06 (work in progress), July 2015. <http://www.rfc-editor.org/info/rfc7627>.
8.2. Informative References
[TRIPLE-HS] [TRIPLE-HS]
Bhargavan, K., Delignat-Lavaud, A., Fournet, C., Pironti, Bhargavan, K., Delignat-Lavaud, A., Fournet, C., Pironti,
A., and P. Strub, "Triple Handshakes and Cookie Cutters: A., and P. Strub, "Triple Handshakes and Cookie Cutters:
Breaking and Fixing Authentication over TLS. IEEE Breaking and Fixing Authentication over TLS. IEEE
Symposium on Security and Privacy", 2014. Symposium on Security and Privacy", 2014.
Authors' Addresses Authors' Addresses
Andrei Popov (editor) Andrei Popov (editor)
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