draft-ietf-tokbind-negotiation-07.txt   draft-ietf-tokbind-negotiation-08.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: August 20, 2017 D. Balfanz Expires: October 23, 2017 D. Balfanz
A. Langley A. Langley
Google Inc. Google Inc.
February 16, 2017 April 21, 2017
Transport Layer Security (TLS) Extension for Token Binding Protocol Transport Layer Security (TLS) Extension for Token Binding Protocol
Negotiation Negotiation
draft-ietf-tokbind-negotiation-07 draft-ietf-tokbind-negotiation-08
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 August 20, 2017. This Internet-Draft will expire on October 23, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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described in the Simplified BSD License. described in the Simplified BSD License.
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 . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6.1. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 5 6.1. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 6
6.2. Triple Handshake Vulnerability in TLS 1.2 and Older TLS 6.2. Triple Handshake Vulnerability in TLS 1.2 and Older TLS
Versions . . . . . . . . . . . . . . . . . . . . . . . . 6 Versions . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 7 8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
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 in TLS 1.2 and earlier
versions. The negotiation of the Token Binding protocol and key
parameters in combination with TLS 1.3 and later versions is beyond
the scope of this document.
1.1. Requirements Language 1.1. 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", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Token Binding Negotiation Client Hello Extension 2. Token Binding Negotiation Client Hello Extension
The client uses the "token_binding" TLS extension to indicate the The client uses the "token_binding" TLS extension to indicate the
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struct { struct {
ProtocolVersion token_binding_version; ProtocolVersion token_binding_version;
TokenBindingKeyParameters key_parameters_list<1..2^8-1> TokenBindingKeyParameters key_parameters_list<1..2^8-1>
} TokenBindingParameters; } TokenBindingParameters;
"token_binding_version" indicates the version of the Token Binding "token_binding_version" indicates the version of the Token Binding
protocol the client wishes to use during this connection. This protocol the client wishes to use during this connection. This
SHOULD be the latest (highest valued) version supported by the SHOULD be the latest (highest valued) version supported by the
client. [I-D.ietf-tokbind-protocol] describes version {1, 0} of the client. [I-D.ietf-tokbind-protocol] describes version {1, 0} of the
protocol. Prototype implementations of Token Binding drafts can protocol.
indicate support of a specific draft version, e.g. {0, 1} or {0, 2}.
RFC EDITOR: PLEASE REMOVE THE FOLLOWING PARAGRAPH: Prototype
implementations of Token Binding drafts can indicate support of a
specific draft version, e.g. {0, 1} or {0, 2}.
"key_parameters_list" contains the list of identifiers of the Token "key_parameters_list" contains the list of identifiers of the Token
Binding key parameters supported by the client, in descending order Binding key parameters supported by the client, in descending order
of preference. [I-D.ietf-tokbind-protocol] defines an initial set of of preference. [I-D.ietf-tokbind-protocol] defines an initial set of
identifiers for Token Binding key parameters. identifiers for Token Binding key parameters.
3. Token Binding Negotiation Server Hello Extension 3. Token Binding Negotiation Server Hello Extension
The server uses the "token_binding" TLS extension to indicate support The server uses the "token_binding" TLS extension to indicate support
for the Token Binding protocol and to select the protocol version and for the Token Binding protocol and to select the protocol version and
key parameters. key parameters.
The server that supports Token Binding and receives a client hello The server that supports Token Binding and receives a client hello
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 the Extended Master Secret 3. The server is also negotiating the Extended Master Secret
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6. Security Considerations 6. Security Considerations
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 Token Binding 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 1.2 and Older TLS Versions 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 vulnerability in TLS 1.2 and handshake attack [TRIPLE-HS] is a known vulnerability in TLS 1.2 and
older TLS versions, allowing the attacker to synchronize keying older TLS versions, allowing the attacker to synchronize keying
material between TLS connections. The attacker can then successfully material between TLS connections. The attacker can then successfully
replay bound tokens. For this reason, the Token Binding protocol replay bound tokens. For this reason, the Token Binding protocol
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Nadalin, Michael B. Jones, Bill Cox, Nick Harper, Brian Campbell and Nadalin, Michael B. Jones, Bill Cox, Nick Harper, Brian Campbell and
others. 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., Langley, A., and J. Popov, A., Nystrom, M., Balfanz, D., Langley, A., and J.
Hodges, "The Token Binding Protocol Version 1.0", draft- Hodges, "The Token Binding Protocol Version 1.0", draft-
ietf-tokbind-protocol-11 (work in progress), November ietf-tokbind-protocol-13 (work in progress), February
2016. 2017.
[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>.
[RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., [RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J.,
and T. Wright, "Transport Layer Security (TLS) and T. Wright, "Transport Layer Security (TLS)
Extensions", RFC 4366, DOI 10.17487/RFC4366, April 2006, Extensions", RFC 4366, DOI 10.17487/RFC4366, April 2006,
<http://www.rfc-editor.org/info/rfc4366>. <http://www.rfc-editor.org/info/rfc4366>.
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