draft-ietf-tokbind-negotiation-00.txt   draft-ietf-tokbind-negotiation-01.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: March 13, 2016 D. Balfanz Expires: April 8, 2016 D. Balfanz
A. Langley A. Langley
Google Inc. Google Inc.
September 10, 2015 October 6, 2015
Transport Layer Security (TLS) Extension for Token Binding Protocol Transport Layer Security (TLS) Extension for Token Binding Protocol
Negotiation Negotiation
draft-ietf-tokbind-negotiation-00 draft-ietf-tokbind-negotiation-01
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 March 13, 2016. This Internet-Draft will expire on April 8, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 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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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 and the Token Binding protocol version and the parameters (signature
hash algorithm, length) of the Token Binding key. This document algorithm, length) of the Token Binding key. This document specifies
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.
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
highest supported Token Binding protocol version and key parameters. highest supported Token Binding protocol version and key parameters.
enum { enum {
token_binding(TBD), (65535) token_binding(TBD), (65535)
} ExtensionType; } ExtensionType;
The "extension_data" field of this extension contains a The "extension_data" field of this extension contains a
"TokenBindingParameters" value. "TokenBindingParameters" value.
struct { struct {
uint8 major; uint8 major;
uint8 minor; uint8 minor;
} ProtocolVersion; } ProtocolVersion;
enum { enum {
rsa2048_pkcs1.5_sha256(0), rsa2048_pss_sha256(1), ecdsap256_sha256(2), (255) rsa2048_pkcs1.5(0), rsa2048_pss(1), ecdsap256(2), (255)
} TokenBindingKeyParameters; } TokenBindingKeyParameters;
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. Prototype implementations of Token Binding drafts can
indicate support of a specific draft version, e.g. {0, 1} or {0, 2}. 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
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[RFC5226]. The designated expert is advised to encourage the [RFC5226]. The designated expert is advised to encourage the
inclusion of a reference to a permanent and readily available inclusion of a reference to a permanent and readily available
specification that enables the creation of interoperable specification that enables the creation of interoperable
implementations using the identified set of Token Binding key implementations using the identified set of Token Binding key
parameters. parameters.
An initial set of registrations for this registry follows: An initial set of registrations for this registry follows:
Value: 0 Value: 0
Description: rsa2048_pkcs1.5_sha256 Description: rsa2048_pkcs1.5
Specification: this document Specification: this document
Value: 1 Value: 1
Description: rsa2048_pss_sha256 Description: rsa2048_pss
Specification: this document Specification: this document
Value: 2 Value: 2
Description: ecdsap256_sha256 Description: ecdsap256
Specification: this document Specification: this document
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 and hash algorithms and key "token_binding" extension. The signature algorithm and key length
length used in the TokenBinding of type "provided_token_binding" MUST used in the TokenBinding of type "provided_token_binding" MUST match
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
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 unless the Extended Master Secret TLS extension
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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-01 (work in progress), May 2015. protocol-02 (work in progress), September 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>.
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