The Token Binding Protocol Version 1.0
RFC 8471
Internet Engineering Task Force (IETF) A. Popov, Ed.
Request for Comments: 8471 M. Nystroem
Category: Standards Track Microsoft Corp.
ISSN: 2070-1721 D. Balfanz
Google Inc.
J. Hodges
Kings Mountain Systems
October 2018
The Token Binding Protocol Version 1.0
Abstract
This document specifies version 1.0 of the Token Binding protocol.
The Token Binding protocol allows client/server applications to
create long-lived, uniquely identifiable TLS bindings spanning
multiple TLS sessions and connections. Applications are then enabled
to cryptographically bind security tokens to the TLS layer,
preventing token export and replay attacks. To protect privacy, the
Token Binding identifiers are only conveyed over TLS and can be reset
by the user at any time.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8471.
Popov, et al. Standards Track [Page 1]
RFC 8471 The Token Binding Protocol Version 1.0 October 2018
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Token Binding Protocol Overview . . . . . . . . . . . . . . . 4
3. Token Binding Protocol Message . . . . . . . . . . . . . . . 5
3.1. TokenBinding.tokenbinding_type . . . . . . . . . . . . . 6
3.2. TokenBinding.tokenbindingid . . . . . . . . . . . . . . . 7
3.3. TokenBinding.signature . . . . . . . . . . . . . . . . . 7
3.4. TokenBinding.extensions . . . . . . . . . . . . . . . . . 9
4. Establishing a Token Binding . . . . . . . . . . . . . . . . 9
4.1. Client Processing Rules . . . . . . . . . . . . . . . . . 9
4.2. Server Processing Rules . . . . . . . . . . . . . . . . . 10
5. Bound Security Token Creation and Validation . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
6.1. Token Binding Key Parameters Registry . . . . . . . . . . 11
6.2. Token Binding Types Registry . . . . . . . . . . . . . . 12
6.3. Token Binding Extensions Registry . . . . . . . . . . . . 13
6.4. Registration of Token Binding TLS Exporter Label . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
7.1. Security Token Replay . . . . . . . . . . . . . . . . . . 14
7.2. Downgrade Attacks . . . . . . . . . . . . . . . . . . . . 14
7.3. Token Binding Key-Sharing between Applications . . . . . 14
7.4. Triple Handshake Vulnerability in TLS 1.2 and Older TLS
Versions . . . . . . . . . . . . . . . . . . . . . . . . 15
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Normative References . . . . . . . . . . . . . . . . . . 16
9.2. Informative References . . . . . . . . . . . . . . . . . 17
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
Popov, et al. Standards Track [Page 2]
RFC 8471 The Token Binding Protocol Version 1.0 October 2018
1. Introduction
Servers often generate various security tokens (e.g., HTTP cookies,
OAuth tokens [RFC6749]) for applications to present when accessing
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