Internet DRAFT - draft-whited-tls-channel-bindings-for-tls13
draft-whited-tls-channel-bindings-for-tls13
Transport Layer Security S. Whited
Internet-Draft 4 May 2020
Intended status: Experimental
Expires: 5 November 2020
Channel Bindings for SCRAM over TLS 1.3
draft-whited-tls-channel-bindings-for-tls13-02
Abstract
This document defines a channel binding type, tls-scram-exporter,
that is compatible with SCRAM [RFC5802] and TLS 1.3 [RFC8446] in
accordance with On Channel Binding [RFC5056].
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 5 November 2020.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions and Terminology . . . . . . . . . . . . . . . 2
2. The 'tls-scram-exporter' Channel Binding Type . . . . . . . . 2
3. Security Considerations . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
4.1. Registration of Channel Binding Type . . . . . . . . . . 3
4.2. Registration of Channel Binding TLS Exporter Label . . . 4
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. Normative References . . . . . . . . . . . . . . . . . . 4
5.2. Informative References . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
After problems were found with the channel binding types defined in
[RFC5929] they were not defined for TLS 1.3 [RFC8446]. To facilitate
channel binding with TLS 1.3, a new channel binding type using keying
material obtained from [RFC5705] is needed.
1.1. Conventions and Terminology
Throughout this document the acronym "EKM" is used to refer to
Exported Keying Material as defined in [RFC5705].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. The 'tls-scram-exporter' Channel Binding Type
IANA will register the 'tls-scram-exporter' channel binding type to
match the description below.
Description: The EKM value obtained from the current TLS connection.
The EKM is obtained using the keying material exporters for TLS as
defined in [RFC5705] by supplying the following inputs. The
definition of "client-first-message-bare" and "server-first-message"
can be found in [RFC5802].
Label: The ASCII string "EXPORTER-SCRAM-Channel-Binding" with no
terminating NUL.
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Context value: client-first-message-bare + "," + server-first-
message
Length: 32 bytes.
When TLS renegotiation is enabled channel binding using the "tls-
scram-exporter" type is not define and MUST NOT be supported.
3. Security Considerations
While it is possible to use this channel binding mechanism with TLS
versions below 1.3, extra precaution must be taken to ensure that the
chosen cipher suites always result in unique master secrets. For
more information see the Security Considerations section of
[RFC5705].
The Security Considerations sections of [RFC5056], [RFC5705],
[RFC5802], and [RFC8446] apply to this document.
4. IANA Considerations
4.1. Registration of Channel Binding Type
This document adds the following registration in the "Channel-Binding
Types" registry:
Subject: Registration of channel binding tls-scram-exporter
Channel binding unique prefix: tls-scram-exporter
Channel binding type: unique
Channel type: TLS [RFC8446]
Published specification:
draft-whited-tls-channel-bindings-for-tls13-00
Channel binding is secret: no
Description: <See specification>
Intended usage: COMMON
Person and email address to contact for further information: Sam
Whited <sam@samwhited.com>.
Owner/Change controller name and email address: IESG.
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Expert reviewer name and contact information: IETF TLS WG
(tls@ietf.org, failing that, ietf@ietf.org).
Note: See the published specification for advice on the
applicability of this channel binding type.
4.2. Registration of Channel Binding TLS Exporter Label
This document adds the following registration in the "TLS Exporter
Labels" registry:
Value: EXPORTER-SCRAM-Channel-Binding
DTLS-OK: Y
Recommended: N
Reference: This document
5. References
5.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5056] Williams, N., "On the Use of Channel Bindings to Secure
Channels", RFC 5056, DOI 10.17487/RFC5056, November 2007,
<https://www.rfc-editor.org/info/rfc5056>.
[RFC5705] Rescorla, E., "Keying Material Exporters for Transport
Layer Security (TLS)", RFC 5705, DOI 10.17487/RFC5705,
March 2010, <https://www.rfc-editor.org/info/rfc5705>.
[RFC5802] Newman, C., Menon-Sen, A., Melnikov, A., and N. Williams,
"Salted Challenge Response Authentication Mechanism
(SCRAM) SASL and GSS-API Mechanisms", RFC 5802,
DOI 10.17487/RFC5802, July 2010,
<https://www.rfc-editor.org/info/rfc5802>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
5.2. Informative References
[RFC5929] Altman, J., Williams, N., and L. Zhu, "Channel Bindings
for TLS", RFC 5929, DOI 10.17487/RFC5929, July 2010,
<https://www.rfc-editor.org/info/rfc5929>.
Author's Address
Sam Whited
Atlanta, GA
United States of America
Email: sam@samwhited.com
URI: https://blog.samwhited.com/
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