Internet DRAFT - draft-jhoyla-req-mtls-flag
draft-jhoyla-req-mtls-flag
Network Working Group J. Hoyland
Internet-Draft Cloudflare
Intended status: Informational October 2023
Expires: 3 May 2024
TLS Flag - Request mTLS
draft-jhoyla-req-mtls-flag-01
Abstract
Normally in TLS there is no way for the client to signal to the
server that it has been configured with a certificate suitable for
mTLS. This document defines a TLS Flag [I-D.ietf-tls-tlsflags] that
enables clients to provide this hint.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at
https://jhoyla.github.io/draft-jhoyla-req-mtls-flag/draft-jhoyla-req-
mtls-flag.html. Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-jhoyla-req-mtls-flag/.
Source for this draft and an issue tracker can be found at
https://github.com/jhoyla/draft-jhoyla-req-mtls-flag.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 3 April 2024.
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RFC 0 TLS Flag - Request mTLS October 2023
Copyright Notice
Copyright (c) 2023 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 (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 2
3. Flag specification . . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
6. Normative References . . . . . . . . . . . . . . . . . . . . 3
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
This document specifies a TLS Flag that indicates to the server that
the client supports mTLS. Sometimes a server does not want to
negotiate mTLS with every client, but might wish to authenticate a
subset of them. In TLS 1.3 this may be done with post-handshake
auth, however this adds an extra round-trip, and requires negotiation
at the application layer. A client sending the request mTLS flag in
the ClientHello allows the server to request authentication during
the initial handshake only when it receives a hint the client
supports it. This enables a number of use cases, for example
allowing bots to authenticate themselves when mixed in with general
traffic.
2. Conventions and Definitions
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.
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RFC 0 TLS Flag - Request mTLS October 2023
3. Flag specification
A server receiving this flag MAY send a CertificateRequest message.
4. Security Considerations
This flag should have no effect on the security of TLS, as the server
may always send a CertificateRequest message during the handshake.
This flag merely provides a hint that the client will be able to
fulfil the request. If the client sets this flag but then fails to
provide a certificate the server MAY terminate the connection with a
bad_certificate error.
5. IANA Considerations
This document requests IANA to add an entry to the TLS Flags registry
in the TLS namespace with the following values:
* Value shall be TBD
* Flag Name shall be request_mtls.
* Message shall be CH
* Recommended shall be set to no (N)
* The reference shall be this document {!draft-jhoyla-req-mtls}
6. Normative References
[I-D.ietf-tls-tlsflags]
Nir, Y., "A Flags Extension for TLS 1.3", Work in
Progress, Internet-Draft, draft-ietf-tls-tlsflags-12, 23
July 2023, <https://datatracker.ietf.org/doc/html/draft-
ietf-tls-tlsflags-12>.
[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/rfc/rfc2119>.
[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/rfc/rfc8174>.
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Acknowledgments
TODO acknowledge.
Author's Address
Jonathan Hoyland
Cloudflare
Email: jonathan.hoyland@gmail.com
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