[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Nits]

Versions: 00

TLS                                                         Alan Smithee
Internet-Draft
Updates: 10000 (if approved)                                Alan Smithee
Intended status: Standards Track                            May 15, 2018
Expires: November 16, 2018


 TLS Downgrade protection extension for TLS DNSSEC Authentication Chain
                               Extension
                 draft-asmithee-tls-dnssec-downprot-00

Abstract

   This draft specifies a TLS extension that adds downgrade protection
   for another TLS extension, [dnssec-chain-extension].  Without the
   downgrade protection specified in this TLS extension, the only effect
   of deploying [dnssec-chain-extension] is to reduce TLS security from
   the standard "WebPKI security" to "WebPKI or DANE, whichever is
   weaker".

   This draft dictates that [dnssec-chain-extension] MUST only be used
   in combination with this TLS extension, whose only content is a two
   octet SupportLifetime value.  A value of 0 prohibits the TLS client
   from unilaterally requiring ongoing use of both TLS extensions based
   on prior observation of their use (pinning).  A non-zero value is the
   value in hours for which this TLS extension as well as
   [dnssec-chain-extension] MUST appear in subsequent TLS handshakes to
   the same TLS hostname and port.  If this TLS extention or
   [dnssec-chain-extension] is missing from the TLS handshake within
   this observed pinning time, the TLS client MUST assume it is under
   attack and abort the TLS connection.

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 http://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 November 16, 2018.



Alan Smithee & Alan SmitExpires November 16, 2018               [Page 1]


Internet-Draft    TLS DNSSEC Chain Downgrade Protection         May 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
   (http://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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Requirements Notation . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  TLS DNSSEC Extension Downgrade Protection Extension format  .   3
   4.  Operational Considerations  . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Requirements Notation

   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.  Introduction

   This draft specifies a TLS extension that adds downgrade protection
   for another TLS extension, [dnssec-chain-extension].  Without the
   downgrade protection specified in this TLS extension, the only effect
   of deploying [dnssec-chain-extension] is to reduce TLS security from
   the standard "WebPKI security" to "WebPKI or DANE, whichever is
   weaker".

   This draft dictates that [dnssec-chain-extension] MUST only be used
   in combination with this TLS extension, whose only content is a two
   byte SupportLifetime value.  A value of 0 prohibits the TLS client
   from unilaterally requiring ongoing use of both TLS extensions based
   on prior observation of their use (pinning).  A non-zero value is the



Alan Smithee & Alan SmitExpires November 16, 2018               [Page 2]


Internet-Draft    TLS DNSSEC Chain Downgrade Protection         May 2018


   value in hours for which this TLS extension as well as
   [dnssec-chain-extension] MUST appear in subsequent TLS handshakes to
   the same hostname and port.  If this TLS extention or
   [dnssec-chain-extension] is missing from the TLS handshake within
   this observed pinning time, the TLS client MUST assume it is under
   attack and abort the TLS connection.

3.  TLS DNSSEC Extension Downgrade Protection Extension format

   The "extension_data" field of the "dnssec_chain_commit" extension
   contains a two octet value specifying the pinning time in hours for
   both this extension and [dnssec-chain-extension] in the following
   form:

       struct {
           uint16 SupportLifetime;
       } DnssecChainExtensionCommitTime;

   A zero "SupportLifetime" prohibits the client from unilaterally
   requiring ongoing use of this extension or [dnssec-chain-extension]
   based on prior observation of their use (pinning).

   A non-zero value signifies the time in hours for which this resource
   commits to publishing both this extension and
   [dnssec-chain-extension].  If within the specified time a TLS
   connection for this resource omits either TLS extension, the TLS
   client MUST conclude it is under attack and MUST abort the TLS
   connection.

4.  Operational Considerations

   A positive DANE validated response for the TLSA record in
   [dnssec-chain-extension] MUST override any previous SupportLifetime
   information that the TLS client stored previously.  In addition, if
   the TLS client previously obtained a valid TLSA record with a
   SupportLifetime commitment further into the future, and as part of
   the current TLS handshake it receives a DNSSEC-validated answer
   containing no TLSA record and a Denial of Existence proof via
   [dnssec-chain-extension], the TLS client MUST clear the previously
   stored TLS extensions pinning value.

   If a specific resource is served using multiple TLS servers or
   clusters, and a non-zero value for SupportLifetime is used, all TLS
   server instances MUST support serving both this extension and
   [dnssec-chain-extension].  As long as no TLS service instance uses a
   non-zero value, both TLS extensions can be rolled out incrementally
   without any TLS clients commiting to either TLS extension.




Alan Smithee & Alan SmitExpires November 16, 2018               [Page 3]


Internet-Draft    TLS DNSSEC Chain Downgrade Protection         May 2018


5.  Security Considerations

   This draft specifies a TLS extension that adds downgrade protection
   for another TLS extension, [dnssec-chain-extension].  Without the
   downgrade protection specified in this TLS extension, the only effect
   of deploying [dnssec-chain-extension] is to reduce TLS security from
   the standard "WebPKI security" to "WebPKI or DANE, whichever is
   weaker".

   This draft dictates that [dnssec-chain-extension] MUST only be used
   in combination with this TLS extension, whose only content is a two
   byte SupportLifetime value.  A value of 0 prohibits the TLS client
   from unilaterally requiring ongoing use of both TLS extensions based
   on prior observation of their use (pinning).  A non-zero value is the
   value in hours for which this TLS extension as well as
   [dnssec-chain-extension] MUST appear in subsequent TLS handshakes to
   the same hostname and port.  If this TLS extention or
   [dnssec-chain-extension] is missing from the TLS handshake within
   this observed pinning time, the TLS client MUST assume it is under
   attack and abort the TLS connection.

6.  IANA Considerations

   This extension requires the registration of a new value in the TLS
   ExtensionsType registry.  The value requested from IANA is [TBD], and
   the extension should be marked "Recommended" in accordance with "IANA
   Registry Updates for TLS and DTLS" [TLSIANA].

7.  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>.

   [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>.

   [dnssec-chain-extension]
              Shore, M., Barnes, R., Hugue, S., and W. Toorop, "A DANE
              Record and DNSSEC Authentication Chain Extension for TLS",
              March 2018, <https://tools.ietf.org/html/draft-ietf-tls-
              dnssec-chain-extension-07>.

   [TLSIANA]  Salowey, J. and S. Turner, "IANA Registry Updates for TLS
              and DTLS", <https://tools.ietf.org/html/draft-ietf-tls-
              iana-registry-updates>.



Alan Smithee & Alan SmitExpires November 16, 2018               [Page 4]


Internet-Draft    TLS DNSSEC Chain Downgrade Protection         May 2018


Authors' Addresses

   Alan Smithee

   EMail: pwouters@redhat.com


   Alan Smithee

   EMail: ietf-dane@dukhovni.org









































Alan Smithee & Alan SmitExpires November 16, 2018               [Page 5]


Html markup produced by rfcmarkup 1.129b, available from https://tools.ietf.org/tools/rfcmarkup/