The DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) Protocol: TLSA
RFC 6698

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Internet Engineering Task Force (IETF)                        P. Hoffman
Request for Comments: 6698                                VPN Consortium
Category: Standards Track                                    J. Schlyter
ISSN: 2070-1721                                                 Kirei AB
                                                             August 2012

         The DNS-Based Authentication of Named Entities (DANE)
             Transport Layer Security (TLS) Protocol: TLSA

Abstract

   Encrypted communication on the Internet often uses Transport Layer
   Security (TLS), which depends on third parties to certify the keys
   used.  This document improves on that situation by enabling the
   administrators of domain names to specify the keys used in that
   domain's TLS servers.  This requires matching improvements in TLS
   client software, but no change in TLS server software.

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 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6698.

Copyright Notice

   Copyright (c) 2012 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.

Hoffman & Schlyter           Standards Track                    [Page 1]
RFC 6698            DNS-Based Authentication for TLS         August 2012

Table of Contents

   1. Introduction ....................................................3
      1.1. Background and Motivation ..................................3
      1.2. Securing the Association of a Domain Name with a
           Server's Certificate .......................................4
      1.3. Method for Securing Certificate Associations ...............5
      1.4. Terminology ................................................6
   2. The TLSA Resource Record ........................................7
      2.1. TLSA RDATA Wire Format .....................................7
           2.1.1. The Certificate Usage Field .........................7
           2.1.2. The Selector Field ..................................8
           2.1.3. The Matching Type Field .............................9
           2.1.4. The Certificate Association Data Field ..............9
      2.2. TLSA RR Presentation Format ................................9
      2.3. TLSA RR Examples ..........................................10
   3. Domain Names for TLSA Certificate Associations .................10
   4. Use of TLSA Records in TLS .....................................11
      4.1. Usable Certificate Associations ...........................11
   5. TLSA and DANE Use Cases and Requirements .......................13
   6. Mandatory-to-Implement Features ................................15
   7. IANA Considerations ............................................15
      7.1. TLSA RRtype ...............................................15
      7.2. TLSA Certificate Usages ...................................15
      7.3. TLSA Selectors ............................................16
      7.4. TLSA Matching Types .......................................16
   8. Security Considerations ........................................16
      8.1. Comparing DANE to Public CAs ..............................18
           8.1.1. Risk of Key Compromise .............................19
           8.1.2. Impact of Key Compromise ...........................20
           8.1.3. Detection of Key Compromise ........................20
           8.1.4. Spoofing Hostnames .................................20
      8.2. DNS Caching ...............................................21
      8.3. External DNSSEC Validators ................................21
   9. Acknowledgements ...............................................22
   10. References ....................................................22
      10.1. Normative References .....................................22
      10.2. Informative References ...................................23
   Appendix A. Operational Considerations for Deploying TLSA