1 Internet Engineering Task Force (IETF)                        P. Hoffman   
    2 Request for Comments: 9157                                         ICANN   
    3 Updates: 5155, 6014, 8624                                  November 2021   
    4 Category: Standards Track                                                  
    5 ISSN: 2070-1721                                                            
    6                                                                            
    7                                                                            
    8                  Revised IANA Considerations for DNSSEC                    
    9                                                                            
   10 Abstract                                                                   
   11                                                                            
   12    This document changes the review requirements needed to get DNSSEC      
   13    algorithms and resource records added to IANA registries.  It updates   
   14    RFC 6014 to include hash algorithms for Delegation Signer (DS)          
   15    records and NextSECure version 3 (NSEC3) parameters (for Hashed         
   16    Authenticated Denial of Existence).  It also updates RFCs 5155 and      
   17    6014, which have requirements for DNSSEC algorithms, and updates RFC    
   18    8624 to clarify the implementation recommendation related to the        
   19    algorithms described in RFCs that are not on the standards track.       
   20    The rationale for these changes is to bring the requirements for DS     
   21    records and hash algorithms used in NSEC3 in line with the              
   22    requirements for all other DNSSEC algorithms.                           
   23                                                                            
   24 Status of This Memo                                                        
   25                                                                            
   26    This is an Internet Standards Track document.                           
   27                                                                            
   28    This document is a product of the Internet Engineering Task Force       
   29    (IETF).  It represents the consensus of the IETF community.  It has     
   30    received public review and has been approved for publication by the     
   31    Internet Engineering Steering Group (IESG).  Further information on     
   32    Internet Standards is available in Section 2 of RFC 7841.               
   33                                                                            
   34    Information about the current status of this document, any errata,      
   35    and how to provide feedback on it may be obtained at                    
   36    https://www.rfc-editor.org/info/rfc9157.                                
   37                                                                            
   38 Copyright Notice                                                           
   39                                                                            
   40    Copyright (c) 2021 IETF Trust and the persons identified as the         
   41    document authors.  All rights reserved.                                 
   42                                                                            
   43    This document is subject to BCP 78 and the IETF Trust's Legal           
   44    Provisions Relating to IETF Documents                                   
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   46    publication of this document.  Please review these documents            
   47    carefully, as they describe your rights and restrictions with respect   
   48    to this document.  Code Components extracted from this document must    
   49    include Revised BSD License text as described in Section 4.e of the     
   50    Trust Legal Provisions and are provided without warranty as described   
   51    in the Revised BSD License.                                             
   52                                                                            
   53 Table of Contents                                                          
   54                                                                            
   55    1.  Introduction                                                        
   56      1.1.  Requirements Language                                           
   57    2.  Update to RFC 6014                                                  
   58    3.  Update to RFC 8624                                                  
   59    4.  IANA Considerations                                                 
   60    5.  Security Considerations                                             
   61    6.  References                                                          
   62      6.1.  Normative References                                            
   63      6.2.  Informative References                                          
   64    Acknowledgements                                                        
   65    Author's Address                                                        
   66                                                                            
   67 1.  Introduction                                                           
   68                                                                            
   69    DNSSEC is primarily described in [RFC4033], [RFC4034], and [RFC4035].   
   70    DNSSEC commonly uses another resource record beyond those defined in    
   71    [RFC4034]: NSEC3 [RFC5155].  DS resource records were originally        
   72    defined in [RFC3658], and that definition was obsoleted by [RFC4034].   
   73                                                                            
   74    [RFC6014] updates the requirements for how DNSSEC cryptographic         
   75    algorithm identifiers in the IANA registries are assigned, reducing     
   76    the requirements from "Standards Action" to "RFC Required".  However,   
   77    the IANA registry requirements for hash algorithms for DS records       
   78    [RFC3658] and for the hash algorithms used in NSEC3 records [RFC5155]   
   79    are still "Standards Action".  This document updates those IANA         
   80    registry requirements.  (For a reference on how IANA registries can     
   81    be updated in general, see [RFC8126].)                                  
   82                                                                            
   83 1.1.  Requirements Language                                                
   84                                                                            
   85    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",     
   86    "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and    
   87    "OPTIONAL" in this document are to be interpreted as described in       
   88    BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all      
   89    capitals, as shown here.                                                
   90                                                                            
   91 2.  Update to RFC 6014                                                     
   92                                                                            
   93    Section 4 updates [RFC6014] to bring the requirements for DS records    
   94    and NSEC3 hash algorithms in line with the rest of the DNSSEC           
   95    cryptographic algorithms by allowing any DS hash algorithms, NSEC3      
   96    hash algorithms, NSEC3 parameters, and NSEC3 flags that are fully       
   97    described in an RFC to have identifiers assigned in the IANA            
   98    registries.  This is an addition to the IANA considerations in          
   99    [RFC6014].                                                              
  100                                                                            
  101 3.  Update to RFC 8624                                                     
  102                                                                            
  103    This document updates [RFC8624] for all DNSKEY and DS algorithms that   
  104    are not on the standards track.                                         
  105                                                                            
  106    The second paragraph of Section 1.2 of [RFC8624] currently says:        
  107                                                                            
  108    |  This document only provides recommendations with respect to          
  109    |  mandatory-to-implement algorithms or algorithms so weak that they    
  110    |  cannot be recommended.  Any algorithm listed in the [DNSKEY-IANA]    
  111    |  and [DS-IANA] registries that are not mentioned in this document     
  112    |  MAY be implemented.  For clarification and consistency, an           
  113    |  algorithm will be specified as MAY in this document only when it     
  114    |  has been downgraded from a MUST or a RECOMMENDED to a MAY.           
  115                                                                            
  116    That paragraph is now replaced with the following:                      
  117                                                                            
  118    |  This document provides recommendations with respect to mandatory-    
  119    |  to-implement algorithms, algorithms so weak that they cannot be      
  120    |  recommended, and algorithms defined in RFCs that are not on the      
  121    |  standards track.  Any algorithm listed in the [DNSKEY-IANA] and      
  122    |  [DS-IANA] registries that are not mentioned in this document MAY     
  123    |  be implemented.  For clarification and consistency, an algorithm     
  124    |  will be specified as MAY in this document only when it has been      
  125    |  downgraded from a MUST or a RECOMMENDED to a MAY.                    
  126                                                                            
  127    This update is also reflected in the IANA considerations in             
  128    Section 4.                                                              
  129                                                                            
  130 4.  IANA Considerations                                                    
  131                                                                            
  132    In the "Domain Name System Security (DNSSEC) NextSECure3 (NSEC3)        
  133    Parameters" registry, the registration procedure for "DNSSEC NSEC3      
  134    Flags", "DNSSEC NSEC3 Hash Algorithms", and "DNSSEC NSEC3PARAM Flags"   
  135    has been changed from "Standards Action" to "RFC Required", and this    
  136    document has been added as a reference.                                 
  137                                                                            
  138    In the "DNSSEC Delegation Signer (DS) Resource Record (RR) Type         
  139    Digest Algorithms" registry, the registration procedure for "Digest     
  140    Algorithms" has been changed from "Standards Action" to "RFC            
  141    Required", and this document has been added as a reference.             
  142                                                                            
  143 5.  Security Considerations                                                
  144                                                                            
  145    Changing the requirements for adding security algorithms to IANA        
  146    registries as described in this document will make it easier to add     
  147    both good and bad algorithms to the registries.  It is impossible to    
  148    weigh the security impact of those two changes.                         
  149                                                                            
  150    Administrators of DNSSEC-signed zones and validating resolvers may      
  151    have been making security decisions based on the contents of the IANA   
  152    registries.  This was a bad idea in the past, and now it is an even     
  153    worse idea because there will be more algorithms in those registries    
  154    that may not have gone through IETF review.  Security decisions about   
  155    which algorithms are safe and not safe should be made by reading the    
  156    security literature, not by looking in IANA registries.                 
  157                                                                            
  158 6.  References                                                             
  159                                                                            
  160 6.1.  Normative References                                                 
  161                                                                            
  162    [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate          
  163               Requirement Levels", BCP 14, RFC 2119,                       
  164               DOI 10.17487/RFC2119, March 1997,                            
  165               <https://www.rfc-editor.org/info/rfc2119>.                   
  166                                                                            
  167    [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.      
  168               Rose, "DNS Security Introduction and Requirements",          
  169               RFC 4033, DOI 10.17487/RFC4033, March 2005,                  
  170               <https://www.rfc-editor.org/info/rfc4033>.                   
  171                                                                            
  172    [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.      
  173               Rose, "Resource Records for the DNS Security Extensions",    
  174               RFC 4034, DOI 10.17487/RFC4034, March 2005,                  
  175               <https://www.rfc-editor.org/info/rfc4034>.                   
  176                                                                            
  177    [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.      
  178               Rose, "Protocol Modifications for the DNS Security           
  179               Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,     
  180               <https://www.rfc-editor.org/info/rfc4035>.                   
  181                                                                            
  182    [RFC5155]  Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS      
  183               Security (DNSSEC) Hashed Authenticated Denial of             
  184               Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008,      
  185               <https://www.rfc-editor.org/info/rfc5155>.                   
  186                                                                            
  187    [RFC6014]  Hoffman, P., "Cryptographic Algorithm Identifier             
  188               Allocation for DNSSEC", RFC 6014, DOI 10.17487/RFC6014,      
  189               November 2010, <https://www.rfc-editor.org/info/rfc6014>.    
  190                                                                            
  191    [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for        
  192               Writing an IANA Considerations Section in RFCs", BCP 26,     
  193               RFC 8126, DOI 10.17487/RFC8126, June 2017,                   
  194               <https://www.rfc-editor.org/info/rfc8126>.                   
  195                                                                            
  196    [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC       
  197               2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,     
  198               May 2017, <https://www.rfc-editor.org/info/rfc8174>.         
  199                                                                            
  200    [RFC8624]  Wouters, P. and O. Sury, "Algorithm Implementation           
  201               Requirements and Usage Guidance for DNSSEC", RFC 8624,       
  202               DOI 10.17487/RFC8624, June 2019,                             
  203               <https://www.rfc-editor.org/info/rfc8624>.                   
  204                                                                            
  205 6.2.  Informative References                                               
  206                                                                            
  207    [RFC3658]  Gudmundsson, O., "Delegation Signer (DS) Resource Record     
  208               (RR)", RFC 3658, DOI 10.17487/RFC3658, December 2003,        
  209               <https://www.rfc-editor.org/info/rfc3658>.                   
  210                                                                            
  211 Acknowledgements                                                           
  212                                                                            
  213    Donald Eastlake, Murray Kucherawy, Dan Harkins, Martin Duke, and        
  214    Benjamin Kaduk contributed to this document.                            
  215                                                                            
  216 Author's Address                                                           
  217                                                                            
  218    Paul Hoffman                                                            
  219    ICANN                                                                   
  220                                                                            
  221    Email: paul.hoffman@icann.org                                           
  222                                                                            

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