idnits 2.17.1 draft-schlyter-pkix-dns-02.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** Looks like you're using RFC 2026 boilerplate. This must be updated to follow RFC 3978/3979, as updated by RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- == No 'Intended status' indicated for this document; assuming Proposed Standard == It seems as if not all pages are separated by form feeds - found 0 form feeds but 7 pages Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack an IANA Considerations section. (See Section 2.2 of https://www.ietf.org/id-info/checklist for how to handle the case when there are no actions for IANA.) ** The document seems to lack separate sections for Informative/Normative References. All references will be assumed normative when checking for downward references. Miscellaneous warnings: ---------------------------------------------------------------------------- -- The first octets (the first characters of the first line) of this draft are 'PK', which can make Internet Explorer erroneously think that it is a zip file. It is recommended that you change this, for instance by inserting a blank line before the line starting with 'PK'. == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (June 10, 2002) is 7990 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 2459 (ref. '2') (Obsoleted by RFC 3280) ** Obsolete normative reference: RFC 2510 (ref. '3') (Obsoleted by RFC 4210) ** Obsolete normative reference: RFC 2535 (ref. '4') (Obsoleted by RFC 4033, RFC 4034, RFC 4035) ** Obsolete normative reference: RFC 2538 (ref. '5') (Obsoleted by RFC 4398) Summary: 7 errors (**), 0 flaws (~~), 3 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 PKIX Working Group J. Schlyter 2 Internet-Draft Carlstedt Research & 3 Expires: December 9, 2002 Technology 4 L. Johansson 5 Stockholm University 6 June 10, 2002 8 DNS as X.509 PKIX Certificate Storage 9 draft-schlyter-pkix-dns-02 11 Status of this Memo 13 This document is an Internet-Draft and is in full conformance with 14 all provisions of Section 10 of RFC2026. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six months 22 and may be updated, replaced, or obsoleted by other documents at any 23 time. It is inappropriate to use Internet-Drafts as reference 24 material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at http:// 27 www.ietf.org/ietf/1id-abstracts.txt. 29 The list of Internet-Draft Shadow Directories can be accessed at 30 http://www.ietf.org/shadow.html. 32 This Internet-Draft will expire on December 9, 2002. 34 Copyright Notice 36 Copyright (C) The Internet Society (2002). All Rights Reserved. 38 Abstract 40 A major problem facing PKIX deployment and implementation is the 41 problem of constructing certificate paths for input to the path 42 validation algorithm. This draft describes the use of the DNS as a 43 certificate store and it's implication for path validation in PKIX. 45 Table of Contents 47 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 48 2. Storing PKIX certificates in DNS . . . . . . . . . . . . . . . . 3 49 3. Certificate lookup algorithm . . . . . . . . . . . . . . . . . . 4 50 4. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 51 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 52 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 53 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 54 A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6 55 Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 7 57 1. Introduction 59 A major problem facing PKIX deployment and implementation is the 60 problem of constructing certificate paths for input to the path 61 validation algorithm described in RFC 2459 [2]. This problem can be 62 solved by successively looking at the issuerAltName extension of each 63 certificate and using the information found there together with a 64 storage and transport protocol for certificates to find a set of 65 candidate certificates associated with the issuerAltName. 67 Using the CERT RR [5] a certificate can be published using DNS. This 68 draft describes the use of DNS as a certificate store and it's 69 implication for path validation in PKIX. 71 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 72 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 73 document are to be interpreted as described in RFC 2119 [1]. 75 2. Storing PKIX certificates in DNS 77 A PKIX certificate is published in DNS using the CERT RR [5] for a 78 given domain name which SHOULD be equal to the dnsName component of 79 the subjectAltName extension in the certificate. Multiple 80 certificates may be present for each domain name and all SHOULD have 81 the same subject DN. If the domain name does not match the dnsName 82 component of the subjectAltName extension the client SHOULD notify 83 the user of this and allow the user to decide weather to allow the 84 use of the certificate or not. 86 When constructing a certificate path for validation the client MAY 87 use the AuthorityKeyIdentifier and SubjectKeyIdentifier extensions to 88 select the (set of) certificates to use. 90 There are a few important cases when multiple CA certificates are 91 published in CERT RRs for given domain name: 93 Multiple certificates each signed by another member of the same 94 set. This situation occurs when a self-signed certificate issues 95 a certificate under the same DN (for the purpose of adding policy 96 for instance). 98 Multiple certificates, either self-signed or issued by another CA, 99 with different validity periods. 101 Root key roll-over as described in section 2.4 of RFC 2510 [3] 102 where exactly 4 certificates would be published using DNS. 104 3. Certificate lookup algorithm 106 Given a certificate with a non-empty issuerAltName extension of type 107 dnsName, perform a DNS lookup of the corresponding domain name with 108 the class IN and type CERT. For each of the certificates returned 109 that are of type PKIX, implementations SHOULD verify that the 110 subjectAltName in the certificate contains a component of type 111 dnsName with the same domain name as the one where the certificate 112 was published using the DNS. 114 If a certificate obtained by this algorithm is a self-signed 115 certificate and was successfully verified by DNSSEC [4], the user 116 SHOULD be given the opportunity to use this certificate as a trust 117 anchor. 119 The result of this algorithm is a set of of certificates suitable for 120 input to the PKIX path validation algorithm. 122 4. Example 124 Client A talks TLS to server B and receives a certificate chain 125 ending in a cert (X) with issuerAltName:dnsName set to 126 ca.example.com. 128 Client A does path validation on the chain and is unable to find X 129 in its list of trusted roots. 131 Client A queries the DNS for the CERT record for ca.example.com 132 and receives a set of certificates. 134 Client A looks for X in the set of certificates. If found, and 135 depending on local configuration, A trusts the certificate for use 136 as a TLS client trust anchor and adds it to the list of trusted 137 roots. 139 Path validation now succeeds. 141 5. Security Considerations 143 This document describes a mechanism for automated download of 144 certificates from DNS with special provision for bridging trust 145 between a PKIX PKI and DNSSEC. However, if only self-signed end- 146 entity PKIX certificates are published using DNS the benefits of PKIX 147 policy and key usage management is lost. 149 The benefit of this mechanism is a potential for added protection of 150 certificate trust anchors in common use on the Internet by leveraging 151 DNSSEC infrastructure. 153 References 155 [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement 156 Levels", BCP 14, RFC 2119, March 1997. 158 [2] Housley, R., Ford, W., Polk, T. and D. Solo, "Internet X.509 159 Public Key Infrastructure Certificate and CRL Profile", RFC 160 2459, January 1999. 162 [3] Adams, C. and S. Farrell, "Internet X.509 Public Key 163 Infrastructure Certificate Management Protocols", RFC 2510, 164 March 1999. 166 [4] Eastlake, D., "Domain Name System Security Extensions", RFC 167 2535, March 1999. 169 [5] Eastlake, D. and O. Gudmundsson, "Storing Certificates in the 170 Domain Name System (DNS)", RFC 2538, March 1999. 172 Authors' Addresses 174 Jakob Schlyter 175 Carlstedt Research & Technology 176 Stora Badhusgatan 18-20 177 Goteborg SE-411 21 178 Sweden 180 EMail: jakob@crt.se 181 URI: http://www.crt.se/~jakob/ 183 Leif Johansson 184 Stockholm University 185 IT and Media Unit 186 Frescati Hagvag 8 187 Stockholm SE-106 91 188 Sweden 190 Phone: +46 8 16 45 41 191 EMail: leifj@it.su.se 192 URI: http://www.it.su.se 194 Appendix A. Acknowledgements 196 The author gratefully acknowledges, in no particular order, the 197 contributions of the following persons: 199 Martin Fredriksson 201 Niklas Hallqvist 203 Edward Lewis 205 Full Copyright Statement 207 Copyright (C) The Internet Society (2002). All Rights Reserved. 209 This document and translations of it may be copied and furnished to 210 others, and derivative works that comment on or otherwise explain it 211 or assist in its implementation may be prepared, copied, published 212 and distributed, in whole or in part, without restriction of any 213 kind, provided that the above copyright notice and this paragraph are 214 included on all such copies and derivative works. However, this 215 document itself may not be modified in any way, such as by removing 216 the copyright notice or references to the Internet Society or other 217 Internet organizations, except as needed for the purpose of 218 developing Internet standards in which case the procedures for 219 copyrights defined in the Internet Standards process must be 220 followed, or as required to translate it into languages other than 221 English. 223 The limited permissions granted above are perpetual and will not be 224 revoked by the Internet Society or its successors or assigns. 226 This document and the information contained herein is provided on an 227 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 228 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 229 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 230 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 231 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 233 Acknowledgement 235 Funding for the RFC Editor function is currently provided by the 236 Internet Society.