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LAMPS Working Group                                        M. Richardson
Internet-Draft                                  Sandelman Software Works
Intended status: Standards Track                               T. Werner
Expires: May 6, 2020                                             Siemens
                                                                  W. Pan
                                                     Huawei Technologies
                                                       November 03, 2019


   Clarification of Enrollment over Secure Transport (EST): transfer
                          encodings and ASN.1
              draft-richardson-lamps-rfc7030est-clarify-05

Abstract

   This document updates RFC7030: Enrollment over Secure Transport (EST)
   to resolve some errata that was reported, and which has proven to
   have interoperability when RFC7030 has been extended.

   This document deprecates the specification of "Content-Transfer-
   Encoding" headers for EST endpoints, providing a way to do this in an
   upward compatible way.  This document additional defines a GRASP
   discovery mechanism for EST endpoints, and specifies requirements for
   them.

   Finally, this document fixes some syntactical errors in ASN.1 that
   was presented.

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 May 6, 2020.







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Copyright Notice

   Copyright (c) 2019 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 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.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   4.  Changes to EST endpoint processing  . . . . . . . . . . . . .   3
   5.  Clarification of ASN.1 for Certificate Attribute set. . . . .   4
     5.1.  CSR Attributes Response . . . . . . . . . . . . . . . . .   4
   6.  Clarification of error messages for certificate enrollment
       operations  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   6
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     11.1.  Normative References . . . . . . . . . . . . . . . . . .   6
     11.2.  Informative References . . . . . . . . . . . . . . . . .   7
   Appendix A.  ASN.1 Module . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   [RFC7030] defines the Enrollment over Secure Transport, or EST
   protocol.

   This specification defines a number of HTTP end points for
   certificate enrollment and management.  The details of the
   transaction were defined in terms of MIME headers as defined in
   [RFC2045], rather than in terms of the HTTP protocol as defined in
   [RFC2616] and [RFC7230].

   [RFC2616] and later [RFC7231] Appendix A.5 has text specifically
   deprecating Content-Transfer-Encoding.



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   [RFC7030] calls it out this header incorrectly.

   [I-D.ietf-anima-bootstrapping-keyinfra] extends [RFC7030], adding new
   functionality, and interop testing of the protocol has revealed that
   unusual processing called out in [RFC7030] causes confusion.

   EST is currently specified as part of IEC 62351, and is widely used
   in Government, Utilities and Financial markets today.

   Changes to [RFC7030] to bring it inline with typical HTTP processing
   would change the on-wire protocol in a way that is not backwards
   compatible.  Reports from the field suggest that many implementations
   do not send the Content-Transfer-Encoding, and many of them ignore
   it.

   This document therefore revises [RFC7030] to reflect the field
   reality, deprecating the extranous field.

   This document deals with errata numbers [errata4384], [errata5107],
   and [errata5108].

2.  Terminology

   The abbreviation "CTE" is used to denote the Content-Transfer-
   Encoding header, and the abbreviation "CTE-base64" is used to denote
   a request or response whose Content-Transfer-Encoding header contains
   the value "base64".

3.  Requirements Language

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
   [RFC2119] and indicate requirement levels for compliant STuPiD
   implementations.

4.  Changes to EST endpoint processing

   The [RFC7030] sections 4.1.3 (CA Certificates Response, /cacerts),
   4.3.1/4.3.2 (Full CMC, /fullcmc), 4.4.2 (Server-Side Key Generation,
   /serverkeygen), and 4.5.2 (CSR Attributes, /csrattrs) specify the use
   of base64 encoding with a Content-Transfer-Encoding for requests and
   response.

   This document updates [RFC7030] to require the POST request and
   payload response of all endpoints in to be [RFC4648] section 4 Base64
   encoded DER.  This format is to be used regardless of whether there




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   is any Content-Transfer-Encoding header, and any value in that header
   is to be ignored.

5.  Clarification of ASN.1 for Certificate Attribute set.

   Section 4.5.2 of [RFC7030] is to be replaced with the following text:

5.1.  CSR Attributes Response

   If locally configured policy for an authenticated EST client
   indicates a CSR Attributes Response is to be provided, the server
   response MUST include an HTTP 200 response code.  An HTTP response
   code of 204 or 404 indicates that a CSR Attributes Response is not
   available.  Regardless of the response code, the EST server and CA
   MAY reject any subsequent enrollment requests for any reason, e.g.,
   incomplete CSR attributes in the request.

   Responses to attribute request messages MUST be encoded as the
   content-type of "application/csrattrs", and are to be "base64"
   [RFC2045] encoded.  The syntax for application/csrattrs body is as
   follows:

   CsrAttrs ::= SEQUENCE SIZE (0..MAX) OF AttrOrOID

   AttrOrOID ::= CHOICE {
     oid        OBJECT IDENTIFIER,
     attribute  Attribute {{AttrSet}} }

   AttrSet ATTRIBUTE ::= { AttributesDefinedInRFC7030, ... }

   An EST server includes zero or more OIDs or attributes [RFC2986] that
   it requests the client to use in the certification request.  The
   client MUST ignore any OID or attribute it does not recognize.  When
   the server encodes CSR Attributes as an empty SEQUENCE, it means that
   the server has no specific additional information it desires in a
   client certification request (this is functionally equivalent to an
   HTTP response code of 204 or 404).

   If the CA requires a particular crypto system or use of a particular
   signature scheme (e.g., certification of a public key based on a
   certain elliptic curve, or signing using a certain hash algorithm) it
   MUST provide that information in the CSR Attribute Response.  If an
   EST server requires the linking of identity and POP information (see
   Section 3.5), it MUST include the challengePassword OID in the CSR
   Attributes Response.

   The structure of the CSR Attributes Response SHOULD, to the greatest
   extent possible, reflect the structure of the CSR it is requesting.



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   Requests to use a particular signature scheme (e.g. using a
   particular hash function) are represented as an OID to be reflected
   in the SignatureAlgorithm of the CSR.  Requests to use a particular
   crypto system (e.g., certification of a public key based on a certain
   elliptic curve) are represented as an attribute, to be reflected as
   the AlgorithmIdentifier of the SubjectPublicKeyInfo, with a type
   indicating the algorithm and the values indicating the particular
   parameters specific to the algorithm.  Requests for descriptive
   information from the client are made by an attribute, to be
   represented as Attributes of the CSR, with a type indicating the
   [RFC2985] extensionRequest and the values indicating the particular
   attributes desired to be included in the resulting certificate's
   extensions.

   The sequence is Distinguished Encoding Rules (DER) encoded [X690] and
   then base64 encoded (Section 4 of [RFC4648]).  The resulting text
   forms the application/csrattr body, without headers.

   For example, if a CA requests a client to submit a certification
   request containing the challengePassword (indicating that linking of
   identity and POP information is requested; see Section 3.5), an
   extensionRequest with the Media Access Control (MAC) address
   ([RFC2307]) of the client, and to use the secp384r1 elliptic curve
   and to sign with the SHA384 hash function.  Then, it takes the
   following:

         OID:        challengePassword (1.2.840.113549.1.9.7)

         Attribute:  type = extensionRequest (1.2.840.113549.1.9.14)
                     value = macAddress (1.3.6.1.1.1.1.22)

         Attribute:  type = id-ecPublicKey (1.2.840.10045.2.1)
                     value = secp384r1 (1.3.132.0.34)

         OID:        ecdsaWithSHA384 (1.2.840.10045.4.3.3)

   and encodes them into an ASN.1 SEQUENCE to produce: ~~~ 30 41 06 09
   2a 86 48 86 f7 0d 01 09 07 30 12 06 07 2a 86 48 ce 3d 02 01 31 07 06
   05 2b 81 04 00 22 30 16 06 09 2a 86 48 86 f7 0d 01 09 0e 31 09 06 07
   2b 06 01 01 01 01 16 06 08 2a 86 48 ce 3d 04 03 03 ~~~

   and then base64 encodes the resulting ASN.1 SEQUENCE to produce:

       MEEGCSqGSIb3DQEJBzASBgcqhkjOPQIBMQcGBSuBBAAiMBYGCSqGSIb3DQEJDjEJ
       BgcrBgEBAQEWBggqhkjOPQQDAw==






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6.  Clarification of error messages for certificate enrollment
    operations

   errata 5108.

7.  Privacy Considerations

   This document does not disclose any additional identifies to either
   active or passive observer would see with [RFC7030].

8.  Security Considerations

   This document clarifies an existing security mechanism.  An option is
   introduced to the security mechanism using an implicit negotiation.

9.  IANA Considerations

   The ASN.1 module in Appendix A of this doucment makes use of object
   identifiers (OIDs).  This document requests that IANA register an OID
   in the SMI Security for PKIX Arc in the Module identifiers subarc
   (1.3.6.1.5.5.7.0) for the ASN.1 module.  The OID for the Asymmetric
   Decryption Key Identifier (1.2.840.113549.1.9.16.2.54) was previously
   defined in [RFC7030].  IANA is requested to update the "Reference"
   column for the Asymmetric Decryption Key Identifier attribute to also
   include a reference to this doducment.

10.  Acknowledgements

   This work was supported by the Huawei Technologies.

   The ASN.1 Module was assembled by Russ Housley and formatted by Sean
   Turner.

11.  References

11.1.  Normative References

   [I-D.ietf-anima-bootstrapping-keyinfra]
              Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
              and K. Watsen, "Bootstrapping Remote Secure Key
              Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
              keyinfra-29 (work in progress), October 2019.

   [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
              <https://www.rfc-editor.org/info/rfc2045>.




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   [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>.

   [RFC2986]  Nystrom, M. and B. Kaliski, "PKCS #10: Certification
              Request Syntax Specification Version 1.7", RFC 2986,
              DOI 10.17487/RFC2986, November 2000,
              <https://www.rfc-editor.org/info/rfc2986>.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
              <https://www.rfc-editor.org/info/rfc4648>.

   [RFC7030]  Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
              "Enrollment over Secure Transport", RFC 7030,
              DOI 10.17487/RFC7030, October 2013,
              <https://www.rfc-editor.org/info/rfc7030>.

   [X680]     ITU-T, "Information technology - Abstract Syntax Notation
              One.", ISO/IEC 8824-1:2002, 2002.

   [X681]     ITU-T, "Information technology - Abstract Syntax Notation
              One: Information Object Specification.", ISO/
              IEC 8824-2:2002, 2002.

   [X682]     ITU-T, "Information technology - Abstract Syntax Notation
              One: Constraint Specification.", ISO/IEC 8824-2:2002,
              2002.

   [X683]     ITU-T, "Information technology - Abstract Syntax Notation
              One: Parameterization of ASN.1 Specifications.", ISO/
              IEC 8824-2:2002, 2002.

   [X690]     ITU-T, "Information technology - ASN.1 encoding Rules:
              Specification of Basic Encoding Rules (BER), Canonical
              Encoding Rules (CER) and Distinguished Encoding Rules
              (DER).", ISO/IEC 8825-1:2002, 2002.

11.2.  Informative References

   [errata4384]
              "EST errata 4384: ASN.1 encoding error", n.d.,
              <https://www.rfc-editor.org/errata/eid4384>.

   [errata5107]
              "EST errata 5107: use Content-Transfer-Encoding", n.d.,
              <https://www.rfc-editor.org/errata/eid5107>.



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   [errata5108]
              "EST errata 5108: use of Content-Type for error message",
              n.d., <https://www.rfc-editor.org/errata/eid5108>.

   [RFC2307]  Howard, L., "An Approach for Using LDAP as a Network
              Information Service", RFC 2307, DOI 10.17487/RFC2307,
              March 1998, <https://www.rfc-editor.org/info/rfc2307>.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616,
              DOI 10.17487/RFC2616, June 1999,
              <https://www.rfc-editor.org/info/rfc2616>.

   [RFC2985]  Nystrom, M. and B. Kaliski, "PKCS #9: Selected Object
              Classes and Attribute Types Version 2.0", RFC 2985,
              DOI 10.17487/RFC2985, November 2000,
              <https://www.rfc-editor.org/info/rfc2985>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,
              <https://www.rfc-editor.org/info/rfc7230>.

   [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
              DOI 10.17487/RFC7231, June 2014,
              <https://www.rfc-editor.org/info/rfc7231>.

Appendix A.  ASN.1 Module

   This annex provides the normative ASN.1 definitions for the
   structures described in this specification using ASN.1 as defined in
   [X680] through [X683].

   There is no ASN.1 Module in RFC 7030.  This module has been created
   by combining the lines that are contained in the document body.

  PKIXEST-2019
       { iso(1) identified-organization(3) dod(6)
         internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
         id-mod-est-2019(TBD) }

  DEFINITIONS IMPLICIT TAGS ::=
  BEGIN

  -- EXPORTS ALL --




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  IMPORTS

  Attribute
  FROM CryptographicMessageSyntax-2010  -- [RFC6268]
        { iso(1) member-body(2) us(840) rsadsi(113549)
          pkcs(1) pkcs-9(9) smime(16) modules(0)
           id-mod-cms-2009(58) }

  ATTRIBUTE
  FROM PKIX-CommonTypes-2009
      { iso(1) identified-organization(3) dod(6) internet(1) security(5)
        mechanisms(5) pkix(7) id-mod(0) id-mod-pkixCommon-02(57) } ;


  -- CSR Attributes

  CsrAttrs ::= SEQUENCE SIZE (0..MAX) OF AttrOrOID

  AttrOrOID ::= CHOICE {
     oid        OBJECT IDENTIFIER,
     attribute  Attribute {{AttrSet}} }

  AttrSet ATTRIBUTE ::= { AttributesDefinedInRFC7030, ... }


  -- Asymmetric Decrypt Key Identifier Attribute

  AttributesDefinedInRFC7030 ATTRIBUTE ::= { aa-asymmDecryptKeyID, ... }

  aa-asymmDecryptKeyID ATTRIBUTE ::=
      { TYPE AsymmetricDecryptKeyIdentifier
        IDENTIFIED BY id-aa-asymmDecryptKeyID }

  id-aa-asymmDecryptKeyID OBJECT IDENTIFIER ::= { iso(1) member-body(2)
      us(840) rsadsi(113549) pkcs(1) pkcs9(9) smime(16) aa(2) 54 }

  AsymmetricDecryptKeyIdentifier ::= OCTET STRING

  END

Authors' Addresses

   Michael Richardson
   Sandelman Software Works

   Email: mcr+ietf@sandelman.ca





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   Thomas Werner
   Siemens

   Email: thomas-werner@siemens.com


   Wei Pan
   Huawei Technologies

   Email: william.panwei@huawei.com









































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