Network Working Group
Independent Submission                                        S. Leonard
Internet-Draft
Request for Comments: 8351                                 Penango, Inc.
Intended Status:
Category: Informational                         November 14, 2017
Expires: May 18,                                        June 2018
ISSN: 2070-1721

             The PKCS #8 EncryptedPrivateKeyInfo Media Type
                    draft-seantek-pkcs8-encrypted-03

Abstract

   This document registers the application/pkcs8-encrypted media type
   for the EncryptedPrivateKeyInfo type of PKCS #8.  An instance of this
   media type carries a single encrypted private key, BER-encoded as a
   single EncryptedPrivateKeyInfo value.

Status of this This Memo

   This Internet-Draft document is submitted in full conformance with not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the
   provisions RFC Series, independently of BCP 78 any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and BCP 79.

   Internet-Drafts makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are working documents not candidates for any level of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list Standard;
   see Section 2 of RFC 7841.

   Information about the current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum status of six months this document, any errata,
   and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."
   https://www.rfc-editor.org/info/rfc8351.

Copyright Notice

   Copyright (c) 2017 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)
   (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

Table of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License. Contents

   1. Definitions  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Registration Application  . . . . . . . . . . . . . . . . . .   2
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   The private key words "SHOULD", "SHOULD NOT", and "RECOMMENDED" in this
   document are to is encrypted with an encryption algorithm, which
   could be interpreted a password-based encryption scheme as that term is used in
   PKCS #5: Password-Based Cryptography Specification Version 2.1 as
   published in [RFC2898] and updated by [RFC8018].  This document
   registers the application/pkcs8-encrypted media type for the
   EncryptedPrivateKeyInfo type of PKCS #8 (as originally described in [RFC2119].
   [RFC5208], which was obsoleted by [RFC5958]).  An instance of this
   media type carries a single encrypted private key [RFC5958] BER-
   encoded as a single EncryptedPrivateKeyInfo value.

2.  Registration Application

   Type name: application

   Subtype name: pkcs8-encrypted

   Required parameters: None.

   Optional parameters:

      password-mapping:  The private key is encrypted with an encryption
        algorithm, which could be a password-based encryption scheme as
        that term is used in PKCS #5 [RFC2898]. ([RFC2898] and [RFC8018]).  Such
        algorithms take a password as input.  A "password" is a secret
        text value (Section (see Section 3 of PKCS #5), [RFC2898] and [RFC8018]), but for
        algorithmic purposes the term "password" refers to an octet
        string (Section (see Section 2 of PKCS #5). [RFC2898] and [RFC8018]).  Therefore,
        there must be some mapping between the text value (which might
        be user input) and the octet string.  Section 3 of PKCS #5 [RFC2898]
        (which was replaced by [RFC8018]) recommends "that applications
        follow some common text encoding rules"; it then offers, but
        does not recommend, ASCII and UTF-8.

        While many modern applications support Unicode and Unicode-based
        encodings such as UTF-8 and UTF-16, interchange is still needed
        with private key artifacts that are encrypted with passwords in
        other encodings.  Therefore, this parameter specifies the
        charset (see Section 1.3 of [RFC2978]) that a recipient SHOULD should
        attempt first, in "reverse", when mapping from a sequence of
        characters to an octet string.  This parameter is not
        cryptographically protected, so recipients SHOULD NOT cannot rely on it as
        the exclusive mapping possibility.

        This parameter has similar semantics to the charset parameter
        from text/plain, except that it only applies to the user's input
        (text value) of a password.  There is no default value.

        The following special values, which all begin with "*" to
        distinguish them from registered charsets, are defined:

        *pkcs12     =      UTF-16LE with U+0000 NULL terminator: PKCS #12-style, #12
                     style, see [RFC7292] [RFC7292].

        *precis     = PRECIS      Preparation, Enforcement, and Comparison of
                     Internationalized Strings (PRECIS) password
                     profile, i.e., OpaqueString from Section 4 of
                     [RFC7613]: always UTF-8 in Normalization Form C (NFC)
                     (NFC).

        *precis-XXX = PRECIS  Any profile from the IANA "PRECIS Profiles"
                     registry where "XXX" is replaced by the profile
                     name as named XXX shown in the IANA PRECIS
                   Profiles Registry registry.

        *hex        =         hexadecimal input: the input is mapped to 0-9, A-F,
                     and then converted directly to octets.  If there
                     are an odd number of hex digits, either the final
                     digit 0 is appended, appended or an error condition is
                     raised.  Compare with Annex M.4 of IEEE 802.11-2012.
                     [IEEE.802.11-2012].

        *dtmf       =        The characters "0"-"9", "A"-"D", "*", and "#",
                     which map to their corresponding ASCII codes.
                     "A"-"D" map to the uppercase range 0x41 - 0x44.
                     (This is to support restricted-input devices, i.e.,
                     telephones and telephone-like equipment.)  User
                     input outside of these values is either ignored, ignored or
                     an error condition is raised.

        Otherwise, the value of this parameter is a charset, from the
        IANA
     Character Sets Registry "Character Sets" registry [CHARREG].

        This parameter is case-insensitive. case insensitive.

   Encoding considerations: Binary.

   Security considerations:

      Carries a cryptographic private key.  See Section 6 of [RFC5958].

      EncryptedPrivateKeyInfo PKCS #8 data contains exactly one private
      key.  Poor password choices, weak algorithms, or improper
      parameter selections (e.g., insufficient salting rounds) will make
      the confidential payloads much easier to compromise.

   Interoperability considerations:

      PKCS #8 is a widely recognized format for private key information
      on all modern cryptographic stacks.  The contents are exactly one
      private key (with optional key attributes), so there is no
      possibility for hidden "Easter eggs" in the payload such as
      unexpected certificates or miscellaneous secrets.

      The encrypted variation in this registration,
      EncryptedPrivateKeyInfo (Section 3, Encrypted "Encrypted Private Key Info, Info",
      of [RFC5958], and Section 6 of PKCS #8), #8 as originally described in
      [RFC5208], which was obsoleted by [RFC5958]), is less widely used
      for exchange than PKCS #12, but it is much simpler to implement.
     Actually
      Actually, PKCS #12 incorporates the PKCS #8 types, so a PKCS #12
      processor ought to be able to process PKCS #8 data by embedding
      the PKCS #8 data in PKCS #12 "scaffolding".

      The password-mapping parameter aids in interoperability when the
      creator (who encrypted the keying material) and the user (who is
      attempting to decrypt the keying material) are not operating in
      the same character encoding character-encoding environment.  An anticipated scenario
      is that the creator may have created the keying material with a
      password in a Shift-JIS environment a long time ago, while the
      user is in a UTF-8 environment.  There are potentially many
      Unicode sequences that code for the same abstract character, such
      as precomposed and decomposed forms; yet, such an abstract
      character (however coded in Unicode) will tend to map to one
      coding in the legacy charset, if it can be represented at all.
      Therefore, the password-mapping parameter will almost never be
      ambiguous when mapping to legacy encodings.  When mapping from one
      Unicode form to another (such as an internal Unicode
      representation to *pkcs12), code sequences are either preserved, preserved or
      folded deterministically to common Unicode code points or
      sequences, producing the same holistic result as mapping to legacy
      encodings.

      It is possible that an abstract character might map to multiple
      legacy encodings under the same charset.  However, the possibility
      is sufficiently remote as to be ignored in this media type
      registration.  One possible workaround is to set the user's
      (decrypting party's) local operating environment to the password-
      mapping legacy encoding parameter for the purpose of generating
      the password octet string from user input.  Another possibility is
      to generate all possible legacy encoding combinations from the
      abstract text (i.e., Unicode text), attempting decryption with
      them.  Customized behavior can be defined by updating this media
      type registration with a new password-mapping special value,
      prefixed with *.

   Published specification:

      RSA Laboratories PKCS #8 v1.2, v1.2 RSA Encryption Standard, November
      1993 (republished as RFC 5208, [RFC5208], May 2008); 2008, and updated as
      [RFC5958], August 2010); RFC 5958, August 2010

   Applications that use this media type:

      Machines, applications, browsers, Internet kiosks, and so on, that
      support this standard allow a user to import, export, and exercise
      a single private key.

   Fragment identifier considerations: None.

   Additional information:

      Deprecated alias names for this type: N/A
      Magic number(s): None.
      File extension(s): .p8e
      Macintosh file type code(s): None.  A uniform type identifier
      (UTI) of "com.rsa.pkcs-8-encrypted" is RECOMMENDED. recommended.

   Object Identifiers: 1.2.840.113549.1.12.10.1.2 (when in PKCS #12)

   Person & email address to contact for further information:

     Sean Leonard <dev+ietf@seantek.com>

   Intended usage: COMMON

   Restrictions on usage: None.

   Author/Change controller: Sean Leonard <dev+ietf@seantek.com>

   Intended usage: COMMON

   Provisional registration?  No

3.  IANA Considerations

   IANA is asked to register has registered the media type application/pkcs8-encrypted in the
   Standards tree using the applications information provided in Section 1 2 of this
   document.

4.  Security Considerations

   See the registration template.

5.  Normative References

   [CHARREG]  IANA, "Character Sets",
              <http://www.iana.org/assignments/character-sets>, December
              2013.

   [RFC2119]  Bradner, S., "Key words 2013,
              <http://www.iana.org/assignments/character-sets>.

   [IEEE.802.11-2012]
              IEEE, "IEEE Standard for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997. Information technology--
              Telecommunications and information exchange between
              systems Local and metropolitan area networks--Specific
              requirements Part 11: Wireless LAN Medium Access Control
              (MAC) and Physical Layer (PHY) Specifications",
              IEEE 802.11-2012, DOI 10.1109/ieeestd.2012.6178212,
              <http://ieeexplore.ieee.org/document/6178212/>.

   [RFC2898]  Kaliski, B., "PKCS #5: Password-Based Cryptography
              Specification Version 2.0", RFC 2898,
              DOI 10.17487/RFC2898, September 2000. 2000,
              <https://www.rfc-editor.org/info/rfc2898>.

   [RFC2978]  Freed, N. and J. Postel, "IANA Charset Registration
              Procedures", BCP 19, RFC 2978, DOI 10.17487/RFC2978,
              October 2000. 2000, <https://www.rfc-editor.org/info/rfc2978>.

   [RFC5208]  Kaliski, B., "Public-Key Cryptography Standards (PKCS) #8:
              Private-Key Information Syntax Specification Version 1.2",
              RFC 5208, DOI 10.17487/RFC5208, May 2008. 2008,
              <https://www.rfc-editor.org/info/rfc5208>.

   [RFC5958]  Turner, S., "Asymmetric Key Packages", RFC 5958,
              DOI 10.17487/RFC5958, August
              2010. 2010,
              <https://www.rfc-editor.org/info/rfc5958>.

   [RFC7292]  Moriarty, K., Ed., Nystrom, S., M., Parkinson, S., Rusch, A.,
              and M. Scott, "PKCS #12: Personal Information Exchange
              Syntax v1.1", RFC 7292, DOI 10.17487/RFC7292, July 2014. 2014,
              <https://www.rfc-editor.org/info/rfc7292>.

   [RFC7613]  Saint-Andre, P. and A. Melnikov, "Preparation,
              Enforcement, and Comparison of Internationalized Strings
              Representing Usernames and Passwords", RFC 7613,
              DOI 10.17487/RFC7613, August
              2015. 2015,
              <https://www.rfc-editor.org/info/rfc7613>.

   [RFC8018]  Moriarty, K., Ed., Kaliski, B., and A. Rusch, "PKCS #5:
              Password-Based Cryptography Specification Version 2.1",
              RFC 8018, DOI 10.17487/RFC8018, January 2017,
              <https://www.rfc-editor.org/info/rfc8018>.

Author's Address

   Sean Leonard
   Penango, Inc.
   5900 Wilshire Blvd
   Ste 2600
   Los Angeles, CA  90036
   USA

   EMail:
   United States of America

   Email: dev+ietf@seantek.com
   URI:   http://www.penango.com/

Appendix A.  Changes from -02 to -03

   Updated the document based on discussions. Added much more
   explanatory text about the password-mapping parameter.