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Network Working Group                                        J. Pechanec
Internet-Draft                                                 D. Moffat
Intended status: Standards Track                      Oracle Corporation
Expires: July 30, 2013                                  January 26, 2013


                         The PKCS#11 URI Scheme
                      draft-pechanec-pkcs11uri-08

Abstract

   This memo specifies a PKCS#11 Uniform Resource Identifier (URI)
   Scheme for identifying PKCS#11 objects stored in PKCS#11 tokens, for
   identifying PKCS#11 tokens themselves, or for identifying PKCS#11
   libraries.  The URI is based on how PKCS#11 objects, tokens, and
   libraries are identified in the PKCS#11 Cryptographic Token Interface
   Standard.

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 http://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 July 30, 2013.

Copyright Notice

   Copyright (c) 2013 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



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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  PKCS#11 URI Scheme Definition . . . . . . . . . . . . . . . . . 4
     3.1.  PKCS#11 URI Scheme Name . . . . . . . . . . . . . . . . . . 4
     3.2.  PKCS#11 URI Scheme Status . . . . . . . . . . . . . . . . . 4
     3.3.  PKCS#11 URI Scheme Syntax . . . . . . . . . . . . . . . . . 4
   4.  Examples of PKCS#11 URIs  . . . . . . . . . . . . . . . . . . . 6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 9
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 9
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9

































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1.  Introduction

   The PKCS #11: Cryptographic Token Interface Standard [pkcs11_spec]
   specifies an API, called Cryptoki, for devices which hold
   cryptographic information and perform cryptographic functions.
   Cryptoki, pronounced crypto-key and short for cryptographic token
   interface, follows a simple object-based approach, addressing the
   goals of technology independence (any kind of device may be used) and
   resource sharing (multiple applications may access multiple devices),
   presenting applications with a common, logical view of the device - a
   cryptographic token.

   It is desirable for applications or libraries that work with PKCS#11
   tokens to accept a common identifier that consumers could use to
   identify an existing PKCS#11 object in a PKCS#11 token, or an
   existing token itself, or an existing Cryptoki library.  The set of
   object types that can be stored in a PKCS#11 token includes a public
   key, a private key, a certificate, a secret key, and a data object.
   These objects can be uniquely identifiable via the PKCS#11 URI scheme
   defined in this document.  The set of attributes describing an object
   can contain an object label, its type, and its ID.  The set of
   attributes that identifies a PKCS#11 token can contain a token label,
   a manufacturer name, a serial number, and a token model.  Attributes
   that can identify a Cryptoki library are a library manufacturer, a
   library description, and a library version.

   Note that the PKCS#11 URI is not intended to be used to create new
   PKCS#11 objects in tokens, or to create PKCS#11 tokens.  It is solely
   to be used to identify and work with existing objects, tokens, and
   Cryptoki libraries through PKCS#11 API.

   The URI scheme defined in this document is designed specifically with
   a mapping to the PKCS#11 API in mind.  The URI uses only the scheme
   and the path components which are required by the Uniform Resource
   Identifier generic syntax [RFC3986].  The URI scheme does not use the
   hierarchical element for a naming authority in the path since the
   authority part could not be mapped to PKCS#11 API elements.  The URI
   scheme does not use the optional query and fragment elements.

   If an application has no access to a producer or producers of the
   PKCS#11 API it is left to its implementation to provide adequate user
   interface to locate and load such producer(s).


2.  Contributors

   Stef Walter, Nikos Mavrogiannopoulos, Nico Williams, Dan Winship, and
   Jaroslav Imrich contributed to the development of this document.



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3.  PKCS#11 URI Scheme Definition

   In accordance with [RFC4395], this section provides the information
   required to register the PKCS#11 URI scheme.

3.1.  PKCS#11 URI Scheme Name

   pkcs11

3.2.  PKCS#11 URI Scheme Status

   Permanent.

3.3.  PKCS#11 URI Scheme Syntax

   The PKCS#11 URI scheme is a sequence of attribute value pairs
   separated by a semicolon.  In accordance with [RFC3986], the data
   should first be encoded as octets according to the UTF-8 character
   encoding [RFC3629]; then only those octets that do not correspond to
   characters in the unreserved set or to permitted characters from the
   reserved set should be percent-encoded.  This specification suggests
   one allowable exception to that rule for the "id" attribute, as
   stated later in this section.  Grammar rules "unreserved" and "pct-
   encoded" in the PKCS#11 URI specification below were imported from
   [RFC3986].  As a special case, note that according to [RFC3986], a
   space must be percent-encoded.

   PKCS#11 specification imposes various limitations on the value of
   attributes, be it a more restrictive character set for the "serial"
   attribute or fixed sized buffers for almost all the others, including
   "token", "manufacturer", and "model" attributes.  However, the
   PKCS#11 URI notation does not impose such limitations aside from
   removing generic and PKCS#11 URI delimiters from a permitted
   character set.  We believe that being too restrictive on the
   attribute values could limit the PKCS#11 URI's usefulness.  What is
   more, possible future changes to the PKCS#11 specification will not
   affect existing attributes.














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   A PKCS#11 URI takes the form (for explanation of Augmented BNF, see
   [RFC5234]):

   pk11-URI            = "pkcs11" ":" pk11-identifier
   pk11-identifier     = *1(pk11-attr *(";" pk11-attr))
   pk11-attr           = pk11-token / pk11-manuf / pk11-serial /
                         pk11-model / pk11-lib-manuf /
                         pk11-lib-ver / pk11-lib-desc /
                         pk11-object / pk11-object-type / pk11-id /
                         pk11-pin-source
   ; Section 2.2 of RFC 3986 specifies that all potentially reserved
   ; characters that do not conflict with actual delimiters of the URI
   ; do not have to be percent-encoded. So, ";" was removed as a
   ; sub-delimiter of the PKCS#11 URI's path and "/", "?", and "#" as
   ; delimiters of generic URI components.
   pk11-reserved-avail = ":" / "[" / "]" / "@" / "!" / "$" /
                         "&" / "'" / "(" / ")" / "*" / "+" /
                         "," / "="
   pk11-char           = unreserved / pk11-reserved-avail /
                         pct-encoded
   pk11-token          = "token" "=" *pk11-char
   pk11-manuf          = "manufacturer" "=" *pk11-char
   pk11-serial         = "serial" "=" *pk11-char
   pk11-model          = "model" "=" *pk11-char
   pk11-lib-manuf      = "library-manufacturer" "=" *pk11-char
   pk11-lib-desc       = "library-description" "=" *pk11-char
   pk11-lib-ver        = "library-version" "=" *DIGIT *1("." 1*DIGIT)
   pk11-object         = "object" "=" *pk11-char
   pk11-object-type    = "object-type" "=" *1("public" / "private" /
                         "cert" / "secret-key" / "data")
   pk11-id             = "id" "=" *pk11-char
   pk11-pin-source     = "pin-source" "=" *pk11-char

   More specifically, "/" delimiter of generic URI components was
   removed from available characters that do not have to be percent-
   encoded so that the initial part of a PKCS#11 URI is never confused
   with "path-rootless" part of "hier-part" generic URI component as
   defined in [RFC3986].  Delimiters "?" and "#" of generic URI
   components were removed to allow for possible future extensions of
   the PKCS#11 URI.  All other delimiters of generic URI components are
   allowed to be used unencoded (":", "[", "]", and "@") in the PKCS#11
   URI.

   The attribute "token" represents a token label and corresponds to the
   "label" member of the CK_TOKEN_INFO structure, the attribute
   "manufacturer" corresponds to the "manufacturerID" member of
   CK_TOKEN_INFO, the attribute "serial" corresponds to the
   "serialNumber" member of CK_TOKEN_INFO, the attribute "model"



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   corresponds to the "model" member of CK_TOKEN_INFO, the attribute
   "library-manufacturer" represents the Cryptoki library manufacturer
   and corresponds to the "manufacturerID" member of the CK_INFO
   structure, the attribute "library-description" corresponds to the
   "libraryDescription" member of CK_INFO, the attribute "library-
   version" corresponds to the "libraryVersion" member of CK_INFO, the
   attribute "object" represents a PKCS#11 object label and corresponds
   to the "CKA_LABEL" object attribute, the attribute "object-type"
   represents the type of the object and corresponds to the "CKA_CLASS"
   object attribute, the attribute "id" represents the object ID and
   corresponds to the "CKA_ID" object attribute, and the attribute "pin-
   source" specifies where the application or library should find the
   token PIN, if needed.

   The "pin-source" attribute may represent a filename that contains a
   token PIN but an application may overload this attribute.  For
   example, "pin-source=%7Cprog-name" could mean to read a PIN from an
   external application (%7C denotes a pipe '|' character).  Note that
   an application may always ask for a PIN and/or interpret the "pin-
   source" attribute by any means it decides to.

   It is recommended to percent-encode the whole value of the "id"
   attribute which is supposed to be handled as arbitrary binary data.


4.  Examples of PKCS#11 URIs

   This section contains some examples of how PKCS#11 token objects,
   PKCS#11 tokens, and PKCS#11 libraries can be identified using the
   PKCS#11 URI scheme.  Note that in some of the following examples,
   newlines and spaces were inserted for better readability which is
   allowed by [RFC3986].  Also note that all spaces as part of the URI
   are percent-encoded, as required by [RFC3986].

   An empty PKCS#11 URI might be useful to PKCS#11 consumers:

     pkcs11:

   One of the simplest and most useful forms might be a PKCS#11 URI that
   specifies only an object label and its type.  The default token is
   used so the URI does not specify it.  Note that when specifying
   public objects, a token PIN might not be required.

     pkcs11:object=my-pubkey;object-type=public







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   When a private key is specified either the "pin-source" attribute or
   an application specific method would be usually used.  Also note that
   "/" must be percent-encoded in the "pin-source" attribute value since
   it must be prevented to be mistaken for a path segment delimiter.

     pkcs11:object=my-key;object-type=private;
            pin-source=%2Fetc%2Ftoken_pin

   The following example identifies a certificate in the software token.
   Note that all attributes may have an empty value.  In our case,
   "serial" is empty.  It is up to the consumer of the URI to perform
   necessary checks if that is not allowed.  Note that the "id"
   attribute value is entirely percent-encoded, as recommended.  While
   "," is in the reserved set it does not have to be percent-encoded
   since it does not conflict with any sub-delimiters used.  The '#'
   character as in "The Software PKCS#11 Softtoken" is a general
   delimiter as "/" so it must be percent-encoded, too.

     pkcs11:token=The%20Software%20PKCS%2311%20Softtoken;
            manufacturer=Snake%20Oil,%20Inc.;
            serial=;
            model=1.0;
            object=my-certificate;
            object-type=cert;
            id=%69%95%3E%5C%f4%BD%EC%91;
            pin-source=%2Fetc%2Ftoken_pin

   The token alone can be identified without specifying any PKCS#11
   objects.  A PIN may still be needed to list all objects, for example.

     pkcs11:token=Software%20PKCS%2311%20softtoken;
            manufacturer=Snake%20Oil,%20Inc.;
            pin-source=%2Fetc%2Ftoken_pin

   The Cryptoki library alone can be also identified without specifying
   any PKCS#11 objects.

     pkcs11:library-manufacturer=Snake%20Oil,%20Inc.;
            library-description=Soft%20Token%20Library;
            library-version=1.23

   The following example shows that the attribute value can contain a
   semicolon.  In such case, it is percent-encoded.  The token value
   must be read as "My token; created by Joe".  Lower characters can
   also be used in percent-encoding as shown below in the "id" attribute
   value but note that [RFC3986] recommends to use upercase hexadecimal
   digits for all percent-encoded characters.  Library version ".9"
   should be interpreted as "0" for the major and "9" for the minor



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   version of the library.  Similarly, library version "9" should be
   interpreted as "9" for the major and "0" for the minor version of the
   library.

     pkcs11:token=My%20token%25%20created%20by%20Joe;
            library-version=.9
            id=%69%95%3e%5c%f4%bd%ec%91;

   And if there is any need to include literal '%;' substring, for
   example, both characters must be escaped.  The token value must be
   read as "A name with a strange substring '\;'".

     pkcs11:token=A%20name%20with%20a%20strange%20substring%20'%25%3B';
            object=my-certificate;
            object-type=cert;
            pin-source=%2Fetc%2Ftoken_pin

   The next example includes a small A with acute in the token name.  It
   must be encoded in octets according to the UTF-8 character encoding
   and then percent-encoded.  Given that a small A with acute is U+225
   unicode code point, the UTF-8 encoding is 195 161 in decimal, and
   that is "%C3%A1" in percent-encoding.

     pkcs11:token=Name%20with%20a%20small%20A%20with%20acute:%20%C3%A1;
            object=my-certificate;
            object-type=cert


5.  IANA Considerations

   This document registers a URI scheme.


6.  Security Considerations

   There are security considerations for URI schemes discussed in
   [RFC3986].

   More specifically, Section 7.1 of [RFC3986] applies since there is no
   guarantee that the same URI will always identify the same object,
   token, or a library in the future.

   Section 7.5 of [RFC3986] applies since the PKCS#11 URI may be used in
   command line arguments to run applications, and those arguments can
   be world readable on some systems.  For that reasons, the URI
   intentionaly does not allow for specifying the PKCS#11 token PIN as a
   URI attribute.




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7.  References

7.1.  Normative References

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", RFC 3629, STD 63, November 2003.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", RFC 3986,
              STD 66, January 2005.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 5234, STD 68, January 2008.

7.2.  Informative References

   [RFC4395]  Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
              Registration Procedures for New URI Schemes", RFC 4395,
              February 2006.

   [pkcs11_spec]
              RSA Laboratories, "PKCS #11: Cryptographic Token Interface
              Standard v2.20", June 2004.


Authors' Addresses

   Jan Pechanec
   Oracle Corporation
   4180 Network Circle
   Santa Clara  CA 95054
   USA

   Email: Jan.Pechanec@Oracle.COM
   URI:   http://www.oracle.com


   Darren J. Moffat
   Oracle Corporation
   Oracle Parkway
   Thames Valley Park
   Reading  RG6 1RA
   UK

   Email: Darren.Moffat@Oracle.COM
   URI:   http://www.oracle.com





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