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Network Working Group                                        J. Pechanec
Internet-Draft                                                 D. Moffat
Intended status: Standards Track                      Oracle Corporation
Expires: November 3, 2011                                    May 2, 2011


                         The PKCS#11 URI Scheme
                      draft-pechanec-pkcs11uri-04

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 libraries, or for identifying PKCS#11 tokens
   themselves.  The URI is based on how PKCS#11 objects, libraries, and
   tokens 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
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 November 3, 2011.

Copyright Notice

   Copyright (c) 2011 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
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   carefully, as they describe your rights and restrictions with respect
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   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 URI Schemes . . . . . . . . . . . . . . . . 6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 8
   7.  Normative References  . . . . . . . . . . . . . . . . . . . . . 8
   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 existing objects, tokens, or Cryptoki
   libraries.

   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.


2.  Contributors

   Stef Walter, Nikos Mavrogiannopoulos, and Nico Williams 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.  Most
   attributes allow for an UTF-8 string to be used as an value.  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.  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.

   A PKCS#11 URL 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-objecttype / pk11-id / pk11-pinfile
 ; 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, we just removed ";".
 pk11-reserved-avail     = ":" / "/" / "?" / "#" / "[" / "]" / "@" /
                           "!" / "$" / "&" / "'" / "(" / ")" / "*" /
                           "+" / "," / "="
 pk11-value              = *(unreserved / pk11-reserved-avail /
                           pct-encoded)
 ; The "pk11-ck-char" rule contains a complete list of characters
 ; of the CK_CHAR type as defined in the PKCS#11 specification. Those
 ; are a-z, A-Z, 0-9, a space, and all special characters from the
 ; following list: !"#%&'()*+,-./:;<=>?[\]^_{|}~. Note that some
 ; special characters not part of the reserved and unreserved sets
 ; must be percent-encoded.



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 pk11-ck-char            = unreserved / "%20" / "!" / "%22" / "#" /
                           "%25" / "&" / "'" / "(" / ")" / "*" /
                           "+" / "," / "-" / "." / "/" / ":" / "%3B" /
                           "%3C" / "=" / "%3E" / "?" / "[" / "%5C" /
                           "]" / "%5E" / "_" / "%7B" / "%7C" / "%7D" /
                           "~"
 ; Corresponds to the label field of the CK_TOKEN_INFO structure.
 pk11-token              = "token" "=" pk11-value
 ; Corresponds to the manufacturerID field of the CK_TOKEN_INFO
 ; structure.
 pk11-manuf              = "manufacturer" "=" pk11-value
 ; Corresponds to the serialNumber field of the CK_TOKEN_INFO structure.
 pk11-serial             = "serial" "=" *pk11-ck-char
 ; Corresponds to the model field of the CK_TOKEN_INFO structure.
 pk11-model              = "model" "=" pk11-value
 ; Corresponds to the manufacturerID field of the CK_INFO structure.
 pk11-lib-manuf          = "library-manufacturer" "=" pk11-value
 ; Corresponds to the libraryDescription field of the CK_INFO structure.
 pk11-lib-desc           = "library-description" "=" pk11-value
 ; Corresponds to the libraryVersion field of the CK_INFO structure.
 pk11-lib-ver            = "library-version" "=" 1*DIGIT *("." 1*DIGIT)
 ; Corresponds to the CKA_LABEL object attribute.
 pk11-object             = "object" "=" pk11-value
 ; Corresponds to the CKA_CLASS object attribute.
 pk11-objecttype         = "objecttype" "=" ("public" / "private" /
                           "cert" / "secretkey" / "data")
 ; Corresponds to the CKA_ID object attribute.
 pk11-id                 = "id" "=" *pct-encoded
 pk11-pinfile            = "pinfile" "=" pk11-value

   While the PKCS#11 specification limits the length of some fields, eg.
   the manufacturer label can be up to thirty-two characters long, the
   PKCS#11 URI does not impose such limitations.  It is up to the
   consumer of the PKCS#11 URI to perform any necessary sanity length
   checks.

   The attribute "token" represents a token label, the attribute
   "manufacturer" represents a token manufacturer ID, the attribute
   "serial" represents a token serial number, the attribute "model"
   represents a token model, the attribute "library-manufacturer"
   represents the Cryptoki library manufacturer, the attribute "library-
   description" represents the character string description of the
   library, the attribute "library-version" represents the Cryptoki
   library version, the attribute "object" represents a PKCS#11 object
   label, the attribute "objecttype" represents the type of the object,
   the attribute "id" represents the object ID, and the attribute
   "pinfile" specifies where the application or library should find the
   token PIN, if needed.  Application could overload this attribute.



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   For example, "pinfile=%7Cprog-name" could mean to read a PIN from an
   external application (%7C denotes a pipe '|' character).  Note that
   an application can always ask for a PIN by any means it decides to.


4.  Examples of PKCS#11 URI Schemes

   This section contains some examples of how PKCS#11 tokens or PKCS#11
   token objects 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;objecttype=public

   When a private key is specified either the "pinfile" attribute or an
   application specific method must be used.  Also note that we can not
   use literal "/" in the "pinfile" attribute since this character is
   part of the reserved set, used to delimit components that are
   significant to the generic parser's hierarchical interpretation of an
   identifier.  We must percent-encode it.

     pkcs11:object=my-key;objecttype=private;pinfile=%2Fetc%2Ftoken_pin

   The following example identifies a certificate in the software token.
   Note that all attributes aside from "objecttype" 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 the
   notation of the "id" attribute value which is entirely percent-
   encoded.  We do not have to percent-encode "," which is in the
   reserverd set since it does not conflict with any sub-delimiter used.
   The '#' character is a general delimiter as "/" so we must percent-
   encode it.








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     pkcs11:token=The%20Software%20PKCS%2311%20softtoken;
            manufacturer=Snake%20Oil,%20Inc.;
            serial=;
            model=1.0;
            object=my-certificate;
            objecttype=cert;
            id=%69%95%3E%5C%f4%BD%EC%91;
            pinfile=%2Fetc%2Fssh%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.;
            pinfile=%2Fetc%2Fssh%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.  We can also have
   lower characters in the "id" attribute value but note that [RFC3986]
   recommends to use upercase hexadecimal digits for all percent-encoded
   characters.

     pkcs11:token=My%20token%25%20created%20by%20Joe;
            object=my-certificate;
            objecttype=cert;
            id=%69%95%3e%5c%f4%bd%ec%91;
            pinfile=%2Fetc%2Fssh%2Ftoken_pin

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

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








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

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


5.  IANA Considerations

   This document registers a URI scheme.  The registration template can
   be found in Section 2 of this document.


6.  Security Considerations

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

   Given that the PKCS#11 URI is also supposed to be used in command
   line arguments to running programs, and those arguments can be world
   readable on some systems, the URI intentionaly does not allow for
   specifying the PKCS#11 token PIN as a URI attribute.


7.  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.

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

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

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




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Authors' Addresses

   Jan Pechanec
   Oracle Corporation
   The Park, building 3
   V parku 2308/8
   Prague  14800
   CZ

   Phone: +420 221 438 852
   Email: Jan.Pechanec@Oracle.COM
   URI:   http://www.oracle.com


   Darren J. Moffat
   Oracle Corporation
   Guillemont Park
   Building 3
   Camberley  GU17 9QG
   UK

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




























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