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2 Network Working Group I. Young, Ed.
3 Internet-Draft Independent
4 Intended status: Informational L. Johansson
5 Expires: December 2, 2016 SUNET
6 S. Cantor
7 Shibboleth Consortium
8 May 31, 2016
10 The Entity Category SAML Attribute Types
11 draft-young-entity-category-04
13 Abstract
15 This document describes a SAML entity attribute which can be used to
16 assign category membership semantics to an entity, and a second
17 attribute for use in claiming interoperation with or support for
18 entities in such categories.
20 This document is a product of the Research and Education Federations
21 (REFEDS) Working Group process.
23 Status of This Memo
25 This Internet-Draft is submitted in full conformance with the
26 provisions of BCP 78 and BCP 79.
28 Internet-Drafts are working documents of the Internet Engineering
29 Task Force (IETF). Note that other groups may also distribute
30 working documents as Internet-Drafts. The list of current Internet-
31 Drafts is at http://datatracker.ietf.org/drafts/current/.
33 Internet-Drafts are draft documents valid for a maximum of six months
34 and may be updated, replaced, or obsoleted by other documents at any
35 time. It is inappropriate to use Internet-Drafts as reference
36 material or to cite them other than as "work in progress."
38 This Internet-Draft will expire on December 2, 2016.
40 Copyright Notice
42 Copyright (c) 2016 IETF Trust and the persons identified as the
43 document authors. All rights reserved.
45 This document is subject to BCP 78 and the IETF Trust's Legal
46 Provisions Relating to IETF Documents
47 (http://trustee.ietf.org/license-info) in effect on the date of
48 publication of this document. Please review these documents
49 carefully, as they describe your rights and restrictions with respect
50 to this document.
52 Table of Contents
54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
55 1.1. REFEDS Document Process . . . . . . . . . . . . . . . . . 3
56 2. Notation and Conventions . . . . . . . . . . . . . . . . . . 3
57 3. Entity Category Attribute . . . . . . . . . . . . . . . . . . 3
58 3.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 3
59 3.2. Semantics . . . . . . . . . . . . . . . . . . . . . . . . 4
60 3.3. Entity Category Example . . . . . . . . . . . . . . . . . 5
61 4. Entity Category Support Attribute . . . . . . . . . . . . . . 6
62 4.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 6
63 4.2. Semantics . . . . . . . . . . . . . . . . . . . . . . . . 6
64 4.3. Entity Category Support Example . . . . . . . . . . . . . 7
65 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
66 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
67 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
68 7.1. Normative References . . . . . . . . . . . . . . . . . . 9
69 7.2. Informative References . . . . . . . . . . . . . . . . . 9
70 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 11
71 Appendix B. Change Log (to be removed by RFC Editor before
72 publication) . . . . . . . . . . . . . . . . . . . . 11
73 B.1. Since draft-young-entity-category-03 . . . . . . . . . . 11
74 B.2. Since draft-young-entity-category-02 . . . . . . . . . . 11
75 B.3. Since draft-young-entity-category-01 . . . . . . . . . . 12
76 B.4. Since draft-young-entity-category-00 . . . . . . . . . . 12
77 B.5. Since draft-macedir-entity-category . . . . . . . . . . . 12
78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
80 1. Introduction
82 This document describes a SAML attribute, referred to here as the
83 "entity category attribute", values of which represent entity types
84 or categories. When used with the SAML V2.0 Metadata Extension for
85 Entity Attributes [SAML2MetadataAttr] each such entity category
86 attribute value represents a claim that the entity thus labelled
87 meets the requirements of, and is asserted to be a member of, the
88 indicated category.
90 These category membership claims MAY be used by a relying party to
91 provision policy for release of attributes from an identity provider,
92 to influence user interface decisions such as those related to
93 identity provider discovery, or for any other purpose. In general,
94 the intended uses of any claim of membership in a given category will
95 depend on the details of the category's definition, and will often be
96 included as part of that definition.
98 Entity category attribute values are URIs, and this document does not
99 specify a controlled vocabulary. Category URIs may therefore be
100 defined by any appropriate authority without any requirement for
101 central registration. It is anticipated that other specifications
102 may provide management and discovery mechanisms for entity category
103 attribute values.
105 A second SAML attribute, referred to here as the "entity category
106 support attribute", contains URI values which represent claims that
107 an entity supports and/or interoperates with entities in a given
108 category or categories. These values, defined in conjunction with
109 specific entity category values, provide entities in a category with
110 the means to identify peer entities that wish to interact with them
111 in category-specific fashion.
113 This document does not specify any values either for the entity
114 category attribute or for the entity category support attribute.
116 1.1. REFEDS Document Process
118 The Research and Education Federations group ([REFEDS]) is the voice
119 that articulates the mutual needs of research and education identity
120 federations worldwide. It aims to represent the requirements of
121 research and education in the ever-growing space of access and
122 identity management.
124 From time to time REFEDS will wish to publish a document in the
125 Internet RFC series. Such documents will be published as part of the
126 RFC Independent Submission Stream [RFC4844]; however the REFEDS
127 working group sign-off process will have been followed for these
128 documents, as described in the REFEDS Participant's Agreement
129 [REFEDS.agreement].
131 This document is a product of the REFEDS Working Group process.
133 2. Notation and Conventions
135 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
136 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
137 document are to be interpreted as described in RFC 2119 [BCP14].
139 3. Entity Category Attribute
141 3.1. Syntax
143 Entity category attribute values MUST be URIs. It is RECOMMENDED
144 that http:-scheme or https:-scheme URLs are used, and further
145 RECOMMENDED that each such value resolves to a human-readable
146 document defining the category.
148 The entity category attribute MUST be encoded as a SAML 2.0 Attribute
149 element with @NameFormat urn:oasis:names:tc:SAML:2.0:attrname-
150 format:uri and @Name http://macedir.org/entity-category.
152 A SAML entity is associated with one or more categories by including
153 the Attribute element described here in the entity's metadata through
154 use of the [SAML2MetadataAttr] metadata extension, in which the
155 Attribute element is contained within an mdattr:EntityAttributes
156 element directly contained within an md:Extensions element directly
157 contained within the entity's md:EntityDescriptor.
159 The meaning of the entity category attribute is undefined by this
160 specification if it appears anywhere else within a metadata instance,
161 or within any other XML document.
163 If the entity category attribute Attribute element appears more than
164 once in the metadata for an entity, the combined set of associated
165 attribute values SHOULD be interpreted by relying parties as if they
166 all appeared within a single Attribute element.
168 3.2. Semantics
170 The presence of the entity category attribute within an entity's
171 entity attributes represents a series of claims (one for each
172 attribute value) that the entity is a member of each named category.
173 The precise semantics of such a claim depend on the definition of the
174 category itself.
176 An entity may be claimed to be a member of more than one category.
177 In this case, the entity is claimed to meet the requirements of each
178 category independently unless otherwise specified by the category
179 definitions themselves.
181 The definition of the concept of a category is intentionally not
182 addressed in this document, in order to leave it as general as
183 possible. However, to be useful, category definitions SHOULD include
184 the following as appropriate:
186 o A definition of the authorities who may validly assert membership
187 in the category. While membership in some categories may be self-
188 asserted informally by an entity's owner, others may need to be
189 validated by third parties such as the entity's home federation or
190 other registrar.
192 o A set of criteria by which an entity's membership in the category
193 can be objectively assessed.
195 o A definition of the processes by which valid authorities may
196 determine that an entity meets the category's membership criteria.
198 o A description of the anticipated uses for category membership by
199 relying parties.
201 o A statement indicating the applicability or otherwise of
202 membership of the entity category to different SAML role
203 descriptors, and any protocol support restrictions that may be
204 relevant.
206 Entity categories SHOULD NOT be used to indicate the certification
207 status of an entity regarding its conformance to the requirements of
208 an identity assurance framework. The [SAML2IDAssuranceProfile]
209 extension SHOULD be used for this purpose.
211 If significant changes are made to a category definition, the new
212 version of the category SHOULD be represented by a different category
213 URI so that the old and new versions can be distinguished by a
214 relying party.
216 No ordering relation is defined over entity category value URIs.
217 Entity category attribute value URIs MUST be treated as opaque
218 strings for the purpose of comparison.
220 3.3. Entity Category Example
222
224
225
227
230 http://example.org/category/dog
232 urn:oid:1.3.6.1.4.1.21829
233
234
235
236 ...
237
239 4. Entity Category Support Attribute
241 4.1. Syntax
243 Entity category support attribute values MUST be URIs. It is
244 RECOMMENDED that http:-scheme or https:-scheme URLs are used, and
245 further RECOMMENDED that each such value resolves to a human-readable
246 document defining the value's semantics. A given entity category
247 value MAY be associated with multiple support values in order to
248 allow for multiple forms of support, participation, or interoperation
249 with entities in the category.
251 The entity category support attribute MUST be encoded as a SAML 2.0
252 Attribute element with @NameFormat
253 urn:oasis:names:tc:SAML:2.0:attrname-format:uri and @Name
254 http://macedir.org/entity-category-support.
256 Claims that a SAML entity implements support for one or more
257 categories are represented by including the Attribute element
258 described here in the entity's metadata through use of the
259 [SAML2MetadataAttr] metadata extension, in which the Attribute
260 element is contained within an mdattr:EntityAttributes element
261 directly contained within an md:Extensions element directly contained
262 within the entity's md:EntityDescriptor.
264 The meaning of the entity category support attribute is undefined by
265 this specification if it appears anywhere else within a metadata
266 instance, or within any other XML document.
268 If the entity category support attribute Attribute element appears
269 more than once in the metadata for an entity, the combined set of
270 associated attribute values SHOULD be interpreted by relying parties
271 as if they all appeared within a single Attribute element.
273 4.2. Semantics
275 The presence of the entity category support attribute within an
276 entity's entity attributes represents a series of claims (one for
277 each attribute value) that the entity supports peer entities in a
278 category in a particular fashion. The precise semantics of such a
279 claim depend on the definition of the category support identifier
280 itself. Category support claims will often be defined to be self-
281 asserted.
283 An entity may be claimed to support more than one category. In this
284 case, the entity is claimed to meet the support requirements of each
285 category independently unless otherwise specified by the category
286 definitions themselves.
288 The definition of the concept of "support" for a category is
289 intentionally not addressed in this document, in order to leave it as
290 general as possible. It is assumed that entity category definitions
291 MAY define one or more support values signifying particular
292 definitions for "support" by peers as motivated by use cases arising
293 from the definition of the category itself.
295 A common case is expected to be the definition of a single support
296 value whose URI is identical to that defined for the category itself.
298 If significant changes are made to a category support definition, the
299 new version SHOULD be represented by a different category support URI
300 so that the old and new versions can be distinguished by a relying
301 party.
303 No ordering relation is defined over entity category value URIs.
304 Entity category attribute value URIs MUST be treated as opaque
305 strings for the purpose of comparison.
307 4.3. Entity Category Support Example
309
311
312
314
317 http://example.org/category/dog/basic
319 http://example.org/category/dog/advanced
321 urn:oid:1.3.6.1.4.1.21829
322
323
324
325 ...
326
328 5. IANA Considerations
330 This memo includes no request to IANA.
332 6. Security Considerations
334 The presence of the entity category attribute within an entity's
335 entity attributes represents a series of claims (one for each
336 attribute value) that the entity is a member of the named categories.
337 Before accepting and acting on such claims, any relying party needs
338 to establish, at a level of assurance sufficient for the intended
339 use, a chain of trust concluding that the claim is justified.
341 Some of the elements in such a chain of trust might include:
343 o The integrity of the metadata delivered to the relying party, as
344 for example assured by a digital signature.
346 o If the entity category attribute is carried within a signed
347 assertion, the assertion itself must be evaluated.
349 o The policies and procedures of the immediate source of the
350 metadata; in particular, any procedures the immediate source has
351 with regard to aggregation of metadata from other sources.
353 o The policies and procedures implemented by agents along the
354 publication path from the original metadata registrar: this may be
355 determined either by examination of the published procedures of
356 each agent in turn, or may be simplified if the entity metadata
357 includes publication path metadata in mdrpi:PublicationPath
358 elements as described in [SAML2MetadataRPI] section 2.3.1.
360 o The policies and procedures implemented by the original metadata
361 registrar. The registrar's identity may be known implicitly, or
362 may be determined from the entity metadata if it includes an
363 mdrpi:RegistrationInfo element and corresponding
364 @registrationAuthority attribute as described in
365 [SAML2MetadataRPI] section 2.1.1.
367 o The definition of the category itself; in particular, any
368 statements it makes about whether membership of the category may
369 be self-asserted, or may only be asserted by particular
370 authorities.
372 Although entity category support attribute values will often be
373 defined as self-asserted claims by the containing entity, the
374 provenance of the metadata remains relevant to a relying party's
375 decision to accept a claim of support as legitimate, and the specific
376 definition of a support claim will influence the assurance required
377 to act on it.
379 The conclusion that a claim of category membership or support is
380 justified and should be acted upon may require a determination of the
381 origin of the claim. This may not be necessary if the immediate
382 source of the metadata is trusted to such an extent that the trust
383 calculation is essentially delegated to it.
385 In many cases, a claim will be included in an entity's metadata by
386 the original metadata registrar on behalf of the entity's owner, and
387 the mdrpi:RegistrationInfo element's @registrationAuthority attribute
388 is available to carry the registrar's identity. However, any agent
389 that is part of the chain of custody between the original registrar
390 and the final relying party may have added, removed or transformed
391 claims according to local policy. For example, an agent charged with
392 redistributing metadata may remove claims it regards as
393 untrustworthy, or add others which were not already present if they
394 have value to its intended audience.
396 7. References
398 7.1. Normative References
400 [BCP14] Bradner, S., "Key words for use in RFCs to Indicate
401 Requirement Levels", BCP 14, RFC 2119, March 1997.
403 [SAML2MetadataAttr]
404 Cantor, S., Ed., "SAML V2.0 Metadata Extension for Entity
405 Attributes", August 2009,
406 .
408 [SAML2MetadataRPI]
409 La Joie, C., Ed., "SAML V2.0 Metadata Extensions for
410 Registration and Publication Information Version 1.0",
411 April 2012,
412 .
414 7.2. Informative References
416 [REFEDS] Research and Education Federations, "REFEDS Home Page",
417 .
419 [REFEDS.agreement]
420 Research and Education Federations, "REFEDS Participant's
421 Agreement", .
424 [RFC4844] Daigle, L. and Internet Architecture Board, "The RFC
425 Series and RFC Editor", RFC 4844, July 2007.
427 [SAML2IDAssuranceProfile]
428 Morgan, RL., Ed., Madsen, P., Ed., and S. Cantor, Ed.,
429 "SAML V2.0 Identity Assurance Profiles Version 1.0",
430 November 2010, .
433 Appendix A. Acknowledgements
435 This work has been a collaborative effort within the REFEDS and MACE-
436 Dir communities. Special thanks to (in no particular order):
438 o RL 'Bob' Morgan
440 o Ken Klingenstein
442 o Keith Hazelton
444 o Steven Olshansky
446 o Mikael Linden
448 o Nicole Harris
450 o Tom Scavo
452 Appendix B. Change Log (to be removed by RFC Editor before publication)
454 B.1. Since draft-young-entity-category-03
456 Additional improvements in response to IETF Gen-Art review:
458 o Section 3.2: additional SHOULD language recommending that category
459 definitions include applicability information for particular SAML
460 role descriptors.
462 o Section 3.2: added an informative reference to
463 [SAML2IDAssuranceProfile] and language recommending its use over
464 entity categories where appropriate.
466 B.2. Since draft-young-entity-category-02
468 Fix link to the REFEDS Participant's Agreement [REFEDS.agreement].
470 Clarifications in response to IETF Gen-Art review:
472 o Section 1: make explicit the fact that we don't specify any values
473 of either attribute in this document.
475 o Section 3.1, Section 4.1: clarify that it is possible for
476 attribute values to appear within multiple Attribute elements, and
477 that this SHOULD be regarded as equivalent to combining them
478 within a single Attribute element.
480 o Section 3.2, Section 4.2: clarify the expectation that categories
481 are independent unless their definitions say otherwise.
483 o Section 3.2, Section 4.2: If significant changes are made to a
484 category definition, the new version of the category SHOULD be
485 represented by a different category URI *so that the old and new
486 versions can be distinguished by a relying party*.
488 o Section 3.2, Section 4.2: *No ordering relation is defined over
489 entity category value URIs.* Entity category attribute value URIs
490 MUST be treated as opaque strings *for the purpose of comparison*.
492 B.3. Since draft-young-entity-category-01
494 Changes from REFEDS consultation process:
496 1. Simplify title from "The Entity Category SAML Entity Metadata
497 Attribute Types" to "The Entity Category SAML Attribute Types".
499 2. Clarify the use of [SAML2MetadataRPI] in Section 6 by indicating
500 the elements and attributes to be used, and the sections of
501 [SAML2MetadataRPI] in which they are defined.
503 3. Remove any implication that category and category support claims
504 are necessarily being made "by" the entity itself.
506 4. Clarify that the origin of a category membership or support claim
507 may not always be the original registrar.
509 Grammar fix in Abstract.
511 Change the reference anchor for the SAML [SAML2MetadataRPI]
512 extension, as it now more commonly known as RPI than its original DRI
513 abbreviation.
515 B.4. Since draft-young-entity-category-00
517 Update affiliations for Leif Johansson and Scott Cantor.
519 Remove authors from acknowledgements.
521 Reorganize some of the introductory boilerplate sections.
523 B.5. Since draft-macedir-entity-category
525 Adopted as base for draft-young-entity-category-00.
527 Changed ipr from "pre5378Trust200902" to "trust200902" and submission
528 type from IETF to independent.
530 Designate Ian Young as editor for this version. Set more general
531 affiliation.
533 Modernised reference to RFC 2119 [BCP14] and moved that reference to
534 the introduction.
536 Adjusted layout of examples so that they don't exceed the RFC
537 standard line length.
539 Minor typographical nits but (intentionally) no substantive content
540 changes.
542 Authors' Addresses
544 Ian A. Young (editor)
545 Independent
547 EMail: ian@iay.org.uk
549 Leif Johansson
550 SUNET
552 EMail: leifj@sunet.se
554 Scott Cantor
555 Shibboleth Consortium
557 EMail: cantor.2@osu.edu