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2 Network Working Group I. Young, Ed.
3 Internet-Draft Independent
4 Intended status: Informational L. Johansson
5 Expires: January 18, 2018 SUNET
6 S. Cantor
7 Shibboleth Consortium
8 July 17, 2017
10 The Entity Category SAML Attribute Types
11 draft-young-entity-category-05
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 January 18, 2018.
40 Copyright Notice
42 Copyright (c) 2017 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 . . . . . . . . . . . . . . . . . . 4
58 3.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 4
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 . . . . . . . . . . . . . . . . . . . . . . . . 7
64 4.3. Entity Category Support Example . . . . . . . . . . . . . 7
65 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
66 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
67 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
68 7.1. Normative References . . . . . . . . . . . . . . . . . . 9
69 7.2. Informative References . . . . . . . . . . . . . . . . . 10
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-04 . . . . . . . . . . 11
74 B.2. Since draft-young-entity-category-03 . . . . . . . . . . 11
75 B.3. Since draft-young-entity-category-02 . . . . . . . . . . 11
76 B.4. Since draft-young-entity-category-01 . . . . . . . . . . 12
77 B.5. Since draft-young-entity-category-00 . . . . . . . . . . 12
78 B.6. Since draft-macedir-entity-category . . . . . . . . . . . 13
79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
81 1. Introduction
83 This document describes a SAML attribute, referred to here as the
84 "entity category attribute", values of which represent entity types
85 or categories. When used with the SAML V2.0 Metadata Extension for
86 Entity Attributes [SAML2MetadataAttr] each such entity category
87 attribute value represents a claim that the entity thus labelled
88 meets the requirements of, and is asserted to be a member of, the
89 indicated category.
91 These category membership claims MAY be used by a relying party to
92 provision policy for release of attributes from an identity provider,
93 to influence user interface decisions such as those related to
94 identity provider discovery, or for any other purpose. In general,
95 the intended uses of any claim of membership in a given category will
96 depend on the details of the category's definition, and will often be
97 included as part of that definition.
99 Entity category attribute values are URIs, and this document does not
100 specify a controlled vocabulary. Category URIs may therefore be
101 defined by any appropriate authority without any requirement for
102 central registration. It is anticipated that other specifications
103 may provide management and discovery mechanisms for entity category
104 attribute values.
106 A second SAML attribute, referred to here as the "entity category
107 support attribute", contains URI values which represent claims that
108 an entity supports and/or interoperates with entities in a given
109 category or categories. These values, defined in conjunction with
110 specific entity category values, provide entities in a category with
111 the means to identify peer entities that wish to interact with them
112 in category-specific fashion.
114 This document does not specify any values either for the entity
115 category attribute or for the entity category support attribute.
117 1.1. REFEDS Document Process
119 The Research and Education Federations group ([REFEDS]) is the voice
120 that articulates the mutual needs of research and education identity
121 federations worldwide. It aims to represent the requirements of
122 research and education in the ever-growing space of access and
123 identity management.
125 From time to time REFEDS will wish to publish a document in the
126 Internet RFC series. Such documents will be published as part of the
127 RFC Independent Submission Stream [RFC4844]; however the REFEDS
128 working group sign-off process will have been followed for these
129 documents, as described in the REFEDS Participant's Agreement
130 [REFEDS.agreement].
132 This document is a product of the REFEDS Working Group process.
134 2. Notation and Conventions
136 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
137 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
138 document are to be interpreted as described in RFC 2119 [BCP14].
140 3. Entity Category Attribute
142 3.1. Syntax
144 Entity category attribute values MUST be URIs. It is RECOMMENDED
145 that http:-scheme or https:-scheme URLs are used, and further
146 RECOMMENDED that each such value resolves to a human-readable
147 document defining the category.
149 The entity category attribute MUST be encoded as a SAML 2.0 Attribute
150 element with @NameFormat urn:oasis:names:tc:SAML:2.0:attrname-
151 format:uri and @Name http://macedir.org/entity-category.
153 A SAML entity is associated with one or more categories by including
154 the Attribute element described here in the entity's metadata through
155 use of the [SAML2MetadataAttr] metadata extension, in which the
156 Attribute element is contained within an mdattr:EntityAttributes
157 element directly contained within an md:Extensions element directly
158 contained within the entity's md:EntityDescriptor.
160 The meaning of the entity category attribute is undefined by this
161 specification if it appears anywhere else within a metadata instance,
162 or within any other XML document.
164 If the entity category attribute Attribute element appears more than
165 once in the metadata for an entity, the combined set of associated
166 attribute values SHOULD be interpreted by relying parties as if they
167 all appeared within a single Attribute element.
169 3.2. Semantics
171 The presence of the entity category attribute within an entity's
172 entity attributes represents a series of claims (one for each
173 attribute value) that the entity is a member of each named category.
174 The precise semantics of such a claim depend on the definition of the
175 category itself.
177 An entity may be claimed to be a member of more than one category.
178 In this case, the entity is claimed to meet the requirements of each
179 category independently unless otherwise specified by the category
180 definitions themselves.
182 The definition of the concept of a category is intentionally not
183 addressed in this document, in order to leave it as general as
184 possible. However, to be useful, category definitions SHOULD include
185 the following as appropriate:
187 o A definition of the authorities who may validly assert membership
188 in the category. While membership in some categories may be self-
189 asserted informally by an entity's owner, others may need to be
190 validated by third parties such as the entity's home federation or
191 other registrar.
193 o A set of criteria by which an entity's membership in the category
194 can be objectively assessed.
196 o A definition of the processes by which valid authorities may
197 determine that an entity meets the category's membership criteria.
199 o A description of the anticipated uses for category membership by
200 relying parties.
202 o A statement indicating the applicability or otherwise of
203 membership of the entity category to different SAML role
204 descriptors, and any protocol support restrictions that may be
205 relevant.
207 Entity categories SHOULD NOT be used to indicate the certification
208 status of an entity regarding its conformance to the requirements of
209 an identity assurance framework. The [SAML2IDAssuranceProfile]
210 extension SHOULD be used for this purpose.
212 If significant changes are made to a category definition, the new
213 version of the category SHOULD be represented by a different category
214 URI so that the old and new versions can be distinguished by a
215 relying party.
217 No ordering relation is defined over entity category value URIs.
218 Entity category attribute value URIs MUST be treated as opaque
219 strings for the purpose of comparison.
221 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
308
310
311
313
316 http://example.org/category/dog/basic
318 http://example.org/category/dog/advanced
320 urn:oid:1.3.6.1.4.1.21829
321
322
323
324 ...
325
327 5. IANA Considerations
329 This memo includes no request to IANA.
331 6. Security Considerations
333 The presence of the entity category attribute within an entity's
334 entity attributes represents a series of claims (one for each
335 attribute value) that the entity is a member of the named categories.
336 Before accepting and acting on such claims, any relying party needs
337 to establish, at a level of assurance sufficient for the intended
338 use, a chain of trust concluding that the claim is justified.
340 Some of the elements in such a chain of trust might include:
342 o The integrity of the metadata delivered to the relying party, as
343 for example assured by a digital signature.
345 o If the entity category attribute is carried within a signed
346 assertion, the assertion itself must be evaluated.
348 o The policies and procedures of the immediate source of the
349 metadata; in particular, any procedures the immediate source has
350 with regard to aggregation of metadata from other sources.
352 o The policies and procedures implemented by agents along the
353 publication path from the original metadata registrar: this may be
354 determined either by examination of the published procedures of
355 each agent in turn, or may be simplified if the entity metadata
356 includes publication path metadata in mdrpi:PublicationPath
357 elements as described in [SAML2MetadataRPI] section 2.3.1.
359 o The policies and procedures implemented by the original metadata
360 registrar. The registrar's identity may be known implicitly, or
361 may be determined from the entity metadata if it includes an
362 mdrpi:RegistrationInfo element and corresponding
363 @registrationAuthority attribute as described in
364 [SAML2MetadataRPI] section 2.1.1.
366 o The definition of the category itself; in particular, any
367 statements it makes about whether membership of the category may
368 be self-asserted, or may only be asserted by particular
369 authorities.
371 Although entity category support attribute values will often be
372 defined as self-asserted claims by the containing entity, the
373 provenance of the metadata remains relevant to a relying party's
374 decision to accept a claim of support as legitimate, and the specific
375 definition of a support claim will influence the assurance required
376 to act on it.
378 The conclusion that a claim of category membership or support is
379 justified and should be acted upon may require a determination of the
380 origin of the claim. This may not be necessary if the immediate
381 source of the metadata is trusted to such an extent that the trust
382 calculation is essentially delegated to it.
384 In many cases, a claim will be included in an entity's metadata by
385 the original metadata registrar on behalf of the entity's owner, and
386 the mdrpi:RegistrationInfo element's @registrationAuthority attribute
387 is available to carry the registrar's identity. However, any agent
388 that is part of the chain of custody between the original registrar
389 and the final relying party may have added, removed or transformed
390 claims according to local policy. For example, an agent charged with
391 redistributing metadata may remove claims it regards as
392 untrustworthy, or add others which were not already present if they
393 have value to its intended audience.
395 7. References
397 7.1. Normative References
399 [BCP14] Bradner, S., "Key words for use in RFCs to Indicate
400 Requirement Levels", BCP 14, RFC 2119, March 1997.
402 [SAML2MetadataAttr]
403 Cantor, S., Ed., "SAML V2.0 Metadata Extension for Entity
404 Attributes", August 2009,
405 .
407 [SAML2MetadataRPI]
408 La Joie, C., Ed., "SAML V2.0 Metadata Extensions for
409 Registration and Publication Information Version 1.0",
410 April 2012,
411 .
413 7.2. Informative References
415 [REFEDS] Research and Education Federations, "REFEDS Home Page",
416 .
418 [REFEDS.agreement]
419 Research and Education Federations, "REFEDS Participant's
420 Agreement", .
423 [RFC4844] Daigle, L. and Internet Architecture Board, "The RFC
424 Series and RFC Editor", RFC 4844, July 2007.
426 [SAML2IDAssuranceProfile]
427 Morgan, RL., Ed., Madsen, P., Ed., and S. Cantor, Ed.,
428 "SAML V2.0 Identity Assurance Profiles Version 1.0",
429 November 2010, .
432 Appendix A. Acknowledgements
434 This work has been a collaborative effort within the REFEDS and MACE-
435 Dir communities. Special thanks to (in no particular order):
437 o RL 'Bob' Morgan
439 o Ken Klingenstein
441 o Keith Hazelton
443 o Steven Olshansky
445 o Mikael Linden
447 o Nicole Harris
449 o Tom Scavo
451 Appendix B. Change Log (to be removed by RFC Editor before publication)
453 B.1. Since draft-young-entity-category-04
455 No substantive changes.
457 B.2. Since draft-young-entity-category-03
459 Additional improvements in response to IETF Gen-Art review:
461 o Section 3.2: additional SHOULD language recommending that category
462 definitions include applicability information for particular SAML
463 role descriptors.
465 o Section 3.2: added an informative reference to
466 [SAML2IDAssuranceProfile] and language recommending its use over
467 entity categories where appropriate.
469 B.3. Since draft-young-entity-category-02
471 Fix link to the REFEDS Participant's Agreement [REFEDS.agreement].
473 Clarifications in response to IETF Gen-Art review:
475 o Section 1: make explicit the fact that we don't specify any values
476 of either attribute in this document.
478 o Section 3.1, Section 4.1: clarify that it is possible for
479 attribute values to appear within multiple Attribute elements, and
480 that this SHOULD be regarded as equivalent to combining them
481 within a single Attribute element.
483 o Section 3.2, Section 4.2: clarify the expectation that categories
484 are independent unless their definitions say otherwise.
486 o Section 3.2, Section 4.2: If significant changes are made to a
487 category definition, the new version of the category SHOULD be
488 represented by a different category URI *so that the old and new
489 versions can be distinguished by a relying party*.
491 o Section 3.2, Section 4.2: *No ordering relation is defined over
492 entity category value URIs.* Entity category attribute value URIs
493 MUST be treated as opaque strings *for the purpose of comparison*.
495 B.4. Since draft-young-entity-category-01
497 Changes from REFEDS consultation process:
499 1. Simplify title from "The Entity Category SAML Entity Metadata
500 Attribute Types" to "The Entity Category SAML Attribute Types".
502 2. Clarify the use of [SAML2MetadataRPI] in Section 6 by indicating
503 the elements and attributes to be used, and the sections of
504 [SAML2MetadataRPI] in which they are defined.
506 3. Remove any implication that category and category support claims
507 are necessarily being made "by" the entity itself.
509 4. Clarify that the origin of a category membership or support claim
510 may not always be the original registrar.
512 Grammar fix in Abstract.
514 Change the reference anchor for the SAML [SAML2MetadataRPI]
515 extension, as it now more commonly known as RPI than its original DRI
516 abbreviation.
518 B.5. Since draft-young-entity-category-00
520 Update affiliations for Leif Johansson and Scott Cantor.
522 Remove authors from acknowledgements.
524 Reorganize some of the introductory boilerplate sections.
526 B.6. Since draft-macedir-entity-category
528 Adopted as base for draft-young-entity-category-00.
530 Changed ipr from "pre5378Trust200902" to "trust200902" and submission
531 type from IETF to independent.
533 Designate Ian Young as editor for this version. Set more general
534 affiliation.
536 Modernised reference to RFC 2119 [BCP14] and moved that reference to
537 the introduction.
539 Adjusted layout of examples so that they don't exceed the RFC
540 standard line length.
542 Minor typographical nits but (intentionally) no substantive content
543 changes.
545 Authors' Addresses
547 Ian A. Young (editor)
548 Independent
550 EMail: ian@iay.org.uk
552 Leif Johansson
553 SUNET
555 EMail: leifj@sunet.se
557 Scott Cantor
558 Shibboleth Consortium
560 EMail: cantor.2@osu.edu