Internet DRAFT - draft-ietf-ace-aif
draft-ietf-ace-aif
ACE Working Group C. Bormann
Internet-Draft Universität Bremen TZI
Intended status: Standards Track 15 March 2022
Expires: 16 September 2022
An Authorization Information Format (AIF) for ACE
draft-ietf-ace-aif-07
Abstract
Information about which entities are authorized to perform what
operations on which constituents of other entities is a crucial
component of producing an overall system that is secure. Conveying
precise authorization information is especially critical in highly
automated systems with large numbers of entities, such as the
"Internet of Things".
This specification provides a generic information model and format
for representing such authorization information, as well as two
variants of a specific instantiation of that format for use with REST
resources identified by URI path.
About This Document
This note is to be removed before publishing as an RFC.
Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-ietf-ace-aif/.
Discussion of this document takes place on the Authentication and
Authorization for Constrained Environments (ace) Working Group
mailing list (mailto:ace@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/ace/.
Source for this draft and an issue tracker can be found at
https://github.com/cabo/ace-aif.
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 https://datatracker.ietf.org/drafts/current/.
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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 16 September 2022.
Copyright Notice
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document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Information Model . . . . . . . . . . . . . . . . . . . . . . 3
2.1. REST-specific Model . . . . . . . . . . . . . . . . . . . 4
2.2. Limitations . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. REST-specific Model With Dynamic Resource Creation . . . 6
3. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Media Types . . . . . . . . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
5.1. Media Types . . . . . . . . . . . . . . . . . . . . . . . 9
5.2. Registries . . . . . . . . . . . . . . . . . . . . . . . 11
5.3. Content-Format . . . . . . . . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1. Normative References . . . . . . . . . . . . . . . . . . 13
7.2. Informative References . . . . . . . . . . . . . . . . . 14
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 16
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
Constrained Devices as they are used in the "Internet of Things" need
security in order to operate correctly and prevent misuse. One
important element of this security is that devices in the Internet of
Things need to be able to decide which operations requested of them
should be considered authorized, need to ascertain that the
authorization to request the operation does apply to the actual
requester as authenticated, and need to ascertain that other devices
they make requests of are the ones they intended.
To transfer detailed authorization information from an authorization
manager (such as an ACE-OAuth Authorization Server
[I-D.ietf-ace-oauth-authz]) to a device, a compact representation
format is needed. This document defines such a format, the
Authorization Information Format (AIF). AIF is defined both as a
general structure that can be used for many different applications
and as a specific instantiation tailored to REST resources and the
permissions on them, including some provision for dynamically created
resources.
1.1. Terminology
This memo uses terms from CoAP [RFC7252] and the Internet Security
Glossary [RFC4949]; CoAP is used for the explanatory examples as it
is a good fit for Constrained Devices.
The shape of data is specified in CDDL [RFC8610] [RFC9165].
Terminology for Constrained Devices is defined in [RFC7228].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The term "byte", abbreviated by "B", is used in its now customary
sense as a synonym for "octet".
2. Information Model
Authorizations are generally expressed through some data structures
that are cryptographically secured (or transmitted in a secure way).
This section discusses the information model underlying the payload
of that data (as opposed to the cryptographic armor around it).
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The semantics of the authorization information defined in this
document are that of an _allow-list_: everything is denied until it
is explicitly allowed.
For the purposes of this specification, the underlying access control
model will be that of an access matrix, which gives a set of
permissions for each possible combination of a subject and an object.
We are focusing the AIF data item on a single row in the access
matrix (such a row has often been called a capability list), without
concern to the subject for which the data item is issued. As a
consequence, AIF MUST be used in a way that the subject of the
authorizations is unambiguously identified (e.g., as part of the
armor around it).
The generic model of such a capability list is a list of pairs of
object identifiers (of type Toid) and the permissions (of type Tperm)
the subject has on the object(s) identified.
AIF-Generic<Toid, Tperm> = [* [Toid, Tperm]]
Figure 1: Definition of Generic AIF
In a specific data model (such as the one also specified in this
document), the object identifier (Toid) will often be a text string,
and the set of permissions (Tperm) will be represented by a bitset in
turn represented as a number (see Section 3).
AIF-Specific = AIF-Generic<tstr, uint>
Figure 2: Commonly used shape of a specific AIF
2.1. REST-specific Model
In the specific instantiation of the REST resources and the
permissions on them, for the object identifiers (Toid), we use the
URI of a resource on a CoAP server. More specifically, since the
parts of the URI that identify the server ("authority" in [RFC3986])
are what are authenticated during REST resource access (Section 4.2.2
of [I-D.ietf-httpbis-semantics] and Section 6.2 of [RFC7252]), they
naturally fall into the realm handled by the cryptographic armor; we
therefore focus on the "path" ("path-abempty") and "query" parts of
the URI (_URI-local-part_ in this specification, as expressed by the
Uri-Path and Uri-Query options in CoAP). As a consequence, AIF MUST
be used in a way that it is clear who is the target (enforcement
point) of these authorizations (note that there may be more than one
target that the same authorization applies to, e.g., in a situation
with homogeneous devices).
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For the permissions (Tperm), we use a simple permissions model that
lists the subset of the REST (CoAP or HTTP) methods permitted. This
model is summarized in Table 1.
+================+================+
| URI-local-part | Permission Set |
+================+================+
| /s/temp | GET |
+----------------+----------------+
| /a/led | PUT, GET |
+----------------+----------------+
| /dtls | POST |
+----------------+----------------+
Table 1: An authorization
instance in the AIF Information
Model
In this example, a device offers a temperature sensor /s/temp for
read-only access, a LED actuator /a/led for read/write, and a /dtls
resource for POST access.
As will be seen in the data model (Section 3), the representations of
REST methods provided are limited to those that have a CoAP method
number assigned; an extension to the model may be necessary to
represent permissions for exotic HTTP methods.
2.2. Limitations
This simple information model only allows granting permissions for
statically identifiable objects, e.g., URIs for the REST-specific
instantiation. One might be tempted to extend the model towards URI
templates [RFC6570] (for instance, to open up an authorization for
many parameter values as in /s/temp{?any*}). However, that requires
some considerations of the ease and unambiguity of matching a given
URI against a set of templates in an AIF data item.
This simple information model also does not allow expressing
conditionalized access based on state outside the identification of
objects (e.g., "opening a door is allowed if that is not locked").
Finally, the model does not provide any special access for a set of
resources that are specific to a subject, e.g., that the subject
created itself by previous operations (PUT, POST, or PATCH/iPATCH
[RFC8132]) or that were specifically created for the subject by
others.
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2.3. REST-specific Model With Dynamic Resource Creation
The REST-specific Model With Dynamic Resource Creation addresses the
need to provide defined access to dynamic resources that were created
by the subject itself, specifically, a resource that is made known to
the subject by providing Location-* options in a CoAP response or
using the Location header field in HTTP [I-D.ietf-httpbis-semantics]
(the Location-indicating mechanisms). (The concept is somewhat
comparable to "ACL inheritance" in NFSv4 [RFC8881], except that it
does not use a containment relationship but the fact that the dynamic
resource was created from a resource to which the subject had
access.) In other words, it addresses an important subset of the
third limitation mentioned in Section 2.2.
+================+===================================+
| URI-local-part | Permission Set |
+================+===================================+
| /a/make-coffee | POST, Dynamic-GET, Dynamic-DELETE |
+----------------+-----------------------------------+
Table 2: An authorization instance in the AIF
Information Model With Dynamic Resource Creation
For a method X, the presence of a Dynamic-X permission means that the
subject holds permission to exercise the method X on resources that
have been returned in a 2.01 (201 Created) response by a Location-
indicating mechanism to a request that the subject made to the
resource listed. In the example shown in Table 2, POST operations on
/a/make-coffee might return the location of a resource dynamically
created on the coffee machine that allows GET to find out about the
status of, and DELETE to cancel, the coffee-making operation.
Since the use of the extension defined in this section can be
detected by the mentioning of the Dynamic-X permissions, there is no
need for another explicit switch between the basic and the model
extended by dynamic resource creation; the extended model is always
presumed once a Dynamic-X permission is present.
3. Data Model
Different data model specializations can be defined for the generic
information model given above.
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In this section, we will give the data model for simple REST
authorization as per Section 2.1 and Section 2.3. As discussed, in
this case the object identifier is specialized as a text string
giving a relative URI (URI-local-part as absolute path on the server
serving as enforcement point). The permission set is specialized to
a single number REST-method-set by the following steps:
* The entries in the table that specify the same URI-local-part are
merged into a single entry that specifies the union of the
permission sets.
* The (non-dynamic) methods in the permission sets are converted
into their CoAP method numbers, minus 1.
* Dynamic-X permissions are converted into what the number would
have been for X, plus a Dynamic-Offset chosen as 32 (e.g., 35 is
the number for Dynamic-DELETE as the number for DELETE is 3).
* The set of numbers is converted into a single number REST-method-
set by taking two to the power of each (decremented) method number
and computing the inclusive OR of the binary representations of
all the power values.
This data model could be interchanged in the JSON [RFC8259]
representation given in Figure 3.
[["/s/temp",1],["/a/led",5],["/dtls",2]]
Figure 3: An authorization instance encoded in JSON (40 bytes)
In Figure 4, a straightforward specification of the data model
(including both the methods from [RFC7252] and the new ones from
[RFC8132], identified by the method code minus 1) is shown in CDDL
[RFC8610] [RFC9165]:
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AIF-REST = AIF-Generic<local-path, REST-method-set>
local-path = tstr ; URI relative to enforcement point
REST-method-set = uint .bits methods
methods = &(
GET: 0
POST: 1
PUT: 2
DELETE: 3
FETCH: 4
PATCH: 5
iPATCH: 6
Dynamic-GET: 32; 0 .plus Dynamic-Offset
Dynamic-POST: 33; 1 .plus Dynamic-Offset
Dynamic-PUT: 34; 2 .plus Dynamic-Offset
Dynamic-DELETE: 35; 3 .plus Dynamic-Offset
Dynamic-FETCH: 36; 4 .plus Dynamic-Offset
Dynamic-PATCH: 37; 5 .plus Dynamic-Offset
Dynamic-iPATCH: 38; 6 .plus Dynamic-Offset
)
Figure 4: AIF in CDDL
For the information shown in Table 1 and Figure 3, a representation
in CBOR [RFC8949] is given in Figure 5; again, several optimizations/
improvements are possible.
83 # array(3)
82 # array(2)
67 # text(7)
2f732f74656d70 # "/s/temp"
01 # unsigned(1)
82 # array(2)
66 # text(6)
2f612f6c6564 # "/a/led"
05 # unsigned(5)
82 # array(2)
65 # text(5)
2f64746c73 # "/dtls"
02 # unsigned(2)
Figure 5: An authorization instance encoded in CBOR (28 bytes)
Note that choosing 32 as Dynamic-Offset means that all future CoAP
methods that can be registered can be represented both as themselves
and in the Dynamic-X variant, but only the dynamic forms of methods 1
to 21 are typically usable in a JSON form [RFC7493].
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4. Media Types
This specification defines media types for the generic information
model, expressed in JSON (application/aif+json) or in CBOR
(application/aif+cbor). These media types have parameters for
specifying Toid and Tperm; default values are the values "URI-local-
part" for Toid and "REST-method-set" for Tperm, as per Section 3 of
the present specification.
A specification that wants to use Generic AIF with different Toid
and/or Tperm is expected to request these as media type parameters
(Section 5.2) and register a corresponding Content-Format
(Section 5.3).
5. IANA Considerations
// RFC Ed.: throughout this section, please replace RFC XXXX with the
// RFC number of this specification and remove this note.
5.1. Media Types
IANA is requested to add the following Media-Types to the "Media
Types" registry.
+==========+======================+=====================+
| Name | Template | Reference |
+==========+======================+=====================+
| aif+cbor | application/aif+cbor | RFC XXXX, Section 4 |
+----------+----------------------+---------------------+
| aif+json | application/aif+json | RFC XXXX, Section 4 |
+----------+----------------------+---------------------+
Table 3: New Media Types
For application/aif+cbor:
Type name: application
Subtype name: aif+cbor
Required parameters: N/A
Optional parameters:
* Toid: the identifier for the object for which permissions are
supplied. A value from the media-type parameter sub-registry
for Toid. Default value: "URI-local-part" (RFC XXXX).
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* Tperm: the data type of a permission set for the object
identified via a Toid. A value from the media-type parameter
sub-registry for Tperm. Default value: "REST-method-set" (RFC
XXXX).
Encoding considerations: binary (CBOR)
Security considerations: Section 6 of RFC XXXX
Interoperability considerations: none
Published specification: Section 4 of RFC XXXX
Applications that use this media type: Applications that need to
convey structured authorization data for identified resources,
conveying sets of permissions.
Fragment identifier considerations: The syntax and semantics of
fragment identifiers is as specified for "application/cbor". (At
publication of RFC XXXX, there is no fragment identification
syntax defined for "application/cbor".)
Person & email address to contact for further information: ACE WG
mailing list (ace@ietf.org), or IETF Applications and Real-Time
Area (art@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration: no
For application/aif+json:
Type name: application
Subtype name: aif+json
Required parameters: N/A
Optional parameters:
* Toid: the identifier for the object for which permissions are
supplied. A value from the media-type parameter sub-registry
for Toid. Default value: "URI-local-part" (RFC XXXX).
* Tperm: the data type of a permission set for the object
identified via a Toid. A value from the media-type parameter
sub-registry for Tperm. Default value: "REST-method-set" (RFC
XXXX).
Encoding considerations: binary (JSON is UTF-8-encoded text)
Security considerations: Section 6 of RFC XXXX
Interoperability considerations: none
Published specification: Section 4 of RFC XXXX
Applications that use this media type: Applications that need to
convey structured authorization data for identified resources,
conveying sets of permissions.
Fragment identifier considerations: The syntax and semantics of
fragment identifiers is as specified for "application/json". (At
publication of RFC XXXX, there is no fragment identification
syntax defined for "application/json".)
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Person & email address to contact for further information: ACE WG
mailing list (ace@ietf.org), or IETF Applications and Real-Time
Area (art@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration: no
5.2. Registries
For the media types application/aif+cbor and application/aif+json,
IANA is requested to create a sub-registry within
[IANA.media-type-sub-parameters] for the two media-type parameters
Toid and Tperm, populated with:
+===========+=================+=====================+===========+
| Parameter | name | Description/ | Reference |
| | | Specification | |
+===========+=================+=====================+===========+
| Toid | URI-local-part | local-part of URI | RFC XXXX |
+-----------+-----------------+---------------------+-----------+
| Tperm | REST-method-set | set of REST methods | RFC XXXX |
| | | represented | |
+-----------+-----------------+---------------------+-----------+
Table 4: New Media Type Parameters
The registration policy is Specification required [RFC8126]. The
designated expert will engage with the submitter to ascertain the
requirements of this document are addressed:
* The specifications for Toid and Tperm need to realize the general
ideas of unambiguous object identifiers and permission lists in
the context where the AIF data item is intended to be used, and
their structure needs to be usable with the intended media types
(application/aif+cbor and application/aif+json) as identified in
the specification.
* The parameter names need to conform to Section 4.3 of [RFC6838],
but preferably are in [KebabCase] so they can easily be translated
into names used in popular programming language APIs.
The designated experts will develop further criteria and guidelines
as needed.
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5.3. Content-Format
IANA is requested to register Content-Format numbers in the "CoAP
Content-Formats" sub-registry, within the "Constrained RESTful
Environments (CoRE) Parameters" Registry [IANA.core-parameters], as
follows:
+======================+================+======+===========+
| Content-Type | Content Coding | ID | Reference |
+======================+================+======+===========+
| application/aif+cbor | - | TBD1 | RFC XXXX |
+----------------------+----------------+------+-----------+
| application/aif+json | - | TBD2 | RFC XXXX |
+----------------------+----------------+------+-----------+
Table 5: New Content-Formats
// RFC Ed.: please replace TBD1 and TBD2 with assigned IDs and remove
this note.
In the registry as defined by Section 12.3 of [RFC7252] at the time
of writing, the column "Content-Type" is called "Media type" and the
column "Content Coding" is called "Encoding".
Note that applications that register Toid and Tperm values are
encouraged to also register Content-Formats for the relevant
combinations.
6. Security Considerations
The security considerations of [RFC7252] apply when AIF is used with
CoAP, and, if complex formats such as URIs are used for Toid or
Tperm, specifically Section 11.1 of [RFC7252]. Some wider issues are
discussed in [RFC8576].
When applying these formats, the referencing specification needs to
be careful to:
* ensure that the cryptographic armor employed around this format
fulfills the referencing specification's security objectives, and
that the armor or some additional information included in it with
the AIF data item (1) unambiguously identifies the subject to
which the authorizations shall apply and (2) provides any context
information needed to derive the identity of the object to which
authorization is being granted from the object identifiers (such
as, for the data models defined in the present specification, the
scheme and authority information that is used to construct the
full URI), and
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* ensure that the types used for Toid and Tperm provide the
appropriate granularity and precision so that application
requirements on the precision of the authorization information are
fulfilled, and that all parties have the same understanding of
each Toid/Tperm pair in terms of specified objects (resources) and
operations on those.
For the data formats, the security considerations of [RFC8259] and
[RFC8949] apply.
A plain implementation of AIF might implement just the basic REST
model as per Section 2.1. If it receives authorizations that include
permissions that use the REST-specific Model With Dynamic Resource
Creation Section 2.3, it needs to either reject the AIF data item
entirely or act only on the permissions that it does understand. In
other words, the semantics underlying an allow-list as discussed
above need to hold here as well.
An implementation of the REST-specific Model With Dynamic Resource
Creation Section 2.3 needs to carefully keep track of the dynamically
created objects and the subjects to which the Dynamic-X permissions
apply -- both on the server side to enforce the permissions and on
the client side to know which permissions are available.
7. References
7.1. Normative References
[I-D.ietf-httpbis-semantics]
Fielding, R. T., Nottingham, M., and J. Reschke, "HTTP
Semantics", Work in Progress, Internet-Draft, draft-ietf-
httpbis-semantics-19, 12 September 2021,
<https://www.ietf.org/archive/id/draft-ietf-httpbis-
semantics-19.txt>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
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[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/info/rfc7252>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[RFC9165] Bormann, C., "Additional Control Operators for the Concise
Data Definition Language (CDDL)", RFC 9165,
DOI 10.17487/RFC9165, December 2021,
<https://www.rfc-editor.org/info/rfc9165>.
7.2. Informative References
[I-D.ietf-ace-oauth-authz]
Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
H. Tschofenig, "Authentication and Authorization for
Constrained Environments (ACE) using the OAuth 2.0
Framework (ACE-OAuth)", Work in Progress, Internet-Draft,
draft-ietf-ace-oauth-authz-46, 8 November 2021,
<https://www.ietf.org/archive/id/draft-ietf-ace-oauth-
authz-46.txt>.
[IANA.core-parameters]
IANA, "Constrained RESTful Environments (CoRE)
Parameters",
<https://www.iana.org/assignments/core-parameters>.
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[IANA.media-type-sub-parameters]
IANA, "MIME Media Type Sub-Parameter Registries",
<https://www.iana.org/assignments/media-type-sub-
parameters>.
[KebabCase]
"KebabCase", 29 August 2014,
<http://wiki.c2.com/?KebabCase>.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
<https://www.rfc-editor.org/info/rfc4949>.
[RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
and D. Orchard, "URI Template", RFC 6570,
DOI 10.17487/RFC6570, March 2012,
<https://www.rfc-editor.org/info/rfc6570>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>.
[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,
DOI 10.17487/RFC7493, March 2015,
<https://www.rfc-editor.org/info/rfc7493>.
[RFC8132] van der Stok, P., Bormann, C., and A. Sehgal, "PATCH and
FETCH Methods for the Constrained Application Protocol
(CoAP)", RFC 8132, DOI 10.17487/RFC8132, April 2017,
<https://www.rfc-editor.org/info/rfc8132>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
[RFC8576] Garcia-Morchon, O., Kumar, S., and M. Sethi, "Internet of
Things (IoT) Security: State of the Art and Challenges",
RFC 8576, DOI 10.17487/RFC8576, April 2019,
<https://www.rfc-editor.org/info/rfc8576>.
[RFC8881] Noveck, D., Ed. and C. Lever, "Network File System (NFS)
Version 4 Minor Version 1 Protocol", RFC 8881,
DOI 10.17487/RFC8881, August 2020,
<https://www.rfc-editor.org/info/rfc8881>.
Bormann Expires 16 September 2022 [Page 15]
Internet-Draft ACE AIF March 2022
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/info/rfc8949>.
Acknowledgements
Jim Schaad, Francesca Palombini, Olaf Bergmann, Marco Tiloca, and
Christian Amsüss provided comments that shaped the direction of this
document. Alexey Melnikov pointed out that there were gaps in the
media type specifications, and Loganaden Velvindron provided a
shepherd review with further comments. Many thanks also to the IESG
reviewers, which provided several small but significant observations.
Benjamin Kaduk provided an extensive review as responsible Area
Director, and indeed is responsible for much improvement in the
document.
Author's Address
Carsten Bormann
Universität Bremen TZI
Postfach 330440
D-28359 Bremen
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
Bormann Expires 16 September 2022 [Page 16]
