ACE Working Group M. Tiloca Internet-Draft R. Hoeglund Intended status: Standards Track RISE AB Expires: August 26, 2021 P. van der Stok Consultant F. Palombini K. Hartke Ericsson AB February 22, 2021 Admin Interface for the OSCORE Group Manager draft-ietf-ace-oscore-gm-admin-02 Abstract Group communication for CoAP can be secured using Group Object Security for Constrained RESTful Environments (Group OSCORE). A Group Manager is responsible to handle the joining of new group members, as well as to manage and distribute the group key material. This document defines a RESTful admin interface at the Group Manager, that allows an Administrator entity to create and delete OSCORE groups, as well as to retrieve and update their configuration. The ACE framework for Authentication and Authorization is used to enforce authentication and authorization of the Administrator at the Group Manager. Protocol-specific transport profiles of ACE are used to achieve communication security, proof-of-possession and server authentication. 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/. 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 August 26, 2021. Tiloca, et al. Expires August 26, 2021 [Page 1] Internet-Draft Admin Interface for the OSCORE GM February 2021 Copyright Notice Copyright (c) 2021 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 (https://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 described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2. Group Administration . . . . . . . . . . . . . . . . . . . . 6 2.1. Getting Access to the Group Manager . . . . . . . . . . . 7 2.1.1. Format of Scope . . . . . . . . . . . . . . . . . . . 8 2.2. Managing OSCORE Groups . . . . . . . . . . . . . . . . . 9 2.3. Collection Representation . . . . . . . . . . . . . . . . 10 2.4. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 10 3. Group Configurations . . . . . . . . . . . . . . . . . . . . 10 3.1. Group Configuration Representation . . . . . . . . . . . 10 3.1.1. Configuration Properties . . . . . . . . . . . . . . 10 3.1.2. Status Properties . . . . . . . . . . . . . . . . . . 12 3.2. Default Values . . . . . . . . . . . . . . . . . . . . . 13 3.2.1. Configuration Parameters . . . . . . . . . . . . . . 13 3.2.2. Status Parameters . . . . . . . . . . . . . . . . . . 14 4. Interactions with the Group Manager . . . . . . . . . . . . . 14 4.1. Retrieve the Full List of Groups Configurations . . . . . 14 4.2. Retrieve a List of Group Configurations by Filters . . . 15 4.3. Create a New Group Configuration . . . . . . . . . . . . 16 4.4. Retrieve a Group Configuration . . . . . . . . . . . . . 21 4.5. Retrieve Part of a Group Configuration by Filters . . . . 23 4.6. Overwrite a Group Configuration . . . . . . . . . . . . . 25 4.6.1. Effects on Joining Nodes . . . . . . . . . . . . . . 27 4.6.2. Effects on the Group Members . . . . . . . . . . . . 28 4.7. Selective Update of a Group Configuration . . . . . . . . 29 4.7.1. Effects on Joining Nodes . . . . . . . . . . . . . . 34 4.7.2. Effects on the Group Members . . . . . . . . . . . . 34 4.8. Delete a Group Configuration . . . . . . . . . . . . . . 34 4.8.1. Effects on the Group Members . . . . . . . . . . . . 35 5. Security Considerations . . . . . . . . . . . . . . . . . . . 35 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36 Tiloca, et al. Expires August 26, 2021 [Page 2] Internet-Draft Admin Interface for the OSCORE GM February 2021 6.1. ACE Groupcomm Parameters Registry . . . . . . . . . . . . 36 6.2. Resource Types . . . . . . . . . . . . . . . . . . . . . 38 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.1. Normative References . . . . . . . . . . . . . . . . . . 38 7.2. Informative References . . . . . . . . . . . . . . . . . 40 Appendix A. Document Updates . . . . . . . . . . . . . . . . . . 41 A.1. Version -01 to -02 . . . . . . . . . . . . . . . . . . . 41 A.2. Version -00 to -01 . . . . . . . . . . . . . . . . . . . 42 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 42 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42 1. Introduction The Constrained Application Protocol (CoAP) [RFC7252] can be used in group communication environments where messages are also exchanged over IP multicast [I-D.ietf-core-groupcomm-bis]. Applications relying on CoAP can achieve end-to-end security at the application layer by using Object Security for Constrained RESTful Environments (OSCORE) [RFC8613], and especially Group OSCORE [I-D.ietf-core-oscore-groupcomm] in group communication scenarios. When group communication for CoAP is protected with Group OSCORE, nodes are required to explicitly join the correct OSCORE group. To this end, a joining node interacts with a Group Manager (GM) entity responsible for that group, and retrieves the required key material to securely communicate with other group members using Group OSCORE. The method in [I-D.ietf-ace-key-groupcomm-oscore] specifies how nodes can join an OSCORE group through the respective Group Manager. Such a method builds on the ACE framework for Authentication and Authorization [I-D.ietf-ace-oauth-authz], so ensuring a secure joining process as well as authentication and authorization of joining nodes (clients) at the Group Manager (resource server). In some deployments, the application running on the Group Manager may know when a new OSCORE group has to be created, as well as how it should be configured and later on updated or deleted, e.g. based on the current application state or on pre-installed policies. In this case, the Group Manager application can create and configure OSCORE groups when needed, by using a local application interface. However, this requires the Group Manager to be application-specific, which in turn leads to error prone deployments and is poorly flexible. In other deployments, a separate Administrator entity, such as a Commissioning Tool, is directly responsible for creating and configuring the OSCORE groups at a Group Manager, as well as for maintaining them during their whole lifetime until their deletion. Tiloca, et al. Expires August 26, 2021 [Page 3] Internet-Draft Admin Interface for the OSCORE GM February 2021 This allows the Group Manager to be agnostic of the specific applications using secure group communication. This document specifies a RESTful admin interface at the Group Manager, intended for an Administrator as a separate entity external to the Group Manager and its application. The interface allows the Administrator to create and delete OSCORE groups, as well as to configure and update their configuration. Interaction examples are provided, in Link Format [RFC6690] and CBOR [RFC8949], as well as in CoRAL [I-D.ietf-core-coral]. While all the CoRAL examples show the CoRAL textual serialization format, its binary serialization format is used on the wire. The ACE framework is used to ensure authentication and authorization of the Administrator (client) at the Group Manager (resource server). In order to achieve communication security, proof-of-possession and server authentication, the Administrator and the Group Manager leverage protocol-specific transport profiles of ACE, such as [I-D.ietf-ace-oscore-profile][I-D.ietf-ace-dtls-authorize]. These include also possible forthcoming transport profiles that comply with the requirements in Appendix C of [I-D.ietf-ace-oauth-authz]. 1.1. Terminology 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. Readers are expected to be familiar with the terms and concepts from the following specifications: o CBOR [RFC8949] and COSE [I-D.ietf-cose-rfc8152bis-struct][I-D.ietf-cose-rfc8152bis-algs]. o The CoAP protocol [RFC7252], also in group communication scenarios [I-D.ietf-core-groupcomm-bis]. These include the concepts of: * "application group", as a set of CoAP nodes that share a common set of resources; and of * "security group", as a set of CoAP nodes that share the same security material, and use it to protect and verify exchanged messages. Tiloca, et al. Expires August 26, 2021 [Page 4] Internet-Draft Admin Interface for the OSCORE GM February 2021 o The OSCORE [RFC8613] and Group OSCORE [I-D.ietf-core-oscore-groupcomm] security protocols. These include the concept of Group Manager, as the entity responsible for a set of OSCORE groups where communications among members are secured using Group OSCORE. An OSCORE group is used as security group for one or many application groups. o The ACE framework for authentication and authorization [I-D.ietf-ace-oauth-authz]. The terminology for entities in the considered architecture is defined in OAuth 2.0 [RFC6749]. In particular, this includes Client (C), Resource Server (RS), and Authorization Server (AS). o The management of keying material for groups in ACE [I-D.ietf-ace-key-groupcomm] and specifically for OSCORE groups [I-D.ietf-ace-key-groupcomm-oscore]. These include the concept of group-membership resource hosted by the Group Manager, that new members access to join the OSCORE group, while current members can access to retrieve updated keying material. Note that, unless otherwise indicated, the term "endpoint" is used here following its OAuth definition, aimed at denoting resources such as /token and /introspect at the AS, and /authz-info at the RS. This document does not use the CoAP definition of "endpoint", which is "An entity participating in the CoAP protocol". This document also refers to the following terminology. o Administrator: entity responsible to create, configure and delete OSCORE groups at a Group Manager. o Group name: stable and invariant name of an OSCORE group. The group name MUST be unique under the same Group Manager, and MUST include only characters that are valid for a URI path segment. o Group-collection resource: a single-instance resource hosted by the Group Manager. An Administrator accesses a group-collection resource to create a new OSCORE group, or to retrieve the list of existing OSCORE groups, under that Group Manager. As an example, this document uses /manage as the url-path of the group-collection resource; implementations are not required to use this name, and can define their own instead. o Group-configuration resource: a resource hosted by the Group Manager, associated to an OSCORE group under that Group Manager. A group-configuration resource is identifiable with the invariant group name of the respective OSCORE group. An Administrator accesses a group-configuration resource to retrieve or update the Tiloca, et al. Expires August 26, 2021 [Page 5] Internet-Draft Admin Interface for the OSCORE GM February 2021 configuration of the respective OSCORE group, or to delete that group. The url-path to a group-configuration resource has GROUPNAME as last segment, with GROUPNAME the invariant group name assigned upon its creation. Building on the considered url-path of the group-collection resource, this document uses /manage/ GROUPNAME as the url-path of a group-configuration resource; implementations are not required to use this name, and can define their own instead. o Admin endpoint: an endpoint at the Group Manager associated to the group-collection resource or to a group-configuration resource hosted by that Group Manager. 2. Group Administration With reference to the ACE framework and the terminology defined in OAuth 2.0 [RFC6749]: o The Group Manager acts as Resource Server (RS). It provides one single group-collection resource, and one group-configuration resource per existing OSCORE group. Each of those is exported by a distinct admin endpoint. o The Administrator acts as Client (C), and requests to access the group-collection resource and group-configuration resources, by accessing the respective admin endpoint at the Group Manager. o The Authorization Server (AS) authorizes the Administrator to access the group-collection resource and group-configuration resources at a Group Manager. Multiple Group Managers can be associated to the same AS. The authorized access for an Administrator can be limited to performing only a subset of operations. The AS can authorize multiple Administrators to access the collection resource and the (same) group-configuration resources at the Group Manager. [ NOTE: This will be enabled by defining the format to use for the 'scope' claim in the Access Token, as encoding permitted actions on groups whose name matches with a name pattern. ] The AS MAY release Access Tokens to the Administrator for other purposes than accessing admin endpoints of registered Group Managers. Tiloca, et al. Expires August 26, 2021 [Page 6] Internet-Draft Admin Interface for the OSCORE GM February 2021 2.1. Getting Access to the Group Manager All communications between the involved entities rely on the CoAP protocol and MUST be secured. In particular, communications between the Administrator and the Group Manager leverage protocol-specific transport profiles of ACE to achieve communication security, proof-of-possession and server authentication. To this end, the AS may explicitly signal the specific transport profile to use, consistently with requirements and assumptions defined in the ACE framework [I-D.ietf-ace-oauth-authz]. With reference to the AS, communications between the Administrator and the AS (/token endpoint) as well as between the Group Manager and the AS (/introspect endpoint) can be secured by different means, for instance using DTLS [RFC6347][I-D.ietf-tls-dtls13] or OSCORE [RFC8613]. Further details on how the AS secures communications (with the Administrator and the Group Manager) depend on the specifically used transport profile of ACE, and are out of the scope of this specification. In order to get access to the Group Manager for managing OSCORE groups, an Administrator performs the following steps. The format and encoding of scope defined in Section 2.1.1 of this specification MUST be used, for both the 'scope' claim in the Access Token, as well as for the 'scope' parameter in the Authorization Request and Authorization Response exchanged with the AS (see Sections 5.8.1 and Section 5.8.2 [I-D.ietf-ace-oauth-authz]). 1. The Administrator requests an Access Token from the AS, in order to access the group-collection and group-configuration resources on the Group Manager. The Administrator will start or continue using secure communications with the Group Manager, according to the response from the AS. 2. The Administrator transfers authentication and authorization information to the Group Manager by posting the obtained Access Token, according to the used profile of ACE, such as [I-D.ietf-ace-dtls-authorize] and [I-D.ietf-ace-oscore-profile]. After that, the Administrator must have secure communication established with the Group Manager, before performing any admin operation on that Group Manager. Possible ways to provide secure communication are DTLS [RFC6347][I-D.ietf-tls-dtls13] and OSCORE [RFC8613]. The Administrator and the Group Manager maintain the secure association, to support possible future communications. Tiloca, et al. Expires August 26, 2021 [Page 7] Internet-Draft Admin Interface for the OSCORE GM February 2021 3. Consistently with what allowed by the authorization information in the Access Token, the Administrator performs admin operations at the Group Manager, as described in the following sections. These include the retrieval of the existing OSCORE groups, the creation of new OSCORE groups, the update and retrieval of OSCORE group configurations, and the removal of OSCORE groups. Messages exchanged among the Administrator and the Group Manager are specified in Section 4. 2.1.1. Format of Scope This section defines the exact format and encoding of scope to use, in order to express authorization information for the Administrator (see Section 2.1). TODO [ DESIGN CONSIDERATIONS o Define a new AIF specific data model, as loosely aligned with the data model AIF-OSCORE-GROUPCOMM defined in Section 3 [I-D.ietf-ace-key-groupcomm-oscore]. * The overall scope is an array of scope entries, each as a pair (Toid, Tperm). * Toid is a text string, i.e. a wildcard pattern against which group names can be matched. * Tperm is a set of specific permissions encoded as a bitmap, applied to groups whose name matches with the wildcard pattern. o A valid Access Token should always allow to at least retrieve the list of existing group configurations. o An Administrator authorized to create a group, should later be able to perform any possible operation on it. o An Administrator can be authorized to perform selected operations on a group earlier created by a different Administrator, still barring the group name matching with the wildcard pattern. ] Tiloca, et al. Expires August 26, 2021 [Page 8] Internet-Draft Admin Interface for the OSCORE GM February 2021 2.2. Managing OSCORE Groups Figure 1 shows the resources of a Group Manager available to an Administrator. ___ Group / \ Collection \___/ \ \____________________ \___ \___ \___ / \ / \ ... / \ Group \___/ \___/ \___/ Configurations Figure 1: Resources of a Group Manager The Group Manager exports a single group-collection resource, with resource type "core.osc.gcoll" defined in Section 6.2 of this specification. The interface for the group-collection resource defined in Section 4 allows the Administrator to: o Retrieve the complete list of existing OSCORE groups. o Retrieve a partial list of existing OSCORE groups, by applying filter criteria. o Create a new OSCORE group, specifying its invariant group name and, optionally, its configuration. The Group Manager exports one group-configuration resource for each of its OSCORE groups. Each group-configuration resource has resource type "core.osc.gconf" defined in Section 6.2 of this specification, and is identified by the group name specified upon creating the OSCORE group. The interface for a group-configuration resource defined in Section 4 allows the Administrator to: o Retrieve the complete current configuration of the OSCORE group. o Retrieve part of the current configuration of the OSCORE group, by applying filter criteria. o Overwrite the current configuration of the OSCORE group. o Selectively update only part of the current configuration of the OSCORE group. o Delete the OSCORE group. Tiloca, et al. Expires August 26, 2021 [Page 9] Internet-Draft Admin Interface for the OSCORE GM February 2021 2.3. Collection Representation A list of group configurations is represented as a document containing the corresponding group-configuration resources in the list. Each group-configuration is represented as a link, where the link target is the URI of the group-configuration resource. The list can be represented as a Link Format document [RFC6690] or a CoRAL document [I-D.ietf-core-coral]. In the former case, the link to each group-configuration resource specifies the link target attribute 'rt' (Resource Type), with value "core.osc.gconf" defined in Section 6.2 of this specification. In the latter case, the CoRAL document specifies the group- configuration resources in the list as top-level elements. In particular, the link to each group-configuration resource has http://coreapps.org/core.osc.gcoll#item as relation type. 2.4. Discovery The Administrator can discover the group-collection resource from a Resource Directory, for instance [I-D.ietf-core-resource-directory] and [I-D.hartke-t2trg-coral-reef], or from .well-known/core, by using the resource type "core.osc.gcoll" defined in Section 6.2 of this specification. The Administrator can discover group-configuration resources for the group-collection resource as specified in Section 4.1 and Section 4.2. 3. Group Configurations A group configuration consists of a set of parameters. 3.1. Group Configuration Representation The group configuration representation is a CBOR map which MUST include configuration properties and status properties. 3.1.1. Configuration Properties The CBOR map MUST include the following configuration parameters: o 'hkdf', defined in Section 6.1 of this document, specifies the HKDF algorithm used in the OSCORE group, encoded as a CBOR text string or a CBOR integer. Possible values are the same ones admitted for the 'hkdf' parameter of the "OSCORE Security Context Tiloca, et al. Expires August 26, 2021 [Page 10] Internet-Draft Admin Interface for the OSCORE GM February 2021 Parameters" registry, defined in Section 3.2.1 of [I-D.ietf-ace-oscore-profile]. o 'alg', defined in Section 6.1 of this document, specifies the AEAD algorithm used in the OSCORE group, encoded as a CBOR text string or a CBOR integer. Possible values are the same ones admitted for the 'alg' parameter of the "OSCORE Security Context Parameters" registry, defined in Section 3.2.1 of [I-D.ietf-ace-oscore-profile]. o 'cs_alg', defined in Section 6.1 of this document, specifies the countersignature algorithm used in the OSCORE group, encoded as a CBOR text string or a CBOR integer. Possible values are the same ones admitted for the 'cs_alg' parameter of the "OSCORE Security Context Parameters" registry, defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore]. o 'cs_params', defined in Section 6.1 of this document, specifies the additional parameters for the countersignature algorithm used in the OSCORE group, encoded as a CBOR array. Possible formats and values are the same ones admitted for the 'cs_params' parameter of the "OSCORE Security Context Parameters" registry, defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore]. o 'cs_key_params', defined in Section 6.1 of this document, specifies the additional parameters for the key used with the countersignature algorithm in the OSCORE group, encoded as a CBOR array. Possible formats and values are the same ones admitted for the 'cs_key_params' parameter of the "OSCORE Security Context Parameters" registry, defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore]. o 'cs_key_enc', defined in Section 6.1 of this document, specifies the encoding of the public keys of group members, encoded as a CBOR integer. Possible values are the same ones admitted for the 'cs_key_enc' parameter of the "OSCORE Security Context Parameters" registry, defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore]. o 'pairwise_mode', defined in Section 6.1 of this document and encoded as a CBOR simple value. Its value is True if the OSCORE group supports the pairwise mode of Group OSCORE [I-D.ietf-core-oscore-groupcomm], or False otherwise. o 'ecdh_alg', defined in Section 6.1 of this document and formatted as follows. If the configuration parameter 'pairwise_mode' has value False, this parameter has as value the CBOR simple value Null. Otherwise, this parameter specifies the ECDH algorithm used Tiloca, et al. Expires August 26, 2021 [Page 11] Internet-Draft Admin Interface for the OSCORE GM February 2021 in the OSCORE group, encoded as a CBOR text string or a CBOR integer. Possible values are the same ones admitted for the 'ecdh_alg' parameter of the "OSCORE Security Context Parameters" registry, defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore]. o 'ecdh_params', defined in Section 6.1 of this document and formatted as follows. If the configuration parameter 'pairwise_mode' has value False, this parameter has as value the CBOR simple value Null. Otherwise, this parameter specifies the parameters for the ECDH algorithm used in the OSCORE group, encoded as a CBOR array. Possible formats and values are the same ones admitted for the 'ecdh_params' parameter of the "OSCORE Security Context Parameters" registry, defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore]. o 'ecdh_key_params', defined in Section 6.1 of this document and formatted as follows. If the configuration parameter 'pairwise_mode' has value False, this parameter has as value the CBOR simple value Null. Otherwise, this parameter specifies the additional parameters for the key used with the ECDH algorithm in the OSCORE group, encoded as a CBOR array. Possible formats and values are the same ones admitted for the 'ecdh_key_params' parameter of the "OSCORE Security Context Parameters" registry, defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore]. 3.1.2. Status Properties The CBOR map MUST include the following status parameters: o 'rt', with value the resource type "core.osc.gconf" associated to group-configuration resources, encoded as a CBOR text string. o 'active', encoding the CBOR simple value True if the OSCORE group is currently active, or the CBOR simple value False otherwise. This parameter is defined in Section 6.1 of this specification. o 'group_name', with value the group name of the OSCORE group encoded as a CBOR text string. This parameter is defined in Section 6.1 of this specification. o 'group_title', with value either a human-readable description of the OSCORE group encoded as a CBOR text string, or the CBOR simple value Null if no description is specified. This parameter is defined in Section 6.1 of this specification. o 'ace-groupcomm-profile', defined in Section 4.1.2.1 of [I-D.ietf-ace-key-groupcomm], with value "coap_group_oscore_app" Tiloca, et al. Expires August 26, 2021 [Page 12] Internet-Draft Admin Interface for the OSCORE GM February 2021 defined in Section 21.3 of [I-D.ietf-ace-key-groupcomm-oscore] encoded as a CBOR integer. o 'exp', defined in Section 4.1.2.1 of [I-D.ietf-ace-key-groupcomm]. o 'app_groups', with value a list of names of application groups, encoded as a CBOR array. Each element of the array is a CBOR text string, specifying the name of an application group using the OSCORE group as security group (see Section 2.1 of [I-D.ietf-core-groupcomm-bis]). o 'joining_uri', with value the URI of the group-membership resource for joining the newly created OSCORE group as per Section 6.2 of [I-D.ietf-ace-key-groupcomm-oscore], encoded as a CBOR text string. This parameter is defined in Section 6.1 of this specification. The CBOR map MAY include the following status parameters: o 'group_policies', defined in Section 4.1.2.1 of [I-D.ietf-ace-key-groupcomm], and consistent with the format and content defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore]. o 'as_uri', defined in Section 6.1 of this document, specifies the URI of the Authorization Server associated to the Group Manager for the OSCORE group, encoded as a CBOR text string. Candidate group members will have to obtain an Access Token from that Authorization Server, before starting the joining process with the Group Manager to join the OSCORE group (see Section 4 and Section 6 of [I-D.ietf-ace-key-groupcomm-oscore]). 3.2. Default Values This section defines the default values that the Group Manager assumes for configuration and status parameters. 3.2.1. Configuration Parameters For each configuration parameter, the Group Manager MUST use a pre- configured default value, if none is specified by the Administrator. In particular: o For 'pairwise_mode', the Group Manager SHOULD use the CBOR simple value False. o If 'pairwise_mode' has value True, the Group Manager SHOULD use the same default values defined in Section 19 of Tiloca, et al. Expires August 26, 2021 [Page 13] Internet-Draft Admin Interface for the OSCORE GM February 2021 [I-D.ietf-ace-key-groupcomm-oscore] for the parameters 'ecdh_alg', 'ecdh_params' and 'ecdh_key_params'. o For any other configuration parameter, the Group Manager SHOULD use the same default values defined in Section 19 of [I-D.ietf-ace-key-groupcomm-oscore]. 3.2.2. Status Parameters For the following status parameters, the Group Manager MUST use a pre-configured default value, if none is specified by the Administrator. In particular: o For 'active', the Group Manager SHOULD use the CBOR simple value False. o For 'group_title', the Group Manager SHOULD use the CBOR simple value Null. o For 'app_groups', the Group Manager SHOULD use the empty CBOR array. 4. Interactions with the Group Manager This section describes the operations available on the group- collection resource and the group-configuration resources. When custom CBOR is used, the Content-Format in messages containing a payload is set to application/ace-groupcomm+cbor, defined in Section 10.2 of [I-D.ietf-ace-key-groupcomm]. Furthermore, the entry labels defined in Section 6.1 of this document MUST be used, when specifying the corresponding configuration and status parameters. 4.1. Retrieve the Full List of Groups Configurations The Administrator can send a GET request to the group-collection resource, in order to retrieve the complete list of the existing OSCORE groups at the Group Manager. This is returned as a list of links to the corresponding group-configuration resources. Example in Link Format: Tiloca, et al. Expires August 26, 2021 [Page 14] Internet-Draft Admin Interface for the OSCORE GM February 2021 => 0.01 GET Uri-Path: manage <= 2.05 Content Content-Format: 40 (application/link-format) ;rt="core.osc.gconf", ;rt="core.osc.gconf", ;rt="core.osc.gconf" Example in CoRAL: => 0.01 GET Uri-Path: manage <= 2.05 Content Content-Format: TBD1 (application/coral+cbor) #using #base item item item 4.2. Retrieve a List of Group Configurations by Filters The Administrator can send a FETCH request to the group-collection resource, in order to retrieve the list of the existing OSCORE groups that fully match a set of specified filter criteria. This is returned as a list of links to the corresponding group-configuration resources. When custom CBOR is used, the set of filter criteria is specified in the request payload as a CBOR map, whose possible entries are specified in Section 3.1 and use the same abbreviations defined in Section 6.1. Entry values are the ones admitted for the corresponding labels in the POST request for creating a group configuration (see Section 4.3). A valid request MUST NOT include the same entry multiple times. When CoRAL is used, the filter criteria are specified in the request payload with top-level elements, each of which corresponds to an entry specified in Section 3.1, with the exception of the 'app_groups' status parameter. If names of application groups are used as filter criteria, each element of the 'app_groups' array from the status properties is included as a separate element with name 'app_group'. With the exception of the 'app_group' element, a valid request MUST NOT include the same element multiple times. Element Tiloca, et al. Expires August 26, 2021 [Page 15] Internet-Draft Admin Interface for the OSCORE GM February 2021 values are the ones admitted for the corresponding labels in the POST request for creating a group configuration (see Section 4.3). Example in custom CBOR and Link Format: => 0.05 FETCH Uri-Path: manage Content-Format: TBD2 (application/ace-groupcomm+cbor) { "alg" : 10, "hkdf" : 5 } <= 2.05 Content Content-Format: 40 (application/link-format) ;rt="core.osc.gconf", ;rt="core.osc.gconf", ;rt="core.osc.gconf" Example in CoRAL: => 0.05 FETCH Uri-Path: manage Content-Format: TBD1 (application/coral+cbor) alg 10 hkdf 5 <= 2.05 Content Content-Format: TBD1 (application/coral+cbor) #using #base item item item 4.3. Create a New Group Configuration The Administrator can send a POST request to the group-collection resource, in order to create a new OSCORE group at the Group Manager. The request MAY specify the intended group name GROUPNAME and group title, and MAY specify pieces of information concerning the group configuration. Tiloca, et al. Expires August 26, 2021 [Page 16] Internet-Draft Admin Interface for the OSCORE GM February 2021 When custom CBOR is used, the request payload is a CBOR map, whose possible entries are specified in Section 3.1 and use the same abbreviations defined in Section 6.1. When CoRAL is used, each element of the request payload corresponds to an entry specified in Section 3.1, with the exception of the 'app_groups' status parameter (see below). In particular: o The payload MAY include any of the configuration parameter defined in Section 3.1.1. o The payload MAY include any of the status parameter 'group_name', 'group_title', 'exp', 'app_groups, 'group_policies', 'as_uri' and 'active' defined in Section 3.1.2. * When CoRAL is used, each element of the 'app_groups' array from the status properties is included as a separate element with name 'app_group'. o The payload MUST NOT include any of the status parameter 'rt', 'ace-groupcomm-profile' and 'joining_uri' defined in Section 3.1.2. If any of the following occurs, the Group Manager MUST respond with a 4.00 (Bad Request) response. o Any of the received parameters is specified multiple times, with the exception of the 'app_group' element when using CoRAL. o Any of the received parameters is not recognized, or not valid, or not consistent with respect to other related parameters. o The 'group_name' parameter specifies the group name of an already existing OSCORE group. o The Group Manager does not trust the Authorization Server with URI specified in the 'as_uri' parameter, and has no alternative Authorization Server to consider for the OSCORE group to create. After a successful processing of the request above, the Group Manager performs the following actions. First, the Group Manager creates a new group-configuration resource, accessible to the Administrator at /manage/GROUPNAME, where GROUPNAME is the name of the OSCORE group as either indicated in the parameter 'group_name' of the request or uniquely assigned by the Group Tiloca, et al. Expires August 26, 2021 [Page 17] Internet-Draft Admin Interface for the OSCORE GM February 2021 Manager. Note that the final decision about the name assigned to the OSCORE group is of the Group Manager, which may have more constraints than the Administrator can be aware of, possibly beyond the availability of suggested names. The value of the status parameter 'rt' is set to "core.osc.gconf". The values of other parameters specified in the request are used as group configuration information for the newly created OSCORE group. For each configuration parameter not specified in the request, the Group Manager MUST use default values as specified in Section 3.2. After that, the Group Manager creates a new group-membership resource accessible at ace-group/GROUPNAME to nodes that want to join the OSCORE group, as specified in Section 6.2 of [I-D.ietf-ace-key-groupcomm-oscore]. Note that such group membership-resource comprises a number of sub-resources intended to current group members, as defined in Section 4.1 of [I-D.ietf-ace-key-groupcomm] and Section 5 of [I-D.ietf-ace-key-groupcomm-oscore]. From then on, the Group Manager will rely on the current group configuration to build the Joining Response message defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore], when handling the joining of a new group member. Furthermore, the Group Manager generates the following pieces of information, and assigns them to the newly created OSCORE group. o The OSCORE Master Secret. o The OSCORE Master Salt (optionally). o The Group ID, used as OSCORE ID Context, which MUST be unique within the set of OSCORE groups under the Group Manager. Finally, the Group Manager replies to the Administrator with a 2.01 (Created) response. The Location-Path option MUST be included in the response, indicating the location of the just created group- configuration resource. The response MUST NOT include a Location- Query option. The response payload specifies the parameters 'group_name', 'joining_uri' and 'as_uri', from the status properties of the newly created OSCORE group (see Section 3.1), as detailed below. When custom CBOR is used, the response payload is a CBOR map, where entries use the same abbreviations defined in Section 6.1. When CoRAL is used, the response payload includes one element for each specified parameter. Tiloca, et al. Expires August 26, 2021 [Page 18] Internet-Draft Admin Interface for the OSCORE GM February 2021 o 'group_name', with value the group name of the OSCORE group. This value can be different from the group name possibly specified by the Administrator in the POST request, and reflects the final choice of the Group Manager as 'group_name' status property for the OSCORE group. This parameter MUST be included. o 'joining_uri', with value the URI of the group-membership resource for joining the newly created OSCORE group. This parameter MUST be included. o 'as_uri', with value the URI of the Authorization Server associated to the Group Manager for the newly created OSCORE group. This parameter MUST be included if specified in the status properties of the group. This value can be different from the URI possibly specified by the Administrator in the POST request, and reflects the final choice of the Group Manager as 'as_uri' status property for the OSCORE group. The Group Manager can register the link to the group-membership resource with URI specified in 'joining_uri' to a Resource Directory [I-D.ietf-core-resource-directory][I-D.hartke-t2trg-coral-reef], as defined in Section 2 of [I-D.tiloca-core-oscore-discovery]. The Group Manager considers the current group configuration when specifying additional information for the link to register. Alternatively, the Administrator can perform the registration in the Resource Directory on behalf of the Group Manager, acting as Commissioning Tool. The Administrator considers the following when specifying additional information for the link to register. o The name of the OSCORE group MUST take the value specified in 'group_name' from the 2.01 (Created) response above. o The names of the application groups using the OSCORE group MUST take the values possibly specified by the elements of the 'app_groups' parameter (when custom CBOR is used) or by the different 'app_group' elements (when CoRAL is used) in the POST request above. o If present, parameters describing the cryptographic algorithms used in the OSCORE group MUST follow the values that the Administrator specified in the POST request above, or the corresponding default values specified in Section 3.2.1 otherwise. o If also registering a related link to the Authorization Server associated to the OSCORE group, the related link MUST have as link target the URI in 'as_uri' from the 2.01 (Created) response above, if the 'as_uri' parameter was included in the response. Tiloca, et al. Expires August 26, 2021 [Page 19] Internet-Draft Admin Interface for the OSCORE GM February 2021 Note that, compared to the Group Manager, the Administrator is less likely to remain closely aligned with possible changes and updates that would require a prompt update to the registration in the Resource Directory. This applies especially to the address of the Group Manager, as well as the URI of the group-membership resource or of the Authorization Server associated to the Group Manager. Therefore, it is RECOMMENDED that registrations of links to group- membership resources in the Resource Directory are made (and possibly updated) directly by the Group Manager, rather than by the Administrator. Example in custom CBOR: => 0.02 POST Uri-Path: manage Content-Format: TBD2 (application/ace-groupcomm+cbor) { "alg" : 10, "hkdf" : 5, "pairwise_mode" : True, "active" : True, "group_title" : "rooms 1 and 2", "app_groups": : ["room1", "room2"], "as_uri" : "coap://as.example.com/token" } <= 2.01 Created Location-Path: manage Location-Path: gp4 Content-Format: TBD2 (application/ace-groupcomm+cbor) { "group_name" : "gp4", "joining_uri" : "coap://[2001:db8::ab]/ace-group/gp4/", "as_uri" : "coap://as.example.com/token" } Example in CoRAL: Tiloca, et al. Expires August 26, 2021 [Page 20] Internet-Draft Admin Interface for the OSCORE GM February 2021 => 0.02 POST Uri-Path: manage Content-Format: TBD1 (application/coral+cbor) #using alg 10 hkdf 5 pairwise_mode True active True group_title "rooms 1 and 2" app_group "room1" app_group "room2" as_uri <= 2.01 Created Location-Path: manage Location-Path: gp4 Content-Format: TBD1 (application/coral+cbor) #using group_name "gp4" joining_uri as_uri 4.4. Retrieve a Group Configuration The Administrator can send a GET request to the group-configuration resource manage/GROUPNAME associated to an OSCORE group with group name GROUPNAME, in order to retrieve the complete current configuration of that group. After a successful processing of the request above, the Group Manager replies to the Administrator with a 2.05 (Content) response. The response has as payload the representation of the group configuration as specified in Section 3.1. The exact content of the payload reflects the current configuration of the OSCORE group. This includes both configuration properties and status properties. When custom CBOR is used, the response payload is a CBOR map, whose possible entries are specified in Section 3.1 and use the same abbreviations defined in Section 6.1. When CoRAL is used, the response payload includes one element for each entry specified in Section 3.1, with the exception of the 'app_groups' status parameter. That is, each element of the 'app_groups' array from the status properties is included as a separate element with name 'app_group'. Tiloca, et al. Expires August 26, 2021 [Page 21] Internet-Draft Admin Interface for the OSCORE GM February 2021 Example in custom CBOR: => 0.01 GET Uri-Path: manage Uri-Path: gp4 <= 2.05 Content Content-Format: TBD2 (application/ace-groupcomm+cbor) { "alg" : 10, "hkdf" : 5, "cs_alg" : -8, "cs_params" : [[1], [1, 6]], "cs_key_params" : [1, 6], "cs_key_enc" : 1, "pairwise_mode" : True, "ecdh_alg" : -27, "ecdh_params" : [[1], [1, 6]], "ecdh_key_params" : [1, 6], "rt" : "core.osc.gconf", "active" : True, "group_name" : "gp4", "group_title" : "rooms 1 and 2", "ace-groupcomm-profile" : "coap_group_oscore_app", "exp" : "1360289224", "app_groups": : ["room1", "room2"], "joining_uri" : "coap://[2001:db8::ab]/ace-group/gp4/", "as_uri" : "coap://as.example.com/token" } Example in CoRAL: Tiloca, et al. Expires August 26, 2021 [Page 22] Internet-Draft Admin Interface for the OSCORE GM February 2021 => 0.01 GET Uri-Path: manage Uri-Path: gp4 <= 2.05 Content Content-Format: TBD1 (application/coral+cbor) #using alg 10 hkdf 5 cs_alg -8 cs_params.alg_capab.key_type 1 cs_params.key_type_capab.key_type 1 cs_params.key_type_capab.curve 6 cs_key_params.key_type 1 cs_key_params.curve 6 cs_key_enc 1 pairwise_mode True ecdh_alg -27 ecdh_params.alg_capab.key_type 1 ecdh_params.key_type_capab.key_type 1 ecdh_params.key_type_capab.curve 6 ecdh_key_params.key_type 1 ecdh_key_params.curve 6 rt "core.osc.gconf", active True group_name "gp4" group_title "rooms 1 and 2" ace-groupcomm-profile "coap_group_oscore_app" exp "1360289224" app_group "room1" app_group "room2" joining_uri as_uri 4.5. Retrieve Part of a Group Configuration by Filters The Administrator can send a FETCH request to the group-configuration resource manage/GROUPNAME associated to an OSCORE group with group name GROUPNAME, in order to retrieve part of the current configuration of that group. When custom CBOR is used, the request payload is a CBOR map, which contains the following fields: o 'conf_filter', defined in Section 6.1 of this document and encoded as a CBOR array. Each element of the array specifies one requested configuration parameter or status parameter of the Tiloca, et al. Expires August 26, 2021 [Page 23] Internet-Draft Admin Interface for the OSCORE GM February 2021 current group configuration (see Section 3.1), using the corresponding abbreviation defined in Section 6.1. When CoRAL is used, the request payload includes one element for each requested configuration parameter or status parameter of the current group configuration (see Section 3.1). All the specified elements have no value. After a successful processing of the request above, the Group Manager replies to the Administrator with a 2.05 (Content) response. The response has as payload a partial representation of the group configuration (see Section 3.1). The exact content of the payload reflects the current configuration of the OSCORE group, and is limited to the configuration properties and status properties requested by the Administrator in the FETCH request. The response payload includes the requested configuration parameters and status parameters, and is formatted as in the response payload of a GET request to a group-configuration resource (see Section 4.4). Example in custom CBOR: => 0.05 FETCH Uri-Path: manage Uri-Path: gp4 Content-Format: TBD2 (application/ace-groupcomm+cbor) { "conf_filter" : ["alg", "hkdf", "pairwise_mode", "active", "group_title", "app_groups"] } <= 2.05 Content Content-Format: TBD2 (application/ace-groupcomm+cbor) { "alg" : 10, "hkdf" : 5, "pairwise_mode" : True, "active" : True, "group_title" : "rooms 1 and 2", "app_groups": : ["room1", "room2"] } Tiloca, et al. Expires August 26, 2021 [Page 24] Internet-Draft Admin Interface for the OSCORE GM February 2021 Example in CoRAL: => 0.05 FETCH Uri-Path: manage Uri-Path: gp4 Content-Format: TBD1 (application/coral+cbor) #using alg hkdf pairwise_mode active group_title app_groups <= 2.05 Content Content-Format: TBD1 (application/coral+cbor) #using alg 10 hkdf 5 pairwise_mode True active True group_title "rooms 1 and 2" app_group "room1" app_group "room2" 4.6. Overwrite a Group Configuration The Administrator can send a PUT request to the group-configuration resource associated to an OSCORE group, in order to overwrite the current configuration of that group with a new one. The payload of the request has the same format of the POST request defined in Section 4.3, with the exception of the status parameter 'group_name' that MUST NOT be included. The error handling for the PUT request is the same as for the POST request defined in Section 4.3. If no error occurs, the Group Manager performs the following actions. First, the Group Manager updates the group-configuration resource, consistently with the values indicated in the PUT request from the Administrator. For each parameter not specified in the PUT request, the Group Manager MUST use the default value as specified in Section 3.2. From then on, the Group Manager relies on the latest updated configuration to build the Joining Response message defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore], when handling the joining of a new group member. Tiloca, et al. Expires August 26, 2021 [Page 25] Internet-Draft Admin Interface for the OSCORE GM February 2021 Then, the Group Manager replies to the Administrator with a 2.04 (Changed) response. The payload of the response has the same format of the 2.01 (Created) response defined in Section 4.3. If the link to the group-membership resource was registered in the Resource Directory [I-D.ietf-core-resource-directory], the GM is responsible to refresh the registration, as defined in Section 3 of [I-D.tiloca-core-oscore-discovery]. Alternatively, the Administrator can update the registration in the Resource Directory on behalf of the Group Manager, acting as Commissioning Tool. The Administrator considers the following when specifying additional information for the link to update. o The name of the OSCORE group MUST take the value specified in 'group_name' from the 2.04 (Changed) response above. o The names of the application groups using the OSCORE group MUST take the values possibly specified by the elements of the 'app_groups' parameter (when custom CBOR is used) or by the different 'app_group' elements (when CoRAL is used) in the PUT request above. o If present, parameters describing the cryptographic algorithms used in the OSCORE group MUST follow the values that the Administrator specified in the PUT request above, or the corresponding default values as specified in Section 3.2.1 otherwise. o If also registering a related link to the Authorization Server associated to the OSCORE group, the related link MUST have as link target the URI in 'as_uri' from the 2.04 (Changed) response above, if the 'as_uri' parameter was included in the response. As discussed in Section 4.3, it is RECOMMENDED that registrations of links to group-membership resources in the Resource Directory are made (and possibly updated) directly by the Group Manager, rather than by the Administrator. Example in custom CBOR: Tiloca, et al. Expires August 26, 2021 [Page 26] Internet-Draft Admin Interface for the OSCORE GM February 2021 => 0.03 PUT Uri-Path: manage Uri-Path: gp4 Content-Format: TBD2 (application/ace-groupcomm+cbor) { "alg" : 11, "hkdf" : 5 } <= 2.04 Changed Content-Format: TBD2 (application/ace-groupcomm+cbor) { "group_name" : "gp4", "joining_uri" : "coap://[2001:db8::ab]/ace-group/gp4/", "as_uri" : "coap://as.example.com/token" } Example in CoRAL: => 0.03 PUT Uri-Path: manage Uri-Path: gp4 Content-Format: TBD1 (application/coral+cbor) #using alg 11 hkdf 5 <= 2.04 Changed Content-Format: TBD1 (application/coral+cbor) #using group_name "gp4" joining_uri as_uri 4.6.1. Effects on Joining Nodes After having overwritten a group configuration, if the value of the status parameter 'active' is changed from True to False, the Group Manager MUST stop admitting new members in the OSCORE group. In particular, until the status parameter 'active' is changed back to True, the Group Manager MUST respond to a Joining Request with a 5.03 (Service Unavailable) response, as defined in Section 6.3 of [I-D.ietf-ace-key-groupcomm-oscore]. Tiloca, et al. Expires August 26, 2021 [Page 27] Internet-Draft Admin Interface for the OSCORE GM February 2021 If the value of the status parameter 'active' is changed from False to True, the Group Manager resumes admitting new members in the OSCORE group, by processing their Joining Requests (see Section 6.3 of [I-D.ietf-ace-key-groupcomm-oscore]). 4.6.2. Effects on the Group Members After having overwritten a group configuration, the Group Manager informs the members of the OSCORE group, over the pairwise secure communication channels established when joining the group (see Section 6 of [I-D.ietf-ace-key-groupcomm-oscore]). To this end, the Group Manager can individually target the 'control_uri' URI of each group member (see Section 4.1.2.1 of [I-D.ietf-ace-key-groupcomm]), if provided by the intended recipient upon joining the OSCORE group (see Section 6.2 of [I-D.ietf-ace-key-groupcomm-oscore]). Alternatively, group members can subscribe for updates to the group-membership resource of the OSCORE group, e.g. by using CoAP Observe [RFC7641]. If the value of the status parameter 'active' is changed from True to False: o The Group Manager MUST stop accepting requests for new keying material from current group members (see Section 9 of [I-D.ietf-ace-key-groupcomm-oscore]). In particular, until the status parameter 'active' is changed back to True, the Group Manager MUST respond to a Key Renewal Request with a 5.03 (Service Unavailable) response, as defined in Section 9 of [I-D.ietf-ace-key-groupcomm-oscore]. o The Group Manager MUST stop accepting updated public keys uploaded by current group members (see Section 11 of [I-D.ietf-ace-key-groupcomm-oscore]). In particular, until the status parameter 'active' is changed back to True, the Group Manager MUST respond to a Public Key Update Request with a 5.03 (Service Unavailable) response, as defined in Section 11 of [I-D.ietf-ace-key-groupcomm-oscore]. Every group member, upon learning that the OSCORE group has been deactivated (i.e. 'active' has value False), SHOULD stop communicating in the group. Every group member, upon learning that the OSCORE group has been reactivated (i.e. 'active' has value True again), can resume communicating in the group. Tiloca, et al. Expires August 26, 2021 [Page 28] Internet-Draft Admin Interface for the OSCORE GM February 2021 Every group member, upon learning that the OSCORE group has stopped supporting the pairwise mode of Group OSCORE (i.e. 'pairwise_mode' has value False), SHOULD stop using the pairwise mode to process messages in the group. Every group member, upon learning that the OSCORE group has resumed supporting the pairwise mode of Group OSCORE (i.e. 'pairwise_mode' has value True again), can resume using the pairwise mode to process messages in the group. Every group member, upon receiving updated values for 'alg' and 'hkdf', MUST either: o Leave the OSCORE group (see Section 16 of [I-D.ietf-ace-key-groupcomm-oscore]), e.g. if not supporting the indicated new algorithms; or o Use the new parameter values, and accordingly re-derive the OSCORE Security Context for the OSCORE group (see Section 2 of [I-D.ietf-core-oscore-groupcomm]). Every group member, upon receiving updated values for 'cs_alg', 'cs_params', 'cs_key_params', 'cs_key_enc', 'ecdh_alg', 'ecdh_params' and 'ecdh_key_params' MUST either: o Leave the OSCORE group, e.g. if not supporting the indicated new algorithm, parameters and encoding; or o Leave the OSCORE group and rejoin it (see Section 6 of [I-D.ietf-ace-key-groupcomm-oscore]), providing the Group Manager with a public key which is compatible with the indicated new algorithm, parameters and encoding; or o Use the new parameter values, and, if required, provide the Group Manager with a new public key to use in the OSCORE group, as compatible with the indicated parameters (see Section 11 of [I-D.ietf-ace-key-groupcomm-oscore]). 4.7. Selective Update of a Group Configuration The Administrator can send a PATCH/iPATCH request [RFC8132] to the group-configuration resource associated to an OSCORE group, in order to update the value of only part of the group configuration. The request payload has the same format of the PUT request defined in Section 4.6, with the difference that it MAY also specify names of application groups to be removed from or added to the 'app_groups' Tiloca, et al. Expires August 26, 2021 [Page 29] Internet-Draft Admin Interface for the OSCORE GM February 2021 status parameter. The names of such application groups are provided as defined below. o When custom CBOR is used, the CBOR map in the request payload includes the field 'app_groups_diff'. This field MUST NOT be present multiple times, and it is encoded as a CBOR array including the following two elements. * The first element is a CBOR array, namely 'app_groups_del'. Each of its elements is a CBOR text string, with value the name of an application group to remove from the 'app_groups' status parameter. * The second element is a CBOR array, namely 'app_groups_add'. Each of its elements is a CBOR text string, with value the name of an application group to add to the 'app_groups' status parameter. The CDDL definition [RFC8610] of the CBOR array 'app_groups_diff' formatted as in the response from the Group Manager is provided below. app-group-name = tstr name-patch = [* app-group-name] app_groups_diff = [app_groups_del: name-patch, app_groups_add: name-patch] Figure 2: CDDL definition of the 'app_groups_diff' field The Group Manager MUST respond with a 4.00 (Bad Request) response, in case both the inner CBOR arrays 'app_groups_del' and 'app_groups_add' are empty, or in case the 'app_groups_diff' field occurs more than once. The Group Manager MUST respond with a 4.00 (Bad Request) response, in case the CBOR map in the request payload includes both the 'app_groups' field and the 'app_groups_diff' field. o When CoRAL is used, the request payload includes the following top-level elements. * 'app_group_del', with value a text string specifying the name of an application group to remove from the 'app_groups' status parameter. This element can be included multiple times. * 'app_group_add', with value a text string specifying the name of an application group to add to the 'app_groups' status parameter. This element can be included multiple times. Tiloca, et al. Expires August 26, 2021 [Page 30] Internet-Draft Admin Interface for the OSCORE GM February 2021 The Group Manager MUST respond with a 4.00 (Bad Request) response, in case the request payload includes both any 'app_group' element as well as any 'app_group_del' and/or 'app_group_add' element. The error handling for the PATCH/iPATCH request is the same as for the PUT request defined in Section 4.6, with the following additions. o The set of group configuration parameters to update MUST NOT be empty. That is, the Group Manager MUST respond with a 4.00 (Bad Request) response, if the request payload includes an empty CBOR map (when custom CBOR is used) or no elements (when CoRAL is used). o If the Request-URI does not point to an existing group- configuration resource, the Group Manager MUST NOT create a new resource, and MUST respond with a 4.04 (Not Found) response. o When applying the specified updated values would yield an inconsistent group configuration, the Group Manager MUST respond with a 4.09 (Conflict) response. The response, MAY include the current representation of the group configuration resource, like when responding to a GET request as defined in Section 4.4. Otherwise, the response SHOULD include a diagnostic payload with additional information for the Administrator to recognize the source of the conflict. o When the request uses specifically the iPATCH method, the Group Manager MUST respond with a 4.00 (Bad Request) response, in case: * When custom CBOR is used, the CBOR map includes the parameter 'app_groups'diffs'; or * When CoRAL is used, any element 'app_group_del' and/or 'app_group_add' is included. If no error occurs, the Group Manager performs the following actions. First, the Group Manager updates the group-configuration resource, consistently with the values indicated in the PATCH/iPATCH request from the Administrator. Unlike for the PUT request defined in Section 4.6, the Group Manager does not alter the value of configuration parameters and status parameters for which updated values are not specified in the request payload. In particular, the Group Manager does not assign possible default values to those parameters. Tiloca, et al. Expires August 26, 2021 [Page 31] Internet-Draft Admin Interface for the OSCORE GM February 2021 Special processing occurs when updating the 'app_groups' status parameter by difference, as defined below. The Administrator should not expect the Group Manager to add or delete names of application group names according to any particular order. o If the name of an application group to add (delete) is specified multiple times, the Group Manager considers it only once for addition to (deletion from) the 'app_groups' status parameter. o If the name of an application group to delete is not present in the 'app_groups' status parameter before any change is applied, the Group Manager ignores that name. o If the name of an application group to add is already present in the 'app_groups' status parameter before any change is applied, the Group Manager ignores that name. o When custom CBOR is used, the Group Manager: * Deletes from the 'app_groups' status parameter the names of the application groups specified in the inner 'app_groups_del' CBOR array of the 'app_groups_diff' field. * Adds to the 'app_groups' status parameter the names of the application groups specified in the inner 'app_groups_add' CBOR array of the 'app_groups_diff' field. o When CoRAL is used, the Group Manager: * Deletes from the 'app_groups' status parameter the names of the application groups specified in the different 'app_group_del' elements. * Adds to the 'app_groups' status parameter the names of the application groups specified in the different 'app_group_add' elements. After having updated the group-configuration resource, from then on the Group Manager relies on the new group configuration to build the Joining Response message defined in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore], when handling the joining of a new group member. Finally, the Group Manager replies to the Administrator with a 2.04 (Changed) response. The payload of the response has the same format of the 2.01 (Created) response defined in Section 4.3. Tiloca, et al. Expires August 26, 2021 [Page 32] Internet-Draft Admin Interface for the OSCORE GM February 2021 The same considerations as for the PUT request defined in Section 4.6 hold also in this case, with respect to refreshing a possible registration of the link to the group-membership resource in the Resource Directory [I-D.ietf-core-resource-directory]. Example in custom CBOR: => 0.06 PATCH Uri-Path: manage Uri-Path: gp4 Content-Format: TBD2 (application/ace-groupcomm+cbor) { "alg" : 10, "app_groups_diff" : [["room1"], ["room3", "room4"]] } <= 2.04 Changed Content-Format: TBD2 (application/ace-groupcomm+cbor) { "group_name" : "gp4", "joining_uri" : "coap://[2001:db8::ab]/ace-group/gp4/", "as_uri" : "coap://as.example.com/token" } Example in CoRAL: => 0.06 PATCH Uri-Path: manage Uri-Path: gp4 Content-Format: TBD1 (application/coral+cbor) #using alg 10 app_group_del "room1" app_group_add "room3" app_group_add "room4" <= 2.04 Changed Content-Format: TBD1 (application/coral+cbor) #using group_name "gp4" joining_uri as_uri Tiloca, et al. Expires August 26, 2021 [Page 33] Internet-Draft Admin Interface for the OSCORE GM February 2021 4.7.1. Effects on Joining Nodes After having selectively updated part of a group configuration, the effects on candidate joining nodes are the same as defined in Section 4.6.1 for the case of group configuration overwriting. 4.7.2. Effects on the Group Members After having selectively updated part of a group configuration, the effects on the current group members are the same as defined in Section 4.6.2 for the case of group configuration overwriting. 4.8. Delete a Group Configuration The Administrator can send a DELETE request to the group- configuration resource, in order to delete that OSCORE group. The deletion would be successful only on an inactive OSCORE group. That is, the DELETE request actually yields a successful deletion of the OSCORE group, only if the corresponding status parameter 'active' has current value False. The Administrator can ensure that, by first performing an update of the group-configuration resource associated to the OSCORE group (see Section 4.6), and setting the corresponding status parameter 'active' to False. If, upon receiving the DELETE request, the current value of the status parameter 'active' is True, the Group Manager MUST respond with a 4.09 (Conflict) response. The response MUST have Content- Format set to application/ace-groupcomm+cbor and is formatted as defined in Section 4 of [I-D.ietf-ace-key-groupcomm]. The value of the 'error' field MUST be set to 6 ("The group is currently not active"). After a successful processing of the request above, the Group Manager performs the following actions. First, the Group Manager deletes the OSCORE group and deallocates both the group-configuration resource as well as the group-membership resource associated to that group. Then, the Group Manager replies to the Administrator with a 2.02 (Deleted) response. Example: Tiloca, et al. Expires August 26, 2021 [Page 34] Internet-Draft Admin Interface for the OSCORE GM February 2021 => 0.04 DELETE Uri-Path: manage Uri-Path: gp4 <= 2.02 Deleted 4.8.1. Effects on the Group Members After having deleted an OSCORE group, the Group Manager can inform the group members by means of the following two methods. When contacting a group member, the Group Manager uses the pairwise secure communication association established with that member during its joining process (see Section 6 of [I-D.ietf-ace-key-groupcomm-oscore]). o The Group Manager sends an individual request message to each group member, targeting the respective resource used to perform the group rekeying process (see Section 18 of [I-D.ietf-ace-key-groupcomm-oscore]). The Group Manager uses the same format of the Joining Response message in Section 6.4 of [I-D.ietf-ace-key-groupcomm-oscore], where only the parameters 'gkty', 'key', and 'ace-groupcomm-profile' are present, and the 'key' parameter is empty. o A group member may subscribe for updates to the group-membership resource associated to the OSCORE group. In particular, if this relies on CoAP Observe [RFC7641], a group member would receive a 4.04 (Not Found) notification response from the Group Manager, since the group-configuration resource has been deallocated upon deleting the OSCORE group (see Section 4.4 of [I-D.ietf-ace-key-groupcomm]). The response MUST have Content- Format set to application/ace-groupcomm+cbor and is formatted as defined in Section 4 of [I-D.ietf-ace-key-groupcomm]. The value of the 'error' field MUST be set to 5 ("Group deleted"). When being informed about the deletion of the OSCORE group, a group member deletes the OSCORE Security Context that it stores as associated to that group, and possibly deallocates any dedicated control resource intended for the Group Manager that it has for that group. 5. Security Considerations Security considerations are inherited from the ACE framework for Authentication and Authorization [I-D.ietf-ace-oauth-authz], and from the specific transport profile of ACE used between the Administrator and the Group Manager, such as [I-D.ietf-ace-dtls-authorize] and [I-D.ietf-ace-oscore-profile]. Tiloca, et al. Expires August 26, 2021 [Page 35] Internet-Draft Admin Interface for the OSCORE GM February 2021 6. IANA Considerations This document has the following actions for IANA. 6.1. ACE Groupcomm Parameters Registry IANA is asked to register the following entries in the "ACE Groupcomm Parameters" Registry defined in Section 10.5 of [I-D.ietf-ace-key-groupcomm]. Tiloca, et al. Expires August 26, 2021 [Page 36] Internet-Draft Admin Interface for the OSCORE GM February 2021 +-----------------+----------+--------------+-------------------+ | Name | CBOR Key | CBOR Type | Reference | +-----------------+----------+--------------+-------------------+ | hkdf | TBD | tstr / int | [[this document]] | | | | | | | alg | TBD | tstr / int | [[this document]] | | | | | | | cs_alg | TBD | tstr / int | [[this document]] | | | | | | | cs_params | TBD | array | [[this document]] | | | | | | | cs_key_params | TBD | array | [[this document]] | | | | | | | cs_key_enc | TBD | int | [[this document]] | | | | | | | pairwise_mode | TBD | simple value | [[this document]] | | | | | | | ecdh_alg | TBD | tstr / int / | [[this document]] | | | | simple value | | | | | | | | ecdh_params | TBD | array / | [[this document]] | | | | simple value | | | | | | | | ecdh_key_params | TBD | array / | [[this document]] | | | | simple value | | | | | | | | active | TBD | simple value | [[this document]] | | | | | | | group_name | TBD | tstr | [[this document]] | | | | | | | group_title | TBD | tstr / | [[this document]] | | | | simple value | | | | | | | | app_groups | TBD | array | [[this document]] | | | | | | | joining_uri | TBD | tstr | [[this document]] | | | | | | | as_uri | TBD | tstr | [[this document]] | | | | | | | conf_filter | TBD | array | [[this document]] | | | | | | | app_groups_diff | TBD | array | [[this document]] | +-----------------+----------+--------------+-------------------+ Tiloca, et al. Expires August 26, 2021 [Page 37] Internet-Draft Admin Interface for the OSCORE GM February 2021 6.2. Resource Types IANA is asked to enter the following values into the Resource Type (rt=) Link Target Attribute Values subregistry within the Constrained Restful Environments (CoRE) Parameters registry defined in [RFC6690]. +----------------+------------------------------+-------------------+ | Value | Description | Reference | +----------------+------------------------------+-------------------+ | core.osc.gcoll | Group-collection resource | [[this document]] | | | of an OSCORE Group Manager | | | | | | | core.osc.gconf | Group-configuration resource | [[this document]] | | | of an OSCORE Group Manager | | +----------------+------------------------------+-------------------+ 7. References 7.1. Normative References [COSE.Algorithms] IANA, "COSE Algorithms", . [COSE.Elliptic.Curves] IANA, "COSE Elliptic Curves", . [COSE.Key.Types] IANA, "COSE Key Types", . [I-D.ietf-ace-key-groupcomm] Palombini, F. and M. Tiloca, "Key Provisioning for Group Communication using ACE", draft-ietf-ace-key-groupcomm-11 (work in progress), February 2021. [I-D.ietf-ace-key-groupcomm-oscore] Tiloca, M., Park, J., and F. Palombini, "Key Management for OSCORE Groups in ACE", draft-ietf-ace-key-groupcomm- oscore-10 (work in progress), February 2021. Tiloca, et al. Expires August 26, 2021 [Page 38] Internet-Draft Admin Interface for the OSCORE GM February 2021 [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)", draft-ietf-ace-oauth-authz-37 (work in progress), February 2021. [I-D.ietf-ace-oscore-profile] Palombini, F., Seitz, L., Selander, G., and M. Gunnarsson, "OSCORE Profile of the Authentication and Authorization for Constrained Environments Framework", draft-ietf-ace- oscore-profile-16 (work in progress), January 2021. [I-D.ietf-core-coral] Hartke, K., "The Constrained RESTful Application Language (CoRAL)", draft-ietf-core-coral-03 (work in progress), March 2020. [I-D.ietf-core-groupcomm-bis] Dijk, E., Wang, C., and M. Tiloca, "Group Communication for the Constrained Application Protocol (CoAP)", draft- ietf-core-groupcomm-bis-03 (work in progress), February 2021. [I-D.ietf-core-oscore-groupcomm] Tiloca, M., Selander, G., Palombini, F., Mattsson, J., and J. Park, "Group OSCORE - Secure Group Communication for CoAP", draft-ietf-core-oscore-groupcomm-11 (work in progress), February 2021. [I-D.ietf-cose-rfc8152bis-algs] Schaad, J., "CBOR Object Signing and Encryption (COSE): Initial Algorithms", draft-ietf-cose-rfc8152bis-algs-12 (work in progress), September 2020. [I-D.ietf-cose-rfc8152bis-struct] Schaad, J., "CBOR Object Signing and Encryption (COSE): Structures and Process", draft-ietf-cose-rfc8152bis- struct-15 (work in progress), February 2021. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link Format", RFC 6690, DOI 10.17487/RFC6690, August 2012, . Tiloca, et al. Expires August 26, 2021 [Page 39] Internet-Draft Admin Interface for the OSCORE GM February 2021 [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", RFC 6749, DOI 10.17487/RFC6749, October 2012, . [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained Application Protocol (CoAP)", RFC 7252, DOI 10.17487/RFC7252, June 2014, . [RFC7641] Hartke, K., "Observing Resources in the Constrained Application Protocol (CoAP)", RFC 7641, DOI 10.17487/RFC7641, September 2015, . [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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [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, . [RFC8613] Selander, G., Mattsson, J., Palombini, F., and L. Seitz, "Object Security for Constrained RESTful Environments (OSCORE)", RFC 8613, DOI 10.17487/RFC8613, July 2019, . [RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", STD 94, RFC 8949, DOI 10.17487/RFC8949, December 2020, . 7.2. Informative References [I-D.hartke-t2trg-coral-reef] Hartke, K., "Resource Discovery in Constrained RESTful Environments (CoRE) using the Constrained RESTful Application Language (CoRAL)", draft-hartke-t2trg-coral- reef-04 (work in progress), May 2020. Tiloca, et al. Expires August 26, 2021 [Page 40] Internet-Draft Admin Interface for the OSCORE GM February 2021 [I-D.ietf-ace-dtls-authorize] Gerdes, S., Bergmann, O., Bormann, C., Selander, G., and L. Seitz, "Datagram Transport Layer Security (DTLS) Profile for Authentication and Authorization for Constrained Environments (ACE)", draft-ietf-ace-dtls- authorize-15 (work in progress), January 2021. [I-D.ietf-core-resource-directory] Amsuess, C., Shelby, Z., Koster, M., Bormann, C., and P. Stok, "CoRE Resource Directory", draft-ietf-core-resource- directory-26 (work in progress), November 2020. [I-D.ietf-tls-dtls13] Rescorla, E., Tschofenig, H., and N. Modadugu, "The Datagram Transport Layer Security (DTLS) Protocol Version 1.3", draft-ietf-tls-dtls13-41 (work in progress), February 2021. [I-D.tiloca-core-oscore-discovery] Tiloca, M., Amsuess, C., and P. Stok, "Discovery of OSCORE Groups with the CoRE Resource Directory", draft-tiloca- core-oscore-discovery-08 (work in progress), February 2021. [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, January 2012, . Appendix A. Document Updates RFC EDITOR: PLEASE REMOVE THIS SECTION. A.1. Version -01 to -02 o Admit multiple Administrators and limited access to admin resources. o Early design considerations for defining the format of scope. o Additional error handling, using also error types. o Selective update of group-configuration resources with PATCH/ iPATCH. o Editorial improvements. Tiloca, et al. Expires August 26, 2021 [Page 41] Internet-Draft Admin Interface for the OSCORE GM February 2021 A.2. Version -00 to -01 o Names of application groups as status parameter. o Parameters related to the pairwise mode of Group OSCORE. o Defined FETCH for group-configuration resources. o Policies on registration of links to the Resource Directory. o Added resource type for group-configuration resources. o Fixes, clarifications and editorial improvements. Acknowledgments The authors sincerely thank Christian Amsuess, Carsten Bormann and Jim Schaad for their comments and feedback. The work on this document has been partly supported by VINNOVA and the Celtic-Next project CRITISEC; and by the H2020 project SIFIS-Home (Grant agreement 952652). Authors' Addresses Marco Tiloca RISE AB Isafjordsgatan 22 Kista SE-16440 Stockholm Sweden Email: marco.tiloca@ri.se Rikard Hoeglund RISE AB Isafjordsgatan 22 Kista SE-16440 Stockholm Sweden Email: rikard.hoglund@ri.se Tiloca, et al. Expires August 26, 2021 [Page 42] Internet-Draft Admin Interface for the OSCORE GM February 2021 Peter van der Stok Consultant Phone: +31-492474673 (Netherlands), +33-966015248 (France) Email: consultancy@vanderstok.org URI: www.vanderstok.org Francesca Palombini Ericsson AB Torshamnsgatan 23 Kista SE-16440 Stockholm Sweden Email: francesca.palombini@ericsson.com Klaus Hartke Ericsson AB Torshamnsgatan 23 Kista SE-16440 Stockholm Sweden Email: klaus.hartke@ericsson.com Tiloca, et al. Expires August 26, 2021 [Page 43]