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MILE Working Group                                              J. Field
Internet-Draft                                                   Pivotal
Intended status: Standards Track                             S. Banghart
Expires: June 13, 2018                                     D. Waltermire
                                                                    NIST
                                                       December 10, 2017


           Resource-Oriented Lightweight Information Exchange
                        draft-ietf-mile-rolie-15

Abstract

   This document defines a resource-oriented approach for security
   automation information publication, discovery, and sharing.  Using
   this approach, producers may publish, share, and exchange
   representations of software descriptors, security incidents, attack
   indicators, software vulnerabilities, configuration checklists, and
   other security automation information as web-addressable resources.
   Furthermore, consumers and other stakeholders may access and search
   this security information as needed, establishing a rapid and on-
   demand information exchange network for restricted internal use or
   public access repositories.  This specification extends the Atom
   Publishing Protocol and Atom Syndication Format to transport and
   share security automation resource representations.

Contributing to this document

   The source for this draft is being maintained on GitHub.  Suggested
   changes should be submitted as pull requests at
   <https://github.com/CISecurity/ROLIE>.  Instructions are on that page
   as well.  Editorial changes can be managed in GitHub, but any
   substantial issues need to be discussed on the MILE mailing list.

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."



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   This Internet-Draft will expire on June 13, 2018.

Copyright Notice

   Copyright (c) 2017 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
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  XML-related Conventions . . . . . . . . . . . . . . . . . . .   4
     3.1.  XML Namespaces  . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  RELAX NG Compact Schema . . . . . . . . . . . . . . . . .   5
   4.  Background and Motivation . . . . . . . . . . . . . . . . . .   5
   5.  ROLIE Requirements for the Atom Publishing Protocol . . . . .   6
     5.1.  AtomPub Service Documents . . . . . . . . . . . . . . . .   7
       5.1.1.  Use of the "app:workspace" Element  . . . . . . . . .   7
       5.1.2.  Use of the "app:collection" Element . . . . . . . . .   8
       5.1.3.  Service Document Discovery  . . . . . . . . . . . . .   9
     5.2.  Category Documents  . . . . . . . . . . . . . . . . . . .   9
     5.3.  Transport Layer Security  . . . . . . . . . . . . . . . .   9
     5.4.  User Authentication and Authorization . . . . . . . . . .  10
     5.5.  / (forward slash) Resource URL  . . . . . . . . . . . . .  10
     5.6.  HTTP methods  . . . . . . . . . . . . . . . . . . . . . .  11
   6.  ROLIE Requirements for the Atom Syndication Format  . . . . .  11
     6.1.  Use of the "atom:feed" element  . . . . . . . . . . . . .  11
       6.1.1.  Use of the "atom:category" Element  . . . . . . . . .  13
       6.1.2.  Use of the "atom:link" Element  . . . . . . . . . . .  13
       6.1.3.  Use of the "atom:updated" Element . . . . . . . . . .  14
     6.2.  Use of the  "atom:entry" Element  . . . . . . . . . . . .  15
       6.2.1.  Use of the "atom:content" Element . . . . . . . . . .  15
       6.2.2.  Use of the "atom:link" Element  . . . . . . . . . . .  16
       6.2.3.  Use of the "rolie:format" Element . . . . . . . . . .  16
       6.2.4.  Use of the rolie:property Element . . . . . . . . . .  18
       6.2.5.  Requirements for a Standalone Entry . . . . . . . . .  19
   7.  Available Extension Points Provided by ROLIE  . . . . . . . .  19
     7.1.  The Category Extension Point  . . . . . . . . . . . . . .  19



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       7.1.1.  General Use of the "atom:category" Element  . . . . .  20
       7.1.2.  Identification of Security Automation Information
               Types . . . . . . . . . . . . . . . . . . . . . . . .  20
     7.2.  The "rolie:format" Extension Point  . . . . . . . . . . .  22
     7.3.  The Link Relation Extension Point . . . . . . . . . . . .  22
     7.4.  The "rolie:property" Extension Point  . . . . . . . . . .  22
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  23
     8.1.  XML Namespaces and Schema URNs  . . . . . . . . . . . . .  23
     8.2.  ROLIE URN Sub-namespace . . . . . . . . . . . . . . . . .  24
     8.3.  ROLIE URN Parameters  . . . . . . . . . . . . . . . . . .  24
     8.4.  ROLIE Security Resource Information Type Sub-Registry . .  26
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  27
   10. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  29
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  30
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  30
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  30
     12.2.  Informative References . . . . . . . . . . . . . . . . .  32
     12.3.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .  34
   Appendix A.  Relax NG Compact Schema for ROLIE  . . . . . . . . .  34
   Appendix B.  Examples of Use  . . . . . . . . . . . . . . . . . .  35
     B.1.  Service Discovery . . . . . . . . . . . . . . . . . . . .  35
     B.2.  Feed Retrieval  . . . . . . . . . . . . . . . . . . . . .  38
     B.3.  Entry Retrieval . . . . . . . . . . . . . . . . . . . . .  40
   Appendix C.  Change History . . . . . . . . . . . . . . . . . . .  41
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  44

1.  Introduction

   This document defines a resource-oriented approach to security
   automation information sharing that follows the Representational
   State Transfer (REST) architectural style [REST].  In this approach,
   computer security resources are maintained in web-accessible
   repositories structured as Atom Syndication Format [RFC4287] Feeds.
   Within a given Feed, which may be requested by the consumer,
   representations of specific types of security automation information
   are organized, categorized, and described.  Furthermore, all
   collections available to a given user are discoverable, allowing the
   consumer to search all available content they are authorized to view,
   and to locate and request the desired information resources.  Through
   use of granular authentication and access controls, only authorized
   consumers may be permitted the ability to read or write to a given
   Feed.

   The goal of this approach is to increase the communication and
   sharing of security information between providers and consumers that
   can be used to automate security processes (e.g., incident reports,
   vulnerability assessments, configuration checklists, and other
   security automation information).  Such sharing allows human



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   operators and computer systems to leverage this standardized
   communication system to gather information that supports the
   automation of security processes.

   To support new types of security automation information being used as
   time goes on, this specification defines a number of extension points
   that can be used either privately or globally.  These global
   extensions are IANA registered by ROLIE extension specifications, and
   provide enhanced interoperability for new use cases and domains.
   Sections 5 and 6 of this document define the core requirements of all
   implementations of this specification, and is resource representation
   agnostic.  An overview of the extension system is provided in
   Section 7.  Implementers seeking to provide support for specific
   security automation information types should refer to the
   specification for that domain described by the IANA registry found in
   Section 8.4.

2.  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.

   The previous key words are used in this document to define the
   requirements for implementations of this specification.  As a result,
   the key words in this document are not used for recommendations or
   requirements for the use of ROLIE.

   Definitions for some of the common computer security-related
   terminology used in this document can be found in Section 2 of
   [RFC7970].

   The following terms are unique to this specification:

   Information Type  A class of security automation information having
      one or more associated data models.  Often such security
      automation information is used in the automation of a security
      process.  See Section 7.1.2 for more information.

3.  XML-related Conventions

3.1.  XML Namespaces

   This specification uses XML Namespaces [W3C.REC-xml-names-20091208]
   to uniquely identify XML element names.  It uses the following
   namespace prefix mappings for the indicated namespace URI:



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      "app" is used for the "http://www.w3.org/2007/app" namespace
      defined in [RFC5023].

      "atom" is used for the "http://www.w3.org/2005/Atom" namespace
      defined in [RFC4287].

      "rolie" is used for the "urn:ietf:params:xml:ns:rolie:1.0"
      namespace defined in Section 8.1 of this specification.

3.2.  RELAX NG Compact Schema

   Some sections of this specification are illustrated with fragments of
   a non-normative RELAX NG Compact schema [relax-NG].  The text of this
   specification provides the definition of conformance.  Schema for the
   "http://www.w3.org/2007/app" and "http://www.w3.org/2005/Atom"
   namespaces appear in RFC5023 appendix B [RFC5023] and RFC4287
   appendix B [RFC4287] respectively.

   A complete informative RELAX NG Compact Schema for the new elements
   introduced by ROLIE is provided in Appendix A.

4.  Background and Motivation

   In order to automate security process, tools need access to
   sufficient sources of structured security information that can be
   used to drive security processes.  Thus, security information sharing
   is one of the core components of automating security processes.
   Vulnerabilities, configurations, software identification, security
   incidents, and patch data are just a few of the classes of
   information that are shared today to enable effective security on a
   wide scale.  However, as the scale of defense broadens as networks
   become larger and more complex, and the volume of information to
   process makes humans-in-the-loop difficult to scale, the need for
   automation and machine-to-machine communication becomes increasingly
   critical.

   ROLIE seeks to address this need by providing four major information
   sharing benefits:

   Extensible information type categories and format agnosticism:  ROLIE
      is not bound to any given data format or category of information.
      Instead, information categories are extensible, and entries
      declare the format of the referenced data.  In cases where several
      formats or serializations are available, ROLIE can use link
      relations to communicate how a consumer can access these formats.
      For example, clients may request that a given resource
      representation be returned as XML, JSON, or in some other format
      or serialization.  This approach allows the provider to support



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      multiple isomorphic formats allowing the consumer to select the
      most suitable version.

   Open and distributed information sharing:  Using the Atom Publishing
      Protocol, ROLIE feeds can easily aggregate feeds and accept
      information POSTed to them from other sources.  Webs of
      communicating ROLIE servers form ad-hoc sharing communities,
      increasing data availability and the ability to correlate linked
      data across sources for participating consumers.  ROLIE servers
      needn't be distributed however, as large ROLIE repositories can
      function as a central or federated collections.

   Stateless communication model:  ROLIE, as a RESTful system, is
      stateless.  That is, the server doesn't keep track of client
      sessions, but rather uses link relations for state transitions.
      In practice, this means that any consumer can find and share
      information at any organizational level and at any time without
      needing to execute a long series of requests.

   Information discovery and navigation:  ROLIE provides a number of
      mechanisms to allow clients to programmatically discover and
      navigate collections of information in order to dynamically
      discover new or revised content.  Extensible information types and
      other categories provide one way of determining content that is
      desirable.  Link elements, each with a target URI and an
      established relationship type, provide a means for ROLIE providers
      to link other information that is relevant to the current entry or
      feed.

   These benefits result in an information sharing protocol that is
   lightweight, interactive, open, and most importantly, machine
   readable.

   The requirements in this specification are broken into two major
   sections, extensions to the Atom Publishing Protocol (AtomPub)
   [RFC5023], and extensions to the Atom Syndication Format [RFC4287].
   All normative requirements in AtomPub and Atom Syndication are
   inherited from their respective specifications, and apply here unless
   the requirement is explicitly overridden in this document.  In this
   way, this document may upgrade the requirement (e.g., make a SHOULD a
   MUST), but will never downgrade a given requirement (e.g., make a
   MUST a SHOULD).

5.  ROLIE Requirements for the Atom Publishing Protocol

   This section describes a number of restrictions of and extensions to
   the Atom Publishing Protocol (AtomPub) [RFC5023] that define the use
   of that protocol in the context of a ROLIE-based solution.  The



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   normative requirements in this section are generally oriented towards
   client and server implementations.  An understanding of the Atom
   Publishing Protocol specification [RFC5023] is helpful to understand
   the requirements in this section.

5.1.  AtomPub Service Documents

   As described in RFC5023 section 8 [RFC5023], a Service Document is an
   XML-based document format that allows a client to dynamically
   discover the Collections provided by a publisher.  A Service Document
   consists of one or more app:workspace elements that may each contain
   a number of app:collection elements.

   The general structure of a service document is as follows (from
   RFC5023 section 4.2 [RFC5023]):

        Service
           o- Workspace
           |    |
           |    o- Collection
           |    |     |
           |    |     o- URI, categories, media types
           |    |
           |    o- ...
           |
           o- Workspace
           |     |
           |     o- Collection
           |     |     |
           |     |     o- URI, categories, media types
           |     |
           |     o- ...
           |
           o- ...

   Note that the IRIs in the original diagram have been replaced with
   URIs.

5.1.1.  Use of the "app:workspace" Element

   In AtomPub, a Workspace, represented by the "app:workspace" element,
   describes a group of one or more Collections.  Building on the
   AtomPub concept of a Workspace, in ROLIE a Workspace represents an
   aggregation of Collections pertaining to security automation
   information resources.  This specification does not restrict the
   number of Workspaces that may be in a Service Document or the
   specific Collections to be provided within a given Workspace.




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   A ROLIE implementation can host Collections containing both public
   and private information entries.  It is suggested that
   implementations segregate Collections into different app:workspace
   elements by their client access requirements.  With proper naming of
   workspaces, this reduces the amount of trial and error a human user
   would need to utilize to discover accessible Collections.

5.1.2.  Use of the "app:collection" Element

   In AtomPub, a Collection in a Service Document, represented by the
   "app:collection" element, provides metadata that can be used to point
   to a specific Atom Feed that contains information Entries that may be
   of interest to a client.  The association between a Collection and a
   Feed is provided by the "href" attribute of the app:collection
   element.  Building on the AtomPub concept of a Collection, in ROLIE a
   Collection represents a pointer to a group of security automation
   information resources pertaining to a given type of security
   automation information.  Collections are represented as Atom Feeds as
   per RFC 5023.  Atom Feed specific requirements are defined in
   Section 6.1.

   ROLIE defines specialized data requirements for Collections, Feeds,
   and Entries containing security automation related data.  The
   difference between a ROLIE and a non-ROLIE Collection defined in a
   Service Document can be determined as follows:

   ROLIE Collection:  An app:collection is considered a ROLIE Collection
      when it contains an app:categories element that contains only one
      atom:category element with the "scheme" attribute value of
      "urn:ietf:params:rolie:category:information-type".  Further, this
      category has an appropriate "term" attribute value as defined in
      Section 7.1.1.  This ensures that a given Collection corresponds
      to a specific type of security automation information.

   Non-ROLIE Collection:  An app:collection is considered a non-ROLIE
      Collection when it does not contain an atom:category element with
      a "scheme" attribute value of
      "urn:ietf:params:rolie:category:information-type".

   By distinguishing between ROLIE and non-ROLIE Collections in this
   way, implementations supporting ROLIE can host Collections pertaining
   to security automation information alongside Collections of other
   non-ROLIE information within the same AtomPub instance.

   The following are additional requirements on the use of the
   app:collection element for a ROLIE Collection:





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   o  The child atom:category elements contained in the app:categories
      element MUST be the same set of atom:category elements used in the
      Atom Feed resource referenced by the app:collection "href"
      attribute value.  This ensures that the category metadata
      associated with the Collection and the associated Feed is
      discoverable in both of these resources.

   o  The app:categories element in an app:collection MAY include
      additional atom:category elements using a scheme other than
      "urn:ietf:params:rolie:category:information-type".  This allows
      other category metadata to be included.

5.1.3.  Service Document Discovery

   The Service Document serves as the "head" of a given ROLIE
   repository: from the Service Document all other repository content
   can be discovered.  A client will need to determine the URL of this
   Service Document to discover the Collections provided by the
   repository.  The client might determine the URL from a web page,
   based on out-of-band communication, or through a "service" link
   relation in a Feed or Entry document that the client has already
   retrieved.  The latter is a typical scenario if the client learns of
   a specific feed or entry through an out-of-band mechanism, and wishes
   to discover additional information provided by the repository.

   This document does not provide a fully automated discovery mechanism.
   A mechanism may be defined in the future that allows automated
   clients to discover the URL to use to retrieve a ROLIE Service
   Document representing the head of the ROLIE repository.

5.2.  Category Documents

   As described in RFC5023 section 7 [RFC5023], a Category Document is
   an XML-based document format that allows a client to dynamically
   discover the Categories used within AtomPub Service Documents, Atom
   Syndication Feeds, and Entry documents provided by a publisher.  A
   Category Document consists of one app:categories element that
   contains a number of inline atom:category elements, or a URI
   referencing a Category Document.

5.3.  Transport Layer Security

   ROLIE is intended to be handled with TLS.  TLS version 1.2 MUST be
   supported.  TLS 1.2 SHOULD be implemented according to all
   recommendations and best practices present in [RFC7525].

   It is RECOMMENDED that the most recent published version of TLS is
   supported.  If this version is TLS 1.3 [I-D.ietf-tls-tls13] it is



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   suggested that 0-RTT (Zero Round Trip Time Resumption) is not used in
   order to prevent replay attacks.  Replay attacks on PUT, POST, or
   DELETE requests can disrupt repository operation by modifying data
   unexpectedly.

   For example, an automated ROLIE repository that updates very
   frequently may receive a PUT request against a given resource a few
   times an hour (or more).  An attacker may store an early PUT request,
   and at the end of the resumption window replay the PUT request,
   reverting the resource to an old version.  Not only could an attacker
   be doing this replay continuously to cause havoc on the server, but
   the client is completely unaware of the attack taking place.

   Given the potentially sensitive nature of data handled by ROLIE, all
   appropriate precautions should be taken at the transport layer to
   protect forward secrecy and user privacy.

   The server MUST implement certificate-based client authentication.
   This MAY be enabled on a workspace by workspace basis.

5.4.  User Authentication and Authorization

   Implementations MUST support user authentication.  However, a given
   implementation MAY allow user authentication to be disabled on a Feed
   by Feed, or Workspace by Workspace basis.

   It is recommended that servers participating in an information
   sharing consortium and supporting interactive user logins by members
   of the consortium support client authentication via a federated
   identity scheme.

   This document does not mandate the use of any specific user
   authorization mechanisms.  However, service implementers SHOULD
   support appropriate authorization checking for all resource accesses,
   including individual Atom Entries, Atom Feeds, and Atom Service
   Documents.

5.5.  / (forward slash) Resource URL

   The "/" resource MAY be supported for compatibility with existing
   deployments that are using Transport of Real-time Inter-network
   Defense (RID) Messages over HTTP/TLS [RFC6546].  The following
   requirements apply only to implementations supporting RFC 6546.

   The following additional requirements only apply if a implementation
   is supporting the "/" resource as described above:





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   o  Consistent with RFC6546 errata, a client requesting a GET on the
      "/" resource SHOULD receive an HTTP status code 405 Method Not
      Allowed.

   o  An implementation MAY provide full support for [RFC6546] such that
      a POST to the "/" resource containing a recognized RID message is
      handled correctly as a RID request.  Alternatively, a client
      requesting a POST to "/" MAY receive an HTTP status code 307
      Temporary Redirect.  In this case, the location header in the HTTP
      response will provide the URL of the appropriate RID endpoint, and
      the client may repeat the POST method at the indicated location.

   If RFC 6546 is unsupported, then a request for the "/" resource may
   be handled as deemed appropriate by the server.

5.6.  HTTP methods

   Servers MAY accept request methods beyond those specified in this
   document.

   Clients MUST be capable of recognizing and processing any standard
   HTTP status code, as defined in [RFC5023] Section 5.

6.  ROLIE Requirements for the Atom Syndication Format

   This section describes a number of restrictions of and extensions to
   the Atom Syndication Format [RFC4287] that define valid use of the
   format in the context of a ROLIE implementation.  An understanding of
   the Atom Syndication Format specification [RFC4287] is helpful to
   understand the requirements in this section.

6.1.  Use of the "atom:feed" element

   As described in RFC4287 section 4.1.1 [RFC4287], an Atom Feed is an
   XML-based document format that describes a list of related
   information items.  The list of Atom Feeds provided by a ROLIE
   service are listed in the service's Service Document through one or
   more app:collection elements.  Each Feed document, represented using
   the atom:feed element, contains a listing of zero or more Entries.

   When applied to the problem domain of security automation information
   sharing, an Atom Feed may be used to represent any meaningful
   collection of security automation information resources.  Each Entry
   in an atom:feed represents an individual resource (e.g., a specific
   checklist, a software vulnerability record).  Additional Feeds can be
   used to represent other collections of security automation resources.





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   As discussed in Section 5.1.2, ROLIE defines specialized data
   requirements for Feeds containing security automation related data.
   The difference between a ROLIE and a non-ROLIE Feed can be determined
   as follows:

   ROLIE Feed:  For an atom:feed to be considered a ROLIE Feed, the
      atom:feed MUST contain only one child atom:category element with
      the "scheme" attribute value of
      "urn:ietf:params:rolie:category:information-type".  This category
      MUST have an appropriate "term" attribute value as defined in
      Section 7.1.1.  This ensures that a given Feed corresponds to a
      specific type of security automation information.

   Non-ROLIE Feed:  For an atom:feed to be considered a non-ROLIE Feed,
      the atom:feed MUST NOT contain an atom:category element with a
      "scheme" attribute value of
      "urn:ietf:params:rolie:category:information-type".

   By distinguishing between ROLIE and non-ROLIE Feeds in this way,
   implementations supporting ROLIE can host Feeds pertaining to
   security automation information alongside Feeds of other non-ROLIE
   information within the same AtomPub instance.  This is parallel to
   the handling of collections ealier in this specification in
   Section 5.1.2.

   The following Atom Feed definition represents a stricter definition
   of the atom:feed element defined in RFC 4287 when used as a ROLIE
   Feed.  Any element not specified here inherits its definition and
   requirements from [RFC4287].

      atomFeed =
         element atom:feed {
            atomCommonAttributes,
            (atomAuthor*
             & atomCategory+
             & atomContributor*
             & atomGenerator?
             & atomIcon?
             & atomId
             & atomLink+
             & atomLogo?
             & atomRights?
             & atomSubtitle?
             & atomTitle
             & atomUpdated
             & extensionElement*),
            atomEntry*
         }



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   The following subsections contain requirements for a ROLIE Feed.

6.1.1.  Use of the "atom:category" Element

   An atom:feed can contain one or more atom:category elements.  In Atom
   the naming scheme and the semantic meaning of the terms used to
   identify an Atom category are application-defined.

   The following are additional requirements on the use of the
   atom:category element when used in a ROLIE Feed:

   o  All member Entries in the Feed MUST represent security automation
      information records of the provided information type category.

   o  An atom:feed MAY include additional atom:category elements using a
      scheme other than "urn:ietf:params:rolie:category:information-
      type".  This allows other category metadata to be included.

6.1.2.  Use of the "atom:link" Element

   Link relations defined by the atom:link element are used to represent
   state transitions using a stateless approach.  In Atom a type of link
   relationship can be defined using the "rel" attribute.

   A ROLIE atom:feed MUST contain one or more atom:link elements with
   rel="service" and href attribute whose value is a URI that points to
   an Atom Service Document associated with the atom:feed.  If a client
   accesses a Feed without first accessing the service's service
   document, a link with the "service" relationship provides a means to
   discover additional security automation information.  The "service"
   link relationship is defined in the IANA Link Relations Registry [1].

   An atom:feed can contain an arbitrary number of Entries.  In some
   cases, a complete Feed may consist of a large number of Entries.
   Additionally, as new and updated Entries are ordered at the beginning
   of a Feed, a client may only be interested in retrieving the first N
   entries in a Feed to process only the Entries that have changed since
   the last retrieval of the Feed.  As a practical matter, a large set
   of Entries will likely need to be divided into more manageable
   portions, or pages.  Based on RFC5005 section 3 [RFC5005], link
   elements SHOULD be included in all Feeds to support paging using the
   following link relation types:

   o  "first" - Indicates that the href attribute value of the link
      identifies a resource URI for the furthest preceding page of the
      Feed.





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   o  "last" - Indicates that the href attribute value of the link
      identifies a resource URI for the furthest following page of the
      Feed.

   o  "previous" - Indicates that the href attribute value of the link
      identifies a resource URI for the immediately preceding page of
      the Feed.

   o  "next" - Indicates that the href attribute value of the link
      identifies a resource URI for the immediately following page of
      the Feed.

   For example:

     <?xml version="1.0" encoding="UTF-8"?>
     <feed xmlns="http://www.w3.org/2005/Atom">
         <id>b7f65304-b63b-4246-88e2-c104049c5fd7</id>
         <title>Paged Feed</title>
         <link rel="self" href="https://example.org/feedA?page=5"/>
         <link rel="first" href="https://example.org/feedA?page=1"/>
         <link rel="prev" href="https://example.org/feedA?page=4"/>
         <link rel="next" href="https://example.org/feedA?page=6"/>
         <link rel="last" href="https://example.org/feedA?page=10"/>
         <updated>2012-05-04T18:13:51.0Z</updated>

         <!-- remainder of feed elements -->
     </feed>

                            Example Paged Feed

   A reference to a historical Feed may need to be stable, and/or a Feed
   may need to be divided into a series of defined epochs.
   Implementations SHOULD support the mechanisms described in RFC5005
   section 4 [RFC5005] to provide link-based state transitions for
   maintaining archiving of Feeds.

   An atom:feed MAY include additional link relationships not specified
   in this document.  If a client encounters an unknown link
   relationship type, the client MUST ignore the unrecognized link and
   continue processing as if the unrecognized link element did not
   appear.  The definition of new Link relations that provide additional
   state transition extensions is discussed in Section 7.3.

6.1.3.  Use of the "atom:updated" Element

   The atom:updated element identifies the date and time that a Feed was
   last updated.




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   The atom:updated element MUST be populated with the current time at
   the instant the Feed was last updated by adding, updating, or
   deleting an Entry; or changing any metadata for the Feed.

6.2.  Use of the "atom:entry" Element

   Each Entry in an Atom Feed, represented by the atom:entry element,
   describes a single referenced information record, along with
   descriptive information about its format, media type, and other
   publication metadata.  The following atom:entry schema definition
   represents a stricter representation of the atom:entry element
   defined in [RFC4287] for use in a ROLIE-based Atom Feed as defined in
   Section 6.1.1.

     atomEntry =
       element atom:entry {
         atomCommonAttributes,
         (atomAuthor*
         & atomCategory*
         & atomContent
         & atomContributor*
         & atomId
         & atomLink*
         & atomPublished?
         & atomRights?
         & atomSource?
         & atomSummary?
         & atomTitle
         & atomUpdated
         & rolieFormat
         & rolieProperty*
         & extensionElement*)
     }

   The notable changes from [RFC4287] are the addition of rolieFormat
   and rolieProperty, and atomContent no longer being optional.

   The following subsections contain requirements for Entries in a ROLIE
   Feed.

6.2.1.  Use of the "atom:content" Element

   An atom:content element associates its containing Entry with a
   content resource identified by the src attribute.

   There MUST be exactly one atom:content element in the Entry.  The
   content element MUST adhere to this definition, which is a stricter
   representation of the atom:content element defined in [RFC4287]:



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     atomContent =
       element atom:content {
         atomCommonAttributes,
         attribute type { atomMediaType },
         attribute src { atomUri },
         empty
     }

   This restricts atomContent in ROLIE to the atomOutofLine formulation
   presented in[RFC4287].

   The type attribute MUST identify the serialization type of the
   content, for example, application/xml or application/json.  A
   prefixed media type MAY be used to reflect a specific model used with
   a given serialization approach (e.g., application/rdf+xml).  The src
   attribute MUST be an URI that can be dereferenced to retrieve the
   related content data.

6.2.2.  Use of the "atom:link" Element

   Link relations can be included in an atom:entry to represent state
   transitions for the Entry.

   If there is a need to provide the same information in different data
   models and/or serialization formats, separate Entry instances can be
   included in the same or a different Feed.  Such an alternate content
   representation can be indicated using an atom:link having a rel
   attribute with the value "alternate".

   An atom:feed MAY include additional link relationships not specified
   in this document.  If a client encounters an unknown link
   relationship type, the client MUST ignore the unrecognized link and
   continue processing as if the unrecognized link element did not
   appear.  The definition of new Link relations that provide additional
   state transition extensions is discussed in Section 7.3.

6.2.3.  Use of the "rolie:format" Element

   As mentioned earlier, a key goal of this specification is to allow a
   consumer to review a set of published security automation information
   resources, and then identify and retrieve any resources of interest.
   The format of the data is a key criteria to consider when deciding
   what information to retrieve.  For a given type of security
   automation information, it is expected that a number of different
   formats may be used to represent this information.  To support this
   use case, both the serialization format and the specific data model
   expressed in that format must be known by the consumer.




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   The rolie:format element is used to describe the data model used to
   express the information referenced in the atom:content element of an
   atom:entry.  It also allows a schema to be identified that can be
   used when parsing the content to verify or better understand the
   structure of the content.

   There MUST be exactly one rolie:format element in an atom:entry.  The
   element MUST adhere to this definition:

     rolieFormat =
       element rolie:format {
         appCommonAttributes,
         attribute ns { atomURI },
         attribute version { text } ?,
         attribute schema-location { atomURI } ?,
         attribute schema-type { atomMediaType } ?,
         empty
     }

   The rolie:format element MUST provide a "ns" attribute that
   identifies the data model of the resource referenced by the
   atom:content element.  For example, the namespace used may be an XML
   namespace URI, or an identifier that represents a serialized JSON
   model.  The URI used for the "ns" attribute MUST be absolute.  The
   resource identified by the URI need not be resolvable.

   The rolie:format element MAY provide a "version" attribute that
   identifies the version of the format used for the related
   atom:content.

   The rolie:format element MAY provide a "schema-location" attribute
   that is a URI that identifies a schema resource that can be used to
   validate the related atom:content.

   The rolie:format element MAY provide a "schema-type" attribute, which
   is a media type (as described in [RFC2045] identifying the format of
   the schema resource identified by the "schema-location" attribute.

   The following nominal example shows how these attributes describe the
   format of the content:

<rolie:format ns="urn:ietf:params:xml:ns:iodef-2.0"
  version="2.0"
  schema-location=
    "https://www.iana.org/assignments/xml-registry/schema/iodef-2.0.xsd"
  schema-type="text/xml"/>





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   The previous element provides an indication that the content of the
   given entry is using the IODEF v2 format.

6.2.4.  Use of the rolie:property Element

   An atom:category element provides a way to associate a name/value
   pair of categorical information using the scheme and term attributes
   to represent the name, and the label attribute to represent the
   value.  When used in this way an atom:category allows a specific
   label to be selected from a finite set of possible label values that
   can be used to further classify a given atom:entry or atom:feed.
   Within ROLIE, there may be a need to associate additional metadata
   with an atom:entry.  In such a case, use of an atom:category is not
   practical to represent name/value data for which the allowed values
   are unbounded.  Instead, ROLIE has introduced a new rolie:property
   element that can represent non-categorical metadata as name/value
   pairs.  Examples include content-specific identifiers, naming data,
   and other properties that allow for unbounded values.

   There MAY be zero or more rolie:property elements in an atom:entry.

   The element MUST adhere to this definition:

     rolieProperty =
       element rolie:property {
         app:appCommonAttributes,
         attribute name { atom:atomURI },
         attribute value { text }
         empty
     }

   The name attribute provides a URI that identifies the namespace and
   name of the property as a URI.

   The value attribute is text that provides a value for the property
   identified by the name attribute.

   For example, the nominal element <rolie:property
   name="urn:ietf:params:rolie:property:content-id" value="12345"/>
   would expose an IODEF ID value contained in a given entry's content.
   The name used in the example also demonstrates the use of a
   registered ROLIE property extension, which is described in
   Section 7.4.

   Implementations MAY use locally defined and namespaced elements in an
   Entry in order to provide additional information.  Clients that do
   not recognize a property with an unregistered name attribute MUST




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   ignore the rolie:property, that is, the client MUST NOT fail parsing
   content that contains an unrecognized property.

6.2.5.  Requirements for a Standalone Entry

   If an Entry is ever shared as a standalone resource, separate from
   its containing Feed, then the following additional requirements
   apply:

   o  The Entry MUST have an atom:link element with rel="collection" and
      href="[URI of the containing Collection]".  This allows the Feed
      or Feeds for which the Entry is a member to be discovered, along
      with the related information the Feed may contain.  In the case of
      the Entry have multiple containing Feeds, the Entry MUST have one
      atom:link for each related Feed.

   o  The Entry MUST declare the information type of the content
      resource referenced by the Entry (see Section 7.1.2).

7.  Available Extension Points Provided by ROLIE

   This specification does not require particular information types or
   data formats; rather, ROLIE is intended to be extended by additional
   specifications that define the use of new categories and link
   relations.  The primary point of extension is through the definition
   of new information type category terms.  Additional specifications
   can register new information type category terms with IANA that serve
   as the main characterizing feature of a ROLIE Collection/Feed or
   Resource/Entry.  These additional specifications defining new
   information type terms, can describe additional requirements for
   including specific categories, link relations, as well as, use of
   specific data formats supporting a given information type term.

7.1.  The Category Extension Point

   The atom:category element, defined in RFC 4287 section 4.2.2
   [RFC4287], provides a mechanism to provide additional categorization
   information for a content resource in ROLIE.  The ability to define
   new categories is one of the core extension points provided by Atom.
   A Category Document, defined in RFC 5023 section 7 [RFC5023],
   provides a mechanism for an Atom implementation to make discoverable
   the atom:category terms and associated allowed values.

   ROLIE further defines the use of the existing Atom extension category
   mechanism by allowing ROLIE specific category extensions to be
   registered with IANA, and additionally has assigned the
   "urn:ietf:params:rolie:category:information-type" category scheme
   that has special meaning for implementations of ROLIE.  This allows



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   category scheme namespaces to be managed in a more consistent way,
   allowing for greater interoperability between content producers and
   consumers.

   Any category whose "scheme" attribute uses an unregistered scheme
   MUST be considered private use.  Implementations encountering such a
   category MUST parse the content without error, but MAY otherwise
   ignore the element.

   Use of the "atom:category" element is discussed in the following
   subsections.

7.1.1.  General Use of the "atom:category" Element

   The atom:category element can be used for characterizing a ROLIE
   Resource.  As discussed earlier in this document, an atom:category
   element has a "term" attribute that indicates the assigned category
   value, and a "scheme" attribute that provides an identifier for the
   category type.  The "scheme" provides a means to describe how a set
   of category terms should be used and provides a namespace that can be
   used to differentiate terms provided by multiple organizations with
   different semantic meaning.

   To further differentiate category types used in ROLIE, an IANA sub-
   registry has been established for ROLIE protocol parameters to
   support the registration of new category "scheme" attribute values by
   ROLIE extension specifications.  Use of this extension point is
   discussed in Section 8.3 using the name field with a type parameter
   of "category" to indicate a category extension.

7.1.2.  Identification of Security Automation Information Types

   A ROLIE specific extension point is provided through the
   atom:category "scheme" value
   "urn:ietf:params:rolie:category:information-type".  This value is a
   Uniform Resource Name (URN) [RFC8141] that is registered with IANA as
   described in Section 8.3.  When used as the "scheme" attribute in
   this way, the "term" attribute is expected to be a registered value
   as defined in Section 8.4.  Through this mechanism a given security
   automation information type can be used to:

   1.  identify that an "app:collection" element in a Service Document
       points to an Atom Feed that contains Entries pertaining to a
       specific type of security automation information (see
       Section 5.1.2), or






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   2.  identify that an "atom:feed" element in an Atom Feed contains
       Entries pertaining to a specific type of security automation
       information (see Section 6.1.1).

   3.  identify the information type of a standalone Resource (see
       Section 6.2.5).

   For example, the notional security automation information type
   "incident" would be identified as follows:

      <atom:category
          scheme="urn:ietf:params:rolie:category:information-type"
          term="incident"/>

   A security automation information type represents a class of
   information that represents the same or similar information model
   [RFC3444].  Note that this document does not register any information
   types, but offers the following as examples of potential information
   types:

   indicator:  Computing device- or network-related "observable features
       and phenomenon that aid in the forensic or proactive detection of
       malicious activity; and associated meta-data" (from [RFC7970]).

   incident:  Information pertaining to and "derived analysis from
       security incidents" (from [RFC7970]).

   vulnerability reports:  Information identifying and describing a
       vulnerability in hardware or software.

   configuration checklists:  Content that can be used to assess the
       configuration settings related to installed software.

   software tags:  Metadata used to identify and characterize
       installable software.

   This is a short list to inspire new engineering of information type
   extensions that support the automation of security processes.

   This document does not specify any information types.  Instead,
   information types in ROLIE are expected to be registered in extension
   documents that describe one or more new information types.  This
   allows the information types used by ROLIE implementations to grow
   over time to support new security automation use cases.  These
   extension documents may also enhance ROLIE Service, Category, Feed,
   and Entry documents by defining link relations, other categories, and
   Format data model extensions to address the representational needs of
   these specific information types.  New information types are added to



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   ROLIE through registrations to the IANA ROLIE Security Resource
   Information Type registry defined in Section 8.4.

7.2.  The "rolie:format" Extension Point

   Security automation data pertaining to a given information type may
   be expressed using a number of supported formats.  As described in
   Section 6.2.3, the rolie:format element is used to describe the
   specific data model used to represent the resource referenced by a
   given "atom:entry".  The structure provided by the rolie:format
   element, provides a mechanism for extension within the atom:entry
   model.  ROLIE extensions MAY further restrict which data models are
   allowed to be used for a given information type.

   By declaring the data model used for a given Resource, a consumer can
   choose to download or ignore the Resource, or look for alternate
   formats.  This saves the consumer from downloading and parsing
   resources that the consumer is not interested in or resources
   expressed in formats that are not supported by the consumer.

7.3.  The Link Relation Extension Point

   This document uses several link relations defined in the IANA Link
   Relation Types registry [2].  Additional link relations can be
   registered in this registry to allow new relationships to be
   represented in ROLIE according to RFC 4287 section 4.2.7.2 [RFC4287].
   Based on the preceding reference, if the link relation is too
   specific or limited in the intended use, an absolute URI can be used
   in lieu of registering a new simple name with IANA.

7.4.  The "rolie:property" Extension Point

   As discussed previously in Section 6.2.4, many formats contain unique
   identifying and characterizing properties that are vital for sharing
   information.  In order to provide a global reference for these
   properties, this document establishes an IANA registry in Section 8.3
   that allows ROLIE extensions to register named properties using the
   name field with a type parameter of "property" to indicate a property
   extension.  Implementations SHOULD prefer the use of registered
   properties over implementation specific properties when possible.

   ROLIE extensions are expected to register new and use existing
   properties to provide valuable identifying and characterizing
   information for a given information type and/or format.

   The namespace "urn:ietf:params:rolie:property:local" has been
   reserved in the IANA ROLIE Parameters table for private use as
   defined in [RFC8126].  Any property whose "name" attribute uses this



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   as a prefix MUST be considered private use.  Implementations
   encountering such a property MUST parse the content without error,
   but MAY otherwise ignore the element.

   This document also registers a number of general use properties that
   can be used to expose content information in any ROLIE use case.  The
   following are descriptions of how to use these registered properties:

   urn:ietf:params:rolie:property:content-author-name  The "value"
      attribute of this property is a text representation indicating the
      individual or organization that authored the content referenced by
      the "src" attribute of the entry's atom:content element.  This
      author may differ from the atom:author when the author of the
      content and the entry are different people or entities.

   urn:ietf:params:rolie:property:content-id  The "value" attribute of
      this property is a text representation of an identifier pertaining
      to or extracted from the content referenced by the "src" attribute
      of the entry's atom:content element.  For example, if the
      atom:entry's atom:content element links to an IODEF document, the
      "content-id" value would be an identifier of that IODEF document.

   urn:ietf:params:rolie:property:content-published-date  The "value"
      attribute of this property is a text representation indicating the
      original publication date of the content referenced by the "src"
      attribute of the entry's atom:content element.  This date may
      differ from the published date of the ROLIE Entry because
      publication of the content and the ROLIE Entry represent different
      events.  The date MUST be formatted as specified in [RFC3339].

   urn:ietf:params:rolie:property:content-updated-date  The "value"
      attribute of this property is a text representation indicating the
      date that the content, referenced by the "src" attribute of the
      entry's atom:content element, was last updated.  This date may
      differ from the updated date of the ROLIE Entry because updates
      made to the content and to the ROLIE Entry are different events.
      The date MUST be formatted as specified in [RFC3339].

8.  IANA Considerations

   This document has a number of IANA considerations described in the
   following subsections.

8.1.  XML Namespaces and Schema URNs

   This document uses URNs to describe XML namespaces and XML schemas
   conforming to a registry mechanism described in [RFC3688].




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   ROLIE XML Namespace  The ROLIE namespace (rolie-1.0) has been
       registered in the "ns" registry.

       URI: urn:ietf:params:xml:ns:rolie-1.0

       Registrant Contact: IESG

       XML: None.  Namespace URIs do not represent an XML specification.

   ROLIE XML Schema  The ROLIE schema (rolie-1.0) has been registered in
       the "schema" registry.

       URI: urn:ietf:params:xml:schema:rolie-1.0

       Registrant Contact: IESG

       XML: See Appendix A of this document.

8.2.  ROLIE URN Sub-namespace

   IANA has added an entry to the "IETF URN Sub-namespace for Registered
   Protocol Parameter Identifiers" registry located at
   <http://www.iana.org/assignments/params/params.xml#params-1> as per
   RFC3553 [RFC3553].

   The entry is as follows:

      Registry name: rolie

      Specification: This document

      Repository: ROLIE URN Parameters.  See Section 8.3 [TO BE REMOVED:
      This registration should take place at the following location:
      https://www.iana.org/assignments/rolie]

      Index value: See Section 8.3

8.3.  ROLIE URN Parameters

   A new top-level registry has been created, entitled "Resource
   Oriented Lightweight Information Exchange (ROLIE) URN Parameters".
   [TO BE REMOVED: This registration should take place at the following
   location: https://www.iana.org/assignments/rolie]

   Registration in the ROLIE URN Parameters registry is via the
   Specification Required policy [RFC8126].  Registration requests must
   be sent to both the MILE WG mailing list (mile@ietf.org) and IANA.
   IANA will forward registration requests to the Designated Expert.



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   Each entry in this sub-registry must record the following fields:

      Name: A URN segment that adheres to the pattern {type}:{label}.
      The keywords are defined as follows:

         {type}: The parameter type.  The allowed values are "category"
         or "property".  "category" denotes a category extension as
         discussed in Section 7.1. "property" denotes a property
         extension as discussed in Section 7.4.

         {label}: A required US-ASCII string that conforms to the URN
         syntax requirements (see [RFC8141]).  This string must be
         unique within the namespace defined by the {type} keyword.  The
         "local" label for both the "category" and "property" types has
         been reserved for private use.

      Extension URI: The identifier to use within ROLIE, which is the
      full URN using the form: urn:ietf:params:rolie:{name}, where
      {name} is the "name" field of this registration.

      Reference: A static link to the specification and section that the
      definition of the parameter can be found.

      Sub-registry: An optional field that links to an IANA sub-registry
      for this parameter.  If the {type} is "category", the sub-registry
      must contain a "name" field whose registered values MUST be US-
      ASCII.  The list of names are the allowed values of the "term"
      attribute in the atom:category element.  (See Section 7.1.2).

   This repository has the following initial values:





















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   +------------+--------------------+-------+-------------------------+
   | Name       | Extension URI      | Refer | Sub-Registry            |
   |            |                    | ence  |                         |
   +------------+--------------------+-------+-------------------------+
   | category:i | urn:ietf:params:ro | This  | [TO BE REMOVED: This    |
   | nformation | lie:category       | docum | registration should     |
   | -type      | :information-type  | ent,  | take place at the       |
   |            |                    | Secti | following location: htt |
   |            |                    | on    | ps://www.iana.org/assig |
   |            |                    | 8.4   | nments/rolie/category   |
   |            |                    |       | /information-type]      |
   | property   | urn:ietf:params:ro | This  | None                    |
   | :content-  | lie:property       | docum |                         |
   | author-    | :content-author-   | ent,  |                         |
   | name       | name               | Secti |                         |
   |            |                    | on    |                         |
   |            |                    | 7.4   |                         |
   | property   | urn:ietf:params:ro | This  | None                    |
   | :content-  | lie:property       | docum |                         |
   | id         | :content-id        | ent,  |                         |
   |            |                    | Secti |                         |
   |            |                    | on    |                         |
   |            |                    | 7.4   |                         |
   | property   | urn:ietf:params:ro | This  | None                    |
   | :content-  | lie:property       | docum |                         |
   | published- | :content-          | ent,  |                         |
   | date       | published-date     | Secti |                         |
   |            |                    | on    |                         |
   |            |                    | 7.4   |                         |
   | property   | urn:ietf:params:ro | This  | None                    |
   | :content-  | lie:property       | docum |                         |
   | updated-   | :content-updated-  | ent,  |                         |
   | date       | date               | Secti |                         |
   |            |                    | on    |                         |
   |            |                    | 7.4   |                         |
   +------------+--------------------+-------+-------------------------+

8.4.  ROLIE Security Resource Information Type Sub-Registry

   A new sub-registry has been created to store ROLIE information type
   values.

      Name of Registry: "ROLIE Information Types"

      Location of Registry:
      https://www.iana.org/assignments/rolie/category/information-type

      Fields to record in the registry:



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         name: The full name of the security resource information type
         as a string from the printable ASCII character set [RFC0020]
         with individual embedded spaces allowed.  This value must be
         unique in the context of this table.  The ABNF [RFC5234] syntax
         for this field is:

            1*VCHAR *(SP 1*VCHAR)

         index: This is an IANA-assigned positive integer that
         identifies the registration.  The first entry added to this
         registry uses the value 1, and this value is incremented for
         each subsequent entry added to the registry.

         reference: A list of one or more URIs [RFC3986] from which the
         registered specification can be obtained.  The registered
         specification MUST be readily and publicly available from that
         URI.  The URI SHOULD be a stable reference.

      Allocation Policy: Specification required as per [RFC8126]

9.  Security Considerations

   This document defines a resource-oriented approach for lightweight
   information exchange using HTTP over TLS, the Atom Syndication
   Format, and the Atom Publishing Protocol.  As such, implementers must
   understand the security considerations described in those
   specifications.  All that follows is guidance, more specific
   instruction is out of scope for this document.

   To protect the confidentiality of a given resource provided by a
   ROLIE implementation, requests for retrieval of the resource need to
   be authenticated to prevent unauthorized users from accessing the
   resource (see Section 5.4).  It can also be useful to log and audit
   access to sensitive resources to verify that proper access controls
   remain in place over time.

   Access control to information published using ROLIE should use
   mechanisms that are appropriate to the sensitivity of the
   information.  Primitive authentication mechanisms like HTTP Basic
   Authentication [RFC7617] are rarely appropriate for sensitive
   information.  A number of authentication schemes are defined in the
   HTTP Authentication Schemes Registry [3].  Of these, HOBA [RFC7486]
   and SCRAM-SHA-256 [RFC7804] provide improved security properties over
   HTTP Basic [RFC7617]and Digest [RFC7616] Authentication Schemes.
   However, sharing communities that are engaged in sensitive
   collaborative analysis and/or operational response for indicators and
   incidents targeting high value information systems should adopt a




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   suitably stronger user authentication solution, such as a risk-based
   or multi-factor approach.

   Collaborating consortiums may benefit from the adoption of a
   federated identity solution, such as those based upon OAuth [RFC6749]
   with JWT [RFC7797], or SAML-core [SAML-core], SAML-bind [SAML-bind],
   and SAML-prof [SAML-prof] for Web-based authentication and cross-
   organizational single sign-on.  Dependency on a trusted third party
   identity provider implies that appropriate care must be exercised to
   sufficiently secure the Identity provider.  Any attacks on the
   federated identity system would present a risk to the consortium, as
   a relying party.  Potential mitigations include deployment of a
   federation-aware identity provider that is under the control of the
   information sharing consortium, with suitably stringent technical and
   management controls.

   Authorization of resource representations is the responsibility of
   the source system, i.e.  based on the authenticated user identity
   associated with an HTTP(S) request.  The required authorization
   policies that are to be enforced must therefore be managed by the
   security administrators of the source system.  Various authorization
   architectures would be suitable for this purpose, such as RBAC [4]
   and/or ABAC, as embodied in XACML [XACML].  In particular,
   implementers adopting XACML may benefit from the capability to
   represent their authorization policies in a standardized,
   interoperable format.  Note that implementers are free to choose any
   suitable authorization mechanism that is capable of fulfilling the
   policy enforcement requirements relevant to their consortium and/or
   organization.

   Additional security requirements such as enforcing message-level
   security at the destination system could supplement the security
   enforcements performed at the source system, however these
   destination-provided policy enforcements are out of scope for this
   specification.  Implementers requiring this capability should
   consider leveraging, e.g. the <RIDPolicy> element in the RID schema.
   Refer to RFC6545 section 9 for more information.  Additionally, the
   underlying serialization approach used in the representation (e.g.,
   XML, JSON) can offer encryption and message authentication
   capabilities.  For example, XMLDSig [RFC3275] for XML, and JSON Web
   Encryption [RFC7516] and JSON Web Signature[RFC7515] for JSON can
   provide such mechanisms.

   When security policies relevant to the source system are to be
   enforced at both the source and destination systems, implementers
   must take care to avoid unintended interactions of the separately
   enforced policies.  Potential risks will include unintended denial of
   service and/or unintended information leakage.  These problems may be



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   mitigated by avoiding any dependence upon enforcements performed at
   the destination system.  When distributed enforcement is unavoidable,
   the usage of a standard language (e.g.  XACML) for the expression of
   authorization policies will enable the source and destination systems
   to better coordinate and align their respective policy expressions.

   A service discovery mechanism is not explicitly specified in this
   document, and there are several approaches available for
   implementers.  When selecting this mechanism, implementations need to
   ensure that their choice provides a means for authenticating the
   server.  As described in the discovery section, DNS SRV Records are a
   possible solution to discovery.

10.  Privacy Considerations

   The optional author field may provide an identification privacy issue
   if populated without the author's consent.  This information may
   become public if posted to a public feed.  Special care should be
   taken when aggregating or sharing entries from other feeds, or when
   programmatically generating ROLIE entries from some data source that
   the author's personal info is not shared without their consent.

   When using the Atom Publishing Protocol to POST entries to a feed,
   attackers may use correlating techniques to profile the user.  The
   request time can be compared to the generated "updated" field of the
   entry in order to build out information about a given user.  This
   correlation attempt can be mitigated by not using HTTP requests to
   POST entries when profiling is a risk, and rather use backend control
   of the Feeds.

   Adoption of the information sharing approach described in this
   document will enable users to more easily perform correlations across
   separate, and potentially unrelated, cyber security information
   providers.  A client may succeed in assembling a data set that would
   not have been permitted within the context of the authorization
   policies of either provider when considered individually.  Thus,
   providers may face a risk of an attacker obtaining an access that
   constitutes an undetected separation of duties (SOD) violation.  It
   is important to note that this risk is not unique to this
   specification, and a similar potential for abuse exists with any
   other cyber security information sharing protocol.  However, the wide
   availability of tools for HTTP clients and Atom Feed handling implies
   that the resources and technical skills required for a successful
   exploit may be less than it was previously.  This risk can be best
   mitigated through appropriate vetting of the client at account
   provisioning time.  In addition, any increase in the risk of this
   type of abuse should be offset by the corresponding increase in
   effectiveness that this specification affords to the defenders.



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   Overall, privacy concerns in ROLIE can be mitigated by following
   security considerations and careful use of the optional personally
   identifying elements (e.g., author) provided by Atom Syndication and
   ROLIE.

11.  Acknowledgements

   The authors gratefully acknowledge the valuable contributions of Tom
   Maguire, Kathleen Moriarty, and Vijayanand Bharadwaj.  These
   individuals provided detailed review comments on earlier drafts, and
   made many suggestions that have helped to improve this document.

   The authors would also like to thank the MILE Working Group, the SACM
   Working Group, and countless other people from both within the IETF
   community and outside of it for their excellent review and effort
   towards constructing this draft.

12.  References

12.1.  Normative References

   [relax-NG]
              Clark, J., Ed., "RELAX NG Compact Syntax", 11 2002,
              <https://www.oasis-open.org/committees/relax-ng/
              compact-20021121.html>.

   [RFC0020]  Cerf, V., "ASCII format for network interchange", STD 80,
              RFC 20, DOI 10.17487/RFC0020, October 1969,
              <https://www.rfc-editor.org/info/rfc20>.

   [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
              <https://www.rfc-editor.org/info/rfc2045>.

   [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>.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
              <https://www.rfc-editor.org/info/rfc3339>.

   [RFC3553]  Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An
              IETF URN Sub-namespace for Registered Protocol
              Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June
              2003, <https://www.rfc-editor.org/info/rfc3553>.



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   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [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>.

   [RFC4287]  Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
              Syndication Format", RFC 4287, DOI 10.17487/RFC4287,
              December 2005, <https://www.rfc-editor.org/info/rfc4287>.

   [RFC5005]  Nottingham, M., "Feed Paging and Archiving", RFC 5005,
              DOI 10.17487/RFC5005, September 2007,
              <https://www.rfc-editor.org/info/rfc5005>.

   [RFC5023]  Gregorio, J., Ed. and B. de hOra, Ed., "The Atom
              Publishing Protocol", RFC 5023, DOI 10.17487/RFC5023,
              October 2007, <https://www.rfc-editor.org/info/rfc5023>.

   [RFC6546]  Trammell, B., "Transport of Real-time Inter-network
              Defense (RID) Messages over HTTP/TLS", RFC 6546,
              DOI 10.17487/RFC6546, April 2012,
              <https://www.rfc-editor.org/info/rfc6546>.

   [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
              2015, <https://www.rfc-editor.org/info/rfc7525>.

   [RFC7970]  Danyliw, R., "The Incident Object Description Exchange
              Format Version 2", RFC 7970, DOI 10.17487/RFC7970,
              November 2016, <https://www.rfc-editor.org/info/rfc7970>.

   [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>.







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   [W3C.REC-xml-names-20091208]
              Bray, T., Hollander, D., Layman, A., Tobin, R., and H.
              Thompson, "Namespaces in XML 1.0 (Third Edition)", World
              Wide Web Consortium Recommendation REC-xml-names-20091208,
              December 2009,
              <http://www.w3.org/TR/2009/REC-xml-names-20091208>.

12.2.  Informative References

   [I-D.ietf-tls-tls13]
              Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", draft-ietf-tls-tls13-21 (work in progress),
              July 2017.

   [REST]     Fielding, R., "Architectural Styles and the Design of
              Network-based Software Architectures", 2000,
              <http://www.ics.uci.edu/~fielding/pubs/dissertation/
              top.htm>.

   [RFC3275]  Eastlake 3rd, D., Reagle, J., and D. Solo, "(Extensible
              Markup Language) XML-Signature Syntax and Processing",
              RFC 3275, DOI 10.17487/RFC3275, March 2002,
              <https://www.rfc-editor.org/info/rfc3275>.

   [RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
              Information Models and Data Models", RFC 3444,
              DOI 10.17487/RFC3444, January 2003,
              <https://www.rfc-editor.org/info/rfc3444>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <https://www.rfc-editor.org/info/rfc5234>.

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,
              <https://www.rfc-editor.org/info/rfc6749>.

   [RFC7486]  Farrell, S., Hoffman, P., and M. Thomas, "HTTP Origin-
              Bound Authentication (HOBA)", RFC 7486,
              DOI 10.17487/RFC7486, March 2015,
              <https://www.rfc-editor.org/info/rfc7486>.

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <https://www.rfc-editor.org/info/rfc7515>.





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   [RFC7516]  Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
              RFC 7516, DOI 10.17487/RFC7516, May 2015,
              <https://www.rfc-editor.org/info/rfc7516>.

   [RFC7616]  Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer, "HTTP
              Digest Access Authentication", RFC 7616,
              DOI 10.17487/RFC7616, September 2015,
              <https://www.rfc-editor.org/info/rfc7616>.

   [RFC7617]  Reschke, J., "The 'Basic' HTTP Authentication Scheme",
              RFC 7617, DOI 10.17487/RFC7617, September 2015,
              <https://www.rfc-editor.org/info/rfc7617>.

   [RFC7797]  Jones, M., "JSON Web Signature (JWS) Unencoded Payload
              Option", RFC 7797, DOI 10.17487/RFC7797, February 2016,
              <https://www.rfc-editor.org/info/rfc7797>.

   [RFC7804]  Melnikov, A., "Salted Challenge Response HTTP
              Authentication Mechanism", RFC 7804, DOI 10.17487/RFC7804,
              March 2016, <https://www.rfc-editor.org/info/rfc7804>.

   [RFC8141]  Saint-Andre, P. and J. Klensin, "Uniform Resource Names
              (URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
              <https://www.rfc-editor.org/info/rfc8141>.

   [SAML-bind]
              Cantor, S., Hirsch, F., Kemp, J., Philpott, R., and E.
              Maler, "Bindings for the OASIS Security Assertion Markup
              Language (SAML) V2.0", OASIS Standard saml-bindings-
              2.0-os, March 2005, <http://docs.oasis-
              open.org/security/saml/v2.0/saml-bindings-2.0-os.pdf>.

   [SAML-core]
              Cantor, S., Kemp, J., Philpott, R., and E. Maler,
              "Assertions and Protocol for the OASIS Security Assertion
              Markup Language (SAML) V2.0", OASIS Standard saml-core-
              2.0-os, March 2005, <http://docs.oasis-
              open.org/security/saml/v2.0/saml-core-2.0-os.pdf>.

   [SAML-prof]
              Hughes, J., Cantor, S., Hodges, J., Hirsch, F., Mishra,
              P., Philpott, R., and E. Maler, "Profiles for the OASIS
              Security Assertion Markup Language (SAML) V2.0", OASIS
              Standard OASIS.saml-profiles-2.0-os, March 2005,
              <http://docs.oasis-open.org/security/saml/v2.0/
              saml-profiles-2.0-os.pdf>.





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   [XACML]    Rissanen, E., "eXtensible Access Control Markup Language
              (XACML) Version 3.0", August 2010, <http://docs.oasis-
              open.org/xacml/3.0/xacml-3.0-core-spec-cs-01-en.pdf>.

12.3.  URIs

   [1] https://www.iana.org/assignments/link-relations/link-
       relations.xhtml

   [2] https://www.iana.org/assignments/link-relations/link-
       relations.xhtml

   [3] https://www.iana.org/assignments/http-authschemes/http-
       authschemes.xhtml

   [4] http://csrc.nist.gov/groups/SNS/rbac/

Appendix A.  Relax NG Compact Schema for ROLIE

   This appendix is informative.

   The Relax NG schema below defines the rolie:format element.





























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   # -*- rnc -*-
   # RELAX NG Compact Syntax Grammar for the rolie ns

   namespace rolie = "urn:ietf:params:xml:ns:rolie-1.0"

   # import the ATOM Syndication RELAX NG Compact Syntax Grammar
   include "atomsynd.rnc"

   # rolie:format
   rolieFormat =
      element rolie:format {
         atomCommonAttributes,
         attribute ns { atomUri },
         attribute version { text } ?,
         attribute schema-location { atomUri } ?,
         attribute schema-type { atomMediaType } ?,
         empty
      }

   # rolie:property

   rolieProperty =
      element rolie:property {
        atomCommonAttributes,
        attribute name { atomUri },
        attribute value { text },
        empty
    }

     }

Appendix B.  Examples of Use

B.1.  Service Discovery

   This section provides a non-normative example of a client doing
   service discovery.

   An Atom Service Document enables a client to dynamically discover
   what Feeds a particular publisher makes available.  Thus, a provider
   uses an Atom Service Document to enable authorized clients to
   determine what specific information the provider makes available to
   the community.  The Service Document should be made accessible from a
   easily found location, such as a link from the producer's home page.

   A client may format an HTTP GET request to retrieve the service
   document from the specified location:




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     GET /rolie/servicedocument
     Host: www.example.org
     Accept: application/atomsvc+xml

   Notice the use of the HTTP Accept: request header, indicating the
   MIME type for Atom service discovery.  The response to this GET
   request will be an XML document that contains information on the
   specific Collections that are provided.

   Example HTTP GET response:

    HTTP/1.1 200 OK
    Date: Fri, 24 Aug 2016 17:09:11 GMT
    Content-Length: 570
    Content-Type: application/atomsvc+xml;charset="utf-8"

    <?xml version="1.0" encoding="UTF-8"?>
    <service xmlns="http://www.w3.org/2007/app"
        xmlns:atom="http://www.w3.org/2005/Atom">
      <workspace>
        <atom:title type="text">Vulnerabilities</atom:title>
        <collection href="https://example.org/provider/vulns">
          <atom:title type="text">Vulnerabilities Feed</atom:title>
          <categories fixed="yes">
            <atom:category
                scheme="urn:ietf:params:rolie:category:information-type"
                term="vulnerability"/>
          </categories>
        </collection>
      </workspace>
    </service>

   This simple Service Document example shows that the server provides
   one workspace, named "Vunerabilities".  Within that workspace, the
   server makes one Collection available.

   A server may also offer a number of different Collections, each
   containing different types of security automation information.  In
   the following example, a number of different Collections are
   provided, each with its own category and authorization scope.  This
   categorization will help the clients to decide which Collections will
   meet their needs.









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    HTTP/1.1 200 OK
    Date: Fri, 24 Aug 2016 17:10:11 GMT
    Content-Length: 1912
    Content-Type: application/atomsvc+xml;charset="utf-8"

    <?xml version="1.0" encoding='utf-8'?>
    <service xmlns="http://www.w3.org/2007/app"
        xmlns:atom="http://www.w3.org/2005/Atom">
      <workspace>
        <atom:title>Public Security Information Sharing</atom:title>
        <collection
            href="https://example.org/provider/public/vulns">
          <atom:title>Public Vulnerabilities</atom:title>
          <atom:link rel="service"
            href="https://example.org/rolie/servicedocument"/>
          <categories fixed="yes">
            <atom:category
                scheme="urn:ietf:params:rolie:category:information-type"
                term="vulnerability"/>
          </categories>
        </collection>
      </workspace>
      <workspace>
        <atom:title>Private Consortium Sharing</atom:title>
        <collection
            href="https://example.org/provider/private/incidents">
          <atom:title>Incidents</atom:title>
          <atom:link rel="service"
            href="https://example.org/rolie/servicedocument"/>
          <categories fixed="yes">
            <atom:category
                scheme="urn:ietf:params:rolie:category:information-type"
                term="incident"/>
          </categories>
        </collection>
      </workspace>
    </service>

   In this example, the provider is making available a total of two
   Collections, organized into two different workspaces.  The first
   workspace contains a Collection consisting of publicly available
   software vulnerabilities.  The second workspace provides an incident
   Collection for use by a private sharing consortium.  An appropriately
   authenticated and authorized client may then proceed to make HTTP
   requests for these Collections.  The publicly provided vulnerability
   information may be accessible with or without authentication.
   However, users accessing the Collection restricted to authorized




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   members of a private sharing consortium are expected to authenticate
   before access is allowed.

B.2.  Feed Retrieval

   This section provides a non-normative example of a client retrieving
   an vulnerability Feed.

   Having discovered the available security information sharing
   Collections, a client who is a member of the general public may be
   interested in receiving the Collection of public vulnerabilities.
   The client may retrieve the Feed for this Collection by performing an
   HTTP GET operation on the URL indicated by the Collection's "href"
   attribute.

   Example HTTP GET request for a Feed:

     GET /provider/public/vulns
     Host: www.example.org
     Accept: application/atom+xml

   The corresponding HTTP response would be an XML document containing
   the vulnerability Feed:

   Example HTTP GET response for a Feed:


























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     HTTP/1.1 200 OK
     Date: Fri, 24 Aug 2016 17:20:11 GMT
     Content-Length: 2882
     Content-Type: application/atom+xml;charset="utf-8"

     <?xml version="1.0" encoding="UTF-8"?>
     <feed xmlns="http://www.w3.org/2005/Atom"
         xmlns:rolie="urn:ietf:params:xml:ns:rolie-1.0"
         xml:lang="en-US">
       <id>2a7e265a-39bc-43f2-b711-b8fd9264b5c9</id>
       <title type="text">
           Atom formatted representation of
           a feed of XML vulnerability documents
       </title>
       <category
           scheme="urn:ietf:params:rolie:category:information-type"
           term="vulnerability"/>
       <updated>2016-05-04T18:13:51.0Z</updated>
       <link rel="self"
           href="https://example.org/provider/public/vulns" />
       <link rel="service"
           href="https://example.org/rolie/servicedocument"/>
       <entry>
         <rolie:format ns="urn:ietf:params:xml:ns:exampleformat"/>
         <id>dd786dba-88e6-440b-9158-b8fae67ef67c</id>
         <title>Sample Vulnerability</title>
         <published>2015-08-04T18:13:51.0Z</published>
         <updated>2015-08-05T18:13:51.0Z</updated>
         <summary>A vulnerability issue identified by CVE-...</summary>
         <content type="application/xml"
             src="https://example.org/provider/vulns/123456/data"/>
       </entry>

       <entry>
           <!-- ...another entry... -->
       </entry>

     </feed>

   This Feed document has two Atom Entries, one of which has been
   elided.  The first Entry illustrates an atom:entry element that
   provides a summary of essential details about one particular
   vulnerability.  Based upon this summary information and the provided
   category information, a client may choose to do an HTTP GET request,
   on the content "src" attribute, to retrieve the full details of the
   vulnerability.





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B.3.  Entry Retrieval

   This section provides a non-normative example of a client retrieving
   an vulnerability as an Atom Entry.

   Having retrieved the Feed of interest, the client may then decide,
   based on the description and/or category information, that one of the
   entries in the Feed is of further interest.  The client may retrieve
   this vulnerability Entry by performing an HTTP GET operation on the
   URL indicated by the "src" attribute of the atom:content element.

   Example HTTP GET request for an Entry:

     GET /provider/public/vulns/123456
     Host: www.example.org
     Accept: application/atom+xml;type=entry

   The corresponding HTTP response would be an XML document containing
   the Atom Entry for the vulnerability record:

   Example HTTP GET response for an Entry:

     HTTP/1.1 200 OK
     Date: Fri, 24 Aug 2016 17:30:11 GMT
     Content-Length: 713
     Content-Type: application/atom+xml;type=entry;charset="utf-8"

     <?xml version="1.0" encoding="UTF-8"?>
     <entry xmlns="http://www.w3.org/2005/Atom"
         xmlns:rolie="urn:ietf:params:xml:ns:rolie-1.0"
         xml:lang="en-US">
       <id>f63aafa9-4082-48a3-9ce6-97a2d69d4a9b</id>
       <title>Sample Vulnerability</title>
       <published>2015-08-04T18:13:51.0Z</published>
       <updated>2015-08-05T18:13:51.0Z</updated>
       <category
           scheme="urn:ietf:params:rolie:category:information-type"
           term="vulnerability"/>
       <summary>A vulnerability issue identified by CVE-...</summary>
       <rolie:format ns="urn:ietf:params:xml:ns:exampleformat"/>
       <content type="application/xml"
           src="https://example.org/provider/vulns/123456/data">
       </content>
     </entry>

   The example response above shows an XML document referenced by the
   "src" attribute of the atom:content element.  The client may retrieve
   the document using this URL.



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Appendix C.  Change History

   Changes in draft-ietf-mile-rolie-14 since draft-ietf-mile-rolie-13
   revision:

      Removed /.well-known registration and updated Discovery text.

      Fixed small namespacing error in RNC schema.

   Changes in draft-ietf-mile-rolie-13 since draft-ietf-mile-rolie-12
   revision:

      Adjusted .well-known registration.

      Updated IANA Consideration text.

   Changes in draft-ietf-mile-rolie-11 since draft-ietf-mile-rolie-09
   revision:

      Incorporated ART last call review and AD review changes.

   Changes in draft-ietf-mile-rolie-09 since draft-ietf-mile-rolie-08
   revision:

      TLS requirements changed to clarify TLS versioning and
      recommendations

      Informative references and textual discussion added to Security
      Considerations around HTTP Authentication and content Signing/
      Encryption.

      IANA Expert review clarified.

      Editorial changes from AD review/WGLC.

   Changes in draft-ietf-mile-rolie-08 since draft-ietf-mile-rolie-07
   revision:

      Reworked "usage of app:collection" and "usage of atom:feed"
      sections to clarify ROLIE vs non-ROLIE collections/feeds

      Removed requirement from Security Considerations that was a
      duplicate of text earlier in the document

      TLS requirement clarifications around mutal authentication

      Clarified requirements around support for the "/" resource




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      Added IANA property registrations for content-id, content-
      published-date, and content-updated-date that can be used across
      all ROLIE extensions to increase consistency/interop

      Assorted editorial changes

   Changes in draft-ietf-mile-rolie-07 since draft-ietf-mile-rolie-06
   revision:

      Condensed and re-focused Sections 1 and 4 to be more concise.

      Added /.well-known/ registration and requirement for service
      discovery.

      Added local category, property namespace, and additional property
      registrations

      Added privacy considerations section.

      Made a number of editorial changes as per WGLC review.

   Changes in draft-ietf-mile-rolie-06 since draft-ietf-mile-rolie-05
   revision:

      Changed to standards track

      Added the rolie:property element

      Fixed references (Normative vs Informative)

      Set Service and Category document URL template requirements

      Fixed XML snippets in examples

   Changes in draft-ietf-mile-rolie-05 since draft-ietf-mile-rolie-04
   revision:

      Added ROLIE specific terminology to section 2

      Added AtomPub Category Document in section 5.2

      Edited document, improving consistency in terminology usage and
      capitalization of key terms, as well as enhancing clarity.

      Removed unused format parameter type in section 8.3

      Schema removed, the normative schema consists of the snippets in
      the requirements sections.



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   Changes in draft-ietf-mile-rolie-04 since draft-ietf-mile-rolie-03
   revision:

   o  Further specification and clarification of requirements

   o  IANA Considerations and extension system fleshed out and
      described.

   o  Examples and References updated.

   o  Schema created.

   o  Fixed both internal section and external document referencing.

   o  Removed XACML Guidance Appendix.  This will be added to a future
      draft on ROLIE Authentication and Access Control.

   Changes made in draft-ietf-mile-rolie-03 since draft-ietf-mile-
   rolie-02 revision:

   o  Atom Syndication and Atom Pub requirements split and greatly
      expanded for increased justification and technical specification.

   o  Reintroduction and reformatting of some use case examples in order
      to provide some guidance on use.

   o  Established rough version of IANA table extension system along
      with explanations of said system.

   o  Re-organized document to put non-vital information in appendices.

   Changes made in draft-ietf-mile-rolie-02 since draft-field-mile-
   rolie-01 revision:

   o  All CSIRT and IODEF/RID material moved to companion CSIRT document

   o  Recast document into a more general use perspective.  The
      implication of CSIRTs as the defacto end-user has been removed
      where ever possible.  All of the original CSIRT based use cases
      remain completely supported by this document, it has been opened
      up to support many other use cases.

   o  Changed the content model to broaden support of representation

   o  Edited and rewrote much of sections 1,2 and 3 in order to
      accomplish a broader scope and greater readability





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   o  Removed any requirements from the Background section and, if not
      already stated, placed them in the requirements section

   o  Re-formatted the requirements section to make it clearer that it
      contains the lions-share of the requirements of the specification

   Changes made in draft-ietf-mile-rolie-01 since draft-field-mile-
   rolie-02 revision:

   o  Added section specifying the use of RFC5005 for Archive and Paging
      of Feeds.

   o  Added section describing use of atom categories that correspond to
      IODEF expectation class and impact classes.  See: normative-
      expectation-impact

   o  Dropped references to adoption of a MILE-specific HTTP media type
      parameter.

   o  Updated IANA Considerations section to clarify that no IANA
      actions are required.

Authors' Addresses

   John P. Field
   Pivotal Software, Inc.
   625 Avenue of the Americas
   New York, New York
   USA

   Phone: (646)792-5770
   Email: jfield@pivotal.io


   Stephen A. Banghart
   National Institute of Standards and Technology
   100 Bureau Drive
   Gaithersburg, Maryland
   USA

   Phone: (301)975-4288
   Email: stephen.banghart@nist.gov









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   David Waltermire
   National Institute of Standards and Technology
   100 Bureau Drive
   Gaithersburg, Maryland  20877
   USA

   Email: david.waltermire@nist.gov












































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