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Versions: 00 01

RATS Working Group                                           H. Birkholz
Internet-Draft                                            Fraunhofer SIT
Intended status: Standards Track                            P. Uiterwijk
Expires: January 14, 2021                                        Red Hat
                                                                N. Smith
                                                                   Intel
                                                     J. Fitzgerald-McKay
                                                   Department of Defense
                                                           D. Waltermire
                                                                    NIST
                                                             S. Bhandari
                                                                   Cisco
                                                           July 13, 2020


     Reference Integrity Measurement Extension for Concise Software
                               Identities
                   draft-birkholz-rats-coswid-rim-01

Abstract

   Concise Software Identification (CoSWID) tags identify and describe
   individual software components, patches, and installation bundles.
   CoSWID is based on ISO/IEC 19770-2:2015 2:2015 that provides a
   complementary XML schema definition (XSD) for Software Identification
   (SWID) tags.  CoSWID supports the same features as the corresponding
   XML SWID tags.  The CoSWID specification also includes more
   structured extensibility features and reduces a few of ambiguities
   that are not explicitly resolved in the ISO XSD.  In this document,
   these extensibility features (extension points) are used to add
   attributes to the CoSWID specification.  The new attributes allow for
   the use of CoSWID as Reference Integrity Measurements (RIM).  There
   are four sets of RIM features defined in this specification. 1.)
   attributes that support RIM manifests for Measured Boot, 2.)
   attributes that support package manager managed structures, 3.)
   attributes that allow for OID to be used in the description of
   Reference Integrity Measurements, and 4.) attributes for object trees
   in support of Target Environments that are chained via Layered
   Attestation.

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




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   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 14, 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Notation . . . . . . . . . . . . . . . . . .   4
   2.  CoSWID Attribute Extensions . . . . . . . . . . . . . . . . .   5
     2.1.  RIM requirements on existing CoSWID attributes  . . . . .   5
     2.2.  RIM Extensions for Measured Boot  . . . . . . . . . . . .   5
     2.3.  RIM Extensions for Software Package Management  . . . . .  11
     2.4.  RIM Extensions for Composite Device . . . . . . . . . . .  12
       2.4.1.  The tcb-info Group  . . . . . . . . . . . . . . . . .  12
       2.4.2.  CoSWID Version Scheme for RPM . . . . . . . . . . . .  14
     2.5.  Additional Measurement Attributes for CoSWID  . . . . . .  14
     2.6.  CoSWID RIM CDDL . . . . . . . . . . . . . . . . . . . . .  14
   3.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  17
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  18
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  18
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  18
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  18
     6.3.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .  19
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  19





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1.  Introduction

   Reference Integrity Measurements describe the intended state of
   (composite) software components installed on a (composite) device.  A
   measurement of all installed software components of a devices allows
   for assertions about the trustworthiness of the given device.  In
   combination with a root of trust (RoT) for reporting (RTR), these
   measurements can be refined into evidence and enable IETF Remote
   ATtestation procedureS (RATS).  RATS support the decision process of
   whether to put trust in the trustworthiness of a device - or not.

   The RATS architecture [I-D.ietf-rats-architecture] defines the roles
   Verifiers, Attesters, Endorsers, and Relying Parties.  The RATS
   architecture also specifies that Attestation Evidence is created by
   Attesters and consumed by Verifiers.  Ultimately, the goal is to
   enable a Relying Party to put trust in the trustworthiness of a
   remote peer (the Attester).  Attestation Evidence is composed of
   believable assertions about an Attester's trustworthiness
   characteristics.  In RATS, these assertions are called Claims.  The
   Verifier conducts a set of appraisal procedures in order to assess
   the compliance of an Attester's trustworthiness characteristics.

   A prominent appraisal procedure in RATS is the comparison of Claim
   values included in Attestation Evidence with Reference Claim values
   provided by Endorsers (e.g. supply chain entities).  The comparison
   of Claim values via Reference Claim values is vital for the
   assessment of compliance metrics with respect to software components
   installed on an Attester.  A typical objective here is the
   remediation of already vulnerabilities discovered in certain versions
   of software components.

   The Integrity Measurement Architecture (IMA) of the Linux Security
   Modules (LSM) provides a detailed Event Log (sometimes also referred
   to as a Measurement Log) that retains a sequence of hash measurements
   of every software sub-component (e.g. a firmware, an ELF executable,
   or a configuration file) that is created and appended to the sequence
   of measurements that composes the event log before the software
   component in question is started or read.

   In essence, to enable this appraisal procedure conducted by Verfiers
   an Attester's IMA provides Event Logs that include the hash values of
   every started software component and therefore are part of the
   Attestation Evidence an Attester creates.  The complementary well-
   known-values that Verifiers require are included in the Reference
   Integrity Measurements (RIM).  RIMs can be provided via Software
   Identification tags created by Endorsers, such as the software
   creators, manufacturers, vendors, or other trusted third parties
   (e.g. supply chain or certification entities).



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   This document provides an extension to the CoSWID specification
   defined in [I-D.ietf-sacm-coswid].  The extension adds attributes to
   CoSWID tags that enable them to express RIMs.  One prominent subset
   of these attributes are illustrated in the TCG Reference Integrity
   Manifest Information Model [ref] specification.  These attributes are
   added to the existing CoSWID specification via the most general
   extension point the CoSWID specification provides: $$coswid-
   extensions.  An additional map definition named "reference-
   measurements" is added and is defined in section [ref] of this
   document.  Another prominent subset is the addition of an object tree
   next to the file system tree as defined by [I-D.ietf-sacm-coswid].
   The object tree enables the representation of multiple layered
   execution environments as described by the Layered Attestation
   concept in the RATS architecture [I-D.ietf-rats-architecture].

   Furthermore, a usage profile for signed CoSWID tags is defined in
   this specification in support of the software-component structure of
   systems managed by package managers.  Signed CoSWID tags that are
   aligned with that software model can be used to describe the contents
   of one or multiple of the packages that make up the contents of a
   system.  In this case, it may be that multiple CoSWID tags are
   provided as Reference Claim values for a attestation by a single
   Attester.  In order to minimize the impact on the sizes of packages,
   it is likely that any CoSWID tags delivered as part of packages as
   part of a package manager managed system will not contain actual
   reference values, but instead a link-entry to a CoSWID tag published
   by the vendor in a repository.

   Reference Integrity Measurements are a subset of the Conceptual
   Messages defined as Endorsements.  RIMs provide a vital resource to
   be consumed by Verifiers in conjunction with Appraisal Policies and
   Evidence.  While RIMs represent nominal values, Appraisal Policies
   represent imperative guidance how to use nominal values in an
   appraisal procedure.  Evidence represents assertions about the
   trustworthiness of a device's Target Environments created by its own
   Attesting Environment.  As Evidence can be rather complex and its
   appraisal therefore a burden for Relying Parties that are interested
   in trustworthiness evaluations, Verifies take on this duty and create
   easier to digest Attestation Results for Relying Parties.  In
   consequence, Verifiers are the entities that have to put trust in the
   provenance and integrity of RIMs - and Endorsements in general -
   relying on proof of integrity and authenticity.

1.1.  Requirements Notation

   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



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   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  CoSWID Attribute Extensions

   This specification defines four types of attribute sets that can be
   added to the CoSWID specification via its defined extension points.

   1.  Attributes that support RIM manifests for Measured Boot (often
       referred to as Secure Boot),

   2.  Attributes that support the RPM package manager structure,

   3.  Attributes that allow to represent composite devices including
       several Target Environments, and

   4.  Attributes that allow for OID to be used in the description of
       Reference Integrity Measurements.

2.1.  RIM requirements on existing CoSWID attributes

   As defined by NIST IR 8060 [ref], there are required "Meta
   Attributes" for XML SWID tags that have to be included in a SWID tag
   in order to compose a valid SWID RIM.  In this section, these
   attributes are mapped to CoSWID attributes and corresponding
   requirements on attributes defined in the CoSWID specification to
   compose valid NIST IR 8060 signed Payload content in the Concise
   Software Identity Reference Integrity Measurement (CoSWID RIM)
   representation.

   The 'software-meta-entry' type defined in the CoSWID specification
   includes the optional members 'product', 'colloquial-version',
   'revision', and 'edition'.  These four members MUST be included in a
   CoSWID RIM in order to compose a valid Reference Integrity
   Measurement in alignment with NIST IR 8060.  Furthermore, the
   semantics of the text (tstr) typed values MUST convey content that
   allows for semantic interoperability in a given scope (e.g., an
   administrative domain).  The software-meta-entries provide vital
   support for steering decisions made by the RATS verifier role in
   order to enable discovery and matching of related or additional
   CoSWID RIM available to or discoverable by the verifier.

2.2.  RIM Extensions for Measured Boot

   The following attributes are derived from the TCG Reference Integrity
   Manifest Information Model [ref] specification.  These attributes
   support the creation of very small CoSWID RIM tags that enable the
   Remote Integrity Verification (RIV



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   [I-D.fedorkow-rats-network-device-attestation]) of small things,
   i.e., constrained devices in constrained network environments.  In
   consequence, the majority of the attributes listed in this section
   represent metadata about firmware and supply chain entities that
   provide firmware for a device (platform).  Analogously to the
   mandated software-meta-entries illustrated above, the attributes
   defined in the table below provide more context and enable steering
   decisions for the appraisal procedures of a Verifier.  Consecutively,
   RIM have to be managed and curated in a consistent manner so that
   there is no significant threshold for a Verifier to make use of them
   during an appraisal procedure.

   The design of the additional RIM attributes in this section is
   motivated by the vast variety of identifier types used in production
   today, e.g. endorsement documents [I-D.ietf-rats-architecture] that
   are enrolled or on-boarded on the Attester itself.  It is vital to
   highlight that this variety can render semantic self-descriptiveness
   more difficult.  Most importantly though: interoperability beats
   self-descriptiveness.  A convergence towards a common identification
   scheme with respect to software components and its subset that is
   firmware is highly encouraged - alas not achieved at the time of
   creating this proposed standard.  The following table defines the
   semantics of the set of new members that are added via the reference-
   measurement-entry map.  The reference-measurement-entry map is added
   using the $$coswid-extension CDDL extension point.

   +--------------------------------+----------+-----------------------+
   | Attribute Name                 | Quantity | Description           |
   +--------------------------------+----------+-----------------------+
   | payload-type                   | 0-1      | The value of this     |
   |                                |          | attribute MUST be one |
   |                                |          | equivalent of the     |
   |                                |          | following three       |
   |                                |          | choices. 'direct':    |
   |                                |          | the representation    |
   |                                |          | used in this RIM (and |
   |                                |          | referred RIMs) is     |
   |                                |          | using the CoSWID      |
   |                                |          | encoding as its       |
   |                                |          | representation.       |
   |                                |          | 'indirect': the       |
   |                                |          | representation used   |
   |                                |          | in referred RIMs      |
   |                                |          | ('Support RIMs) is    |
   |                                |          | using a different     |
   |                                |          | representation than   |
   |                                |          | CoSWID as it's        |
   |                                |          | encoding.             |



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   |                                |          | Analogously, a        |
   |                                |          | reference to the      |
   |                                |          | corresponding         |
   |                                |          | specification MUST be |
   |                                |          | provided if the value |
   |                                |          | is set to an          |
   |                                |          | equivalent of         |
   |                                |          | 'indirect' (see       |
   |                                |          | binding-spec-name and |
   |                                |          | binding-spec-         |
   |                                |          | version). 'hybrid':   |
   |                                |          | the representation    |
   |                                |          | used in the referred  |
   |                                |          | RIMs ('Support RIMs') |
   |                                |          | is a mix of CoSWID    |
   |                                |          | representations and   |
   |                                |          | other                 |
   |                                |          | representations. In   |
   |                                |          | this case, a          |
   |                                |          | reference to the      |
   |                                |          | representation used   |
   |                                |          | MUST be included -    |
   |                                |          | even if it is the     |
   |                                |          | CoSWID representation |
   |                                |          | - for every Support   |
   |                                |          | RIM (see 'binding-    |
   |                                |          | spec-name' and        |
   |                                |          | 'binding-spec-        |
   |                                |          | version' definition   |
   |                                |          | in this table).       |
   |                                |          |                       |
   | platform-configuration-uri-    | 0-1      | A byte-comparable     |
   | global                         |          | reference to a        |
   |                                |          | Platform              |
   |                                |          | Configuration URI as  |
   |                                |          | defined by the TCG    |
   |                                |          | Platform Certificate  |
   |                                |          | Profile [ref TCG      |
   |                                |          | Platform Certificate  |
   |                                |          | Profile, Version 1.1] |
   |                                |          | for X.509v3           |
   |                                |          | certificates that     |
   |                                |          | MUST be identical to  |
   |                                |          | the URI included in a |
   |                                |          | TCG Platform          |
   |                                |          | Certificate pointing  |
   |                                |          | to a resource         |
   |                                |          | providing a copy of   |



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   |                                |          | the CoSWID RIM this   |
   |                                |          | attribute is included |
   |                                |          | in.                   |
   |                                |          |                       |
   | platform-configuration-uri-    | 0-1      | A byte-comparable     |
   | local                          |          | reference to a        |
   |                                |          | Platform              |
   |                                |          | Configuration URI     |
   |                                |          | defined by the TCG    |
   |                                |          | Platform Certificate  |
   |                                |          | Profile [ref TCG      |
   |                                |          | Platform Certificate  |
   |                                |          | Profile, Version 1.1] |
   |                                |          | that MUST represent   |
   |                                |          | the resource at which |
   |                                |          | a copy of this CoSWID |
   |                                |          | RIM can be found      |
   |                                |          | within the            |
   |                                |          | (composite)           |
   |                                |          | device/platform       |
   |                                |          | itself.               |
   |                                |          |                       |
   | binding-spec-name              | 1        | If the value of       |
   |                                |          | 'payload-type' is an  |
   |                                |          | equivalent to the     |
   |                                |          | enumeration           |
   |                                |          | 'indirect', the value |
   |                                |          | of this attribute     |
   |                                |          | MUST contain a global |
   |                                |          | unique text (tstr)    |
   |                                |          | identifier referring  |
   |                                |          | to the specification  |
   |                                |          | that defines the      |
   |                                |          | representation of the |
   |                                |          | referred RIM in order |
   |                                |          | to enable its         |
   |                                |          | decoding.             |
   |                                |          |                       |
   | binding-spec-version           | 1        | If the value of       |
   |                                |          | 'payload-type' is an  |
   |                                |          | equivalent to the     |
   |                                |          | enumeration           |
   |                                |          | 'indirect', the value |
   |                                |          | of this attribute     |
   |                                |          | MUST contain a unique |
   |                                |          | version number with   |
   |                                |          | respect to the        |
   |                                |          | specification         |



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   |                                |          | represented in the    |
   |                                |          | value of 'binding-    |
   |                                |          | spec-name'.           |
   |                                |          |                       |
   | platform-manufacturer-id       | 0-1      | An identifier based   |
   |                                |          | on the IANA Private   |
   |                                |          | Enterprise Number     |
   |                                |          | registry that is      |
   |                                |          | assigned to firmware  |
   |                                |          | manufacturer. This    |
   |                                |          | identifier MUST be    |
   |                                |          | included unless the   |
   |                                |          | firmware manufacturer |
   |                                |          | and the platform      |
   |                                |          | manufacturer are      |
   |                                |          | represented by the    |
   |                                |          | same text (tstr)      |
   |                                |          | value. Analogously,   |
   |                                |          | if the firmware       |
   |                                |          | manufacturer and the  |
   |                                |          | platform manufacturer |
   |                                |          | are represented via   |
   |                                |          | the same text (tstr)  |
   |                                |          | value, this attribute |
   |                                |          | MAY be omitted.       |
   |                                |          |                       |
   | platform-manufacturer-name     | 0-1      | An identifier number  |
   |                                |          | (uint) value that     |
   |                                |          | uniquely represents   |
   |                                |          | the firmware          |
   |                                |          | manufacturer. This    |
   |                                |          | identifier MUST be    |
   |                                |          | included unless the   |
   |                                |          | firmware manufacturer |
   |                                |          | and the platform      |
   |                                |          | manufacturer are      |
   |                                |          | represented via the   |
   |                                |          | same number (unit)    |
   |                                |          | value, this attribute |
   |                                |          | MAY be omitted.       |
   |                                |          |                       |
   | platform-model-name            | 1        | An identifier text    |
   |                                |          | (tstr) value enabling |
   |                                |          | the identification of |
   |                                |          | a certain device      |
   |                                |          | model/type composite. |
   |                                |          | The reliability of    |
   |                                |          | this identifier is    |



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   |                                |          | not absolute. In      |
   |                                |          | consequence this      |
   |                                |          | identifier MUST NOT   |
   |                                |          | be omitted. In an     |
   |                                |          | case, the use of this |
   |                                |          | identifier requires   |
   |                                |          | foresight and         |
   |                                |          | preparation as it's   |
   |                                |          | purpose supports      |
   |                                |          | semantic              |
   |                                |          | interoperability.     |
   |                                |          | Arbitrary,            |
   |                                |          | conflicting, or       |
   |                                |          | unresolvable values   |
   |                                |          | SHOULD be avoided.    |
   |                                |          |                       |
   | platform-version               | 0-1      | A byte-comparable     |
   |                                |          | reference to a        |
   |                                |          | Platform              |
   |                                |          | Certificate's         |
   |                                |          | 'Manufacturer-        |
   |                                |          | Specific Identifier'  |
   |                                |          | extension value [ref  |
   |                                |          | TCG Platform          |
   |                                |          | Certificate Profile,  |
   |                                |          | Version 1.1].         |
   |                                |          |                       |
   | firmware-manufacturer-id       | 0-1      | An IANA defined       |
   |                                |          | unique value that is  |
   |                                |          | a Private Enterprise  |
   |                                |          | Number (Platform      |
   |                                |          | manufacturer unique   |
   |                                |          | identifier) that      |
   |                                |          | SHOULD be included in |
   |                                |          | a CoSWID RIM that     |
   |                                |          | covers firmware.      |
   |                                |          |                       |
   | firmware-manufacturer-name     | 0-1      | An identifier that is |
   |                                |          | represented as the    |
   |                                |          | name of a platform    |
   |                                |          | manufacturer via a    |
   |                                |          | text (tstr) value     |
   |                                |          | that SHOULD be        |
   |                                |          | included in a CoSWID  |
   |                                |          | RIM that covers       |
   |                                |          | firmware.             |
   |                                |          |                       |
   | firmware-model-name            | 0-1      | An identifier that    |



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   |                                |          | represents the target |
   |                                |          | platform model via a  |
   |                                |          | text (tstr) value     |
   |                                |          | that SHOULD be        |
   |                                |          | included in a CoSWID  |
   |                                |          | RIM.                  |
   |                                |          |                       |
   | firmware-version               | 0-1      | An identifier that is |
   |                                |          | represented as the    |
   |                                |          | version number of a   |
   |                                |          | specific firmware     |
   |                                |          | version corresponding |
   |                                |          | to a given set of     |
   |                                |          | platform identifiers  |
   |                                |          | and SHOULD be         |
   |                                |          | included in a CoSWID  |
   |                                |          | RIM.                  |
   |                                |          |                       |
   | boot-events                    | 0-1      | A reference to the    |
   |                                |          | platform measured     |
   |                                |          | boot event logs that  |
   |                                |          | can be compared to    |
   |                                |          | individual events     |
   |                                |          | from the platform     |
   |                                |          | measured boot events  |
   |                                |          | collected at platform |
   |                                |          | runtime.              |
   +--------------------------------+----------+-----------------------+

2.3.  RIM Extensions for Software Package Management

   To enable very small CoSWID tags that basically are signed references
   to full Base RIMs for each software package that ultimately include
   all the hash values required by the appraisal procedure of a
   Verifier, the member rim-reference is added using the $$payload-
   extension CDDL extension point.

   +---------------+----------+----------------------------------------+
   | Attribute     | Quantity | Description                            |
   | Name          |          |                                        |
   +---------------+----------+----------------------------------------+
   | rim-reference | 0-1      | A URI pointing to the CoSWID Base RIM  |
   |               |          | that will list the payload reference   |
   |               |          | measurements (hashes) in case of a     |
   |               |          | minimal CoSWID tag.                    |
   +---------------+----------+----------------------------------------+





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2.4.  RIM Extensions for Composite Device

   Attesters that are composite devices can include several Target
   Environments.  Some of these Target Environments can take on the
   duties of Attesting Environments during a boot sequence as described
   in section 4.3. of the RATS architecture
   [I-D.ietf-rats-architecture].  The corresponding procedure is called
   Layered Attestation and requires a dedicated RIM for each Target
   Environment of the Attester.  The addition of object tree attributes
   to CoSWID using the $$resource-collection-extension extension point
   addresses the resulting requirements.

   Each Target Environment involved in Layered Attestation can be
   considered its own Trusted Computing Base (TCB) [ref].  TCB metadata
   can be used to identify or locate RIMs.  The addition of TCB
   information to the new object tree structure is in support of these
   identifiers for RIM discovery.

   Additionally, software components started in these Target
   Environments might not be referenceable via a filesystem (e.g., in
   the case of firmware).  To enable RIMs to represent firmware items
   that are not associated with a filesystem, attributes for object
   trees are added to the existing filesystem items tree.

2.4.1.  The tcb-info Group

   Every object in the object tree can be represented with a set of
   metadata items pertaining a specific TCB.  The following items can be
   associated with a dedicate object-entry:

   +-----------------------+----------+--------------------------------+
   | Attribute Name        | Quantity | Description                    |
   +-----------------------+----------+--------------------------------+
   | tcb-info.id           | 1        | A hash of the tcb-info.key-    |
   |                       |          | elements value including the   |
   |                       |          | map structure                  |
   |                       |          |                                |
   | tcb-info.key-elements | 1        | A collection of attributes     |
   |                       |          | that disambiguates the various |
   |                       |          | TCB objects in a composite     |
   |                       |          | device scope                   |
   |                       |          |                                |
   | tcb-info.vendor       | 1        | The entity that named the      |
   |                       |          | measurement of the Target      |
   |                       |          | Environment TCB referenced by  |
   |                       |          | an object-entry                |
   |                       |          |                                |
   | tcb-info.model        | 0-1      | The product name associated    |



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   |                       |          | with the object-entry in a     |
   |                       |          | measurement                    |
   |                       |          |                                |
   | tcb-info.layer        | 0-1      | The layer in the composite     |
   |                       |          | devive (and therefore object   |
   |                       |          | tree) of the TCB associated    |
   |                       |          | with the object-entry in a     |
   |                       |          | measurement                    |
   |                       |          |                                |
   | tcb-info.index        | 0-1      | An index that enumerates       |
   |                       |          | TCB/object-entries in a CoSWID |
   |                       |          | RIM tag                        |
   |                       |          |                                |
   | tcb-info.type         | 1        | A machine-readable description |
   |                       |          | of the measurement             |
   |                       |          |                                |
   | tcb-info.version      | 0-1      | A revision string associated   |
   |                       |          | with the measurement and a     |
   |                       |          | reference value                |
   |                       |          |                                |
   | tcb-info.SVN          | 0-1      | The security version number    |
   |                       |          | associated with the            |
   |                       |          | measurement and a reference    |
   |                       |          | value                          |
   |                       |          |                                |
   | tcb-info.flags        | 0-1      | Operational states associated  |
   |                       |          | with a TCB or composite device |
   |                       |          | that affects the object being  |
   |                       |          | measured. If omitted, the TCB  |
   |                       |          | or omposite device is not      |
   |                       |          | capable of entering this       |
   |                       |          | state. Valid states are: not-  |
   |                       |          | configured, not-secure,        |
   |                       |          | recovery, debug.               |
   |                       |          |                                |
   | tcb-info.fwids        | 0-1      | A list of digests resulting    |
   |                       |          | from applying the hash         |
   |                       |          | algorithm over the object      |
   |                       |          | being measured                 |
   |                       |          |                                |
   | tcb-info.vendorinfo   | 0-1      | Actual values or state that is |
   |                       |          | associated with a TVB element  |
   |                       |          |                                |
   | tcb-info.vendormask   | 0-1      | A mask that allows a Verifier  |
   |                       |          | to ignore a subset of          |
   |                       |          | collected tcb-info.vendorinfo  |
   |                       |          | values that the Endorser       |
   |                       |          | asserts are not security       |



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   |                       |          | relevant                       |
   +-----------------------+----------+--------------------------------+

2.4.2.  CoSWID Version Scheme for RPM

   To enable encoding version information into a CoSWID of RPM packages,
   the SWID version scheme value index TBD1 has been registered.  RPM
   versions are defined as epoch:version-release-architecture, where the
   "epoch:" component is optional.  Epoch is a numerical value, which
   should be considered zero if the epoch component is missing.  Version
   and Release can be any string as long as they do not contain a hyphen
   (-).  Architecture is an alphanumerical string.

   Sorting of RPM versions is a multi-step process: - The epoch, version
   and release components are compared in that order, as soon as a
   difference is found, that is the overall difference. - The epoch
   component is compared as integers.  A higher number means a higher
   version. - The version and release components are compared
   alphabetically, until a digit is encountered in both strings, at
   which point as many digits are consumed from both to form an integer,
   which is then compared.  If the integers are identical, the
   comparison continues alphabetically. - The architecture component is
   never sorted.  If they are different between two versions, the
   versions are inequal, not higher or lower.

2.5.  Additional Measurement Attributes for CoSWID

   [I-D.ietf-sacm-coswid] specifies a well-defined file hash structure
   for integrity measurements of individual files in a file-system.
   This documents extends this feature to all additional members of the
   resource-collection group: 'directory', 'resource', and 'process'.
   These new well-defined measurement options extend the scope of RIM to
   (sub-)trees of files, software running in memory (e.g. available from
   Trusted Execution Environments, such as SGX enclaves), and even
   external resources, such as remote services of collections of RIM
   bundles.

2.6.  CoSWID RIM CDDL

   The following CDDL specification uses the existing CDDL extension
   points as defined in [I-D.ietf-sacm-coswid]:

   o  $$coswid-extension

   o  $$payload-extension

   o  $$directory-extension




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   o  $$resource-extension

   o  $$process-extension

   o  $$link-extension

   o  $$resource-collection-extension

<CODE BEGINS>
$$coswid-extension //= (reference-measurement => reference-measurement-entry)

reference-measurement-entry = {
  ? payload-type => direct / indirect / hybrid,
  ? platform-configuration-uri-global => any-uri,
  ? platform-configuration-uri-local => any-uri,
  binding-spec-name => text,
  binding-spec-version => text,
  platform-manufacturer-id => uint,
  platform-manufacturer-name => text,
  platform-model-name => text,
  ? platform-version => uint,
  ? firmware-manufacturer-id => uint,
  ? firmware-manufacturer-name => text,
  ? firmware-model-name => text,
  ? firmware-version => uint,
  ? boot-events => [ * boot-event-entry ],
  rim-link-hash => bytes,
}

boot-event-entry = {
   boot-event-number => uint,
   boot-event-type => uint,
   boot-digest-list => [ 1* hash-entry ],
   boot-event-data => bytes
}

$$payload-extension //= ( ? support-rim-type-kramdown => direct / indirect )
$$payload-extension //= ( ? support-rim-format => text )
$$payload-extension //= ( ? support-rim-uri-global => any-uri )
$$payload-extension //= ( ? rim-reference => any-uri )

reference-measurement = 58
payload-type = 59
payload-rim = 60
platform-configuration-uri-global = 61
platform-configuration-uri-local = 62
binding-spec-name = 63
binding-spec-version = 64



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platform-manufacturer-id = 65
platform-manufacturer-name = 66
platform-model-name = 67
platform-version = 68
firmware-manufacturer-id = 69
firmware-manufacturer-name = 70
firmware-model-name = 71
firmware-version = 72
rim-link-hash = 73
support-rim-type-kramdown = 74
support-rim-format = 75
support-rim-uri-global = 76
rim-reference = 77
boot-events = 78
boot-event-number = 79
boot-event-type = 80
boot-digest-list = 81
boot-event-data = 82

direct = 0
indirect = 1
hybrid = 2

$$directory-extension //= ( ? hash => hash-entry )

$$resource-extension //= ( ? hash => hash-entry )

$$process-extension //= ( ? hash => hash-entry )

$$link-extension //= ( ? thumbprint => hash-entry )

$$resource-collection-extension //= (
  ? object => object-entry / [ 2* object-entry ]
)

object-entry = {
  resource-collection,
  tcb-info,
  $$object-extension,
}

tcb-info = (
  tcb-info.id => hash-entry,
  tcb-info.key-elements => {
    tcb-info.vendor => text,
    ? tcb-info.model => text,
    ? tcb-info.layer => int,
    ? tcb-info.index => int,



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    tcb-info.type => tagged-bytes / uuid-bytes,
  },
  ? tcb-info.version => text,
  ? tcb-info.SVN => int,
  ? tcb-info.flags => uint .bits tcb-info.operational-flags,
  ? tcb-info.fwids,
  ? tcb-info.vendorinfo => bytes .size 8,
  ? tcb-info.vendormask => bytes,
)

uuid-bytes = bytes .size 8

tcb-info.operational-flags = &(
  not-configured: 0,
  not-secure: 1,
  recovery: 2,
  debug: 3,
)

tcb-info.fwids = [
  + [ hash-alg: [ * int ] / text,
      digest: bytes,
    ]
]

object = 83
tcb-info.id = 84
tcb-info.key-elements = 85
tcb-info.vendor = 86
tcb-info.model = 87
tcb-info.layer = 88
tcb-info.index = 89
tcb-info.type = 90
tcb-info.version = 91
tcb-info.SVN = 92
tcb-info.flags = 93
tcb-info.fwids = 94
tcb-info.vendorinfo = 95
tcb-info.vendormask = 96
<CODE ENDS>

3.  Privacy Considerations

   TBD







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4.  Security Considerations

   To be elaborated on

5.  IANA Considerations

   This document has added the following entries to the SWID/CoSWID
   Version Scheme Values registry at https://www.iana.org/assignments/
   swid [1]:

   Index: TBD1
   Version Scheme Name: rpm
   Specification: See {{rpm-version-scheme}}

6.  References

6.1.  Normative References

   [I-D.ietf-sacm-coswid]
              Birkholz, H., Fitzgerald-McKay, J., Schmidt, C., and D.
              Waltermire, "Concise Software Identification Tags", draft-
              ietf-sacm-coswid-15 (work in progress), May 2020.

   [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>.

   [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>.

6.2.  Informative References

   [I-D.fedorkow-rats-network-device-attestation]
              Fedorkow, G., Voit, E., and J. Fitzgerald-McKay, "TPM-
              based Network Device Remote Integrity Verification",
              draft-fedorkow-rats-network-device-attestation-05 (work in
              progress), April 2020.

   [I-D.ietf-rats-architecture]
              Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
              W. Pan, "Remote Attestation Procedures Architecture",
              draft-ietf-rats-architecture-05 (work in progress), July
              2020.






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6.3.  URIs

   [1] https://www.iana.org/assignments/swid

Authors' Addresses

   Henk Birkholz
   Fraunhofer SIT
   Rheinstrasse 75
   Darmstadt  64295
   Germany

   Email: henk.birkholz@sit.fraunhofer.de


   Patrick Uiterwijk
   Red Hat
   100 E Davie Street
   Raleigh  27601
   Netherlands

   Email: puiterwijk@redhat.com


   Ned Smith
   Intel Corporation
   USA

   Email: ned.smith@intel.com


   Jessica Fitzgerald-McKay
   Department of Defense
   9800 Savage Road
   Ft. Meade, Maryland
   USA

   Email: jmfitz2@nsa.gov


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

   Email: david.waltermire@nist.gov




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   Shwetha Bhandari
   Cisco Systems, Inc.
   Cessna Business Park, Sarjapura Marathalli Outer Ring Road
   Bangalore, KARNATAKA  560087
   India

   Email: shwethab@cisco.com












































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