Software Update for the Internet of Things (SUIT) Manifest Extensions for Multiple Trust Domain
draft-ietf-suit-trust-domains-12

SUIT                                                            B. Moran
Internet-Draft                                               Arm Limited
Intended status: Standards Track                             K. Takayama
Expires: 23 January 2026                                 SECOM CO., LTD.
                                                            22 July 2025

 Software Update for the Internet of Things (SUIT) Manifest Extensions
                       for Multiple Trust Domain
                    draft-ietf-suit-trust-domains-12

Abstract

   A device has more than one trust domain when it enables delegation of
   different rights to mutually distrusting entities for use for
   different purposes or Components in the context of firmware or
   software update.  This specification describes extensions to the
   Software Update for the Internet of Things (SUIT) Manifest format for
   use in deployments with multiple trust domains.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

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

   This Internet-Draft will expire on 23 January 2026.

Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   5
   3.  Changes to SUIT Workflow Model  . . . . . . . . . . . . . . .   6
   4.  Changes to Manifest Metadata Structure  . . . . . . . . . . .   6
   5.  Dependencies  . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1.    Changes to Required Checks  . . . . . . . . . . . . . .   8
     5.2.  Changes to Manifest Structure . . . . . . . . . . . . . .  10
       5.2.1.  Manifest Component ID . . . . . . . . . . . . . . . .  10
       5.2.2.  SUIT_Dependencies Manifest Element  . . . . . . . . .  10
     5.3.  Changes to Abstract Machine Description . . . . . . . . .  12
     5.4.  Processing Dependencies . . . . . . . . . . . . . . . . .  13
       5.4.1.  Multiple Manifest Processors  . . . . . . . . . . . .  13
     5.5.  Dependency Resolution . . . . . . . . . . . . . . . . . .  14
     5.6.  Added and Modified Commands . . . . . . . . . . . . . . .  14
       5.6.1.  suit-directive-set-parameters . . . . . . . . . . . .  15
       5.6.2.  suit-directive-process-dependency . . . . . . . . . .  16
       5.6.3.  suit-condition-is-dependency  . . . . . . . . . . . .  17
       5.6.4.  suit-condition-dependency-integrity . . . . . . . . .  17
       5.6.5.  suit-directive-unlink . . . . . . . . . . . . . . . .  17
   6.  Uninstall . . . . . . . . . . . . . . . . . . . . . . . . . .  18
   7.  Staging and Installation  . . . . . . . . . . . . . . . . . .  19
     7.1.  suit-candidate-verification . . . . . . . . . . . . . . .  19
   8.  Creating Manifests  . . . . . . . . . . . . . . . . . . . . .  20
     8.1.  Dependency Template . . . . . . . . . . . . . . . . . . .  20
       8.1.1.  Integrated Dependencies . . . . . . . . . . . . . . .  21
     8.2.  Encrypted Manifest Template . . . . . . . . . . . . . . .  21
     8.3.  Overriding Encryption Info Template . . . . . . . . . . .  22
     8.4.  Operating on Multiple Components  . . . . . . . . . . . .  24
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  25
     9.1.  SUIT Envelope Elements  . . . . . . . . . . . . . . . . .  26
     9.2.  SUIT Manifest Elements  . . . . . . . . . . . . . . . . .  26
     9.3.  SUIT Common Elements  . . . . . . . . . . . . . . . . . .  26
     9.4.  SUIT Commands . . . . . . . . . . . . . . . . . . . . . .  26
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  27
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  28
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  28
     11.2.  Informative References . . . . . . . . . . . . . . . . .  29

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   Appendix A.  A.  Full CDDL  . . . . . . . . . . . . . . . . . . .  30
   Appendix B.  B.  Examples . . . . . . . . . . . . . . . . . . . .  31
     B.1.  Example 0: Process Dependency . . . . . . . . . . . . . .  32
     B.2.  Example 1: Integrated Dependency  . . . . . . . . . . . .  36
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  38

1.  Introduction

   Devices that require more advanced configurations than a Manifest
   signed by a single authority also require more complex rules for
   deploying software updates.  For example, devices may require:

   *  Components from multiple software signing authorities

   *  a mechanism to remove an unneeded Component

   *  Dependencies delivered in the same envelope as the Manifest

   *  a partly encrypted Manifest so that distribution does not reveal
      private information

   *  installation performed by a different execution mode than payload
      fetch

   Devices implementing this specification typically partition their
   software, dividing it, according to physical or logical features,
   into multiple "domains" with different requirements for authorities:
   multiple trust domains.  Because of the more complex use cases that
   are typically targetted by devices implementing this specification,
   the applicable device class is typically Class 2 or higher and often
   isolation level Is8, for example Arm TrustZone for Cortex-M, as
   described in [I-D.ietf-iotops-7228bis].

   Dependencies enable several additional use cases.  In particular,
   they enable two or more entities who are trusted for different
   privileges to coordinate.  This can be used in many scenarios.  For
   example:

   *  Devices with network interface controllers (NICs), including
      radios, may contain secondary processors in the NICs in addition
      to the device primary processor.  These two processors may have
      separate Software with separate signing authorities.  Dependencies
      allow the Manifest for the primary processor to reference a
      Manifest signed by a different authority.

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   *  A network operator may wish to provide local caching of Update
      Payloads.  The network creates a Dependent Manifest that provides
      a different URI for any Payloads they wish to cache the parameter
      override mechanism described in Section 5.6.1.

   *  A Device Administrator provides a device with some additional
      configuration.  The Device Administrator wants to test their
      configuration with each new Software version before releasing it.
      The configuration is delivered as a binary in the same way as a
      Software Image.  The Device Administrator references the Software
      Manifest from the Software author in their own Manifest which also
      defines the configuration.

   *  An Author wants to entrust a Distributor to provide devices with
      firmware decryption keys, but not permit the Distributor to sign
      code.  Dependencies allow the Distributor to deliver a device's
      decryption information without also granting code signing
      authority.

   *  A Trusted Application Manager (TAM) wants to distribute
      personalisation information to a Trusted Execution Environment in
      addition to a Trusted Application (TA), but does not have code
      signing authority (see [RFC9397], Section 2).  Dependencies enable
      the TAM to construct an update containing the personalisation
      information and a dependency on the TA, but leaves the TA signed
      by the TA's Author.

   When a system has multiple trust domains, each domain might require
   independent verification of authenticity or security policies.  Trust
   domains might be divided by separation technology such as Arm
   TrustZone, Intel SGX, or another Trusted Execution Environment (TEE)
   technology.  Trust domains might also be divided into separate
   processors and memory spaces, with a communication interface between
   them.

   For example, an application processor may have an attached
   communications module that contains a processor.  The communications
   module might require metadata signed by a specific Trust Authority
   for regulatory approval.  This may be a different Trust Authority
   than the application processor.

   Dependencies enable Components such as Software, configuration, and
   other Resource data authenticated by different Trust Anchors to be
   delivered to devices.

   These mechanisms are not part of the core Manifest specification
   ([I-D.ietf-suit-manifest]), but they are needed for more advanced use
   cases, such as the architecture described in [RFC9397].

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   This specification extends the SUIT Manifest specification
   ([I-D.ietf-suit-manifest]) with:

   *  Integrated Components

   *  Dependencies

   *  Manifest Component Identifier

   *  Candidate Verification

   *  Parameter Override support

   *  Uninstall support

2.  Conventions and 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 terminology from [I-D.ietf-suit-manifest], Section 2 and
   [RFC9397], Section 2 is used in this specification.  Additionally,
   the following terminology is used:

   *  Dependency: A Manifest that is required by a second Manifest in
      order for operations described by the second Manifest to complete
      successfully.

   *  Dependent: A Manifest that depends on another Mani

   *  Root Manifest: A manifest that has no dependents and, combined
      with all Dependencies (recursively) specifies a complete Component
      Set.

   *  Staging Procedure: A procedure that fetches dependencies and
      images referenced by an Update and stores them to a Staging Area.

   *  Installation Procedure: A procedure that installs dependencies and
      images stored in a Staging Area; copying (and optionally,
      transforming them) into an active Image storage location.

   *  Staging Area: A Component or group of Components that are used for
      transient storage of Images between fetch and installation.
      Images in this area are opaque, except for use by the Installation
      Procedure.

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   *  Reference Count: An implementation-defined mechanism to track the
      number of manifests that refer to another manifest.

3.  Changes to SUIT Workflow Model

   The use of the features presented for use with multiple trust domains
   requires some augmentation of the workflow presented in the SUIT
   Manifest specification ([I-D.ietf-suit-manifest]):

   One additional assumption is added to the list of assumptions for the
   Update Procedure in [I-D.ietf-suit-manifest], Section 4.2:

   *  All Dependencies must be fetched and integrity checked before any
      Payload is fetched.

   One additional assumption is added to the list of assumptions for the
   Invocation Procedure in [I-D.ietf-suit-manifest], Section 4.2:

   *  All Dependencies must be validated prior to loading.

   Steps 3 and 5 are added to the expected installation workflow of a
   Recipient:

   1.  Verify the signature of the Manifest.

   2.  Verify the applicability of the Manifest.

   3.  Resolve Dependencies.

   4.  Fetch Payload(s).

   5.  Verify Candidate Component Set.

   6.  Install Payload(s).

   7.  Verify image(s).

   In addition, when multiple Manifests are used for an Update, each
   Manifest's steps occur in a lockstep fashion: all Manifests have
   Dependency resolution performed before any Manifest performs a
   Payload fetch, etc.  The lockstep process is described in
   Section 5.4.

4.  Changes to Manifest Metadata Structure

   To accommodate the additional metadata needed to enable these
   features, the Envelope and Manifest are augmented with several new
   elements:

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   *  Envelope

      -  Integrated Dependency

   *  Manifest

      -  Common

         o  Dependency Metadata

      -  Component Identifier

      -  Dependency Resolution SUIT_Command_Sequence

      -  Candidate Verification SUIT_Command_Sequence

   In addition several new SUIT_Commands are added:

   *  SUIT Conditions

      -  Dependency Integrity Check

      -  Component Is Dependency Check

   *  SUIT Directives

      -  Process Dependency

      -  Set Parameters

      -  Unlink

   The Envelope gains two more elements: Integrated Dependencies and
   Integrated Payloads.  The Common metadata section in the Manifest
   also gains a list of Dependencies.

   The new metadata structure is shown below.

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   +-------------------------+
   | Envelope                |
   +-------------------------+
   | Authentication Block    |
   | Manifest           --------------> +------------------------------+
   | Severable Elements      |          | Manifest                     |
   | Integrated Dependencies |          +------------------------------+
   | Integrated Payloads     |          | Structure Version            |
   +-------------------------+          | Sequence Number              |
                                        | Reference to Full Manifest   |
                                  +------ Common Structure             |
                                  | +---- Command Sequences            |
   +-------------------------+    | |   | Digests of Envelope Elements |
   | Common Structure        | <--+ |   +------------------------------+
   +-------------------------+      |
   | Dependency Indices      |      +-> +-----------------------+
   | Component IDs           |          | Command Sequence      |
   | Common Command Sequence ---------> +-----------------------+
   +-------------------------+          | List of ( pairs of (  |
                                        |   * command code      |
                                        |   * argument /        |
                                        |      reporting policy |
                                        | ))                    |
                                        +-----------------------+

                     Figure 1: SUIT Metadata Structure

   This is an update of the figure in Section 4.2 of
   [I-D.ietf-suit-manifest]

5.  Dependencies

   A Dependency is another SUIT_Envelope ([I-D.ietf-suit-manifest],
   section 8.2) that describes additional Components.

5.1.    Changes to Required Checks

   This section augments the definitions in Required Checks
   ([I-D.ietf-suit-manifest], Section 6.2).

   More checks are required when handling Dependencies.  By default, any
   signature of a Dependency MUST be verified.  However, there are some
   exceptions to this rule: where a device supports only one level of
   access (no ACLs, [I-D.ietf-suit-manifest], Section 9, declaring which
   authorities have access to different Components/Commands/Parameters),
   it MAY choose to skip signature verification of Dependencies, since
   they are verified by digest.  Where a device differentiates between
   trust levels, such as with an ACL, it MAY choose to defer the

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   verification of signatures of Dependencies until the list of affected
   Components is known so that it can skip redundant signature
   verifications.  For example, if a dependent's signer has access
   rights to all Components specified in a Dependency, then that
   Dependency does not require a signature verification.  Similarly, if
   the signer of the dependent has full rights to the device, according
   to the ACL, then no signature verification is necessary on the
   Dependency.

   Components that should be treated as Dependencies are identified in
   the suit-common metadata (Section 5.2).

   Any required check that fails MUST result in an Abort.

   Prior to executing any Command Sequence:

   1.  If the interpreter does not support Dependencies and a Manifest
       specifies a Dependency, then the interpreter MUST Abort.

   2.  If the Manifest contains more than one Component and/or
       Dependency, each Command sequence MUST begin with a Set Component
       Index Command.

   If a Dependency is specified, then the Manifest Processor MUST
   perform the following additional checks:

   1.  Prior to executing any Command Sequence: the dependent MUST
       populate all Command Sequences for each Procedure specified by
       the Dependency; either the Staging Procedure, the Update
       Procedure, the Installation Procedure, or the Invocation
       Procedure.

   2.  At the end of each section in the dependent: The corresponding
       section in each Dependency has been executed, if present.

   If a Recipient supports groups of interdependent Components (a
   Component Set), then prior to fetching any payload, it SHOULD verify
   that all Components in the Component Set are specified by a single
   Manifest and all its Dependencies that together:

   1.  Have sufficient permissions imparted by their signatures.

   2.  Specify a digest and a Payload for every Component in the
       Component Set.

   Failing to verify the availablility of all components may lead to API
   mismatches and other version mismatch problems.

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   The single dependent Manifest is called a Root Manifest.

5.2.  Changes to Manifest Structure

   This section augments the Manifest Structure (Section 8.4) in
   [I-D.ietf-suit-manifest].

5.2.1.  Manifest Component ID

   In complex systems, it may not always be clear where the Root
   Manifest is stored; this is particularly complex when a system has
   multiple, independent Root Manifests.  The Manifest Component ID
   resolves this contention.  The manifest-component-id is intended to
   be used by the Root Manifest.  The manifest-component-id is only used
   when storing a Root Manifest.  The manifest-component-id is ignored
   when processing Dependencies.

   The following CDDL (see [RFC8610]) describes the Manifest Component
   ID:

   $$SUIT_Manifest_Extensions //=
       (suit-manifest-component-id => SUIT_Component_Identifier)

5.2.2.  SUIT_Dependencies Manifest Element

   The suit-common section, as described in [I-D.ietf-suit-manifest],
   Section 8.4.5 is extended with a map of Component indices that
   indicate a Dependency.  The keys of the map are the Component indices
   and the values of the map are any extra metadata needed to describe
   those Dependencies.

   Because some operations treat Dependencies differently from other
   Components, it is necessary to identify them.  SUIT_Dependencies
   identifies which Components from suit-components
   ([I-D.ietf-suit-manifest], Section 8.4.5) are to be treated as the
   SUIT_Envelope of a Dependency.  SUIT_Dependencies is a map of
   Components, referenced by Component Index.  Optionally, a Component
   prefix or other metadata may be delivered with the Component index.
   The CDDL for suit-dependencies is shown below:

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   $$SUIT_Common-extensions //= (
       suit-dependencies => SUIT_Dependencies
   )
   SUIT_Dependencies = {
       + uint => SUIT_Dependency_Metadata
   }
   SUIT_Dependency_Metadata = {
       ? suit-dependency-prefix => SUIT_Component_Identifier
       * $$SUIT_Dependency_Extensions
   }

   If no extended metadata is needed for an extension,
   SUIT_Dependency_Metadata is an empty map (this is the same encoding
   size as a null).  SUIT_Dependencies MUST be sorted according to Core
   Deterministic Encoding Requirements ([RFC8949], Section 4.2.1).

   The Components specified by SUIT_Dependency_Metadata will contain a
   Manifest Envelope that describes a Dependency of the current
   Manifest.  The Manifest is identified, but the Recipient should
   expect an Envelope when it acquires the Dependency.  This is because
   the Manifest is the one invariant element of the Envelope, where
   other elements may change by countersigning, adding authentication
   blocks, or severing elements.

   When executing suit-condition-image-match over a Component that is
   designated in SUIT_Dependency_Metadata, the digest MUST be computed
   over just the bstr-wrapped SUIT_Manifest contained in the Manifest
   Envelope designated by the Component Index.  This enables a
   Dependency reference to uniquely identify a particular Manifest
   structure.  This is identical to the digest that is present as the
   first element of the suit-authentication-block in the Dependency's
   Envelope.  The digest is calculated over the Manifest structure to
   ensure that removing a signature from a Manifest does not break
   Dependencies due to missing signature elements.  This is also
   necessary to support the trusted intermediary use case, where an
   intermediary re-signs the Manifest, removing the original signature,
   potentially with a different algorithm, or trading COSE_Sign for
   COSE_Mac.

   The suit-dependency-prefix element contains a
   SUIT_Component_Identifier ([I-D.ietf-suit-manifest],
   Section 8.4.5.1).  This specifies the scope at which the Dependency
   operates.  This allows the Dependency to be forwarded on to a
   Component that is capable of parsing its own Manifests.  It also
   allows one Manifest to be deployed to multiple dependent Recipients
   without those Recipients needing consistent Component hierarchy.
   suit-dependency-prefix is OPTIONAL for Recipients to implement.

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   A Dependency prefix can be used with a Component identifier.  This
   allows complex systems to understand where Dependencies need to be
   applied.  The Dependency prefix can be used in one of two ways.  The
   first simply prepends the prefix to all Component Identifiers in the
   Dependency.

   A Dependency prefix can also be used to indicate when a Dependency
   needs to be processed by a secondary Manifest Processor, as described
   in Section 5.4.1.

5.3.  Changes to Abstract Machine Description

   This section augments the Abstract Machine Description in
   [I-D.ietf-suit-manifest], Section 6.4.  With the addition of
   Dependencies, some changes are necessary to the abstract machine,
   outside the typical scope of added Commands.  These changes alter the
   behaviour of an existing Command and way that the parser processes
   Manifests:

   *  Five new Commands are introduced in Section 5.6:

      -  Set Parameters

      -  Process Dependency

      -  Is Dependency

      -  Dependency Integrity

      -  Unlink

   *  Dependencies have Component Identifiers.  All Commands may target
      Dependencies as well as Components, with one exception: suit-
      directive-process-dependency.  Future commands MAY define their
      own restrictions on applicability to Dependencies and non-
      Dependency Components.

   *  Dependencies are processed in lockstep with the Root Manifest.
      This means that every Dependency's current Command sequence must
      be executed before a dependent's later Command sequence may be
      executed.  For example, every Dependency's Dependency Resolution
      step must be executed before any dependent's Payload fetch step.

   *  When a Manifest Processor supports multiple independent
      Components, they may have shared Dependencies.

   *  When a Manifest Processor supports shared Dependencies, it MUST
      support reference counting of those Dependencies.

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   *  When reference counting is used, Components MUST NOT be
      overwritten.  The Manifest Uninstall section must be called, then
      the component MUST be Unlinked.

5.4.  Processing Dependencies

   As described in Section 5.1, the Manifest Processor must ensure that
   a Manifest with Dependencies invokes suit-directive-process-
   dependency for each of its Dependencies' sections from the
   corresponding section of the dependent.  Any changes made to
   Parameters by the Dependency persist in the dependent.

   When a Process Dependency Command is encountered, the Manifest
   Processor:

   1.  Checks whether the map of Dependencies contains an entry for the
       current Component Index.  If not present, it causes an immediate
       Abort.

   2.  Checks whether the Dependency has been the target of a Dependency
       integrity check.  If not, it causes an immediate Abort.

   3.  Performs any application-specific setup that is required to parse
       the specified Component as a SUIT_Envelope of a Dependency.

   4.  Authenticates the Dependency.

   5.  Executes the common-sequence section of the Dependency.

   6.  Executes the section of the Dependency that corresponds to the
       currently executing section of the dependent.

   If the specified Dependency does not contain the current section,
   Process Dependency succeeds immediately.

   The interpreter also performs the checks described in Section 5.1 to
   ensure that the dependent is processing the Dependency correctly.

5.4.1.  Multiple Manifest Processors

   When there are two or more trust domains, a Manifest Processor might
   be required in each.  The first Manifest Processor is the normal
   Manifest Processor as described for the Recipient in Section 6 of
   [I-D.ietf-suit-manifest].  The second Manifest Processor only
   executes sections when the first Manifest Processor requests it.  An
   API interface is provided from the second Manifest Processor to the
   first.  This allows the first Manifest Processor to request a limited
   set of operations from the second.  These operations are limited to:

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   setting Parameters, inserting an Envelope, and invoking a Manifest
   Command Sequence.  The second Manifest Processor declares a prefix to
   the first, which tells the first Manifest Processor when it should
   delegate to the second.  These rules are enforced by underlying
   separation of privilege infrastructure, such as TEEs, or physical
   separation.

   When the first Manifest Processor encounters a Dependency prefix,
   that informs the first Manifest Processor that it should provide the
   second Manifest Processor with the corresponding Dependency Envelope.
   This is done when the Dependency is fetched.  The second Manifest
   Processor immediately verifies any authentication information in the
   Dependency Envelope.  When a Parameter is set for any Component that
   matches the prefix, this Parameter setting is passed to the second
   Manifest Processor via an API.  As the first Manifest Processor works
   through the Procedure (set of Command sequences) it is executing,
   each time it sees a Process Dependency Command that is associated
   with the prefix declared by the second Manifest Processor, it uses
   the API to ask the second Manifest Processor to invoke that
   Dependency section instead.

   This mechanism ensures that the two or more Manifest Processors do
   not need to trust each other, except in a very limited case.  When
   Parameter setting across trust domains is used, it must be very
   carefully considered.  Only Parameters that do not have an effect on
   security properties should be allowed.  The Dependency MAY control
   which Parameters are allowed to be set by using the Override
   Parameters Directive.  The second Manifest Processor MAY also control
   which Parameters may be set by the first Manifest Processor by means
   of an ACL that lists the allowed Parameters.  For example, a URI may
   be set by a dependent without a substantial impact on the security
   properties of the Manifest.

5.5.  Dependency Resolution

   The Dependency Resolution Command Sequence is a container for the
   Commands needed to acquire and process the Dependencies of the
   current Manifest.  All Dependencies MUST be fetched before any
   Payload is fetched to ensure that all Manifests are available and
   authenticated before any of the (larger) Payloads are acquired.

5.6.  Added and Modified Commands

   All Commands are modified in that they can also target Dependencies.
   However, Set Component Index has a larger modification.

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          +================+====================================+
          | Command Name   | Semantic of the Operation          |
          +================+====================================+
          | Set Parameters | current.params[k] := v if not k in |
          |                | current.params for-each k,v in arg |
          +----------------+------------------------------------+
          | Process        | exec(current[common]);             |
          | Dependency     | exec(current[current-segment])     |
          +----------------+------------------------------------+
          | Dependency     | verify(current,                    |
          | Integrity      | current.params[image-digest])      |
          +----------------+------------------------------------+
          | Is Dependency  | assert(current exists in           |
          |                | Dependencies)                      |
          +----------------+------------------------------------+
          | Unlink         | unlink(current)                    |
          +----------------+------------------------------------+

             Table 1: Added/Modified Abstract Machine Commands

5.6.1.  suit-directive-set-parameters

   Similar to suit-directive-override-parameters
   ([I-D.ietf-suit-manifest], section 8.4.10.3), suit-directive-set-
   parameters allows the Manifest to configure behavior of future
   Directives by changing Parameters that are read by those Directives.
   Set Parameters is for use when Dependencies are used because it
   allows a Manifest to modify the behavior of its Dependencies.
   Because of this modification behavior, suit-directive-set-parameters
   MUST only be used for parameters that are intended to be overridden.

   Available Parameters are defined in [I-D.ietf-suit-manifest], section
   8.4.8.

   If a Parameter is already set, suit-directive-set-parameters will
   skip setting the Parameter to its argument.  This enables parameter
   replacement in Manifest trees.  A Dependency can specify a default
   Parameter using suit-directive-set-parameters.  Then, a dependent of
   that Dependency can use suit-directive-set-parameters prior to
   invoking suit-directive-process-dependency.  Since suit-directive-
   set-parameters has set-if-unset behaviour, this means that the
   dependent has effectively overriden the Dependency's Parameter.
   Manifests that wish to enforce a specific value of a Parameter MUST
   use suit-directive-override-parameters instead.  This satisfies
   USER_STORY.OVERRIDE and REQ.USE.MFST.COMPONENT of [RFC9124].

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   While suit-directive-set-parameters can be used outside of a
   Dependency use case, it has limited applicability: in linear
   manifests (without try-each, [I-D.ietf-suit-manifest], section
   8.4.10.2) it either behaves as suit-directive-override-parameters or
   has no effect, depending on whether its targets are already set.
   When used as a set-if-unset construction following a try-each, suit-
   directive-override-parameters has the same effect as if a suit-
   directive-override-parameters were placed in the final element of the
   try-each with no preceding condition.  This limits the applicability
   of suit-directive-set-parameters outside dependency use cases.

   suit-directive-set-parameters does not specify a reporting policy.

5.6.2.  suit-directive-process-dependency

   Execute the Commands in the common section of the current Dependency,
   followed by the Commands in the equivalent section of the current
   Dependency.  For example, if the current section is "Payload Fetch,"
   this will execute "Common metadata" in the current Dependency, then
   "Payload Fetch" in the current Dependency.  Once this is complete,
   the Command following suit-directive-process-dependency will be
   processed.

   If the current Component Index matches any of the following
   conditions, the Manifest Processor MUST Abort:

   *  The current Component index does not have an entry in the suit-
      dependencies map

   *  The current Component index has not been the target of a suit-
      condition-dependency-integrity

   *  The current section is "Common metadata"

   If the current Component is True, then this Directive applies to all
   Dependencies.

   When suit-directive-process-dependency completes, it forwards the
   last status code that occurred in the Dependency; an Abort in a
   Dependency causes an Abort in the suit-directive-process-dependency
   of the Dependent.

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5.6.3.  suit-condition-is-dependency

   Check whether the current Component index is present in the
   Dependency list.  If the current Component is in the Dependency list,
   suit-condition-is-dependency succeeds.  Otherwise, it fails.  This
   can be used along with component-id = True to act on all Dependencies
   or on all non-Dependency Components (Section 8).

5.6.4.  suit-condition-dependency-integrity

   Verify the integrity of a Dependency.  When a Manifest Processor
   executes suit-condition-dependency-integrity, it performs the
   following operations:

   1.  Verify the signature of the Dependency's suit-authentication-
       wrapper.

   2.  Compare the Dependency's suit-authentication-wrapper digest to
       the dependent's suit-parameter-image-digest

   3.  Verify the Dependency against the Depedency's suit-
       authentication-wrapper digest

   If any of these steps fails, the Manifest Processor MUST immediately
   Abort.

   The Manifest Processor MAY cache the results of these operations for
   later use from the context of the current Manifest.  The Manifest
   Processor MUST NOT use cached results from any other Manifest
   context.  The Manifest Processor MUST prevent tampering with the
   cached results, e.g. through tamper-evident memory.  If the Manifest
   Processor caches the results of these checks, it MUST eliminate this
   cache if:

   *  Any Fetch, or Copy operation targets the Dependency's Component ID

   *  An Abort is encountered

   *  A Procedure completes

5.6.5.  suit-directive-unlink

   A Manifest Processor that supports multiple independent root
   manifests MUST support suit-directive-unlink.  When a Component is no
   longer needed, the Manifest Processor unlinks the Component to inform
   the Manifest Processor that it is no longer needed.

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   If a Manifest is no longer needed, the Manifest Processor unlinks it.
   This causes the Manifest Processor to execute the suit-uninstall
   section of the unlinked Manifest, after which it decrements the
   reference count of the unlinked Manifest.  The suit-uninstall section
   of a manifest typically contains an unlink of all its dependencies
   and components.

   All components, including Manifests must be unlinked before deletion
   or overwrite.  If the reference count of a component is non-zero, any
   command that alters that component MUST cause the Manifest Processor
   to Abort.  Affected commands are:

   *  suit-directive-copy

   *  suit-directive-fetch

   *  suit-directive-write

   The unlink Command decrements an implementation-defined reference
   counter.  This reference counter MUST persist across restarts.  The
   reference counter MUST NOT be decremented by a given Manifest more
   than once, and the Manifest Processor must enforce this.  The
   Manifest Processor MAY choose to ignore an Unlink Directive depending
   on device policy.

   When the reference counter of a Manifest reaches zero, the suit-
   uninstall Command sequence is invoked (Section 6).

   suit-directive-unlink is OPTIONAL to implement in Manifest
   Processors, but Manifest Processors that support multiple independent
   Root Manifests MUST support suit-directive-unlink.

6.  Uninstall

   In some systems, particularly with multiple, independent, optional
   Components, it may be that there is a need to uninstall the
   Components that have been installed by a Manifest.  Where this is
   expected, the uninstall Command sequence can provide the sequence
   needed to cleanly remove the Components defined by the Manifest and
   its Dependencies.  In general, the suit-uninstall Command Sequence
   will contain primarily unlink Directives.

   WARNING: This can cause faults where there are loose Dependencies
   (e.g., version range matching, [I-D.ietf-suit-update-management],
   Section 5.5), since a Component can be removed while it is depended
   upon by another Component.  To avoid Dependency faults, a Manifest
   author MUST use explicit Dependencies where possible.  To enable
   applications where explicit Dependency matching is not possible, a

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   Manifest Processor can track references to loose Dependencies via
   reference counting in the same way as explicit Dependencies, as
   described in Section 5.6.5.

   The suit-uninstall Command Sequence is not severable, since it must
   always be available to enable uninstalling.

7.  Staging and Installation

   In order to coordinate between download and installation in different
   trust domains, the Update Procedure defined in
   [I-D.ietf-suit-manifest], Section 8.4.6 is divided into two sub-
   procedures:

   *  The Staging Procedure: This procedure is responsible for
      dependency resolution and acquiring all payloads required for the
      Update to proceed.  It is composed of two command sequences

      -  suit-dependency-resolution

      -  suit-payload-fetch

   *  The Installation Procedure: This procedure is responsible for
      verifying staged components and installing them.  It is composed
      of:

      -  suit-candidate-verification

      -  suit-install

   This extension is backwards compatible when used with a Manifest
   Processor that supports the Update Procedure but does not support the
   Staging Procedure and Installation Procedure: the payload-fetch
   command sequence already contains suit-condition-image tests for each
   payload ([I-D.ietf-suit-manifest], section 7.3) which means that
   images are already validated when suit-install is invoked.  This
   makes suit-candidate-verification OPTIONAL to implement.

   The Staging and Installation Procedures are only required when
   Staging occurs in a different trust domain to Installation.

7.1.  suit-candidate-verification

   This command sequence is responsible for verifying that all elements
   of an update are present and correct prior to installation.  This is
   only required when Installation occurs in a trust domain different
   from Staging, such as an installer invoked by the bootloader.

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8.  Creating Manifests

   This section details a set of templates for creating Manifests.
   These templates explain which Parameters, Commands, and orders of
   Commands are necessary to achieve a stated goal.

8.1.  Dependency Template

   The goal of the Dependency template is to obtain, verify, and process
   a Dependency as appropriate.

   The following Commands are added to the shared sequence:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

   *  Set Parameters Directive (Section 5.6.1) for digest
      ([I-D.ietf-suit-manifest], Section 8.4.8.6).  Note that the digest
      MUST match the SUIT_Digest in the Dependency's suit-
      authentication-block ([I-D.ietf-suit-manifest], Section 8.3).

   The following Commands are placed into the Dependency resolution
   sequence:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

   *  Set Parameters Directive (Section 5.6.1) for a URI
      ([I-D.ietf-suit-manifest], Section 8.4.8.10)

   *  Fetch Directive ([I-D.ietf-suit-manifest], Section 8.4.10.4)

   *  Dependency Integrity Condition (Section 5.6.4)

   *  Process Dependency Directive (Section 5.6.2)

   Then, the validate sequence contains the following operations:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

   *  Dependency Integrity Condition (Section 5.6.4)

   *  Process Dependency Directive (Section 5.6.2)

   If any Dependency is declared, the dependent MUST populate all
   Command sequences for the current Procedure (Update or Invoke).

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   NOTE: Any changes made to Parameters in a Dependency persist in the
   dependent.

8.1.1.  Integrated Dependencies

   An implementer MAY choose to place a Dependency's Envelope in the
   Envelope of its dependent.  The dependent Envelope key for the
   Dependency Envelope MUST be a text string.  The URI for the
   Dependency MUST match the text string key of the dependent's Envelope
   key.  It is RECOMMENDED to make the text string key a resolvable URI
   so that a Dependency that is removed from the Envelope can still be
   fetched.

8.2.  Encrypted Manifest Template

   The goal of the Encrypted Manifest template is to fetch and decrypt a
   Manifest so that it can be used as a Dependency.  To use an encrypted
   Manifest, create a plaintext dependent, and add the encrypted
   Manifest as a Dependency.  The dependent can include very little
   information.

   NOTE: This template also requires the extensions defined in
   [I-D.ietf-suit-firmware-encryption].

   The following Commands are added to the shared sequence:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

   *  Set Parameters Directive (Section 5.6.1) for digest
      ([I-D.ietf-suit-manifest], Section 8.4.8.6).  Note that the digest
      MUST match the SUIT_Digest in the Dependency's suit-
      authentication-block ([I-D.ietf-suit-manifest], Section 8.3).

   The following operations are placed into the Dependency resolution
   block:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

   *  Set Parameters Directive (Section 5.6.1) for

      -  URI ([I-D.ietf-suit-manifest], Section 8.4.8.9)

      -  Encryption Info ([I-D.ietf-suit-firmware-encryption])

   *  Fetch Directive ([I-D.ietf-suit-manifest], Section 8.4.10.4)

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   *  Dependency Integrity Condition (Section 5.6.4)

   *  Process Dependency Directive (Section 5.6.2)

   Then, the validate block contains the following operations:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

   *  Check Image Match Condition ([I-D.ietf-suit-manifest],
      Section 8.4.9.2)

   *  Process Dependency Directive (Section 5.6.2)

   A plaintext Manifest and its encrypted Dependency may also form a
   composite Manifest (Section 8.1.1).

8.3.  Overriding Encryption Info Template

   The goal of overriding the Encryption Info template is to separate
   the role of generating encrypted Payload and Encryption Info with
   Key-Encryption Key addressing Section 3 of
   [I-D.ietf-suit-firmware-encryption].

   As an example, this template describes two manifests: - The dependent
   Manifest created by the Distribution System contains Encryption Info,
   allowing the Device to generate the Content-Encryption Key. - The
   Dependency created by the Author contains Commands to decrypt the
   encrypted Payload using Encryption Info above and to validate the
   plaintext Payload with SUIT_Digest.

   NOTE: This template also requires the extensions defined in
   [I-D.ietf-suit-firmware-encryption].

   The following operations are placed into the Dependency resolution
   block of dependent Manifest:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1) pointing at Dependency

   *  Set Parameters Directive (Section 5.6.1) for

      -  Image Digest ([I-D.ietf-suit-manifest], Section 8.4.8.6)

      -  URI ([I-D.ietf-suit-manifest], Section 8.4.8.9) of Dependency

   *  Fetch Directive ([I-D.ietf-suit-manifest], Section 8.4.10.4)

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   *  Dependency Integrity Condition (Section 5.6.4)

   The following Commands are placed into the Fetch/Install block of
   dependent Manifest

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1) pointing at encrypted Payload

   *  Set Parameters Directive (Section 5.6.1) for

      -  URI ([I-D.ietf-suit-manifest], Section 8.4.8.9)

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1) pointing at Dependency

   *  Set Parameters Directive (Section 5.6.1) for

      -  Encryption Info ([I-D.ietf-suit-firmware-encryption])

   *  Process Dependency Directive (Section 5.6.2)

   The following Commands are placed into the same block of Dependency:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1) pointing at encrypted Payload

   *  Fetch Directive ([I-D.ietf-suit-manifest], Section 8.4.10.4)

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1) pointing at to be decrypted Payload

   *  Override Parameters Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.3) for

      -  Source Component ([I-D.ietf-suit-manifest], Section 8.4.8.11)
         pointing at encrypted Payload

   *  Copy Directive ([I-D.ietf-suit-manifest], Section 8.4.10.5)
      consuming the Encryption Info above

   The Distribution System can Set the URI Parameter in the Fetch/
   Install block of dependent Manifest if it wants to overwrite the URI
   of the encrypted Payload.

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   Because the Author and the Distribution System have different roles
   and may be separate entities, it is highly recommended to leverage
   permissions ([I-D.ietf-suit-manifest], Section 9).  For example, the
   Device can protect itself from an attacker who breaches the
   Distribution System by allowing only the Author's Manifest to modify
   the Component of (to be) decrypted Payload.

8.4.  Operating on Multiple Components

   In order to produce compact encoding, it is efficient to perform
   operations on multiple Components simultaneously.  Because
   Dependencies and Component Images are processed at different times,
   there is a mechanism to distinguish between these elements: suit-
   condition-is-dependency.  This can be used with suit-directive-try-
   each to perform operations just on Dependencies or just on Component
   Images.

   For example, to fetch all Dependencies, the following Commands are
   added to the Dependency resolution block:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

   *  Set Parameters Directive (Section 5.6.1) for a URI
      ([I-D.ietf-suit-manifest], Section 8.4.8.9)

   *  Set Component Index Directive, with argument "True"
      ([I-D.ietf-suit-manifest], Section 8.4.10.1)

   *  Try Each Directive

      -  Sequence 0

         o  Condition Is Dependency

         o  Fetch

         o  Dependency Integrity Condition (Section 5.6.4)

         o  Process Dependency

      -  Sequence 1 (Empty; no Commands, succeeds immediately)

   Another example is to fetch and validate all Component Images.  The
   Image fetch sequence contains the following Commands:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

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   *  Set Parameters Directive (Section 5.6.1) for a URI
      ([I-D.ietf-suit-manifest], Section 8.4.8.9)

   *  Set Component Index Directive, with argument "True"
      ([I-D.ietf-suit-manifest], Section 8.4.10.1)

   *  Try Each Directive

      -  Sequence 0

         o  Condition Is Dependency

         o  Process Dependency

      -  Sequence 1

         o  Fetch

         o  Condition Image Match

   When some Components are "installed" or "loaded" it is more
   productive to use lists of Component indices rather than Component
   Index = True.  For example, to install several Components, the
   following Commands should be placed in the Image Install Sequence:

   *  Set Component Index Directive ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

   *  Set Parameters Directive (Section 5.6.1) for the Source Component
      ([I-D.ietf-suit-manifest], Section 8.4.8.11)

   *  Set Component Index Directive, with argument containing list of
      destination Component indices ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

   *  Copy

   *  Set Component Index Directive, with argument containing list
      Dependency Component indices ([I-D.ietf-suit-manifest],
      Section 8.4.10.1)

   *  Process Dependency

9.  IANA Considerations

   IANA is requested to allocate the following numbers in the listed
   registries created by draft-ietf-suit-manifest:

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9.1.  SUIT Envelope Elements

             +=======+========================+=============+
             | Label | Name                   | Reference   |
             +=======+========================+=============+
             | 15    | Dependency Resolution  | Section 5.5 |
             +-------+------------------------+-------------+
             | 18    | Candidate Verification | Section 7.1 |
             +-------+------------------------+-------------+

                   Table 2: New SUIT Envelope Elements

9.2.  SUIT Manifest Elements

            +=======+========================+===============+
            | Label | Name                   | Reference     |
            +=======+========================+===============+
            | 5     | Manifest Component ID  | Section 5.2.1 |
            +-------+------------------------+---------------+
            | 15    | Dependency Resolution  | Section 5.5   |
            +-------+------------------------+---------------+
            | 18    | Candidate Verification | Section 7.1   |
            +-------+------------------------+---------------+
            | 24    | Uninstall              | Section 6     |
            +-------+------------------------+---------------+

                   Table 3: New SUIT Manifest Elements

9.3.  SUIT Common Elements

                 +=======+==============+===============+
                 | Label | Name         | Reference     |
                 +=======+==============+===============+
                 | 1     | Dependencies | Section 5.2.2 |
                 +-------+--------------+---------------+

                    Table 4: New SUIT Common Elements

9.4.  SUIT Commands

             +=======+======================+===============+
             | Label | Name                 | Reference     |
             +=======+======================+===============+
             | 7     | Dependency Integrity | Section 5.6.4 |
             +-------+----------------------+---------------+
             | 8     | Is Dependency        | Section 5.6.3 |
             +-------+----------------------+---------------+
             | 11    | Process Dependency   | Section 5.6.2 |

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             +-------+----------------------+---------------+
             | 19    | Set Parameters       | Section 5.6.1 |
             +-------+----------------------+---------------+
             | 33    | Unlink               | Section 5.6.5 |
             +-------+----------------------+---------------+

                        Table 5: New SUIT Commands

10.  Security Considerations

   This specification is about a Manifest format protecting and
   describing how to retrieve, install, and invoke Images and as such it
   is part of a larger solution for delivering software updates to
   devices.  A detailed security treatment can be found in the SUIT
   architecture [RFC9019] and in the SUIT information model [RFC9124].

   The features added in this specification introduce several new
   threats.  The introduction of Dependencies enables multiple entities
   to operate on a device with different privileges.  While this is
   necessary to fulfill REQ.USE.MFST.COMPONENT ([RFC9124],
   Section 4.5.4), it also introduces a new requirement:
   REQ.SEC.ACCESS_CONTROL ([RFC9124], Section 4.3.13), which is required
   to address THREAT.MFST.OVERRIDE ([RFC9124], Section 4.2.13) and
   THREAT.UPD.UNAPPROVED ([RFC9124], Section 4.2.11).

   Simultaneous processing of multiple Manifests, as enabled by
   Dependency processing, introduces risks of TOCTOU threats
   (THREAT.MFST.TOCTOU: [RFC9124], Section 4.2.18).  Holding multiple
   Manifest Envelopes in memory simultaneously can exceed the capacity
   of the Manifest Processor's tamper-protected memory
   (REQ.SEC.MFST.CONST: [RFC9124], Section 4.3.21).  To address this
   threat, the Manifest Processor MAY use modular processing as
   described in REQ.USE.PAYLOAD ([RFC9124], Section 4.5.12).  If
   retaining the Manifests only, excluding envelopes, in immutable
   memory does not provide enough capacity, the Manifest Processor MAY
   reduce overhead by retaining the following elements for each manifest
   in immutable memory:

   *  Manifest Digest

   *  Parameters

   *  Current Component Index

   *  Current Command Sequence

   *  Current Command Sequence Offset

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   This allows a Manifest Processor to resume processing a manifest as
   follows:

   *  Copy the Manifest into immutable memory

   *  Validate the Manifest using the stored Manifest Digest

   *  Parse forward to find the Current Command Sequence

   *  Jump within the Command Seqeunce to the stored Command Sequence
      Offset

   When identifying a Root Manifest's correct storage location, the
   Component Identifier MUST be evaluated vs. the access priviliges of
   an Author.  Otherwise, the Component Identifier may permit an
   escalation of privilege: an authorised Author causes a manifest to be
   installed in a location for which the Author does not have access
   rights.

   Since Dependencies are stored as Components, Dependency Integrity
   Checks and Image Verification are slightly different operations.
   While a typical Image is immutable, a Manifest Envelope can be
   modified in some ways (e.g. removing a Severable Element) without
   changing the Integrity Check result.  Because of these factors, suit-
   directive-process-dependency requires that a dependency first be
   validated with suit-check suit-condition-dependency-integrity.

11.  References

11.1.  Normative References

   [I-D.ietf-suit-firmware-encryption]
              Tschofenig, H., Housley, R., Moran, B., Brown, D., and K.
              Takayama, "Encrypted Payloads in SUIT Manifests", Work in
              Progress, Internet-Draft, draft-ietf-suit-firmware-
              encryption-25, 7 July 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-suit-
              firmware-encryption-25>.

   [I-D.ietf-suit-manifest]
              Moran, B., Tschofenig, H., Birkholz, H., Zandberg, K., and
              O. Rønningstad, "A Concise Binary Object Representation
              (CBOR)-based Serialization Format for the Software Updates
              for Internet of Things (SUIT) Manifest", Work in Progress,
              Internet-Draft, draft-ietf-suit-manifest-34, 28 May 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-suit-
              manifest-34>.

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   [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/rfc/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/rfc/rfc8174>.

   [RFC8610]  Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
              Definition Language (CDDL): A Notational Convention to
              Express Concise Binary Object Representation (CBOR) and
              JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
              June 2019, <https://www.rfc-editor.org/rfc/rfc8610>.

   [RFC8949]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", STD 94, RFC 8949,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/rfc/rfc8949>.

11.2.  Informative References

   [I-D.ietf-iotops-7228bis]
              Bormann, C., Ersue, M., Keränen, A., and C. Gomez,
              "Terminology for Constrained-Node Networks", Work in
              Progress, Internet-Draft, draft-ietf-iotops-7228bis-02, 7
              July 2025, <https://datatracker.ietf.org/doc/html/draft-
              ietf-iotops-7228bis-02>.

   [I-D.ietf-suit-update-management]
              Moran, B. and K. Takayama, "Update Management Extensions
              for Software Updates for Internet of Things (SUIT)
              Manifests", Work in Progress, Internet-Draft, draft-ietf-
              suit-update-management-09, 17 March 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-suit-
              update-management-09>.

   [RFC6024]  Reddy, R. and C. Wallace, "Trust Anchor Management
              Requirements", RFC 6024, DOI 10.17487/RFC6024, October
              2010, <https://www.rfc-editor.org/rfc/rfc6024>.

   [RFC9019]  Moran, B., Tschofenig, H., Brown, D., and M. Meriac, "A
              Firmware Update Architecture for Internet of Things",
              RFC 9019, DOI 10.17487/RFC9019, April 2021,
              <https://www.rfc-editor.org/rfc/rfc9019>.

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   [RFC9124]  Moran, B., Tschofenig, H., and H. Birkholz, "A Manifest
              Information Model for Firmware Updates in Internet of
              Things (IoT) Devices", RFC 9124, DOI 10.17487/RFC9124,
              January 2022, <https://www.rfc-editor.org/rfc/rfc9124>.

   [RFC9397]  Pei, M., Tschofenig, H., Thaler, D., and D. Wheeler,
              "Trusted Execution Environment Provisioning (TEEP)
              Architecture", RFC 9397, DOI 10.17487/RFC9397, July 2023,
              <https://www.rfc-editor.org/rfc/rfc9397>.

Appendix A.  A.  Full CDDL

   To be valid, the following CDDL (see [RFC8610]) MUST be appended to
   the SUIT Manifest CDDL.  The SUIT CDDL is defined in Appendix A of
   [I-D.ietf-suit-manifest]

   $$SUIT_Envelope_Extensions //= (
       suit-integrated-dependency-key => bstr .cbor SUIT_Envelope)

   $$SUIT_Manifest_Extensions //=
       (suit-manifest-component-id => SUIT_Component_Identifier)

   $$SUIT_severable-members-extensions //=
       (suit-dependency-resolution => bstr .cbor SUIT_Command_Sequence)

   $$SUIT_severable-members-extensions //=
       (suit-candidate-verification => bstr .cbor SUIT_Command_Sequence)

   $$unseverable-manifest-member-extensions //=
       (suit-uninstall => bstr .cbor SUIT_Command_Sequence)

   suit-integrated-dependency-key = tstr

   $$severable-manifest-members-choice-extensions //= (
       suit-dependency-resolution =>
           bstr .cbor SUIT_Command_Sequence / SUIT_Digest)

   $$SUIT_Common-extensions //= (
       suit-dependencies => SUIT_Dependencies
   )
   SUIT_Dependencies = {
       + uint => SUIT_Dependency_Metadata
   }
   SUIT_Dependency_Metadata = {
       ? suit-dependency-prefix => SUIT_Component_Identifier
       * $$SUIT_Dependency_Extensions
   }

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   SUIT_Condition //= (
       suit-condition-dependency-integrity, SUIT_Rep_Policy)
   SUIT_Condition //= (
       suit-condition-is-dependency, SUIT_Rep_Policy)

   SUIT_Directive //= (
       suit-directive-process-dependency, SUIT_Rep_Policy)
   SUIT_Directive //= (suit-directive-set-parameters,
       {+ $$SUIT_Parameters})
   SUIT_Directive //= (
       suit-directive-unlink, SUIT_Rep_Policy)

   suit-manifest-component-id = 5

   suit-delegation = 1
   suit-dependency-resolution = 15
   suit-candidate-verification = 18
   suit-uninstall = 24

   suit-dependencies = 1

   suit-dependency-prefix = 1

   suit-condition-dependency-integrity     = 7
   suit-condition-is-dependency            = 8
   suit-directive-process-dependency       = 11
   suit-directive-set-parameters           = 19
   suit-directive-unlink                   = 33

Appendix B.  B.  Examples

   The following examples demonstrate a small subset of the
   functionalities in this document.

   The examples are signed using the following ECDSA secp256r1 key:

   -----BEGIN PRIVATE KEY-----
   MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgApZYjZCUGLM50VBC
   CjYStX+09jGmnyJPrpDLTz/hiXOhRANCAASEloEarguqq9JhVxie7NomvqqL8Rtv
   P+bitWWchdvArTsfKktsCYExwKNtrNHXi9OB3N+wnAUtszmR23M4tKiW
   -----END PRIVATE KEY-----

   The corresponding public key can be used to verify these examples:

   -----BEGIN PUBLIC KEY-----
   MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEhJaBGq4LqqvSYVcYnuzaJr6qi/Eb
   bz/m4rVlnIXbwK07HypLbAmBMcCjbazR14vTgdzfsJwFLbM5kdtzOLSolg==
   -----END PUBLIC KEY-----

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   Each example uses SHA256 as the digest function.

B.1.  Example 0: Process Dependency

   This example uses functionalities:

   *  manifest component id

   *  dependency resolution

   *  process dependency

   The Dependency:

   / SUIT_Envelope_Tagged / 107({
     / authentication-wrapper / 2: << [
       << [
         / digest-algorithm-id: / -16 / SHA256 /,
         / digest-bytes: / h'AEBA316A9A1E38253B29E6C99B605383
                             68B8AC8B5E6B9ACE1D239970830BBE62'
       ] >>,
       << / COSE_Sign1_Tagged / 18([
         / protected: / << {
           / algorithm-id / 1: -9 / ESP256 /
         } >>,
         / unprotected: / {},
         / payload: / null,
         / signature: / h'3F3E9A2CA98208FEAEAEEADF7E1A0323
                          C97896ABFB79F91E8D0C1509B0A533CD
                          0B96BFC876A8F3B8ACE712FFF8EF7EA9
                          45E62A61E0BA5BD9929E4A1B47EC6475'
       ]) >>
     ] >>,
     / manifest / 3: << {
       / manifest-version / 1: 1,
       / manifest-sequence-number / 2: 0,
       / common / 3: << {
         / dependencies / 1: {
           / component-index / 1: {
             / dependency-prefix / 1: [
               'dependent.suit'
             ]
           }
         },
         / components / 2: [
           ['10']
         ]
       } >>,

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       / manifest-component-id / 5: [
         'depending.suit'
       ],
       / invoke / 9: << [
         / directive-set-component-index / 12, 0,
         / directive-override-parameters / 20, {
           / parameter-invoke-args / 23: 'cat 00 10'
         },
         / directive-invoke / 23, 15
       ] >>,
       / dependency-resolution / 15: << [
         / directive-set-component-index / 12, 1,
         / directive-override-parameters / 20, {
           / parameter-image-digest / 3: << [
             / digest-algorithm-id: / -16 / SHA256 /,
             / digest-bytes: / h'0F02CAF6D3E61920D36BF3CEA7F862A1
                                 3BB8FB1F09C3F4C29B121FEAB78EF3D8'
           ] >>,
           / parameter-image-size / 14: 190,
           / parameter-uri / 21: "http://example.com/dependent.suit"
         },
         / directive-fetch / 21, 2,
         / condition-image-match / 3, 15
       ] >>,
       / install / 20: << [
         / directive-set-component-index / 12, 1,
         / directive-override-parameters / 20, {
           / parameter-image-digest / 3: << [
             / digest-algorithm-id: / -16 / SHA256 /,
             / digest-bytes: / h'0F02CAF6D3E61920D36BF3CEA7F862A1
                                 3BB8FB1F09C3F4C29B121FEAB78EF3D8'
           ] >>
         },
         / condition-dependency-integrity / 7, 15,
         / directive-process-dependency / 11, 0,

         / directive-set-component-index / 12, 0,
         / directive-override-parameters / 20, {
           / parameter-content / 18: ' in multiple trust domains'
         },
         / directive-write / 18, 15
       ] >>
     } >>
   })

   Total size of Envelope with COSE authentication object: 373

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   D86BA2025873825824822F5820AEBA316A9A1E38253B29E6C99B60538368
   B8AC8B5E6B9ACE1D239970830BBE62584AD28443A10128A0F658403F3E9A
   2CA98208FEAEAEEADF7E1A0323C97896ABFB79F91E8D0C1509B0A533CD0B
   96BFC876A8F3B8ACE712FFF8EF7EA945E62A61E0BA5BD9929E4A1B47EC64
   750358F9A70101020003581CA201A101A101814E646570656E64656E742E
   7375697402818142313005814E646570656E64696E672E73756974095286
   0C0014A11749636174203030203130170F0F5857880C0114A3035824822F
   58200F02CAF6D3E61920D36BF3CEA7F862A13BB8FB1F09C3F4C29B121FEA
   B78EF3D80E18BE157821687474703A2F2F6578616D706C652E636F6D2F64
   6570656E64656E742E737569741502030F1458538E0C0114A1035824822F
   58200F02CAF6D3E61920D36BF3CEA7F862A13BB8FB1F09C3F4C29B121FEA
   B78EF3D8070F0B000C0014A112581A20696E206D756C7469706C65207472
   75737420646F6D61696E73120F

   The dependent Manifest (fetched from "https://example.com/
   dependent.suit"):

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   / SUIT_Envelope_Tagged / 107({
     / authentication-wrapper / 2: << [
       << [
         / digest-algorithm-id: / -16 / SHA256 /,
         / digest-bytes: / h'0F02CAF6D3E61920D36BF3CEA7F862A1
                             3BB8FB1F09C3F4C29B121FEAB78EF3D8'
       ] >>,
       << / COSE_Sign1_Tagged / 18([
         / protected: / << {
           / algorithm-id / 1: -9 / ESP256 /
         } >>,
         / unprotected: / {},
         / payload: / null,
         / signature: / h'A25F337126369D2E0B451C01DBD8CDB8
                          4A77E7F6C39E789DB3D227753494000C
                          9D250001FDDCA39B4B4E3755A7278C11
                          998171905F56C394CFBB907105DA804F'
       ]) >>
     ] >>,
     / manifest / 3: << {
       / manifest-version / 1: 1,
       / manifest-sequence-number / 2: 0,
       / common / 3: << {
         / components / 2: [
           ['00']
         ]
       } >>,
       / manifest-component-id / 5: [
         'dependent.suit'
       ],
       / invoke / 9: << [
         / directive-override-parameters / 20, {
           / parameter-invoke-args / 23: 'cat 00'
         },
         / directive-invoke / 23, 15
       ] >>,
       / install / 20: << [
         / directive-override-parameters / 20, {
           / parameter-content / 18: 'hello world'
         },
         / directive-write / 18, 15
       ] >>
     } >>
   })

   Total size of Envelope with COSE authentication object: 190

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   D86BA2025873825824822F58200F02CAF6D3E61920D36BF3CEA7F862A13B
   B8FB1F09C3F4C29B121FEAB78EF3D8584AD28443A10128A0F65840A25F33
   7126369D2E0B451C01DBD8CDB84A77E7F6C39E789DB3D227753494000C9D
   250001FDDCA39B4B4E3755A7278C11998171905F56C394CFBB907105DA80
   4F035842A6010102000347A102818142303005814E646570656E64656E74
   2E73756974094D8414A11746636174203030170F14528414A1124B68656C
   6C6F20776F726C64120F

B.2.  Example 1: Integrated Dependency

   *  manifest component id

   *  dependency resolution

   *  process dependency

   *  integrated dependency

   / SUIT_Envelope_Tagged / 107({
     / authentication-wrapper / 2: << [
       << [
         / digest-algorithm-id: / -16 / SHA256 /,
         / digest-bytes: / h'88E1199580864EB1D1AD35EB5925BE68
                             CA565EE3BB39C27CDB31CEDA4DD667DF'
       ] >>,
       << / COSE_Sign1_Tagged / 18([
         / protected: / << {
           / algorithm-id / 1: -9 / ESP256 /
         } >>,
         / unprotected: / {},
         / payload: / null,
         / signature: / h'074A361F7BBFA2ACF4EC3CFDAF4FDD87
                          38414BAD672CAEA4F43607BE6031EA90
                          CB0C283A03C728608B0509C6FD2AFED4
                          0CFB0C3D341340830A00905E6A729890'
       ]) >>
     ] >>,
     / manifest / 3: << {
       / manifest-version / 1: 1,
       / manifest-sequence-number / 2: 0,
       / common / 3: << {
         / dependencies / 1: {
           / component-index / 1: {
             / dependency-prefix / 1: [
               'dependent.suit'
             ]
           }
         },

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         / components / 2: [
           ['10']
         ]
       } >>,
       / manifest-component-id / 5: [
         'depending.suit'
       ],
       / invoke / 9: << [
         / directive-set-component-index / 12, 0,
         / directive-override-parameters / 20, {
           / parameter-invoke-args / 23: 'cat 00 10'
         },
         / directive-invoke / 23, 15
       ] >>,
       / dependency-resolution / 15: << [
         / directive-set-component-index / 12, 1,
         / directive-override-parameters / 20, {
           / parameter-image-digest / 3: << [
             / digest-algorithm-id: / -16 / SHA256 /,
             / digest-bytes: / h'0F02CAF6D3E61920D36BF3CEA7F862A1
                                 3BB8FB1F09C3F4C29B121FEAB78EF3D8'
           ] >>,
           / parameter-image-size / 14: 190,
           / parameter-uri / 21: "#dependent.suit"
         },
         / directive-fetch / 21, 2,
         / condition-image-match / 3, 15
       ] >>,
       / install / 20: << [
         / directive-set-component-index / 12, 1,
         / directive-process-dependency / 11, 0,

         / directive-set-component-index / 12, 0,
         / directive-override-parameters / 20, {
           / parameter-content / 18: ' in multiple trust domains'
         },
         / directive-write / 18, 15
       ] >>
     } >>,
     "#dependent.suit":
       h'D86BA2025873825824822F58200F02CAF6D3E61920D36BF3CEA7F862A13B
         B8FB1F09C3F4C29B121FEAB78EF3D8584AD28443A10128A0F65840A25F33
         7126369D2E0B451C01DBD8CDB84A77E7F6C39E789DB3D227753494000C9D
         250001FDDCA39B4B4E3755A7278C11998171905F56C394CFBB907105DA80
         4F035842A6010102000347A102818142303005814E646570656E64656E74
         2E73756974094D8414A11746636174203030170F14528414A1124B68656C
         6C6F20776F726C64120F'
   })

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   Total size of Envelope with COSE authentication object: 519

   Envelope with COSE authentication object:

   D86BA3025873825824822F582088E1199580864EB1D1AD35EB5925BE68CA
   565EE3BB39C27CDB31CEDA4DD667DF584AD28443A10128A0F65840074A36
   1F7BBFA2ACF4EC3CFDAF4FDD8738414BAD672CAEA4F43607BE6031EA90CB
   0C283A03C728608B0509C6FD2AFED40CFB0C3D341340830A00905E6A7298
   900358BBA70101020003581CA201A101A101814E646570656E64656E742E
   7375697402818142313005814E646570656E64696E672E73756974095286
   0C0014A11749636174203030203130170F0F5844880C0114A3035824822F
   58200F02CAF6D3E61920D36BF3CEA7F862A13BB8FB1F09C3F4C29B121FEA
   B78EF3D80E18BE156F23646570656E64656E742E737569741502030F1458
   288A0C010B000C0014A112581A20696E206D756C7469706C652074727573
   7420646F6D61696E73120F6F23646570656E64656E742E7375697458BED8
   6BA2025873825824822F58200F02CAF6D3E61920D36BF3CEA7F862A13BB8
   FB1F09C3F4C29B121FEAB78EF3D8584AD28443A10128A0F65840A25F3371
   26369D2E0B451C01DBD8CDB84A77E7F6C39E789DB3D227753494000C9D25
   0001FDDCA39B4B4E3755A7278C11998171905F56C394CFBB907105DA804F
   035842A6010102000347A102818142303005814E646570656E64656E742E
   73756974094D8414A11746636174203030170F14528414A1124B68656C6C
   6F20776F726C64120F

Authors' Addresses

   Brendan Moran
   Arm Limited
   Email: brendan.moran.ietf@gmail.com

   Ken Takayama
   SECOM CO., LTD.
   Email: ken.takayama.ietf@gmail.com

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