SUIT B. Moran
Internet-Draft H. Tschofenig
Intended status: Standards Track Arm Limited
Expires: January 13, 2021 H. Birkholz
Fraunhofer SIT
K. Zandberg
July 12, 2020

A Concise Binary Object Representation (CBOR)-based Serialization Format for the Software Updates for Internet of Things (SUIT) Manifest


This specification describes the format of a manifest. A manifest is a bundle of metadata about the firmware for an IoT device, where to find the firmware, the devices to which it applies, and cryptographic information protecting the manifest. Firmware updates and secure boot both tend to use sequences of common operations, so the manifest encodes those sequences of operations, rather than declaring the metadata. The manifest also serves as a building block for secure boot.

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

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 13, 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 ( 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

A firmware update mechanism is an essential security feature for IoT devices to deal with vulnerabilities. While the transport of firmware images to the devices themselves is important there are already various techniques available. Equally important is the inclusion of metadata about the conveyed firmware image (in the form of a manifest) and the use of a security wrapper to provide end-to-end security protection to detect modifications and (optionally) to make reverse engineering more difficult. End-to-end security allows the author, who builds the firmware image, to be sure that no other party (including potential adversaries) can install firmware updates on IoT devices without adequate privileges. For confidentiality protected firmware images it is additionally required to encrypt the firmware image. Starting security protection at the author is a risk mitigation technique so firmware images and manifests can be stored on untrusted repositories; it also reduces the scope of a compromise of any repository or intermediate system to be no worse than a denial of service.

A manifest is a bundle of metadata about the firmware for an IoT device, where to find the firmware, the devices to which it applies, and cryptographic information protecting the manifest.

This specification defines the SUIT manifest format and it is intended to meet several goals:

The SUIT manifest can be used for a variety of purposes throughout its lifecycle, such as:

Each of these uses happens at a different stage of the manifest lifecycle, so each has different requirements.

It is assumed that the reader is familiar with the high-level firmware update architecture [I-D.ietf-suit-architecture] and the threats, requirements, and user stories in [I-D.ietf-suit-information-model].

The design of this specification is based on an observation that the vast majority of operations that a device can perform during an update or secure boot are composed of a small group of operations:

In the SUIT manifest specification, these operations are called commands. Commands are classed as either conditions or directives. Conditions have no side-effects, while directives do have side-effects. Conceptually, a sequence of commands is like a script but the used language is tailored to software updates and secure boot.

The available commands support simple steps, such as copying a firmware image from one place to another, checking that a firmware image is correct, verifying that the specified firmware is the correct firmware for the device, or unpacking a firmware. By using these steps in different orders and changing the parameters they use, a broad range of use cases can be supported. The SUIT manifest uses this observation to optimize metadata for consumption by constrained devices.

While the SUIT manifest is informed by and optimized for firmware update and secure boot use cases, there is nothing in the [I-D.ietf-suit-information-model] that restricts its use to only those use cases. Other use cases include the management of trusted applications in a Trusted Execution Environment (TEE), see [I-D.ietf-teep-architecture].

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 following terminology is used throughout this document:

3. How to use this Document

This specification covers five aspects of firmware update:

To implement an updatable device, see Section 6 and Section 8. To implement a tool that generates updates, see Section 7 and Section 8.

The IANA consideration section, see Section 11, provides instructions to IANA to create several registries. This section also provides the CBOR labels for the structures defined in this document.

The complete CDDL description is provided in [full-cddl], examples are given in [examples] and a design rational is offered in [design-rationale]. Finally, [implementation-matrix] gives a summarize of the mandatory-to-implement features of this specification.

4. Background

Distributing firmware updates to diverse devices with diverse trust anchors in a coordinated system presents unique challenges. Devices have a broad set of constraints, requiring different metadata to make appropriate decisions. There may be many actors in production IoT systems, each of whom has some authority. Distributing firmware in such a multi-party environment presents additional challenges. Each party requires a different subset of data. Some data may not be accessible to all parties. Multiple signatures may be required from parties with different authorities. This topic is covered in more depth in [I-D.ietf-suit-architecture]. The security aspects are described in [I-D.ietf-suit-information-model].

4.1. IoT Firmware Update Constraints

The various constraints of IoT devices and the range of use cases that need to be supported create a broad set of urequirements. For example, devices with:

Supporting the requirements introduced by the constraints on IoT devices requires the flexibility to represent a diverse set of possible metadata, but also requires that the encoding is kept simple.

4.2. SUIT Workflow Model

There are several fundamental assumptions that inform the model of Update Procedure workflow:

There are several fundamental assumptions that inform the model of the Boot Procedure workflow:

Based on these assumptions, the manifest is structured to work with a pull parser, where each section of the manifest is used in sequence. The expected workflow for a Recipient installing an update can be broken down into five steps:

  1. Verify the signature of the manifest.
  2. Verify the applicability of the manifest.
  3. Resolve dependencies.
  4. Fetch payload(s).
  5. Install payload(s).

When installation is complete, similar information can be used for validating and running images in a further three steps:

  1. Verify image(s).
  2. Load image(s).
  3. Run image(s).

If verification and running is implemented in a bootloader, then the bootloader MUST also verify the signature of the manifest and the applicability of the manifest in order to implement secure boot workflows. The bootloader may add its own authentication, e.g. a MAC, to the manifest in order to prevent further verifications.

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.

5. Metadata Structure Overview

This section provides a high level overview of the manifest structure. The full description of the manifest structure is in Section 8.6

The manifest is structured from several key components:

  1. The Envelope (see Section 5.1) contains Delegation Chains, the Authentication Block, the Manifest, any Severable Elements, and any Integrated Payloads or Dependencies.
  2. Delegation Chains (see Section 5.2) allow a Recipient to work from one of its Trust Anchors to an authority of the Authentication Block.
  3. The Authentication Block (see Section 5.3) contains a list of signatures or MACs of the manifest..
  4. The Manifest (see Section 5.4) contains all critical, non-severable metadata that the Recipient requires. It is further broken down into:
    1. Critical metadata, such as sequence number.
    2. Common metadata, including lists of dependencies and affected components.
    3. Command sequences, directing the Recipient how to install and use the payload(s).
    4. Integrity check values for severable fields.
  5. Severable fields (see Section 5.5).
  6. Integrated dependencies (see Section 5.6).
  7. Integrated payloads (see Section 5.6).

The diagram below illustrates the hierarchy of the Envelope.

| Envelope                |
| Delegation Chains       |
| Authentication Block    |
| Manifest           ------------> +------------------------------+
| Severable Elements      |        | Manifest                     |
| Human-Readable Text     |        +------------------------------+
| COSWID                  |        | Structure Version            |
| Integrated Dependencies |        | Sequence Number              |
| Integrated Payloads     |        | Reference to Full Manifest   |
+-------------------------+  +------ Common Structure             |
                             | +---- Commands                     |
+-----------------------+    | |   | Digests of Envelope Elements |
| Common Structure      | <--+ |   +------------------------------+
+-----------------------+      |
| Dependencies          |      +-> +-----------------------+
| Components IDs        |          | Commands              |
| Common Commands ---------------> +-----------------------+
+-----------------------+          | List of ( pairs of (  |
                                   |   * command code      |
                                   |   * argument          |
                                   | ))                    |

5.1. Envelope

The SUIT Envelope is a container that encloses Delegation Chains, the Authentication Block, the Manifest, any Severable Elements, and any integrated payloads or dependencies. The Envelope is used instead of conventional cryptographic envelopes, such as COSE_Envelope because it allows modular processing, severing of elements, and integrated payloads in a way that would add substantial complexity with existing solutions. See Appendix C.1 for a description of the reasoning for this.

See Section 8.2 for more detail.

5.2. Delegation Chains

Delegation Chains allow a Recipient to validate intermediate Update Authorities against long-term a Trust Anchor. These are lists of CWTs, where the first in the list is signed by a Trust Anchor.

See Section 8.3 for more detail.

5.3. Authentication Block

The Authentication Block contains one or more COSE authentication blocks. These blocks are one of:

The payload element in each of these COSE elements is a SUIT_Digest Section 10.

See Section 8.4 for more detail.

5.4. Manifest

The Manifest contains most metadata about one or more images. The Manifest is divided into Critical Metadata, Common Metadata, Command Sequences, and Integrity Check Values.

See Section 8.6 for more detail.

5.4.1. Critical Metadata

Some metadata needs to be accessed before the manifest is processed. This metadata can be used to determine which the newest manifest is and whether the structure version is supported. It also MAY provide a URI for obtaining a canonical copy of the manifest and Envelope.

See Section 8.6.1, Section 8.6.2, Section 8.6.3 for more detail.

5.4.2. Common

Some metadata is used repeatedly and in more than one command sequence. In order to reduce the size of the manifest, this metadata is collected into the Common section. Common is composed of three parts: a list of dependencies, a list of components referenced by the manifest, and a command sequence to execute prior to each other command sequence. The common command sequence is typically used to set commonly used values and perform compatibility checks. The common command sequence MUST NOT have any side-effects outside of setting parameter values.

See Section 8.7.2, Section for more detail.

5.4.3. Command Sequences

Command sequences provide the instructions that a Recipient requires in order to install or use an image. These sequences tell a device to set parameter values, test system parameters, copy data from one place to another, transform data, digest data, and run code.

Command sequences are broken up into three groups: Common Command Sequence (see Section 5.4.2), update commands, and secure boot commands.

Update Command Sequences are: Dependency Resolution, Payload Fetch, and Payload Installation. An Update Procedure is the complete set of each Update Command Sequence, each preceded by the Common Command Sequence.

Boot Command Sequences are: System Validation, Image Loading, and Image Invocation. A Boot Procedure is the complete set of each Boot Command Sequence, each preceded by the Common Command Sequence.

Command Sequences are grouped into these sets to ensure that there is common coordination between dependencies and dependents on when to execute each command.

See Section 8.7.3 for more detail.

5.4.4. Integrity Check Values

To enable Section 5.5, there needs to be a mechanism to verify integrity of any metadata outside the manifest. Integrity Check Values are used to verify the integrity of metadata that is not contained in the manifest. This MAY include Severable Command Sequences, CoSWID, or Text data. Integrated Dependencies and Integrated Payloads are integrity-checked using Command Sequences, so they do not have Integrity Check Values present in the Manifest.

See Section 8.7.8 for more detail.

5.4.5. Human-Readable Text

Text is typically a Severable Element. It contains all the text that describes the update. Because text is explicitly for human consumption, it is all grouped together so that it can be Severed easily. The text section has space both for describing the manifest as a whole and for describing each individual component.

See Section 8.6.4 for more detail.

5.5. Severable Elements

Severable Elements are elements of the Envelope that have Integrity Check Values in the Manifest.

Because of this organisation, these elements can be discarded or “Severed” from the Envelope without changing the signature of the Manifest. This allows savings based on the size of the Envelope in several scenarios, for example:

See Section 8.8 for more detail.

5.6. Integrated Dependencies and Payloads

In some cases, it is beneficial to include a dependency or a payload in the Envelope of a manifest. For example:

See Section 7.8.1, Section 8.5 for more detail.

6. Interpreter Behavior

This section describes the behavior of the manifest interpreter and focuses primarily on interpreting commands in the manifest. However, there are several other important behaviors of the interpreter: encoding version detection, rollback protection, and authenticity verification are chief among these.

6.1. Interpreter Setup

Prior to executing any command sequence, the interpreter or its host application MUST inspect the manifest version field and fail when it encounters an unsupported encoding version. Next, the interpreter or its host application MUST extract the manifest sequence number and perform a rollback check using this sequence number. The exact logic of rollback protection may vary by application, but it has the following properties:

Here, valid means that a manifest has a supported encoding version and it has not been excluded for other reasons. Reasons for excluding typically involve first executing the manifest and may include:

These failure reasons MAY be combined with retry mechanisms prior to marking a manifest as invalid.

Following these initial tests, the interpreter clears all parameter storage. This ensures that the interpreter begins without any leaked data.

6.2. Required Checks

The RECOMMENDED process is to verify the signature of the manifest prior to parsing/executing any section of the manifest. This guards the parser against arbitrary input by unauthenticated third parties, but it costs extra energy when a Recipient receives an incompatible manifest.

When validating authenticity of manifests, the interpreter MAY use an ACL (see Section 9) to determine the extent of the rights conferred by that authenticity. Where a device supports only one level of access, it MAY choose to skip signature verification of dependencies, since they are referenced by digest. Where a device supports more than one trusted party, it MAY choose to defer the verification of signatures of dependencies until the list of affected components is known so that it can skip redundant signature verifications. For example, a dependency signed by the same author as the dependent 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.

Once a valid, authentic manifest has been selected, the interpreter MUST examine the component list and verify that its maximum number of components is not exceeded and that each listed component ID is supported.

For each listed component, the interpreter MUST provide storage for the supported parameters. If the interpreter does not have sufficient temporary storage to process the parameters for all components, it MAY process components serially for each command sequence. See Section 6.5 for more details.

The interpreter SHOULD check that the common section contains at least one vendor ID check and at least one class ID check.

If the manifest contains more than one component, each command sequence MUST begin with a Set Current Component command.

If a dependency is specified, then the interpreter MUST perform the following checks:

  1. At the beginning of each section in the dependent: all previous sections of each dependency have been executed.
  2. At the end of each section in the dependent: The corresponding section in each dependency has been executed.

If the interpreter does not support dependencies and a manifest specifies a dependency, then the interpreter MUST reject the manifest.

If a Recipient supports groups of interdependent components (a Component Set), then it SHOULD require that all Components in the Component Set are specified by one manifest and its dependencies. This manifest is called the Root Manifest.

6.2.1. Minimizing Signature Verifications

Signature verification can be energy and time expensive on a constrained device. MAC verification is typically unaffected by these concerns. A Recipient MAY choose to parse and execute only the SUIT_Common section of the manifest prior to signature verification, if all of the below apply:

The guidelines in Creating Manifests require that the common section contains the applicability checks, so this section is sufficient for applicability verification. The parser MUST restrict acceptable commands to: Conditions, Override Parameters, Set Parameters, Try-Each, and Run Sequence ONLY. The manifest parser MUST NOT execute any command with side-effects outside the parser (for example, Run, Copy, Swap, or Fetch commands) prior to authentication and any such command MUST Abort. The Common Sequence MUST be executed again in its entirety after authenticity validation.

When executing Common prior to authenticity validation, the Manifest Processor MUST evaluate the integrity of the manifest using the SUIT_Digest present in the authentication block.

Alternatively, a Recipient MAY rely on network infrastructure to filter inapplicable manifests.

6.3. Interpreter Fundamental Properties

The interpreter has a small set of design goals:

  1. Executing an update MUST either result in an error, or a verifiably correct system state.
  2. Executing a secure boot MUST either result in an error, or a booted system.
  3. Executing the same manifest on multiple Recipients MUST result in the same system state.

NOTE: when using A/B images, the manifest functions as two (or more) logical manifests, each of which applies to a system in a particular starting state. With that provision, design goal 3 holds.

6.4. Abstract Machine Description

The heart of the manifest is the list of commands, which are processed by an interpreter. This interpreter can be modeled as a simple abstract machine. This machine consists of several data storage locations that are modified by commands.

There are two types of commands, namely those that modify state (directives) and those that perform tests (conditions). Parameters are used as the inputs to commands. Some directives offer control flow operations. Directives target a specific component or dependency. A dependency is another SUIT_Envelope that describes additional components. Dependencies are identified by digest, but referenced in commands by Dependency Index, the index into the array of Dependencies. A component is a unit of code or data that can be targeted by an update. Components are identified by Component Identifiers, i.e. arrays of binary strings, but referenced in commands by Component Index, the index into the array of Component Identifiers.

Conditions MUST NOT have any side-effects other than informing the interpreter of success or failure. The Interpreter does not Abort if the Soft Failure flag is set when a Condition reports failure.

Directives MAY have side-effects in the parameter table, the interpreter state, or the current component. The Interpreter MUST Abort if a Directive reports failure regardless of the Soft Failure flag.

The following table describes the behavior of each command. “params” represents the parameters for the current component or dependency. Most commands operate on either a component or a dependency. Setting the Component Index clears the Dependency Index. Setting the Dependency Index clears the Component Index.

Command Name Semantic of the Operation
Check Vendor Identifier assert(binary-match(current, current.params[vendor-id]))
Check Class Identifier assert(binary-match(current, current.params[class-id]))
Verify Image assert(binary-match(digest(current), current.params[digest]))
Set Component Index current := components[arg]
Override Parameters current.params[k] := v for k,v in arg
Set Dependency Index current := dependencies[arg]
Set Parameters current.params[k] := v if not k in params for k,v in arg
Process Dependency exec(current[common]); exec(current[current-segment])
Run run(current)
Fetch store(current, fetch(current.params[uri]))
Use Before assert(now() < arg)
Check Component Offset assert(offsetof(current) == arg)
Check Device Identifier assert(binary-match(current, current.params[device-id]))
Check Image Not Match assert(not binary-match(digest(current), current.params[digest]))
Check Minimum Battery assert(battery >= arg)
Check Update Authorized assert(isAuthorized())
Check Version assert(version_check(current, arg))
Abort assert(0)
Try Each break if exec(seq) is not error for-each seq in arg
Copy store(current, current.params[src-component])
Swap swap(current, current.params[src-component])
Wait For Event until event(arg), wait
Run Sequence exec(arg)
Run with Arguments run(current, arg)

6.5. Serialized Processing Interpreter

In highly constrained devices, where storage for parameters is limited, the manifest processor MAY handle one component at a time, traversing the manifest tree once for each listed component. In this mode, the interpreter ignores any commands executed while the component index is not the current component. This reduces the overall volatile storage required to process the update so that the only limit on number of components is the size of the manifest. However, this approach requires additional processing power.

In order to operate in this mode, the manifest processor loops on each section for every supported component, simply ignoring commands when the current component is not selected.

6.6. Parallel Processing Interpreter

Advanced Recipients MAY make use of the Strict Order parameter and enable parallel processing of some Command Sequences, or it may reorder some Command Sequences. To perform parallel processing, once the Strict Order parameter is set to False, the Recipient may fork a process for each command until the Strict Order parameter is returned to True or the Command Sequence ends. Then, it joins all forked processes before continuing processing of commands. To perform out-of-order processing, a similar approach is used, except the Recipient consumes all commands after the Strict Order parameter is set to False, then it sorts these commands into its preferred order, invokes them all, then continues processing.

Under each of these scenarios the parallel processing must halt:

To perform more useful parallel operations, sequences of commands may be collected in a suit-directive-run-sequence. Then, each of these sequences may be run in parallel. Each sequence defaults to Strict Order = True. To isolate each sequence from each other sequence, each sequence MUST begin with a Set Component Index directive. The interpreter MUST track each Set Component Index directive, and cause an Abort if more than one Set Component Index directive targets the same Component Index. When Strict Order = False, each suit-directive-run-sequence MUST begin with a Set Component Index directive. Any further Set Component Index directives MUST cause an Abort. This allows the interpreter that forks suit-directive-run-sequence processes to check that the first element is correct, then fork a process to handle the remainder of the sequence.

6.7. Processing Dependencies

As described in Section 6.2, each manifest must invoke 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 interpreter loads the dependency identified by the Current Dependency Index. The interpreter first executes the common-sequence section of the identified dependency, then it executes the section of the dependency that corresponds to the currently executing section of the dependent.

The interpreter also performs the checks described in Section 6.2 to ensure that the dependent is processing the dependency correctly.

6.8. Multiple Manifest Processors

When a system has multiple security domains they MAY require independent verification of authenticity or security policies. Security domains may be divided by separation technology such as Arm TrustZone, or Intel SGX. Security domains may 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 may require metadata signed by a specific Trust Authority for regulatory approval. This may be a different Trust Authority than the application processor.

When there are two or more security domains, a manifest processor MAY be required in each. The first manifest processor is the normal manifest processor as described for the Recipient in Abstract Machine. 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: setting parameters, inserting an Envelope, 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.

7. Creating Manifests

Manifests are created using tools for constructing COSE structures, calculating cryptographic values and compiling desired system state into a sequence of operations required to achieve that state. The process of constructing COSE structures and the calculation of cryptographic values is covered in [RFC8152].

Compiling desired system state into a sequence of operations can be accomplished in many ways. Several templates are provided below to cover common use-cases. These templates can be combined to produce more complex behavior.

NOTE: On systems that support only a single component, Set Current Component has no effect and can be omitted.

NOTE: A digest MUST always be set using Override Parameters, since this prevents a less-privileged dependent from replacing the digest.

7.1. Compatibility Check Template

The compatibility check ensures that Recipients only install compatible images. In this template all information is contained in the common block and the following sequence of operations are used:

7.2. Secure Boot Template

This template performs a secure boot operation.

The following operations are placed into the common block:

Then, the run block contains the following operations:

According to Section 6.4, the Run directive applies to the component referenced by the current Component Index. Hence, the Set Component Index directive has to be used to target a specific component.

7.3. Firmware Download Template

This template triggers the download of firmware.

The following operations are placed into the common block:

Then, the install block contains the following operations:

The Fetch directive needs the URI parameter to be set to determine where the image is retrieved from. Additionally, the destination of where the component shall be stored has to be configured. The URI is configured via the Set Parameters directive while the destination is configured via the Set Component Index directive.

7.4. Install Template

This template modifies the Firmware Download template and adds an additional sequence. The Firmware Download operations are moved from the Payload Install sequence to the Payload Fetch sequence.

Then, the Install sequence contains the following operations:

7.5. Integrated Payload Template

This template triggers the installation of a payload included in the manifest envelope. It is identical to Section 7.3 except that it places an added restriction on the URI passed to the Set Parameters directive.

An implementor MAY choose to place a payload in the envelope of a manifest. The payload envelope key MAY be a positive or negative integer. The payload envelope key MUST NOT be a value between 0 and 24 and it MUST NOT be used by any other envelope element in the manifest. The payload MUST be serialized in a bstr element.

The URI for a payload enclosed in this way MUST be expressed as a fragment-only reference, as defined in [RFC3986], Section 4.4. The fragment identifier is the stringified envelope key of the payload. For example, an envelope that contains a payload a key 42 would use a URI “#42”, key -73 would use a URI “#-73”.

7.6. Load from Nonvolatile Storage Template

This directive loads an firmware image from external storage.

The following operations are placed into the load block:

As outlined in Section 6.4, the Copy directive needs a source and a destination to be configured. The source is configured via Component Index (with the Set Parameters directive) and the destination is configured via the Set Component Index directive.

7.7. Load & Decompress from Nonvolatile Storage Template

The following operations are placed into the load block:

This template is similar to Section 7.6 but additionally performs decompression. Hence, the only difference is in setting the Compression Info parameter.

7.8. Dependency Template

The following operations are placed into the dependency resolution block:

Then, the validate block contains the following operations:

NOTE: Any changes made to parameters in a dependency persist in the dependent.

7.8.1. Composite Manifests

An implementor MAY choose to place a dependency’s envelope in the envelope of its dependent. The dependent envelope key for the dependency envelope MUST NOT be a value between 0 and 24 and it MUST NOT be used by any other envelope element in the dependent manifest.

The URI for a dependency enclosed in this way MUST be expressed as a fragment-only reference, as defined in [RFC3986], Section 4.4. The fragment identifier is the stringified envelope key of the dependency. For example, an envelope that contains a dependency at key 42 would use a URI “#42”, key -73 would use a URI “#-73”.

7.9. Encrypted Manifest Template

To use an encrypted manifest, create a plaintext dependent, and add the encrypted manifest as a dependency. The dependent can include very little information.

The following operations are placed into the dependency resolution block:

Then, the validate block contains the following operations:

A plaintext manifest and its encrypted dependency may also form a composite manifest.

7.10. A/B Image Template

The following operations are placed in the common block:

The following operations are placed in the fetch block or install block

8. Metadata Structure

The metadata for SUIT updates is composed of several primary constituent parts: the Envelope, Delegation Chains, Authentication Information, Manifest, and Severable Elements.

For a diagram of the metadata structure, see Section 5.

8.1. Encoding Considerations

The map indices in the envelope encoding are reset to 1 for each map within the structure. This is to keep the indices as small as possible. The goal is to keep the index objects to single bytes (CBOR positive integers 1-23).

Wherever enumerations are used, they are started at 1. This allows detection of several common software errors that are caused by uninitialised variables. Positive numbers in enumerations are reserved for IANA registration. Negative numbers are used to identify application-specific implementations.

All elements of the envelope must be wrapped in a bstr to minimize the complexity of the code that evaluates the cryptographic integrity of the element and to ensure correct serialization for integrity and authenticity checks.

8.2. Envelope

The Envelope contains each of the other primary constituent parts of the SUIT metadata. It allows for modular processing of the manifest by ordering components in the expected order of processing.

The Envelope is encoded as a CBOR Map. Each element of the Envelope is enclosed in a bstr, which allows computation of a message digest against known bounds.

8.3. Delegation Chains

The suit-delegation field MAY carry one or more CBOR Web Tokens (CWTs) [RFC8392], with [RFC8747] cnf claims. They can be used to perform enhanced authorization decisions. The CWTs are arranged into a list of lists. Each list starts with CWT authorized by a Trust Anchor, and finishes with a key used to authenticate the Manifest (see Section 8.4). This allows an Update Authority to delegate from a long term Trust Anchor, down through intermediaries, to a delegate without any out-of-band updates Trust Anchors.

A Recipient MAY choose to cache intermediaries and/or delegates. If an Update Distributor knows that a targeted Recipient has cached some intermediaries or delegates, it MAY choose to strip any cached intermediaries or delegates from the Delegation Chains in order to reduce bandwidth and energy.

8.4. Authenticated Manifests

The suit-authentication-wrapper contains a list of one or more cryptographic authentication wrappers for the Manifest. These are implemented as COSE_Mac_Tagged or COSE_Sign_Tagged blocks. Each of these blocks contains a SUIT_Digest of the Manifest. This enables modular processing of the manifest. The COSE_Mac_Tagged and COSE_Sign_Tagged blocks are described in RFC 8152 [RFC8152]. The suit-authentication-wrapper MUST come before any element in the SUIT_Envelope, except for the OPTIONAL suit-delegation, regardless of canonical encoding of CBOR. All validators MUST reject any SUIT_Envelope that begins with any element other than a suit-authentication-wrapper or suit-delegation.

A SUIT_Envelope that has not had authentication information added MUST still contain the suit-authentication-wrapper element, but the content MUST be an empty list.

8.5. Encrypted Manifests

To use an encrypted manifest, it must be a dependency of a plaintext manifest. This allows fine-grained control of what information is accessible to intermediate systems for the purposes of management, while still preserving the confidentiality of the manifest contents. This also means that a Recipient can process an encrypted manifest in the same way as an encrypted payload, allowing code reuse.

A template for using an encrypted manifest is covered in Encrypted Manifest Template.

8.6. Manifest

The manifest contains:

The CoSWID, Text section, or any Command Sequence of the Update Procedure (Dependency Resolution, Image Fetch, Image Installation) can be either a CBOR structure or a SUIT_Digest. In each of these cases, the SUIT_Digest provides for a severable field. Severable fields are RECOMMENDED to implement. In particular, the human-readable text SHOULD be severable, since most useful text elements occupy more space than a SUIT_Digest, but are not needed by the Recipient. Because SUIT_Digest is a CBOR Array and each severable element is a CBOR bstr, it is straight-forward for a Recipient to determine whether an element has been severed. The key used for a severable element is the same in the SUIT_Manifest and in the SUIT_Envelope so that a Recipient can easily identify the correct data in the envelope. See Section 8.7.8 for more detail.

8.6.1. suit-manifest-version

The suit-manifest-version indicates the version of serialization used to encode the manifest. Version 1 is the version described in this document. suit-manifest-version is REQUIRED to implement.

8.6.2. suit-manifest-sequence-number

The suit-manifest-sequence-number is a monotonically increasing anti-rollback counter. It also helps Recipients to determine which in a set of manifests is the “root” manifest in a given update. Each manifest MUST have a sequence number higher than each of its dependencies. Each Recipient MUST reject any manifest that has a sequence number lower than its current sequence number. It MAY be convenient to use a UTC timestamp in seconds as the sequence number. suit-manifest-sequence-number is REQUIRED to implement.

8.6.3. suit-reference-uri

suit-reference-uri is a text string that encodes a URI where a full version of this manifest can be found. This is convenient for allowing management systems to show the severed elements of a manifest when this URI is reported by a Recipient after installation.

8.6.4. suit-text

suit-text SHOULD be a severable element. suit-text is a map of pairs. It MAY contain two different types of pair:

Each SUIT_Component_Identifier => map entry contains a map of integer => text values. All SUIT_Component_Identifiers present in suit-text MUST also be present in suit-common or the suit-common of a dependency.

suit-text contains all the human-readable information that describes any and all parts of the manifest, its payload(s) and its resource(s). The text section is typically severable, allowing manifests to be distributed without the text, since end-nodes do not require text. The meaning of each field is described below.

Each section MAY be present. If present, each section MUST be as described. Negative integer IDs are reserved for application-specific text values.

The following table describes the text fields available in suit-text:

CDDL Structure Description
suit-text-manifest-description Free text description of the manifest
suit-text-update-description Free text description of the update
suit-text-manifest-json-source The JSON-formatted document that was used to create the manifest
suit-text-manifest-yaml-source The yaml-formatted document that was used to create the manifest

The following table describes the text fields available in each map identified by a SUIT_Component_Identifier.

CDDL Structure Description
suit-text-vendor-name Free text vendor name
suit-text-model-name Free text model name
suit-text-vendor-domain The domain used to create the vendor-id condition
suit-text-model-info The information used to create the class-id condition
suit-text-component-description Free text description of each component in the manifest
suit-text-component-version A text version number
suit-text-version-required A text expression of the required version number

suit-text is OPTIONAL to implement.

8.7. text-version-required

suit-text-version-required is used to represent a version-based dependency on suit-parameter-version as described in Section and Section To describe a version dependency, a Manifest Author should populate the suit-text map with a SUIT_Component_Identifier key for the dependency component, and place in the corresponding map a suit-text-version-required key with a text expression that is representative of the version constraints placed on the dependency.

For example, to express a dependency on a component “[‘x’, ‘y’]”, where the version should be any v1.x later than v1.2.5, but not v2.0 or above, the author would add the following structure to the suit-text element. Note that this text is in cbor-diag notation.

[h'78',h'79'] : { 7 : ">=1.2.5,<2" }

8.7.1. suit-coswid

suit-coswid contains a Concise Software Identifier. This element SHOULD be made severable so that it can be discarded by the Recipient or an intermediary if it is not required by the Recipient.

suit-coswid is OPTIONAL to implement.

8.7.2. suit-common

suit-common encodes all the information that is shared between each of the command sequences, including: suit-dependencies, suit-components, and suit-common-sequence. suit-common is REQUIRED to implement.

suit-dependencies is a list of Section blocks that specify manifests that must be present before the current manifest can be processed. suit-dependencies is OPTIONAL to implement.

suit-components is a list of SUIT_Component_Identifier blocks that specify the component identifiers that will be affected by the content of the current manifest. suit-components is REQUIRED to implement; at least one manifest in a dependency tree MUST contain a suit-components block.

suit-common-sequence is a SUIT_Command_Sequence to execute prior to executing any other command sequence. Typical actions in suit-common-sequence include setting expected Recipient identity and image digests when they are conditional (see Section and Section 7.10 for more information on conditional sequences). suit-common-sequence is RECOMMENDED to implement. It is REQUIRED if the optimizations described in Section 6.2.1 will be used. Whenever a parameter or try-each is required by more than one Command Sequence, suit-common-sequence results in a smaller encoding. Dependencies

SUIT_Dependency specifies a manifest that describes a dependency of the current manifest. The Manifest is identified, however 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.

The suit-dependency-digest specifies the dependency manifest uniquely by identifying a particular Manifest structure. This is identical to the digest that would be present as the payload of any suit-authentication-block in the dependency’s Envelope. The digest is calculated over the Manifest structure instead of the COSE Sig_structure or Mac_structure. This is necessary 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 (see Section 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. This element is OPTIONAL.

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 manifest needs to be processed by a secondary manifest processor, as described in Section 6.8. SUIT_Component_Identifier

A component is a unit of code or data that can be targeted by an update. To facilitate composite devices, components are identified by a list of CBOR byte strings, which allows construction of hierarchical component structures. A dependency MAY declare a prefix to the components defined in the dependency manifest. Components are identified by Component Identifiers, i.e. arrays of binary strings, but referenced in commands

A Component Identifier can be trivial, such as the simple array [h’00’]. It can also represent a filesystem path by encoding each segment of the path as an element in the list. For example, the path “/usr/bin/env” would encode to [‘usr’,’bin’,’env’].

This hierarchical construction allows a component identifier to identify any part of a complex, multi-component system.

8.7.3. SUIT_Command_Sequence

A SUIT_Command_Sequence defines a series of actions that the Recipient MUST take to accomplish a particular goal. These goals are defined in the manifest and include:

  1. Dependency Resolution: suit-dependency-resolution is a SUIT_Command_Sequence to execute in order to perform dependency resolution. Typical actions include configuring URIs of dependency manifests, fetching dependency manifests, and validating dependency manifests’ contents. suit-dependency-resolution is REQUIRED to implement and to use when suit-dependencies is present.
  2. Payload Fetch: suit-payload-fetch is a SUIT_Command_Sequence to execute in order to obtain a payload. Some manifests may include these actions in the suit-install section instead if they operate in a streaming installation mode. This is particularly relevant for constrained devices without any temporary storage for staging the update. suit-payload-fetch is OPTIONAL to implement.
  3. Payload Installation: suit-install is a SUIT_Command_Sequence to execute in order to install a payload. Typical actions include verifying a payload stored in temporary storage, copying a staged payload from temporary storage, and unpacking a payload. suit-install is OPTIONAL to implement.
  4. Image Validation: suit-validate is a SUIT_Command_Sequence to execute in order to validate that the result of applying the update is correct. Typical actions involve image validation and manifest validation. suit-validate is REQUIRED to implement. If the manifest contains dependencies, one process-dependency invocation per dependency or one process-dependency invocation targeting all dependencies SHOULD be present in validate.
  5. Image Loading: suit-load is a SUIT_Command_Sequence to execute in order to prepare a payload for execution. Typical actions include copying an image from permanent storage into RAM, optionally including actions such as decryption or decompression. suit-load is OPTIONAL to implement.
  6. Run or Boot: suit-run is a SUIT_Command_Sequence to execute in order to run an image. suit-run typically contains a single instruction: either the “run” directive for the bootable manifest or the “process dependencies” directive for any dependents of the bootable manifest. suit-run is OPTIONAL to implement. Only one manifest in an update may contain the “run” directive.

Goals 1,2,3 form the Update Procedure. Goals 4,5,6 form the Boot Procedure.

Each Command Sequence follows exactly the same structure to ensure that the parser is as simple as possible.

Lists of commands are constructed from two kinds of element:

  1. Conditions that MUST be true–any failure is treated as a failure of the update/load/boot
  2. Directives that MUST be executed.

Each condition is a command code identifier, followed by a SUIT_Reporting_Policy.

Each directive is composed of:

  1. A command code identifier
  2. An argument block or a reporting policy

Argument blocks are consumed only by flow-control directives:

Reporting policies provide a hint to the manifest processor of whether or not to add the success or failure of a command to any report that it generates.

Many conditions and directives apply to a given component, and these generally grouped together. Therefore, a special command to set the current component index is provided with a matching command to set the current dependency index. This index is a numeric index into the component ID tables defined at the beginning of the document. For the purpose of setting the index, the two component ID tables are considered to be concatenated together.

To facilitate optional conditions, a special directive, Section, is provided. It runs several new lists of conditions/directives, one after another, that are contained as an argument to the directive. By default, it assumes that a failure of a condition should not indicate a failure of the update/boot, but a parameter is provided to override this behavior. See Section

8.7.4. Reporting Policy

TODO: Records, bitfield

To facilitate construction of Reports that describe the success, or failure of a given Procedure, each command is given a Reporting Policy. This is an integer bitfield that follows the command and indicates what the Recipient should do with the Record of executing the command. The options are summarized in the table below.

Policy Description
suit-send-record-on-success Record when the command succeeds
suit-send-record-on-failure Record when the command fails
suit-send-sysinfo-success Add system information when the command succeeds
suit-send-sysinfo-failure Add system information when the command fails

Any or all of these policies may be enabled at once.

SUIT does NOT REQUIRE a particular format of Records or Reports. SUIT only defines hints to the Reporting engine for which Records it should aggregate into the Report.

An OPTIONAL Record format, SUIT_Record is defined in [full-cddl]. It is encoded as a map, with the following elements.

Element Description
suit-record-success The boolean or integer success or failure code of the command.
suit-record-component-id The current component when the record was generated.
suit-record-dependency-id The current dependency digest when the record was generated.
suit-record-command-sequence-id The label of the Command Sequence that was executing when the record was generated.
suit-record-command-id The label of the command that was in progress when the record was generated.
suit-record-params The set of parameters that was consumed by the current command.
suit-record-actual The value against which a suit-condition compared a parameter.

In Secure Boot operations, the Reporting engine MAY aggregate the Records produced in a Procedure into the evidence used for an attestation report.

8.7.5. SUIT_Parameters

Many conditions and directives require additional information. That information is contained within parameters that can be set in a consistent way. This allows reduction of manifest size and replacement of parameters from one manifest to the next.

Most parameters are scoped to a specific component. This means that setting a parameter for one component has no effect on the parameters of any other component. The only exceptions to this are two Manifest Processor parameters: Strict Order and Soft Failure.

The defined manifest parameters are described below.

Name CDDL Structure Reference
Vendor ID suit-parameter-vendor-identifier Section
Class ID suit-parameter-class-identifier Section
Image Digest suit-parameter-image-digest Section
Image Size suit-parameter-image-size Section
Use Before suit-parameter-use-before Section
Component Offset suit-parameter-component-offset Section
Encryption Info suit-parameter-encryption-info Section
Compression Info suit-parameter-compression-info Section
Unpack Info suit-parameter-unpack-info Section
URI suit-parameter-uri Section
Source Component suit-parameter-source-component Section
Run Args suit-parameter-run-args Section
Device ID suit-parameter-device-identifier Section
Minimum Battery suit-parameter-minimum-battery Section
Update Priority suit-parameter-update-priority Section
Version suit-parameter-version Section
Wait Info suit-parameter-wait-info Section
URI List suit-parameter-uri-list Section
Fetch Arguments suit-parameter-fetch-arguments Section
Strict Order suit-parameter-strict-order Section
Soft Failure suit-parameter-soft-failure Section
Custom suit-parameter-custom Section

CBOR-encoded object parameters are still wrapped in a bstr. This is because it allows a parser that is aggregating parameters to reference the object with a single pointer and traverse it without understanding the contents. This is important for modularization and division of responsibility within a pull parser. The same consideration does not apply to Directives because those elements are invoked with their arguments immediately Constructing Identifiers

Several conditions use identifiers to determine whether a manifest matches a given Recipient or not. These identifiers are defined to be RFC 4122 [RFC4122] UUIDs. These UUIDs are not human-readable and are therefore used for machine-based processing only.

A Recipient MAY match any number of UUIDs for vendor or class identifier. This may be relevant to physical or software modules. For example, a Recipient that has an OS and one or more applications might list one Vendor ID for the OS and one or more additional Vendor IDs for the applications. This Recipient might also have a Class ID that must be matched for the OS and one or more Class IDs for the applications.

Identifiers are used for compatibility checks. They MUST NOT be used as assertions of identity. They are evaluated by identifier conditions.

A more complete example: Imagine a device has the following physical components: 1. A host MCU 2. A WiFi module

This same device has three software modules: 1. An operating system 2. A WiFi module interface driver 3. An application

Suppose that the WiFi module’s firmware has a proprietary update mechanism and doesn’t support manifest processing. This device can report four class IDs:

  1. Hardware model/revision
  2. OS
  3. WiFi module model/revision
  4. Application

This allows the OS, WiFi module, and application to be updated independently. To combat possible incompatibilities, the OS class ID can be changed each time the OS has a change to its API.

This approach allows a vendor to target, for example, all devices with a particular WiFi module with an update, which is a very powerful mechanism, particularly when used for security updates.

UUIDs MUST be created according to RFC 4122 [RFC4122]. UUIDs SHOULD use versions 3, 4, or 5, as described in RFC4122. Versions 1 and 2 do not provide a tangible benefit over version 4 for this application.

The RECOMMENDED method to create a vendor ID is: Vendor ID = UUID5(DNS_PREFIX, vendor domain name)

The RECOMMENDED method to create a class ID is: Class ID = UUID5(Vendor ID, Class-Specific-Information)

Class-specific information is composed of a variety of data, for example: suit-parameter-vendor-identifier

A RFC 4122 UUID representing the vendor of the device or component. The UUID is encoded as a 16 byte bstr, containing the raw bytes of the UUID. It MUST be constructed as described in Section suit-parameter-class-identifier

A RFC 4122 UUID representing the class of the device or component. The UUID is encoded as a 16 byte bstr, containing the raw bytes of the UUID. It MUST be constructed as described in Section suit-parameter-device-identifier

A RFC 4122 UUID representing the specific device or component. The UUID is encoded as a 16 byte bstr, containing the raw bytes of the UUID. It MUST be constructed as described in Section suit-parameter-image-digest

A fingerprint computed over the component itself, encoded in the Section 10 structure. The SUIT_Digest is wrapped in a bstr, as required in Section 8.7.5. suit-parameter-image-size

The size of the firmware image in bytes. This size is encoded as a positive integer. suit-parameter-use-before

An expiry date for the use of the manifest encoded as a POSIX timestamp; a positive integer. Implementations that use this parameter MUST use a 64-bit internal representation of the integer. suit-parameter-component-offset

This parameter sets the offset in a component. Some components support multiple possible Slots (offsets into a storage area). This parameter describes the intended Slot to use, identified by its offset into the component’s storage area. This offset MUST be encoded as a positive integer. suit-parameter-encryption-info

Encryption Info defines the mechanism that Fetch or Copy should use to decrypt the data they transfer. SUIT_Parameter_Encryption_Info is encoded as a COSE_Encrypt_Tagged or a COSE_Encrypt0_Tagged, wrapped in a bstr. suit-parameter-compression-info

Compression Info defines any information that is required for a Recipient to perform decompression operations. Typically, this includes the algorithm identifier. This document defines the use of ZLIB [RFC1950], Brotli [RFC7932], and ZSTD [I-D.kucherawy-rfc8478bis].

Additional compression formats can be registered through the IANA-maintained registry. suit-parameter-unpack-info

SUIT_Unpack_Info defines the information required for a Recipient to interpret a packed format. This document defines the use of the following binary encodings: Intel HEX [HEX], Motorola S-record [SREC], Executable and Linkable Format (ELF) [ELF], and Common Object File Format (COFF) [COFF].

Additional packing formats can be registered through the IANA-maintained registry. suit-parameter-uri

A URI from which to fetch a resource. suit-parameter-source-component

This parameter sets the source component to be used with either Section or with Section The current Component, as set by suit-directive-set-component-index defines the destination, and suit-parameter-source-component defines the source. suit-parameter-run-args

This parameter contains an encoded set of arguments for Section The arguments MUST be provided as an implementation-defined bstr. suit-parameter-minimum-battery

This parameter sets the minimum battery level in mWh. This parameter is encoded as a positive integer. Used with Section suit-parameter-update-priority

This parameter sets the priority of the update. This parameter is encoded as an integer. It is used along with suit-condition-update-authorized to ask an application for permission to initiate an update. This does not constitute a privilege inversion because an explicit request for authorization has been provided by the Update Authority in the form of the suit-condition-update-authorized command.

Applications MAY define their own meanings for the update priority. For example, critical reliability & vulnerability fixes MAY be given negative numbers, while bug fixes MAY be given small positive numbers, and feature additions MAY be given larger positive numbers, which allows an application to make an informed decision about whether and when to allow an update to proceed. suit-parameter-version

Indicates allowable versions for the specified component. Allowable versions can be specified, either with a list or with range matching. This parameter is compared with version asserted by the current component when Section is invoked. The current component may assert the current version in many ways, including storage in a parameter storage database, in a metadata object, or in a known location within the component itself.

The component version can be compared as:

Versions are encoded as a CBOR list of integers. Comparisons are done on each integer in sequence. Comparison stops after all integers in the list defined by the manifest have been consumed OR after a non-equal match has occurred. For example, if the manifest defines a comparison, “Equal [1]”, then this will match all version sequences starting with 1. If a manifest defines both “Greater or Equal [1,0]” and “Lesser [1,10]”, then it will match versions 1.0.x up to, but not including 1.10.

While the exact encoding of versions is application-defined, semantic versions map conveniently. For example,

suit-condition-version is OPTIONAL to implement.

Versions SHOULD be provided as follows:

  1. The first integer represents the major number. This indicates breaking changes to the component.
  2. The second integer represents the minor number. This is typically reserved for new features or large, non-breaking changes.
  3. The third integer is the patch version. This is typically reserved for bug fixes.
  4. The fourth integer is the build number.

Where Alpha (-3), Beta (-2), and Release Candidate (-1) are used, they are inserted as a negative number between Minor and Patch numbers. This allows these releases to compare correctly with final releases. For example, Version 2.0, RC1 should be lower than Version 2.0.0 and higher than any Version 1.x. By encoding RC as -1, this works correctly: [2,0,-1,1] compares as lower than [2,0,0]. Similarly, beta (-2) is lower than RC and alpha (-3) is lower than RC. suit-parameter-wait-info

suit-directive-wait Section directs the manifest processor to pause until a specified event occurs. The suit-parameter-wait-info encodes the parameters needed for the directive.

The exact implementation of the pause is implementation-defined. For example, this could be done by blocking on a semaphore, registering an event handler and suspending the manifest processor, polling for a notification, or aborting the update entirely, then restarting when a notification is received.

suit-parameter-wait-info is encoded as a map of wait events. When ALL wait events are satisfied, the Manifest Processor continues. The wait events currently defined are described in the following table.

Name Encoding Description
suit-wait-event-authorization int Same as Section
suit-wait-event-power int Wait until power state
suit-wait-event-network int Wait until network state
suit-wait-event-other-device-version See below Wait for other device to match version
suit-wait-event-time uint Wait until time (POSIX timestamp)
suit-wait-event-time-of-day uint Wait until seconds since 00:00:00
suit-wait-event-day-of-week uint Wait until days since Sunday

suit-wait-event-other-device-version reuses the encoding of suit-parameter-version-match. It is encoded as a sequence that contains an implementation-defined bstr identifier for the other device, and a list of one or more SUIT_Parameter_Version_Match. suit-parameter-uri-list

Indicates a list of URIs from which to fetch a resource. The URI list is encoded as a list of tstr, in priority order. The Recipient should attempt to fetch the resource from each URI in turn, ruling out each, in order, if the resource is inaccessible or it is otherwise undesirable to fetch from that URI. suit-parameter-uri-list is consumed by Section suit-parameter-fetch-arguments

An implementation-defined set of arguments to Section Arguments are encoded in a bstr. suit-parameter-strict-order

The Strict Order Parameter allows a manifest to govern when directives can be executed out-of-order. This allows for systems that have a sensitivity to order of updates to choose the order in which they are executed. It also allows for more advanced systems to parallelize their handling of updates. Strict Order defaults to True. It MAY be set to False when the order of operations does not matter. When arriving at the end of a command sequence, ALL commands MUST have completed, regardless of the state of SUIT_Parameter_Strict_Order. If SUIT_Parameter_Strict_Order is returned to True, ALL preceding commands MUST complete before the next command is executed.

See Section 6.6 for behavioral description of Strict Order. suit-parameter-soft-failure

When executing a command sequence inside Section or Section and a condition failure occurs, the manifest processor aborts the sequence. For suit-directive-try-each, if Soft Failure is True, the next sequence in Try Each is invoked, otherwise suit-directive-try-each fails with the condition failure code. In suit-directive-run-sequence, if Soft Failure is True the suit-directive-run-sequence simply halts with no side-effects and the Manifest Processor continues with the following command, otherwise, the suit-directive-run-sequence fails with the condition failure code.

suit-parameter-soft-failure is scoped to the enclosing SUIT_Command_Sequence. Its value is discarded when SUIT_Command_Sequence terminates. It MUST NOT be set outside of suit-directive-try-each or suit-directive-run-sequence.

When suit-directive-try-each is invoked, Soft Failure defaults to True. An Update Author may choose to set Soft Failure to False if they require a failed condition in a sequence to force an Abort.

When suit-directive-run-sequence is invoked, Soft Failure defaults to False. An Update Author may choose to make failures soft within a suit-directive-run-sequence. suit-parameter-custom

This parameter is an extension point for any proprietary, application specific conditions and directives.

8.7.6. SUIT_Condition

Conditions are used to define mandatory properties of a system in order for an update to be applied. They can be pre-conditions or post-conditions of any directive or series of directives, depending on where they are placed in the list. All Conditions specify a Reporting Policy as described Section 8.7.4. Conditions include:

Name CDDL Structure Reference
Vendor Identifier suit-condition-vendor-identifier Section
Class Identifier suit-condition-class-identifier Section
Device Identifier suit-condition-device-identifier Section
Image Match suit-condition-image-match Section
Image Not Match suit-condition-image-not-match Section
Use Before suit-condition-use-before Section
Component Offset suit-condition-component-offset Section
Minimum Battery suit-condition-minimum-battery Section
Update Authorized suit-condition-update-authorized Section
Version suit-condition-version Section
Custom Condition SUIT_Condition_Custom Section

The abstract description of these conditions is defined in Section 6.4.

Conditions compare parameters against properties of the system. These properties may be asserted in many different ways, including: calculation on-demand, volatile definition in memory, static definition within the manifest processor, storage in known location within an image, storage within a key storage system, storage in One-Time-Programmable memory, inclusion in mask ROM, or inclusion as a register in hardware. Some of these assertion methods are global in scope, such as a hardware register, some are scoped to an individual component, such as storage at a known location in an image, and some assertion methods can be either global or component-scope, based on implementation.

Each condition MUST report a result code on completion. If a condition reports failure, then the current sequence of commands MUST terminate. A subsequent command or command sequence MAY continue executing if Section is set. If a condition requires additional information, this MUST be specified in one or more parameters before the condition is executed. If a Recipient attempts to process a condition that expects additional information and that information has not been set, it MUST report a failure. If a Recipient encounters an unknown condition, it MUST report a failure.

Condition labels in the positive number range are reserved for IANA registration while those in the negative range are custom conditions reserved for proprietary use. See Section 11 for more details. suit-condition-vendor-identifier, suit-condition-class-identifier, and suit-condition-device-identifier

There are three identifier-based conditions: suit-condition-vendor-identifier, suit-condition-class-identifier, and suit-condition-device-identifier. Each of these conditions match a RFC 4122 [RFC4122] UUID that MUST have already been set as a parameter. The installing Recipient MUST match the specified UUID in order to consider the manifest valid. These identifiers are scoped by component in the manifest. The Recipient MAY treat them as scoped by component or as global identifiers.

The Recipient uses the ID parameter that has already been set using the Set Parameters directive. If no ID has been set, this condition fails. suit-condition-class-identifier and suit-condition-vendor-identifier are REQUIRED to implement. suit-condition-device-identifier is OPTIONAL to implement.

Each identifier condition compares the corresponding identifier parameter to a parameter asserted to the Manifest Processor by the Recipient. Identifiers MUST be known to the Manifest Processor in order to evaluate compatibility.

Globally-scoped identifiers MUST match, regardless of current component index. Component-scoped identifiers match only when the current component index resolves to the component associated with the component-scoped identifier. suit-condition-image-match

Verify that the current component matches the Section for the current component. The digest is verified against the digest specified in the Component’s parameters list. If no digest is specified, the condition fails. suit-condition-image-match is REQUIRED to implement. suit-condition-image-not-match

Verify that the current component does not match the Section If no digest is specified, the condition fails. suit-condition-image-not-match is OPTIONAL to implement. suit-condition-use-before

Verify that the current time is BEFORE the specified time. suit-condition-use-before is used to specify the last time at which an update should be installed. The recipient evaluates the current time against the suit-parameter-use-before parameter, which must have already been set as a parameter, encoded as a POSIX timestamp, that is seconds after 1970-01-01 00:00:00. Timestamp conditions MUST be evaluated in 64 bits, regardless of encoded CBOR size. suit-condition-use-before is OPTIONAL to implement. suit-condition-component-offset

Verify that the offset of the current component matches the offset set in Section This condition allows a manifest to select between several images to match a target offset. suit-condition-minimum-battery

suit-condition-minimum-battery provides a mechanism to test a Recipient’s battery level before installing an update. This condition is primarily for use in primary-cell applications, where the battery is only ever discharged. For batteries that are charged, suit-directive-wait is more appropriate, since it defines a “wait” until the battery level is sufficient to install the update. suit-condition-minimum-battery is specified in mWh. suit-condition-minimum-battery is OPTIONAL to implement. suit-condition-minimum-battery consumes Section suit-condition-update-authorized

Request Authorization from the application and fail if not authorized. This can allow a user to decline an update. Section provides an integer priority level that the application can use to determine whether or not to authorize the update. Priorities are application defined. suit-condition-update-authorized is OPTIONAL to implement. suit-condition-version

suit-condition-version allows comparing versions of firmware. Verifying image digests is preferred to version checks because digests are more precise. suit-condition-version examines a component’s version against the version info specified in Section SUIT_Condition_Custom

SUIT_Condition_Custom describes any proprietary, application specific condition. This is encoded as a negative integer, chosen by the firmware developer. If additional information must be provided to the condition, it should be encoded in a custom parameter (a nint) as described in Section 8.7.5. SUIT_Condition_Custom is OPTIONAL to implement.

8.7.7. SUIT_Directive

Directives are used to define the behavior of the recipient. Directives include:

Name CDDL Structure Reference
Set Component Index suit-directive-set-component-index Section
Set Dependency Index suit-directive-set-dependency-index Section
Abort suit-directive-abort Section
Try Each suit-directive-try-each Section
Process Dependency suit-directive-process-dependency Section
Set Parameters suit-directive-set-parameters Section
Override Parameters suit-directive-override-parameters Section
Fetch suit-directive-fetch Section
Copy suit-directive-copy Section
Run suit-directive-run Section
Wait For Event suit-directive-wait Section
Run Sequence suit-directive-run-sequence Section
Swap suit-directive-swap Section
Fetch URI list suit-directive-fetch-uri-list Section

The abstract description of these commands is defined in Section 6.4.

When a Recipient executes a Directive, it MUST report a result code. If the Directive reports failure, then the current Command Sequence MUST terminate. suit-directive-set-component-index

Set Component Index defines the component to which successive directives and conditions will apply. The supplied argument MUST be either a boolean or an unsigned integer index into suit-components. If the following directives apply to ALL components, then the boolean value “True” is used instead of an index. If the following directives apply to NO components, then the boolean value “False” is used. When suit-directive-set-dependency-index is used, suit-directive-set-component-index = False is implied. When suit-directive-set-component-index is used, suit-directive-set-dependency-index = False is implied. suit-directive-set-dependency-index

Set Dependency Index defines the manifest to which successive directives and conditions will apply. The supplied argument MUST be either a boolean or an unsigned integer index into the dependencies. If the following directives apply to ALL dependencies, then the boolean value “True” is used instead of an index. If the following directives apply to NO dependencies, then the boolean value “False” is used. When suit-directive-set-component-index is used, suit-directive-set-dependency-index = False is implied. When suit-directive-set-dependency-index is used, suit-directive-set-component-index = False is implied.

Typical operations that require suit-directive-set-dependency-index include setting a source URI or Encryption Information, invoking “Fetch,” or invoking “Process Dependency” for an individual dependency. suit-directive-abort

Unconditionally fail. This operation is typically used in conjunction with suit-directive-try-each. suit-directive-try-each

This command runs several SUIT_Command_Sequence, one after another, in a strict order. Use this command to implement a “try/catch-try/catch” sequence. Manifest processors MAY implement this command.

Section is initialized to True at the beginning of each sequence. If one sequence aborts due to a condition failure, the next is started. If no sequence completes without condition failure, then suit-directive-try-each returns an error. If a particular application calls for all sequences to fail and still continue, then an empty sequence (nil) can be added to the Try Each Argument.

The argument to suit-directive-try-each is a list of SUIT_Command_Sequence. suit-directive-try-each does not specify a reporting policy. 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 “fetch payload,” this will execute “common” in the current dependency, then “fetch payload” in the current dependency. Once this is complete, the command following suit-directive-process-dependency will be processed.

If the current dependency is False, this directive has no effect. If the current dependency is True, then this directive applies to all dependencies. If the current section is “common,” this directive MUST have no effect.

When SUIT_Process_Dependency completes, it forwards the last status code that occurred in the dependency. suit-directive-set-parameters

suit-directive-set-parameters allows the manifest to configure behavior of future directives by changing parameters that are read by those directives. When dependencies are used, suit-directive-set-parameters also allows a manifest to modify the behavior of its dependencies.

Available parameters are defined in Section 8.7.5.

If a parameter is already set, suit-directive-set-parameters will skip setting the parameter to its argument. This provides the core of the override mechanism, allowing dependent manifests to change the behavior of a manifest.

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

suit-directive-override-parameters replaces any listed parameters that are already set with the values that are provided in its argument. This allows a manifest to prevent replacement of critical parameters.

Available parameters are defined in Section 8.7.5.

suit-directive-override-parameters does not specify a reporting policy. suit-directive-fetch

suit-directive-fetch instructs the manifest processor to obtain one or more manifests or payloads, as specified by the manifest index and component index, respectively.

suit-directive-fetch can target one or more manifests and one or more payloads. suit-directive-fetch retrieves each component and each manifest listed in component-index and dependency-index, respectively. If component-index or dependency-index is True, instead of an integer, then all current manifest components/manifests are fetched. The current manifest’s dependent-components are not automatically fetched. In order to pre-fetch these, they MUST be specified in a component-index integer.

suit-directive-fetch typically takes no arguments unless one is needed to modify fetch behavior. If an argument is needed, it must be wrapped in a bstr and set in suit-parameter-fetch-arguments.

suit-directive-fetch reads the URI parameter to find the source of the fetch it performs.

The behavior of suit-directive-fetch can be modified by setting one or more of SUIT_Parameter_Encryption_Info, SUIT_Parameter_Compression_Info, SUIT_Parameter_Unpack_Info. These three parameters each activate and configure a processing step that can be applied to the data that is transferred during suit-directive-fetch. suit-directive-fetch-uri-list

suit-directive-fetch-uri-list uses the same semantics as Section, however it iterates over the URI List to select a URI to fetch from. suit-directive-copy

suit-directive-copy instructs the manifest processor to obtain one or more payloads, as specified by the component index. suit-directive-copy retrieves each component listed in component-index, respectively. If component-index is True, instead of an integer, then all current manifest components are copied. The current manifest’s dependent-components are not automatically copied. In order to copy these, they MUST be specified in a component-index integer.

The behavior of suit-directive-copy can be modified by setting one or more of SUIT_Parameter_Encryption_Info, SUIT_Parameter_Compression_Info, SUIT_Parameter_Unpack_Info. These three parameters each activate and configure a processing step that can be applied to the data that is transferred during suit-directive-copy.

suit-directive-copy reads its source from Section suit-directive-run

suit-directive-run directs the manifest processor to transfer execution to the current Component Index. When this is invoked, the manifest processor MAY be unloaded and execution continues in the Component Index. Arguments are provided to suit-directive-run through suit-parameter-run-arguments and are forwarded to the executable code located in Component Index in an application-specific way. For example, this could form the Linux Kernel Command Line if booting a Linux device.

If the executable code at Component Index is constructed in such a way that it does not unload the manifest processor, then the manifest processor may resume execution after the executable completes. This allows the manifest processor to invoke suitable helpers and to verify them with image conditions. suit-directive-wait

suit-directive-wait directs the manifest processor to pause until a specified event occurs. Some possible events include:

  1. Authorization
  2. External Power
  3. Network availability
  4. Other Device Firmware Version
  5. Time
  6. Time of Day
  7. Day of Week suit-directive-run-sequence

To enable conditional commands, and to allow several strictly ordered sequences to be executed out-of-order, suit-directive-run-sequence allows the manifest processor to execute its argument as a SUIT_Command_Sequence. The argument must be wrapped in a bstr.

When a sequence is executed, any failure of a condition causes immediate termination of the sequence.

When suit-directive-run-sequence completes, it forwards the last status code that occurred in the sequence. If the Soft Failure parameter is true, then suit-directive-run-sequence only fails when a directive in the argument sequence fails.

Section defaults to False when suit-directive-run-sequence begins. Its value is discarded when suit-directive-run-sequence terminates. suit-directive-swap

suit-directive-swap instructs the manifest processor to move the source to the destination and the destination to the source simultaneously. Swap has nearly identical semantics to suit-directive-copy except that suit-directive-swap replaces the source with the current contents of the destination in an application-defined way. If SUIT_Parameter_Compression_Info or SUIT_Parameter_Encryption_Info are present, they MUST be handled in a symmetric way, so that the source is decompressed into the destination and the destination is compressed into the source. The source is decrypted into the destination and the destination is encrypted into the source. suit-directive-swap is OPTIONAL to implement.

8.7.8. Integrity Check Values

When the CoSWID, Text section, or any Command Sequence of the Update Procedure is made severable, it is moved to the Envelope and replaced with a SUIT_Digest. The SUIT_Digest is computed over the entire bstr enclosing the Manifest element that has been moved to the Envelope. Each element that is made severable from the Manifest is placed in the Envelope with an identical key, so that it matches the key of the corresponding Integrity Check Value.

Each Integrity Check Value covers the corresponding Envelope Element as described in Section 8.8.

8.8. Severable Elements

Because the manifest can be used by different actors at different times, some parts of the manifest can be removed or “Severed” without affecting later stages of the lifecycle. Severing of information is achieved by separating that information from the signed container so that removing it does not affect the signature. This means that ensuring integrity of severable parts of the manifest is a requirement for the signed portion of the manifest. Severing some parts makes it possible to discard parts of the manifest that are no longer necessary. This is important because it allows the storage used by the manifest to be greatly reduced. For example, no text size limits are needed if text is removed from the manifest prior to delivery to a constrained device.

Elements are made severable by removing them from the manifest, encoding them in a bstr, and placing a SUIT_Digest of the bstr in the manifest so that they can still be authenticated. The SUIT_Digest typically consumes 4 bytes more than the size of the raw digest, therefore elements smaller than (Digest Bits)/8 + 4 SHOULD NOT be severable. Elements larger than (Digest Bits)/8 + 4 MAY be severable, while elements that are much larger than (Digest Bits)/8 + 4 SHOULD be severable.

Because of this, all command sequences in the manifest are encoded in a bstr so that there is a single code path needed for all command sequences.

9. Access Control Lists

To manage permissions in the manifest, there are three models that can be used.

First, the simplest model requires that all manifests are authenticated by a single trusted key. This mode has the advantage that only a root manifest needs to be authenticated, since all of its dependencies have digests included in the root manifest.

This simplest model can be extended by adding key delegation without much increase in complexity.

A second model requires an ACL to be presented to the Recipient, authenticated by a trusted party or stored on the Recipient. This ACL grants access rights for specific component IDs or component ID prefixes to the listed identities or identity groups. Any identity may verify an image digest, but fetching into or fetching from a component ID requires approval from the ACL.

A third model allows a Recipient to provide even more fine-grained controls: The ACL lists the component ID or component ID prefix that an identity may use, and also lists the commands that the identity may use in combination with that component ID.

10. SUIT Digest Container

RFC 8152 [RFC8152] provides containers for signature, MAC, and encryption, but no basic digest container. The container needed for a digest requires a type identifier and a container for the raw digest data. Some forms of digest may require additional parameters. These can be added following the digest.

The SUIT digest is a CBOR List containing two elements: a suit-digest-algorithm-id and a bstr containing the bytes of the digest.

11. IANA Considerations

IANA is requested to:

IANA is requested to setup a registry for SUIT manifests. Several registries defined in the subsections below need to be created.

For each registry, values 0-23 are Standards Action, 24-255 are IETF Review, 256-65535 are Expert Review, and 65536 or greater are First Come First Served.

Negative values -23 to 0 are Experimental Use, -24 and lower are Private Use.

11.1. SUIT Commands

Label Name
1 Vendor Identifier
2 Class Identifier
3 Image Match
4 Use Before
5 Component Offset
12 Set Component Index
13 Set Dependency Index
14 Abort
15 Try Each
16 Reserved
17 Reserved
18 Process Dependency
19 Set Parameters
20 Override Parameters
21 Fetch
22 Copy
23 Run
24 Device Identifier
25 Image Not Match
26 Minimum Battery
27 Update Authorized
28 Version
29 Wait For Event
30 Fetch URI List
31 Swap
32 Run Sequence
nint Custom Condition

11.2. SUIT Parameters

Label Name
1 Vendor ID
2 Class ID
3 Image Digest
4 Use Before
5 Component Offset
12 Strict Order
13 Soft Failure
14 Image Size
18 Encryption Info
19 Compression Info
20 Unpack Info
21 URI
22 Source Component
23 Run Args
24 Device ID
26 Minimum Battery
27 Update Priority
28 Version
29 Wait Info
30 URI List
31 Component Index
nint Custom

11.3. SUIT Text Values

Label Name
1 Manifest Description
2 Update Description
3 Manifest JSON Source
4 Manifest YAML Source
nint Custom

11.4. SUIT Component Text Values

Label Name
1 Vendor Name
2 Model Name
3 Vendor Domain
4 Model Info
5 Component Description
6 Component Version
7 Component Version Required
nint Custom

11.5. SUIT Algorithm Identifiers

11.5.1. SUIT Digest Algorithm Identifiers

Label Name
1 SHA224
2 SHA256
3 SHA384
4 SHA512
5 SHA3-224
6 SHA3-256
7 SHA3-384
8 SHA3-512

11.5.2. SUIT Compression Algorithm Identifiers

Label Name
1 zlib
2 Brotli
3 zstd

11.5.3. Unpack Algorithms

Label Name

12. Security Considerations

This document is about a manifest format describing and protecting firmware images and as such it is part of a larger solution for offering a standardized way of delivering firmware updates to IoT devices. A detailed security treatment can be found in the architecture [I-D.ietf-suit-architecture] and in the information model [I-D.ietf-suit-information-model] documents.

13. Acknowledgements

We would like to thank the following persons for their support in designing this mechanism:

14. References

14.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC3986] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005.
[RFC4122] Leach, P., Mealling, M. and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, DOI 10.17487/RFC4122, July 2005.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", RFC 8152, DOI 10.17487/RFC8152, July 2017.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.

14.2. Informative References

[COFF] Wikipedia, ., "Common Object File Format (COFF)", 2020.
[ELF] Wikipedia, ., "Executable and Linkable Format (ELF)", 2020.
[HEX] Wikipedia, ., "Intel HEX", 2020.
[I-D.ietf-suit-architecture] Moran, B., Tschofenig, H., Brown, D. and M. Meriac, "A Firmware Update Architecture for Internet of Things", Internet-Draft draft-ietf-suit-architecture-11, May 2020.
[I-D.ietf-suit-information-model] Moran, B., Tschofenig, H. and H. Birkholz, "An Information Model for Firmware Updates in IoT Devices", Internet-Draft draft-ietf-suit-information-model-07, June 2020.
[I-D.ietf-teep-architecture] Pei, M., Tschofenig, H., Thaler, D. and D. Wheeler, "Trusted Execution Environment Provisioning (TEEP) Architecture", Internet-Draft draft-ietf-teep-architecture-11, July 2020.
[I-D.kucherawy-rfc8478bis] Collet, Y. and M. Kucherawy, "Zstandard Compression and the application/zstd Media Type", Internet-Draft draft-kucherawy-rfc8478bis-05, April 2020.
[RFC1950] Deutsch, P. and J-L. Gailly, "ZLIB Compressed Data Format Specification version 3.3", RFC 1950, DOI 10.17487/RFC1950, May 1996.
[RFC7228] Bormann, C., Ersue, M. and A. Keranen, "Terminology for Constrained-Node Networks", RFC 7228, DOI 10.17487/RFC7228, May 2014.
[RFC7932] Alakuijala, J. and Z. Szabadka, "Brotli Compressed Data Format", RFC 7932, DOI 10.17487/RFC7932, July 2016.
[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S. and H. Tschofenig, "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392, May 2018.
[RFC8747] Jones, M., Seitz, L., Selander, G., Erdtman, S. and H. Tschofenig, "Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs)", RFC 8747, DOI 10.17487/RFC8747, March 2020.
[SREC] Wikipedia, ., "SREC (file format)", 2020.

A. Full CDDL

In order to create a valid SUIT Manifest document the structure of the corresponding CBOR message MUST adhere to the following CDDL data definition.

SUIT_Envelope = {
  ? suit-delegation => bstr .cbor SUIT_Delegation,
  ? suit-authentication-wrapper => bstr .cbor SUIT_Authentication,
  suit-manifest  => bstr .cbor SUIT_Manifest,
  * $$SUIT_Envelope_Extensions,
  (int => bstr)

SUIT_Delegation = [ + [ + bstr .cbor CWT ] ]

CWT = SUIT_Authentication_Block

SUIT_Authentication = [ + bstr .cbor SUIT_Authentication_Block ]

SUIT_Authentication_Block /= COSE_Mac_Tagged
SUIT_Authentication_Block /= COSE_Sign_Tagged
SUIT_Authentication_Block /= COSE_Mac0_Tagged
SUIT_Authentication_Block /= COSE_Sign1_Tagged

SUIT_Severable_Manifest_Members = (
  ? suit-dependency-resolution => bstr .cbor SUIT_Command_Sequence,
  ? suit-payload-fetch => bstr .cbor SUIT_Command_Sequence,
  ? suit-install => bstr .cbor SUIT_Command_Sequence,
  ? suit-text => bstr .cbor SUIT_Text_Map,
  ? suit-coswid => bstr .cbor concise-software-identity,
  * $$SUIT_severable-members-extensions,

COSE_Mac_Tagged = any
COSE_Sign_Tagged = any
COSE_Mac0_Tagged = any
COSE_Sign1_Tagged = any
COSE_Encrypt_Tagged = any
COSE_Encrypt0_Tagged = any

SUIT_Digest = [
  suit-digest-algorithm-id : suit-digest-algorithm-ids,
  suit-digest-bytes : bstr,
  * $$SUIT_Digest-extensions

; Named Information Hash Algorithm Identifiers
suit-digest-algorithm-ids /= algorithm-id-sha224
suit-digest-algorithm-ids /= algorithm-id-sha256
suit-digest-algorithm-ids /= algorithm-id-sha384
suit-digest-algorithm-ids /= algorithm-id-sha512
suit-digest-algorithm-ids /= algorithm-id-sha3-224
suit-digest-algorithm-ids /= algorithm-id-sha3-256
suit-digest-algorithm-ids /= algorithm-id-sha3-384
suit-digest-algorithm-ids /= algorithm-id-sha3-512

algorithm-id-sha224 = 1
algorithm-id-sha256 = 2
algorithm-id-sha384 = 3
algorithm-id-sha512 = 4
algorithm-id-sha3-224 = 5
algorithm-id-sha3-256 = 6
algorithm-id-sha3-384 = 7
algorithm-id-sha3-512 = 8

SUIT_Manifest = {
    suit-manifest-version         => 1,
    suit-manifest-sequence-number => uint,
    suit-common                   => bstr .cbor SUIT_Common,
    ? suit-reference-uri          => tstr,
    * $$SUIT_Manifest_Extensions,

SUIT_Unseverable_Members = (
  ? suit-validate => bstr .cbor SUIT_Command_Sequence,
  ? suit-load => bstr .cbor SUIT_Command_Sequence,
  ? suit-run => bstr .cbor SUIT_Command_Sequence,
  * $$unserverble-manifest-member-extensions,

SUIT_Severable_Members_Digests = (
  ? suit-dependency-resolution-digest => SUIT_Digest,
  ? suit-payload-fetch-digest => SUIT_Digest,
  ? suit-install-digest => SUIT_Digest,
  ? suit-text-digest => SUIT_Digest,
  ? suit-coswid-digest => SUIT_Digest,
  * $$severable-manifest-members-digests-extensions

SUIT_Common = {
    ? suit-dependencies           => SUIT_Dependencies,
    ? suit-components             => SUIT_Components,
    ? suit-common-sequence        => bstr .cbor SUIT_Common_Sequence,
    * $$SUIT_Common-extensions,

SUIT_Dependencies         = [ + SUIT_Dependency ]
SUIT_Components           = [ + SUIT_Component_Identifier ]

concise-software-identity = any

SUIT_Dependency = {
    suit-dependency-digest => SUIT_Digest,
    ? suit-dependency-prefix => SUIT_Component_Identifier,
    * $$SUIT_Dependency-extensions,

SUIT_Component_Identifier =  [* bstr]

SUIT_Component_Reference = {
    suit-component-identifier => SUIT_Component_Identifier,
    suit-component-dependency-index => uint

SUIT_Common_Sequence = [
    + ( SUIT_Condition // SUIT_Common_Commands )

SUIT_Common_Commands //= (suit-directive-set-component-index,  uint/bool)
SUIT_Common_Commands //= (suit-directive-set-dependency-index, uint/bool)
SUIT_Common_Commands //= (suit-directive-run-sequence,
    bstr .cbor SUIT_Command_Sequence)
SUIT_Common_Commands //= (suit-directive-try-each,
SUIT_Common_Commands //= (suit-directive-set-parameters,
    {+ SUIT_Parameters})
SUIT_Common_Commands //= (suit-directive-override-parameters,
    {+ SUIT_Parameters})

SUIT_Command_Sequence = [ + (
    SUIT_Condition // SUIT_Directive // SUIT_Command_Custom
) ]

SUIT_Command_Custom = (suit-command-custom, bstr/tstr/int/nil)
SUIT_Condition //= (suit-condition-vendor-identifier, SUIT_Reporting_Policy)
SUIT_Condition //= (suit-condition-class-identifier,  SUIT_Reporting_Policy)
SUIT_Condition //= (suit-condition-device-identifier, SUIT_Reporting_Policy)
SUIT_Condition //= (suit-condition-image-match,       SUIT_Reporting_Policy)
SUIT_Condition //= (suit-condition-image-not-match,   SUIT_Reporting_Policy)
SUIT_Condition //= (suit-condition-use-before,        SUIT_Reporting_Policy)
SUIT_Condition //= (suit-condition-minimum-battery,   SUIT_Reporting_Policy)
SUIT_Condition //= (suit-condition-update-authorized, SUIT_Reporting_Policy)
SUIT_Condition //= (suit-condition-version,           SUIT_Reporting_Policy)
SUIT_Condition //= (suit-condition-component-offset,  SUIT_Reporting_Policy)

SUIT_Directive //= (suit-directive-set-component-index,  uint/bool)
SUIT_Directive //= (suit-directive-set-dependency-index, uint/bool)
SUIT_Directive //= (suit-directive-run-sequence,
    bstr .cbor SUIT_Command_Sequence)
SUIT_Directive //= (suit-directive-try-each,
SUIT_Directive //= (suit-directive-process-dependency,   SUIT_Reporting_Policy)
SUIT_Directive //= (suit-directive-set-parameters,
    {+ SUIT_Parameters})
SUIT_Directive //= (suit-directive-override-parameters,
    {+ SUIT_Parameters})
SUIT_Directive //= (suit-directive-fetch,                SUIT_Reporting_Policy)
SUIT_Directive //= (suit-directive-copy,                 SUIT_Reporting_Policy)
SUIT_Directive //= (suit-directive-swap,                 SUIT_Reporting_Policy)
SUIT_Directive //= (suit-directive-run,                  SUIT_Reporting_Policy)
SUIT_Directive //= (suit-directive-wait,                 SUIT_Reporting_Policy)
SUIT_Directive //= (suit-directive-abort,                SUIT_Reporting_Policy)
SUIT_Directive //= (suit-directive-fetch-uri-list,       SUIT_Reporting_Policy)

SUIT_Directive_Try_Each_Argument = [
    + bstr .cbor SUIT_Command_Sequence,
    nil / bstr .cbor SUIT_Command_Sequence

SUIT_Reporting_Policy = uint .bits suit-reporting-bits

suit-reporting-bits = &(
    suit-send-record-success : 0,
    suit-send-record-failure : 1,
    suit-send-sysinfo-success : 2,
    suit-send-sysinfo-failure : 3

SUIT_Command_ID /= suit-command-custom
SUIT_Command_ID /= suit-condition-vendor-identifier
SUIT_Command_ID /= suit-condition-class-identifier
SUIT_Command_ID /= suit-condition-image-match
SUIT_Command_ID /= suit-condition-use-before
SUIT_Command_ID /= suit-condition-component-offset
SUIT_Command_ID /= suit-condition-device-identifier
SUIT_Command_ID /= suit-condition-image-not-match
SUIT_Command_ID /= suit-condition-minimum-battery
SUIT_Command_ID /= suit-condition-update-authorized
SUIT_Command_ID /= suit-condition-version
SUIT_Command_ID /= suit-directive-set-component-index
SUIT_Command_ID /= suit-directive-set-dependency-index
SUIT_Command_ID /= suit-directive-abort
SUIT_Command_ID /= suit-directive-try-each
;SUIT_Command_ID /= suit-directive-do-each
;SUIT_Command_ID /= suit-directive-map-filter
SUIT_Command_ID /= suit-directive-process-dependency
SUIT_Command_ID /= suit-directive-set-parameters
SUIT_Command_ID /= suit-directive-override-parameters
SUIT_Command_ID /= suit-directive-fetch
SUIT_Command_ID /= suit-directive-copy
SUIT_Command_ID /= suit-directive-run
SUIT_Command_ID /= suit-directive-wait
SUIT_Command_ID /= suit-directive-run-sequence
SUIT_Command_ID /= suit-directive-swap
SUIT_Command_ID /= suit-directive-fetch-uri-list

suit-record = {
  suit-record-success             => bool/int,
  ? suit-record-component-id      => SUIT_Component_ID,
  ? suit-record-dependency-id     => SUIT_Digest,
  ? suit-record-command-sequence-id => (
      suit-common-sequence /
      suit-dependency-resolution /
      suit-payload-fetch /
      suit-install /
      suit-validate /
      suit-load /
      suit-run /
      * $$suit-command-sequence-list-extensions
  ? suit-record-interpeter-offset => uint,
  ? suit-record-command-id        => SUIT_Command_ID,
  ? suit-record-params            => SUIT_Parameters,
  ? suit-record-actual            => SUIT_Parameters,
  * $$suit-record-extensions

SUIT_Wait_Event = { + SUIT_Wait_Events }

SUIT_Wait_Events //= (suit-wait-event-authorization => int)
SUIT_Wait_Events //= (suit-wait-event-power => int)
SUIT_Wait_Events //= (suit-wait-event-network => int)
SUIT_Wait_Events //= (suit-wait-event-other-device-version
    => SUIT_Wait_Event_Argument_Other_Device_Version)
SUIT_Wait_Events //= (suit-wait-event-time => uint); Timestamp
SUIT_Wait_Events //= (suit-wait-event-time-of-day
    => uint); Time of Day (seconds since 00:00:00)
SUIT_Wait_Events //= (suit-wait-event-day-of-week
    => uint); Days since Sunday

SUIT_Wait_Event_Argument_Other_Device_Version = [
    other-device: bstr,
    other-device-version: [ + SUIT_Parameter_Version_Match ]

SUIT_Parameters //= (suit-parameter-vendor-identifier => RFC4122_UUID)
SUIT_Parameters //= (suit-parameter-class-identifier => RFC4122_UUID)
SUIT_Parameters //= (suit-parameter-image-digest
    => bstr .cbor SUIT_Digest)
SUIT_Parameters //= (suit-parameter-image-size => uint)
SUIT_Parameters //= (suit-parameter-use-before => uint)
SUIT_Parameters //= (suit-parameter-component-offset => uint)

SUIT_Parameters //= (suit-parameter-encryption-info
    => bstr .cbor SUIT_Encryption_Info)
SUIT_Parameters //= (suit-parameter-compression-info
    => bstr .cbor SUIT_Compression_Info)
SUIT_Parameters //= (suit-parameter-unpack-info
    => bstr .cbor SUIT_Unpack_Info)

SUIT_Parameters //= (suit-parameter-uri => tstr)
SUIT_Parameters //= (suit-parameter-source-component => uint)
SUIT_Parameters //= (suit-parameter-run-args => bstr)

SUIT_Parameters //= (suit-parameter-device-identifier => RFC4122_UUID)
SUIT_Parameters //= (suit-parameter-minimum-battery => uint)
SUIT_Parameters //= (suit-parameter-update-priority => uint)
SUIT_Parameters //= (suit-parameter-version =>
SUIT_Parameters //= (suit-parameter-wait-info =>
    bstr .cbor SUIT_Wait_Event)

SUIT_Parameters //= (suit-parameter-custom => int/bool/tstr/bstr)

SUIT_Parameters //= (suit-parameter-strict-order => bool)
SUIT_Parameters //= (suit-parameter-soft-failure => bool)

SUIT_Parameters //= (suit-parameter-uri-list =>
    bstr .cbor SUIT_URI_List)

RFC4122_UUID = bstr .size 16

SUIT_Parameter_Version_Match = [
SUIT_Condition_Version_Comparison_Types /=
SUIT_Condition_Version_Comparison_Types /=
SUIT_Condition_Version_Comparison_Types /=
SUIT_Condition_Version_Comparison_Types /=
SUIT_Condition_Version_Comparison_Types /=

suit-condition-version-comparison-greater = 1
suit-condition-version-comparison-greater-equal = 2
suit-condition-version-comparison-equal = 3
suit-condition-version-comparison-lesser-equal = 4
suit-condition-version-comparison-lesser = 5

SUIT_Condition_Version_Comparison_Value = [+int]

SUIT_Encryption_Info = COSE_Encrypt_Tagged/COSE_Encrypt0_Tagged
SUIT_Compression_Info = {
    suit-compression-algorithm => SUIT_Compression_Algorithms,
    * $$SUIT_Compression_Info-extensions,

SUIT_Compression_Algorithms /= SUIT_Compression_Algorithm_zlib
SUIT_Compression_Algorithms /= SUIT_Compression_Algorithm_brotli
SUIT_Compression_Algorithms /= SUIT_Compression_Algorithm_zstd

SUIT_Compression_Algorithm_zlib = 1
SUIT_Compression_Algorithm_brotli = 2
SUIT_Compression_Algorithm_zstd = 3

SUIT_Unpack_Info = {
    suit-unpack-algorithm => SUIT_Unpack_Algorithms,
    * $$SUIT_Unpack_Info-extensions,


SUIT_Unpack_Algorithms /= SUIT_Unpack_Algorithm_Hex
SUIT_Unpack_Algorithms /= SUIT_Unpack_Algorithm_Elf
SUIT_Unpack_Algorithms /= SUIT_Unpack_Algorithm_Coff
SUIT_Unpack_Algorithms /= SUIT_Unpack_Algorithm_Srec

SUIT_Unpack_Algorithm_Hex = 1
SUIT_Unpack_Algorithm_Elf = 2
SUIT_Unpack_Algorithm_Coff = 3
SUIT_Unpack_Algorithm_Srec = 4

SUIT_URI_List = [+ tstr ]

SUIT_Text_Map = {
    ? suit-text-components =>
        + {
            1 => SUIT_Component_Identifier

SUIT_Text_Component_Keys = (
    ? suit-text-vendor-name           => tstr,
    ? suit-text-model-name            => tstr,
    ? suit-text-vendor-domain         => tstr,
    ? suit-text-model-info            => tstr,
    ? suit-text-component-description => tstr,
    ? suit-text-component-version     => tstr,
    ? suit-text-version-required      => tstr,
    * $$suit-text-component-key-extensions

SUIT_Text_Keys = (
    ? suit-text-manifest-description => tstr,
    ? suit-text-update-description   => tstr,
    ? suit-text-manifest-json-source => tstr,
    ? suit-text-manifest-yaml-source => tstr,
    * $$suit-text-key-extensions

suit-delegation = 1
suit-authentication-wrapper = 2
suit-manifest = 3

suit-manifest-version = 1
suit-manifest-sequence-number = 2
suit-common = 3
suit-reference-uri = 4
suit-dependency-resolution = 7
suit-payload-fetch = 8
suit-install = 9
suit-validate = 10
suit-load = 11
suit-run = 12
suit-text = 13
suit-coswid = 14

suit-dependencies = 1
suit-components = 2
suit-dependency-components = 3
suit-common-sequence = 4

suit-dependency-digest = 1
suit-dependency-prefix = 2

suit-component-identifier = 1
suit-component-dependency-index = 2

suit-command-custom = nint

suit-condition-vendor-identifier = 1
suit-condition-class-identifier  = 2
suit-condition-image-match       = 3
suit-condition-use-before        = 4
suit-condition-component-offset  = 5

suit-condition-device-identifier        = 24
suit-condition-image-not-match          = 25
suit-condition-minimum-battery          = 26
suit-condition-update-authorized        = 27
suit-condition-version                  = 28

suit-directive-set-component-index      = 12
suit-directive-set-dependency-index     = 13
suit-directive-abort                    = 14
suit-directive-try-each                 = 15
;suit-directive-do-each                  = 16 ; TBD
;suit-directive-map-filter               = 17 ; TBD
suit-directive-process-dependency       = 18
suit-directive-set-parameters           = 19
suit-directive-override-parameters      = 20
suit-directive-fetch                    = 21
suit-directive-copy                     = 22
suit-directive-run                      = 23

suit-directive-wait                     = 29
suit-directive-fetch-uri-list           = 30
suit-directive-swap                     = 31
suit-directive-run-sequence             = 32

suit-wait-event-authorization = 1
suit-wait-event-power = 2
suit-wait-event-network = 3
suit-wait-event-other-device-version = 4
suit-wait-event-time = 5
suit-wait-event-time-of-day = 6
suit-wait-event-day-of-week = 7

suit-parameter-vendor-identifier = 1
suit-parameter-class-identifier  = 2
suit-parameter-image-digest      = 3
suit-parameter-use-before        = 4
suit-parameter-component-offset  = 5

suit-parameter-strict-order      = 12
suit-parameter-soft-failure      = 13
suit-parameter-image-size        = 14

suit-parameter-encryption-info   = 18
suit-parameter-compression-info  = 19
suit-parameter-unpack-info       = 20
suit-parameter-uri               = 21
suit-parameter-source-component  = 22
suit-parameter-run-args          = 23

suit-parameter-device-identifier = 24
suit-parameter-minimum-battery   = 26
suit-parameter-update-priority   = 27
suit-parameter-version           = 28
suit-parameter-wait-info         = 29
suit-parameter-uri-list          = 30

suit-parameter-custom = nint

suit-compression-algorithm = 1
suit-compression-parameters = 2

suit-unpack-algorithm  = 1
suit-unpack-parameters = 2

suit-text-manifest-description  = 1
suit-text-update-description    = 2
suit-text-manifest-json-source  = 3
suit-text-manifest-yaml-source  = 4

suit-text-vendor-name           = 1
suit-text-model-name            = 2
suit-text-vendor-domain         = 3
suit-text-model-info            = 4
suit-text-component-description = 5
suit-text-component-version     = 6
suit-text-version-required      = 7

B. Examples

The following examples demonstrate a small subset of the functionality of the manifest. However, despite this, even a simple manifest processor can execute most of these manifests.

The examples are signed using the following ECDSA secp256r1 key:


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

-----END PUBLIC KEY-----

Each example uses SHA256 as the digest function.

Note that reporting policies are declared for each non-flow-control command in these examples. The reporting policies used in the examples are described in the following tables.

Policy Label
suit-send-record-on-success Rec-Pass
suit-send-record-on-failure Rec-Fail
suit-send-sysinfo-success Sys-Pass
suit-send-sysinfo-failure Sys-Fail
Command Sys-Fail Sys-Pass Rec-Fail Rec-Pass
suit-condition-vendor-identifier 1 1 1 1
suit-condition-class-identifier 1 1 1 1
suit-condition-image-match 1 1 1 1
suit-condition-component-offset 0 1 0 1
suit-directive-fetch 0 0 1 0
suit-directive-copy 0 0 1 0
suit-directive-run 0 0 1 0

B.1. Example 0: Secure Boot

This example covers the following templates:

It also serves as the minimum example.

    / authentication-wrapper / 2:h'81588fd28443a10126a0584482025840356
b54e6704847de49efe60e9a7b821215d83368a2c8c7c088' / [
d83368a2c8c7c088' / 18([
                / protected / h'a10126' / {
                    / alg / 1:-7 / "ES256" /,
                } /,
                / unprotected / {
                / payload / h'8202584035633039376566363462663362623962
63396166336539656464623939' / [
                    / algorithm-id / 2 / "sha256" /,
                    / digest-bytes / h'3563303937656636346266336262396
                ] /,
                / signature / h'93347ceebc1209a2d660bfbbe78e461079f195
            ]) /
    ] /,
    / manifest / 3:h'a50101020003585fa202818141000458568614a40150fa6b4
00e1987d0010f020f0a4382030f0c43821702' / {
        / manifest-version / 1:1,
        / manifest-sequence-number / 2:0,
        / common / 3:h'a202818141000458568614a40150fa6b4a53d5ad5fdfbe9
20f' / {
            / components / 2:[
            / common-sequence / 4:h'8614a40150fa6b4a53d5ad5fdfbe9de663
/ [
                / directive-override-parameters / 20,{
                    / vendor-id /
1:h'"fa6b4a53d5ad5fdfbe9de663e4d41ffe"' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
                    / class-id /
2:h'"1492af1425695e48bf429b2d51f2ab45"' /
1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
                    / image-digest / 3:h'8202582000112233445566778899a
abbccddeeff0123456789abcdeffedcba9876543210' / [
                        / algorithm-id / 2 / "sha256" /,
                        / digest-bytes /
                    ] /,
                    / image-size / 14:34768,
                } ,
                / condition-vendor-identifier / 1,15 ,
                / condition-class-identifier / 2,15
            ] /,
        } /,
        / validate / 10:h'82030f' / [
            / condition-image-match / 3,15
        ] /,
        / run / 12:h'821702' / [
            / directive-run / 23,2
        ] /,
    } /,

Total size of Envelope without COSE authentication object: 117



Total size of Envelope with COSE authentication object: 266

Envelope with COSE authentication object:


B.2. Example 1: Simultaneous Download and Installation of Payload

This example covers the following templates:

Simultaneous download and installation of payload. No secure boot is present in this example to demonstrate a download-only manifest.

    / authentication-wrapper / 2:h'81588fd28443a10126a0584482025840393
23e7f7f928ee92a9893afedd35d06a936d6ed3d5843bf2a' / [
36d6ed3d5843bf2a' / 18([
                / protected / h'a10126' / {
                    / alg / 1:-7 / "ES256" /,
                } /,
                / unprotected / {
                / payload / h'8202584039383765656338356661393966643331
32303765643030666666373530' / [
                    / algorithm-id / 2 / "sha256" /,
                    / digest-bytes / h'3938376565633835666139396664333
                ] /,
                / signature / h'4931df82e153bf1e3af5a59800216d8a47c33a
            ]) /
    ] /,
    / manifest / 3:h'a50101020103585fa202818141000458568614a40150fa6b4
d2f66696c652e62696e1502030f0a4382030f' / {
        / manifest-version / 1:1,
        / manifest-sequence-number / 2:1,
        / common / 3:h'a202818141000458568614a40150fa6b4a53d5ad5fdfbe9
20f' / {
            / components / 2:[
            / common-sequence / 4:h'8614a40150fa6b4a53d5ad5fdfbe9de663
/ [
                / directive-override-parameters / 20,{
                    / vendor-id /
1:h'"fa6b4a53d5ad5fdfbe9de663e4d41ffe"' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
                    / class-id /
2:h'"1492af1425695e48bf429b2d51f2ab45"' /
1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
                    / image-digest / 3:h'8202582000112233445566778899a
abbccddeeff0123456789abcdeffedcba9876543210' / [
                        / algorithm-id / 2 / "sha256" /,
                        / digest-bytes /
                    ] /,
                    / image-size / 14:34768,
                } ,
                / condition-vendor-identifier / 1,15 ,
                / condition-class-identifier / 2,15
            ] /,
        } /,
        / install / 9:h'8613a115781b687474703a2f2f6578616d706c652e636f
6d2f66696c652e62696e1502030f' / [
            / directive-set-parameters / 19,{
                / uri / 21:'',
            } ,
            / directive-fetch / 21,2 ,
            / condition-image-match / 3,15
        ] /,
        / validate / 10:h'82030f' / [
            / condition-image-match / 3,15
        ] /,
    } /,

Total size of Envelope without COSE authentication object: 152



Total size of Envelope with COSE authentication object: 301

Envelope with COSE authentication object:


B.3. Example 2: Simultaneous Download, Installation, Secure Boot, Severed Fields

This example covers the following templates:

This example also demonstrates severable elements (Section 5.5), and text (Section 8.6.4).

    / authentication-wrapper / 2:h'81588fd28443a10126a0584482025840373
658b80215185e32d8ec6feb15c7275d64437c36418463e4' / [
64437c36418463e4' / 18([
                / protected / h'a10126' / {
                    / alg / 1:-7 / "ES256" /,
                } /,
                / unprotected / {
                / payload / h'8202584037353638353537396138336261626437
61643330623635393864313761' / [
                    / algorithm-id / 2 / "sha256" /,
                    / digest-bytes / h'3735363835353739613833626162643
                ] /,
                / signature / h'faca70796c319ce6dae69690a64ced3ab91b9b
            ]) /
    ] /,
    / manifest / 3:h'a70101020203585fa202818141000458568614a40150fa6b4
144234aee18401ffe3cce4733b23881c3a8ae2d2b66e8' / {
        / manifest-version / 1:1,
        / manifest-sequence-number / 2:2,
        / common / 3:h'a202818141000458568614a40150fa6b4a53d5ad5fdfbe9
20f' / {
            / components / 2:[
            / common-sequence / 4:h'8614a40150fa6b4a53d5ad5fdfbe9de663
/ [
                / directive-override-parameters / 20,{
                    / vendor-id /
1:h'"fa6b4a53d5ad5fdfbe9de663e4d41ffe"' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
                    / class-id /
2:h'"1492af1425695e48bf429b2d51f2ab45"' /
1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
                    / image-digest / 3:h'8202582000112233445566778899a
abbccddeeff0123456789abcdeffedcba9876543210' / [
                        / algorithm-id / 2 / "sha256" /,
                        / digest-bytes /
                    ] /,
                    / image-size / 14:34768,
                } ,
                / condition-vendor-identifier / 1,15 ,
                / condition-class-identifier / 2,15
            ] /,
        } /,
        / install / 9:[
            / algorithm-id / 2 / "sha256" /,
            / digest-bytes /
        / validate / 10:h'82030f' / [
            / condition-image-match / 3,15
        ] /,
        / run / 12:h'821702' / [
            / directive-run / 23,2
        ] /,
        / text / 13:[
            / algorithm-id / 2 / "sha256" /,
            / digest-bytes /
    } /,
    / install / 9:h'8613a1157832687474703a2f2f6578616d706c652e636f6d2f
' / [
        / directive-set-parameters / 19,{
            / uri /
        } ,
        / directive-fetch / 21,2 ,
        / condition-image-match / 3,15
    ] /,
    / text / 13:h'a1814100a2036761726d2e636f6d0578525468697320636f6d70
6e652e' / {
                / vendor-domain / 3:'',
                / component-description / 5:'This component is a
demonstration. The digest is a sample pattern, not a real one.',
    } /,

Total size of the Envelope without COSE authentication object or Severable Elements: 191



Total size of the Envelope with COSE authentication object but without Severable Elements: 340



Total size of Envelope with COSE authentication object: 923

Envelope with COSE authentication object:


B.4. Example 3: A/B images

This example covers the following templates:

    / authentication-wrapper / 2:h'81588fd28443a10126a0584482025840616
ca298900208d92d352faf86e6cddc902a726bbc443c21ff' / [
2a726bbc443c21ff' / 18([
                / protected / h'a10126' / {
                    / alg / 1:-7 / "ES256" /,
                } /,
                / unprotected / {
                / payload / h'8202584061653063316561363839633938303061
38653738346461343364343763' / [
                    / algorithm-id / 2 / "sha256" /,
                    / digest-bytes / h'6165306331656136383963393830306
                ] /,
                / signature / h'10222ddbce4e82a85f6ec7b72db34d7c5be8d2
            ]) /
    ] /,
    / manifest / 3:h'a5010102030358aaa202818141000458a18814a20150fa6b4
22e62696e1502030f0a4382030f' / {
        / manifest-version / 1:1,
        / manifest-sequence-number / 2:3,
        / common / 3:h'a202818141000458a18814a20150fa6b4a53d5ad5fdfbe9
12c22010f020f' / {
            / components / 2:[
            / common-sequence / 4:h'8814a20150fa6b4a53d5ad5fdfbe9de663
010f020f' / [
                / directive-override-parameters / 20,{
                    / vendor-id /
1:h'"fa6b4a53d5ad5fdfbe9de663e4d41ffe"' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
                    / class-id /
2:h'"1492af1425695e48bf429b2d51f2ab45"' /
1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
                } ,
                / directive-try-each / 15,[
66778899aabbccddeeff0123456789abcdeffedcba98765432100e1987d0' / [
                        / directive-override-parameters / 20,{
                            / offset / 5:33792,
                        } ,
                        / condition-component-offset / 5,5 ,
                        / directive-override-parameters / 20,{
                            / image-digest / 3:h'820258200011223344556
6778899aabbccddeeff0123456789abcdeffedcba9876543210' / [
                                / algorithm-id / 2 / "sha256" /,
                                / digest-bytes /
                            ] /,
                            / image-size / 14:34768,
                    ] / ,
/ [
                        / directive-override-parameters / 20,{
                            / offset / 5:541696,
                        } ,
                        / condition-component-offset / 5,5 ,
                        / directive-override-parameters / 20,{
                            / image-digest / 3:h'820258200123456789abc
deffedcba987654321000112233445566778899aabbccddeeff' / [
                                / algorithm-id / 2 / "sha256" /,
                                / digest-bytes /
                            ] /,
                            / image-size / 14:76834,
                    ] /
                ] ,
                / condition-vendor-identifier / 1,15 ,
                / condition-class-identifier / 2,15
            ] /,
        } /,
        / install / 9:h'860f82582a8613a105198400050513a115781c68747470
1502030f' / [
            / directive-try-each / 15,[
6c652e636f6d2f66696c65312e62696e' / [
                    / directive-set-parameters / 19,{
                        / offset / 5:33792,
                    } ,
                    / condition-component-offset / 5,5 ,
                    / directive-set-parameters / 19,{
                        / uri / 21:'',
                ] / ,
6d706c652e636f6d2f66696c65322e62696e' / [
                    / directive-set-parameters / 19,{
                        / offset / 5:541696,
                    } ,
                    / condition-component-offset / 5,5 ,
                    / directive-set-parameters / 19,{
                        / uri / 21:'',
                ] /
            ] ,
            / directive-fetch / 21,2 ,
            / condition-image-match / 3,15
        ] /,
        / validate / 10:h'82030f' / [
            / condition-image-match / 3,15
        ] /,
    } /,

Total size of Envelope without COSE authentication object: 288



Total size of Envelope with COSE authentication object: 437

Envelope with COSE authentication object:


B.5. Example 4: Load and Decompress from External Storage

This example covers the following templates:

    / authentication-wrapper / 2:h'81588fd28443a10126a0584482025840346
8d35b3b20ceef50a69b94dcff12beee92e426a06ea31320' / [
92e426a06ea31320' / 18([
                / protected / h'a10126' / {
                    / alg / 1:-7 / "ES256" /,
                } /,
                / unprotected / {
                / payload / h'8202584034623463376338633066646137366339
64346538663933353961393238' / [
                    / algorithm-id / 2 / "sha256" /,
                    / digest-bytes / h'3462346337633863306664613736633
                ] /,
                / signature / h'd7063361f653d57e63691e1bd9c856058c773b
            ]) /
    ] /,
    / manifest / 3:h'a801010204035867a20283814100814102814101045858880
c45840c021702' / {
        / manifest-version / 1:1,
        / manifest-sequence-number / 2:4,
        / common / 3:h'a20283814100814102814101045858880c0014a40150fa6
2100e1987d0010f020f' / {
            / components / 2:[
                [h'00'] ,
                [h'02'] ,
            / common-sequence / 4:h'880c0014a40150fa6b4a53d5ad5fdfbe9d
0f' / [
                / directive-set-component-index / 12,0 ,
                / directive-override-parameters / 20,{
                    / vendor-id /
1:h'"fa6b4a53d5ad5fdfbe9de663e4d41ffe"' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
                    / class-id /
2:h'"1492af1425695e48bf429b2d51f2ab45"' /
1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
                    / image-digest / 3:h'8202582000112233445566778899a
abbccddeeff0123456789abcdeffedcba9876543210' / [
                        / algorithm-id / 2 / "sha256" /,
                        / digest-bytes /
                    ] /,
                    / image-size / 14:34768,
                } ,
                / condition-vendor-identifier / 1,15 ,
                / condition-class-identifier / 2,15
            ] /,
        } /,
        / payload-fetch / 8:h'880c0113a115781b687474703a2f2f6578616d70
6c652e636f6d2f66696c652e62696e1502030f' / [
            / directive-set-component-index / 12,1 ,
            / directive-set-parameters / 19,{
                / uri / 21:'',
            } ,
            / directive-fetch / 21,2 ,
            / condition-image-match / 3,15
        ] /,
        / install / 9:h'880c0013a116011602030f' / [
            / directive-set-component-index / 12,0 ,
            / directive-set-parameters / 19,{
                / source-component / 22:1 / [h'02'] /,
            } ,
            / directive-copy / 22,2 ,
            / condition-image-match / 3,15
        ] /,
        / validate / 10:h'840c00030f' / [
            / directive-set-component-index / 12,0 ,
            / condition-image-match / 3,15
        ] /,
        / load / 11:h'880c0213a4035824820258200123456789abcdeffedcba98
/ [
            / directive-set-component-index / 12,2 ,
            / directive-set-parameters / 19,{
                / image-digest / 3:h'820258200123456789abcdeffedcba987
654321000112233445566778899aabbccddeeff' / [
                    / algorithm-id / 2 / "sha256" /,
                    / digest-bytes /
                ] /,
                / image-size / 14:76834,
                / source-component / 22:0 / [h'00'] /,
                / compression-info / 19:1 / "gzip" /,
            } ,
            / directive-copy / 22,2 ,
            / condition-image-match / 3,15
        ] /,
        / run / 12:h'840c021702' / [
            / directive-set-component-index / 12,2 ,
            / directive-run / 23,2
        ] /,
    } /,

Total size of Envelope without COSE authentication object: 245



Total size of Envelope with COSE authentication object: 394

Envelope with COSE authentication object:


B.6. Example 5: Two Images

This example covers the following templates:

Furthermore, it shows using these templates with two images.

    / authentication-wrapper / 2:h'81588fd28443a10126a0584482025840323
db824a7e6b0bc233e753940dfb7131fa145ddc456da3cf6' / [
a145ddc456da3cf6' / 18([
                / protected / h'a10126' / {
                    / alg / 1:-7 / "ES256" /,
                } /,
                / unprotected / {
                / payload / h'8202584032313062313238353063323339303931
66363730316564353833343263' / [
                    / algorithm-id / 2 / "sha256" /,
                    / digest-bytes / h'3231306231323835306332333930393
                ] /,
                / signature / h'b5b8cb30c2bbb646c4d32426d72768668d6d6a
            ]) /
    ] /,
    / manifest / 3:h'a601010205035895a202828141008141010458898c0c0014a
e1502030f0a49880c00030f0c01030f0c47860c0017021702' / {
        / manifest-version / 1:1,
        / manifest-sequence-number / 2:5,
        / common / 3:h'a202828141008141010458898c0c0014a40150fa6b4a53d
12233445566778899aabbccddeeff0e1a00012c22' / {
            / components / 2:[
                [h'00'] ,
            / common-sequence / 4:h'8c0c0014a40150fa6b4a53d5ad5fdfbe9d
778899aabbccddeeff0e1a00012c22' / [
                / directive-set-component-index / 12,0 ,
                / directive-override-parameters / 20,{
                    / vendor-id /
1:h'"fa6b4a53d5ad5fdfbe9de663e4d41ffe"' / fa6b4a53-d5ad-5fdf-
be9d-e663e4d41ffe /,
                    / class-id /
2:h'"1492af1425695e48bf429b2d51f2ab45"' /
1492af14-2569-5e48-bf42-9b2d51f2ab45 /,
                    / image-digest / 3:h'8202582000112233445566778899a
abbccddeeff0123456789abcdeffedcba9876543210' / [
                        / algorithm-id / 2 / "sha256" /,
                        / digest-bytes /
                    ] /,
                    / image-size / 14:34768,
                } ,
                / condition-vendor-identifier / 1,15 ,
                / condition-class-identifier / 2,15 ,
                / directive-set-component-index / 12,1 ,
                / directive-override-parameters / 20,{
                    / image-digest / 3:h'820258200123456789abcdeffedcb
a987654321000112233445566778899aabbccddeeff' / [
                        / algorithm-id / 2 / "sha256" /,
                        / digest-bytes /
                    ] /,
                    / image-size / 14:76834,
            ] /,
        } /,
        / install / 9:h'900c0013a115781c687474703a2f2f6578616d706c652e
706c652e636f6d2f66696c65322e62696e1502030f' / [
            / directive-set-component-index / 12,0 ,
            / directive-set-parameters / 19,{
                / uri / 21:'',
            } ,
            / directive-fetch / 21,2 ,
            / condition-image-match / 3,15 ,
            / directive-set-component-index / 12,1 ,
            / directive-set-parameters / 19,{
                / uri / 21:'',
            } ,
            / directive-fetch / 21,2 ,
            / condition-image-match / 3,15
        ] /,
        / validate / 10:h'880c00030f0c01030f' / [
            / directive-set-component-index / 12,0 ,
            / condition-image-match / 3,15 ,
            / directive-set-component-index / 12,1 ,
            / condition-image-match / 3,15
        ] /,
        / run / 12:h'860c0017021702' / [
            / directive-set-component-index / 12,0 ,
            / directive-run / 23,2 ,
            / directive-run / 23,2
        ] /,
    } /,

Total size of Envelope without COSE authentication object: 264



Total size of Envelope with COSE authentication object: 413

Envelope with COSE authentication object:


C. Design Rational

In order to provide flexible behavior to constrained devices, while still allowing more powerful devices to use their full capabilities, the SUIT manifest encodes the required behavior of a Recipient device. Behavior is encoded as a specialized byte code, contained in a CBOR list. This promotes a flat encoding, which simplifies the parser. The information encoded by this byte code closely matches the operations that a device will perform, which promotes ease of processing. The core operations used by most update and trusted execution operations are represented in the byte code. The byte code can be extended by registering new operations.

The specialized byte code approach gives benefits equivalent to those provided by a scripting language or conventional byte code, with two substantial differences. First, the language is extremely high level, consisting of only the operations that a device may perform during update and trusted execution of a firmware image. Second, the language specifies linear behavior, without reverse branches. Conditional processing is supported, and parallel and out-of-order processing may be performed by sufficiently capable devices.

By structuring the data in this way, the manifest processor becomes a very simple engine that uses a pull parser to interpret the manifest. This pull parser invokes a series of command handlers that evaluate a Condition or execute a Directive. Most data is structured in a highly regular pattern, which simplifies the parser.

The results of this allow a Recipient to implement a very small parser for constrained applications. If needed, such a parser also allows the Recipient to perform complex updates with reduced overhead. Conditional execution of commands allows a simple device to perform important decisions at validation-time.

Dependency handling is vastly simplified as well. Dependencies function like subroutines of the language. When a manifest has a dependency, it can invoke that dependency’s commands and modify their behavior by setting parameters. Because some parameters come with security implications, the dependencies also have a mechanism to reject modifications to parameters on a fine-grained level.

Developing a robust permissions system works in this model too. The Recipient can use a simple ACL that is a table of Identities and Component Identifier permissions to ensure that operations on components fail unless they are permitted by the ACL. This table can be further refined with individual parameters and commands.

Capability reporting is similarly simplified. A Recipient can report the Commands, Parameters, Algorithms, and Component Identifiers that it supports. This is sufficiently precise for a manifest author to create a manifest that the Recipient can accept.

The simplicity of design in the Recipient due to all of these benefits allows even a highly constrained platform to use advanced update capabilities.

C.1. C.1 Design Rationale: Envelope

The Envelope is used instead of a COSE structure for several reasons:

  1. This enables the use of Severable Elements
  2. This enables modular processing of manifests, particularly with large signatures.
  3. This enables multiple authentication schemes.
  4. This allows integrity verification by a dependent to be unaffected by adding or removing authentication structures.

Modular processing is important because it allows a Manifest Processor to iterate forward over an Envelope, processing Delegation Chains and Authentication Blocks, retaining only intermediate values, without any need to seek forward and backwards in a stream until it gets to the Manifest itself. This allows the use of large, Post-Quantum signatures without requiring retention of the signature itself, or seeking forward and back.

Four authentication objects are supported by the Envelope:

The SUIT Envelope allows an Update Authority or intermediary to mix and match any number of different authentication blocks it wants without any concern for modifying the integrity of another authentication block. This also allows the addition or removal of an authentication blocks without changing the integrity check of the Manifest, which is important for dependency handling. See Section 6.2

C.2. C.2 Byte String Wrappers

Byte string wrappers are used in several places in the suit manifest. The primary reason for wrappers it to limit the parser extent when invoked at different times, with a possible loss of context.

The elements of the suit envelope are wrapped both to set the extents used by the parser and to simplify integrity checks by clearly defining the length of each element.

The common block is re-parsed in order to find components identifiers from their indices, to find dependency prefixes and digests from their identifiers, and to find the common sequence. The common sequence is wrapped so that it matches other sequences, simplifying the code path.

A severed SUIT command sequence will appear in the envelope, so it must be wrapped as with all envelope elements. For consistency, command sequences are also wrapped in the manifest. This also allows the parser to discern the difference between a command sequence and a SUIT_Digest.

Parameters that are structured types (arrays and maps) are also wrapped in a bstr. This is so that parser extents can be set correctly using only a reference to the beginning of the parameter. This enables a parser to store a simple list of references to parameters that can be retrieved when needed.

D. Implementation Conformance Matrix

This section summarizes the functionality a minimal implementation needs to offer to claim conformance to this specification, in the absence of an application profile standard specifying otherwise.

The subsequent table shows the conditions.

Name Reference Implementation
Vendor Identifier Section REQUIRED
Class Identifier Section REQUIRED
Device Identifier Section OPTIONAL
Image Match Section REQUIRED
Image Not Match Section OPTIONAL
Use Before Section OPTIONAL
Component Offset Section OPTIONAL
Minimum Battery Section OPTIONAL
Update Authorized Section OPTIONAL
Version Section OPTIONAL
Custom Condition Section OPTIONAL

The subsequent table shows the directives.

Name Reference Implementation
Set Component Index Section REQUIRED if more than one component
Set Dependency Index Section REQUIRED if dependencies used
Abort Section OPTIONAL
Try Each Section OPTIONAL
Process Dependency Section OPTIONAL
Set Parameters Section OPTIONAL
Override Parameters Section REQUIRED
Fetch Section REQUIRED for Updater
Copy Section OPTIONAL
Run Section REQUIRED for Bootloader
Wait For Event Section OPTIONAL
Run Sequence Section OPTIONAL
Swap Section OPTIONAL
Fetch URI List Section OPTIONAL

The subsequent table shows the parameters.

Name Reference Implementation
Vendor ID Section REQUIRED
Class ID Section REQUIRED
Image Digest Section REQUIRED
Image Size Section REQUIRED
Use Before Section RECOMMENDED
Component Offset Section OPTIONAL
Encryption Info Section RECOMMENDED
Compression Info Section RECOMMENDED
Unpack Info Section RECOMMENDED
URI Section REQUIRED for Updater
Source Component Section OPTIONAL
Run Args Section OPTIONAL
Device ID Section OPTIONAL
Minimum Battery Section OPTIONAL
Update Priority Section OPTIONAL
Version Match Section OPTIONAL
Wait Info Section OPTIONAL
Strict Order Section OPTIONAL
Soft Failure Section OPTIONAL
Custom Section OPTIONAL

Authors' Addresses

Brendan Moran Arm Limited EMail:
Hannes Tschofenig Arm Limited EMail:
Henk Birkholz Fraunhofer SIT EMail:
Koen Zandberg Inria EMail: