< draft-ietf-suit-architecture-06.txt   draft-ietf-suit-architecture-07.txt >
SUIT B. Moran SUIT B. Moran
Internet-Draft Arm Limited Internet-Draft Arm Limited
Intended status: Informational M. Meriac Intended status: Informational M. Meriac
Expires: March 16, 2020 Consultant Expires: April 22, 2020 Consultant
H. Tschofenig H. Tschofenig
Arm Limited Arm Limited
D. Brown D. Brown
Linaro Linaro
September 13, 2019 October 20, 2019
A Firmware Update Architecture for Internet of Things Devices A Firmware Update Architecture for Internet of Things Devices
draft-ietf-suit-architecture-06 draft-ietf-suit-architecture-07
Abstract Abstract
Vulnerabilities with Internet of Things (IoT) devices have raised the Vulnerabilities with Internet of Things (IoT) devices have raised the
need for a solid and secure firmware update mechanism that is also need for a solid and secure firmware update mechanism that is also
suitable for constrained devices. Incorporating such update suitable for constrained devices. Incorporating such update
mechanism to fix vulnerabilities, to update configuration settings as mechanism to fix vulnerabilities, to update configuration settings as
well as adding new functionality is recommended by security experts. well as adding new functionality is recommended by security experts.
This document lists requirements and describes an architecture for a This document lists requirements and describes an architecture for a
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 16, 2020. This Internet-Draft will expire on April 22, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Agnostic to how firmware images are distributed . . . . . 7 3.1. Agnostic to how firmware images are distributed . . . . . 7
3.2. Friendly to broadcast delivery . . . . . . . . . . . . . 8 3.2. Friendly to broadcast delivery . . . . . . . . . . . . . 8
3.3. Use state-of-the-art security mechanisms . . . . . . . . 8 3.3. Use state-of-the-art security mechanisms . . . . . . . . 8
3.4. Rollback attacks must be prevented . . . . . . . . . . . 8 3.4. Rollback attacks must be prevented . . . . . . . . . . . 9
3.5. High reliability . . . . . . . . . . . . . . . . . . . . 9 3.5. High reliability . . . . . . . . . . . . . . . . . . . . 9
3.6. Operate with a small bootloader . . . . . . . . . . . . . 9 3.6. Operate with a small bootloader . . . . . . . . . . . . . 9
3.7. Small Parsers . . . . . . . . . . . . . . . . . . . . . . 10 3.7. Small Parsers . . . . . . . . . . . . . . . . . . . . . . 10
3.8. Minimal impact on existing firmware formats . . . . . . . 10 3.8. Minimal impact on existing firmware formats . . . . . . . 10
3.9. Robust permissions . . . . . . . . . . . . . . . . . . . 10 3.9. Robust permissions . . . . . . . . . . . . . . . . . . . 10
3.10. Operating modes . . . . . . . . . . . . . . . . . . . . . 10 3.10. Operating modes . . . . . . . . . . . . . . . . . . . . . 11
3.11. Suitability to software and personalization data . . . . 12 3.11. Suitability to software and personalization data . . . . 12
4. Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4. Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5. Communication Architecture . . . . . . . . . . . . . . . . . 13 5. Communication Architecture . . . . . . . . . . . . . . . . . 13
6. Manifest . . . . . . . . . . . . . . . . . . . . . . . . . . 17 6. Manifest . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7. Device Firmware Update Examples . . . . . . . . . . . . . . . 18 7. Device Firmware Update Examples . . . . . . . . . . . . . . . 18
7.1. Single CPU SoC . . . . . . . . . . . . . . . . . . . . . 18 7.1. Single CPU SoC . . . . . . . . . . . . . . . . . . . . . 18
7.2. Single CPU with Secure - Normal Mode Partitioning . . . . 18 7.2. Single CPU with Secure - Normal Mode Partitioning . . . . 18
7.3. Dual CPU, shared memory . . . . . . . . . . . . . . . . . 18 7.3. Dual CPU, shared memory . . . . . . . . . . . . . . . . . 18
7.4. Dual CPU, other bus . . . . . . . . . . . . . . . . . . . 18 7.4. Dual CPU, other bus . . . . . . . . . . . . . . . . . . . 18
8. Bootloader . . . . . . . . . . . . . . . . . . . . . . . . . 19 8. Bootloader . . . . . . . . . . . . . . . . . . . . . . . . . 19
9. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 9. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
11. Security Considerations . . . . . . . . . . . . . . . . . . . 24 11. Security Considerations . . . . . . . . . . . . . . . . . . . 25
12. Mailing List Information . . . . . . . . . . . . . . . . . . 25 12. Mailing List Information . . . . . . . . . . . . . . . . . . 26
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
14.1. Normative References . . . . . . . . . . . . . . . . . . 27 14.1. Normative References . . . . . . . . . . . . . . . . . . 27
14.2. Informative References . . . . . . . . . . . . . . . . . 27 14.2. Informative References . . . . . . . . . . . . . . . . . 27
14.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 28 14.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction 1. Introduction
When developing IoT devices, one of the most difficult problems to When developing IoT devices, one of the most difficult problems to
solve is how to update the firmware on the device. Once the device solve is how to update the firmware on the device. Once the device
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC "OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119]. 2119 [RFC2119].
This document uses the following terms: This document uses the following terms:
- Manifest: The manifest contains meta-data about the firmware - Manifest: The manifest contains meta-data about the firmware
image. The manifest is protected against modification and image. The manifest is protected against modification and
provides information about the author. provides information about the author.
- Firmware Image: The firmware image is a binary that may contain - Firmware Image: The firmware image, or image, is a binary that may
the complete software of a device or a subset of it. The firmware contain the complete software of a device or a subset of it. The
image may consist of multiple images, if the device contains more firmware image may consist of multiple images, if the device
than one microcontroller. The image may consist of a differential contains more than one microcontroller. Often it is also a
update for performance reasons. Firmware is the more universal compressed archive that contains code, configuration data, and
term. Both terms are used in this document and are even the entire file system. The image may consist of a
interchangeable. differential update for performance reasons. Firmware is the more
universal term. The terms, firmware image, firmware, and image,
are used in this document and are interchangeable.
- Bootloader: A bootloader is a piece of software that is executed - Bootloader: A bootloader is a piece of software that is executed
once a microcontroller has been reset. It is responsible for once a microcontroller has been reset. It is responsible for
deciding whether to boot a firmware image that is present or deciding whether to boot a firmware image that is present or
whether to obtain and verify a new firmware image. Since the whether to obtain and verify a new firmware image. Since the
bootloader is a security critical component its functionality may bootloader is a security critical component its functionality may
be split into separate stages. Such a multi-stage bootloader may be split into separate stages. Such a multi-stage bootloader may
offer very basic functionality in the first stage and resides in offer very basic functionality in the first stage and resides in
ROM whereas the second stage may implement more complex ROM whereas the second stage may implement more complex
functionality and resides in flash memory so that it can be functionality and resides in flash memory so that it can be
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including USB, UART, WiFi, BLE, low-power WAN technologies, etc. and including USB, UART, WiFi, BLE, low-power WAN technologies, etc. and
use different protocols (e.g., CoAP, HTTP). The specified mechanism use different protocols (e.g., CoAP, HTTP). The specified mechanism
needs to be agnostic to the distribution of the firmware images and needs to be agnostic to the distribution of the firmware images and
manifests. manifests.
3.2. Friendly to broadcast delivery 3.2. Friendly to broadcast delivery
This architecture does not specify any specific broadcast protocol. This architecture does not specify any specific broadcast protocol.
However, given that broadcast may be desirable for some networks, However, given that broadcast may be desirable for some networks,
updates must cause the least disruption possible both in metadata and updates must cause the least disruption possible both in metadata and
payload transmission. firmware transmission.
For an update to be broadcast friendly, it cannot rely on link layer, For an update to be broadcast friendly, it cannot rely on link layer,
network layer, or transport layer security. In addition, the same network layer, or transport layer security. A solution has to rely
message must be deliverable to many devices, both those to which it on security protection applied to the manifest and firmware image
applies and those to which it does not, without a chance that the instead. In addition, the same manifest must be deliverable to many
wrong device will accept the update. Considerations that apply to devices, both those to which it applies and those to which it does
network broadcasts apply equally to the use of third-party content not, without a chance that the wrong device will accept the update.
distribution networks for payload distribution. Considerations that apply to network broadcasts apply equally to the
use of third-party content distribution networks for payload
distribution.
3.3. Use state-of-the-art security mechanisms 3.3. Use state-of-the-art security mechanisms
End-to-end security between the author and the device, as shown in End-to-end security between the author and the device is shown in
Section 5, is used to ensure that the device can verify firmware Section 5.
images and manifests produced by authorized authors.
The use of post-quantum secure signature mechanisms, such as hash- Authentication ensures that the device can cryptographically identify
based signatures, should be explored. A migration to post-quantum the author(s) creating firmware images and manifests. Authenticated
secure signatures would require significant effort, therefore, identities may be used as input to the authorization process.
mandatory-to-implement support for post-quantum secure signatures is
a goal. Integrity protection ensures that no third party can modify the
manifest or the firmware image.
For confidentiality protection of the firmware image, it must be done
in such a way that every intended recipient can decrypt it. The
information that is encrypted individually for each device must
maintain friendliness to Content Distribution Networks, bulk storage,
and broadcast protocols.
A manifest specification must support different cryptographic
algorithms and algorithm extensibility. Because of the nature of
unchangeable code in ROM for use with bootloaders the use of post-
quantum secure signature mechanisms, such as hash-based signatures
[I-D.ietf-cose-hash-sig], are attractive because they maintain
security in presence of quantum computers.
A mandatory-to-implement set of algorithms has to be defined offering A mandatory-to-implement set of algorithms has to be defined offering
a key length of 112-bit symmetric key or security or more, as a key length of 112-bit symmetric key or security or more, as
outlined in Section 20 of RFC 7925 [RFC7925]. This corresponds to a outlined in Section 20 of RFC 7925 [RFC7925]. This corresponds to a
233 bit ECC key or a 2048 bit RSA key. 233 bit ECC key or a 2048 bit RSA key.
If the firmware image is to be encrypted, it must be done in such a
way that every intended recipient can decrypt it. The information
that is encrypted individually for each device must be an absolute
minimum, for example AES Key Wrap [RFC5649], in order to maintain
friendliness to Content Distribution Networks, bulk storage, and
broadcast protocols.
3.4. Rollback attacks must be prevented 3.4. Rollback attacks must be prevented
A device presented with an old, but valid manifest and firmware must A device presented with an old, but valid manifest and firmware must
not be tricked into installing such firmware since a vulnerability in not be tricked into installing such firmware since a vulnerability in
the old firmware image may allow an attacker to gain control of the the old firmware image may allow an attacker to gain control of the
device. device.
3.5. High reliability 3.5. High reliability
A power failure at any time must not cause a failure of the device. A power failure at any time must not cause a failure of the device.
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bootloader with build-in full featured firmware update functionality bootloader with build-in full featured firmware update functionality
such that it is possible to return to the update process after power such that it is possible to return to the update process after power
down. down.
Note: This is an implementation requirement rather than a requirement Note: This is an implementation requirement rather than a requirement
on the manifest format. on the manifest format.
3.6. Operate with a small bootloader 3.6. Operate with a small bootloader
Throughout this document we assume that the bootloader itself is Throughout this document we assume that the bootloader itself is
distinct from the role of the fw consumer and therefore does not distinct from the role of the firmware consumer and therefore does
manage the firmware update process. This may give the impression not manage the firmware update process. This may give the impression
that the bootloader itself is a completely separate component, which that the bootloader itself is a completely separate component, which
is mainly responsible for selecting a firmware image to boot. is mainly responsible for selecting a firmware image to boot.
The overlap between the firmware update process and the bootloader The overlap between the firmware update process and the bootloader
functionality comes in two forms, namely functionality comes in two forms, namely
- First, a bootloader must verify the firmware image it boots as - First, a bootloader must verify the firmware image it boots as
part of the secure boot process. Doing so requires meta-data to part of the secure boot process. Doing so requires meta-data to
be stored alongside the firmware image so that the bootloader can be stored alongside the firmware image so that the bootloader can
cryptographically verify the firmware image before booting it to cryptographically verify the firmware image before booting it to
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used by the bootloader may well be the same manifest obtained with used by the bootloader may well be the same manifest obtained with
the firmware image during the update process (with the severable the firmware image during the update process (with the severable
fields stripped off). fields stripped off).
- Second, an IoT device needs a recovery strategy in case the - Second, an IoT device needs a recovery strategy in case the
firmware update / boot process fails. The recovery strategy may firmware update / boot process fails. The recovery strategy may
include storing two or more firmware images on the device or include storing two or more firmware images on the device or
offering the ability to have a second stage bootloader perform the offering the ability to have a second stage bootloader perform the
firmware update process again using firmware updates over serial, firmware update process again using firmware updates over serial,
USB or even wireless connectivity like a limited version of USB or even wireless connectivity like a limited version of
Bluetooth Smart. In the latter case the fw consumer functionality Bluetooth Smart. In the latter case the firmware consumer
is contained in the second stage bootloader and requires the functionality is contained in the second stage bootloader and
necessary functionality for executing the firmware update process, requires the necessary functionality for executing the firmware
including manifest parsing. update process, including manifest parsing.
In general, it is assumed that the bootloader itself, or a minimal In general, it is assumed that the bootloader itself, or a minimal
part of it, will not be updated since a failed update of the part of it, will not be updated since a failed update of the
bootloader poses a risk in reliability. bootloader poses a risk in reliability.
All information necessary for a device to make a decision about the All information necessary for a device to make a decision about the
installation of a firmware update must fit into the available RAM of installation of a firmware update must fit into the available RAM of
a constrained IoT device. This prevents flash write exhaustion. a constrained IoT device. This prevents flash write exhaustion.
This is typically not a difficult requirement to accomplish because This is typically not a difficult requirement to accomplish because
there are not other task/processing running while the bootloader is there are not other task/processing running while the bootloader is
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together by a single author (although that author may obtain code together by a single author (although that author may obtain code
from other developers, some of it only in binary form). from other developers, some of it only in binary form).
Later it turns out that other use cases may benefit from a Later it turns out that other use cases may benefit from a
standardized manifest format also for conveying software and even standardized manifest format also for conveying software and even
personalization data alongside software. Trusted Execution personalization data alongside software. Trusted Execution
Environments (TEEs), for example, greatly benefit from a protocol for Environments (TEEs), for example, greatly benefit from a protocol for
managing the lifecycle of trusted applications (TAs) running inside a managing the lifecycle of trusted applications (TAs) running inside a
TEE. TEEs may obtain TAs from different authors and those TAs may TEE. TEEs may obtain TAs from different authors and those TAs may
require personalization data, such as payment information, to be require personalization data, such as payment information, to be
securely be conveyed to the TEE. securely conveyed to the TEE.
To support this wider range of use cases the manifest format should To support this wider range of use cases the manifest format should
therefore be extensible to convey other forms of payloads as well. therefore be extensible to convey other forms of payloads as well.
4. Claims 4. Claims
Claims in the manifest offer a way to convey instructions to a device Claims in the manifest offer a way to convey instructions to a device
that impact the firmware update process. To have any value the that impact the firmware update process. To have any value the
manifest containing those claims must be authenticated and integrity manifest containing those claims must be authenticated and integrity
protected. The credential used to must be directly or indirectly protected. The credential used must be directly or indirectly
related to the trust anchor installed at the device by the Trust related to the trust anchor installed at the device by the Trust
Provisioning Authority. Provisioning Authority.
The baseline claims for all manifests are described in The baseline claims for all manifests are described in
[I-D.ietf-suit-information-model]. For example, there are: [I-D.ietf-suit-information-model]. For example, there are:
- Do not install firmware with earlier metadata than the current - Do not install firmware with earlier metadata than the current
metadata. metadata.
- Only install firmware with a matching vendor, model, hardware - Only install firmware with a matching vendor, model, hardware
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8. Bootloader 8. Bootloader
More devices today than ever before are being connected to the More devices today than ever before are being connected to the
Internet, which drives the need for firmware updates to be provided Internet, which drives the need for firmware updates to be provided
over the Internet rather than through traditional interfaces, such as over the Internet rather than through traditional interfaces, such as
USB or RS232. Updating a device over the Internet requires the USB or RS232. Updating a device over the Internet requires the
device to fetch not only the firmware image but also the manifest. device to fetch not only the firmware image but also the manifest.
Hence, the following building blocks are necessary for a firmware Hence, the following building blocks are necessary for a firmware
update solution: update solution:
- the Internet protocol stack for (possibly large) firmware - the Internet protocol stack for firmware downloads (*),
downloads,
- the capability to write the received firmware image to persistent - the capability to write the received firmware image to persistent
storage (most likely flash memory) prior to performing the update, storage (most likely flash memory) prior to performing the update,
- the ability to unpack, decompress or otherwise process the - the ability to unpack, decompress or otherwise process the
received firmware image, received firmware image,
- the features to verify an image and a manifest, including digital - the features to verify an image and a manifest, including digital
signature verification or checking a message authentication code, signature verification or checking a message authentication code,
- a manifest parsing library, and - a manifest parsing library, and
- integration of the device into a device management server to - integration of the device into a device management server to
perform automatic firmware updates and to track their progress. perform automatic firmware updates and to track their progress.
(*) Because firmware images are often multiple kilobytes, sometimes
exceeding one hundred kilobytes, in size for low end IoT devices and
even several megabytes large for IoT devices running full-fletched
operating systems like Linux the protocol mechanism for retrieving
these images needs to offer features like congestion control, flow
control, fragmentation and reassembly, and mechanisms to resume
interrupted or corrupted transfers.
All these features are most likely offered by the application, i.e. All these features are most likely offered by the application, i.e.
firmware consumer, running on the device (except for basic security firmware consumer, running on the device (except for basic security
algorithms that may run either on a trusted execution environment or algorithms that may run either on a trusted execution environment or
on a separate hardware security MCU/module) rather than by the on a separate hardware security MCU/module) rather than by the
bootloader itself. bootloader itself.
Once manifests have been processed and firmware images successfully Once manifests have been processed and firmware images successfully
downloaded and verified the device needs to hand control over to the downloaded and verified the device needs to hand control over to the
bootloader. In most cases this requires the MCU to restart. Once bootloader. In most cases this requires the MCU to restart. Once
the MCU has initiated a restart, the bootloader takes over control the MCU has initiated a restart, the bootloader takes over control
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verification process. Whether to re-use the standardized manifest verification process. Whether to re-use the standardized manifest
format that was used during the initial firmware retrieval process or format that was used during the initial firmware retrieval process or
whether it is better to use a different format for the secure boot- whether it is better to use a different format for the secure boot-
specific meta-data depends on the system design. The manifest format specific meta-data depends on the system design. The manifest format
does, however, have the capability to serve also as a building block does, however, have the capability to serve also as a building block
for secure boot with its severable elements that allow shrinking the for secure boot with its severable elements that allow shrinking the
size of the manifest by stripping elements that are no longer needed. size of the manifest by stripping elements that are no longer needed.
If the application image contains the firmware consumer If the application image contains the firmware consumer
functionality, as described above, then it is necessary that a functionality, as described above, then it is necessary that a
working image is left on the device to ensure that the bootloader can working image is left on the device. This allows the bootloader to
roll back to a working firmware image to re-do the firmware download roll back to a working firmware image to execute a firmware download
since the bootloader itself does not have enough functionality to if the bootloader itself does not have enough functionality to fetch
fetch a firmware image plus manifest from a firmware server over the a firmware image plus manifest from a firmware server over the
Internet. A multi-stage bootloader may soften this requirement at Internet. A multi-stage bootloader may soften this requirement at
the expense of a more sophisticated boot process. the expense of a more sophisticated boot process.
For a bootloader to offer a secure boot mechanism it needs to provide For a bootloader to offer a secure boot mechanism it needs to provide
the following features: the following features:
- ability to access security algorithms, such as SHA-256 to compute - ability to access security algorithms, such as SHA-256 to compute
a fingerprint over the firmware image and a digital signature a fingerprint over the firmware image and a digital signature
algorithm. algorithm.
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Figure 5 illustrates an example message flow for distributing a Figure 5 illustrates an example message flow for distributing a
firmware image to a device starting with an author uploading the new firmware image to a device starting with an author uploading the new
firmware to firmware server and creating a manifest. The firmware firmware to firmware server and creating a manifest. The firmware
and manifest are stored on the same firmware server. This setup does and manifest are stored on the same firmware server. This setup does
not use a status tracker and the firmware consumer component is not use a status tracker and the firmware consumer component is
therefore responsible for periodically checking whether a new therefore responsible for periodically checking whether a new
firmware image is available for download. firmware image is available for download.
+--------+ +-----------------+ +------------+ +----------+ +--------+ +-----------------+ +------------+ +----------+
| Author | | Firmware Server | |FW Consumer | |Bootloader| | | | | | Firmware | | |
| Author | | Firmware Server | | Consumer | |Bootloader|
+--------+ +-----------------+ +------------+ +----------+ +--------+ +-----------------+ +------------+ +----------+
| | | + | | | +
| Create Firmware | | | | Create Firmware | | |
|--------------+ | | | |--------------+ | | |
| | | | | | | | | |
|<-------------+ | | | |<-------------+ | | |
| | | | | | | |
| Upload Firmware | | | | Upload Firmware | | |
|------------------>| | | |------------------>| | |
| | | | | | | |
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device management systems being used. In any case, the status device management systems being used. In any case, the status
tracker learns about the firmware version of the devices it manages. tracker learns about the firmware version of the devices it manages.
In our example, the device under management is using firmware version In our example, the device under management is using firmware version
A.B.C. At a later point in time the author uploads a new firmware A.B.C. At a later point in time the author uploads a new firmware
along with the manifest to the firmware server and the status along with the manifest to the firmware server and the status
tracker, respectively. While there is no need to store the manifest tracker, respectively. While there is no need to store the manifest
and the firmware on different servers this example shows a common and the firmware on different servers this example shows a common
pattern used in the industry. The status tracker may then pattern used in the industry. The status tracker may then
automatically, based on human intervention or based on a more complex automatically, based on human intervention or based on a more complex
policy decide to inform the device about the newly available firmware policy decide to inform the device about the newly available firmware
image. In our example, it does so by pushing the manifest to the FW image. In our example, it does so by pushing the manifest to the
consumer. The firmware consumer downloads the firmware image with firmware consumer. The firmware consumer downloads the firmware
the newer version X.Y.Z after successful validation of the manifest. image with the newer version X.Y.Z after successful validation of the
Subsequently, a reboot is initiated and the secure boot process manifest. Subsequently, a reboot is initiated and the secure boot
starts. process starts.
+---------+ +-----------------+ |-----------------------------. +---------+ +-----------------+ +-----------------------------+
| Status | | Firmware Server | | +------------+ +----------+ | | Status | | | | +------------+ +----------+ |
| Tracker | | | | |FW Consumer | |Bootloader| | | Tracker | | Firmware Server | | | Firmware | |Bootloader| |
| | | | | | Consumer | | | |
+---------+ +-----------------+ | +------------+ +----------+ | +---------+ +-----------------+ | +------------+ +----------+ |
| | | | IoT Device | | | | | | IoT Device | |
| | `'''''''''''''''''''''''''''' | | `''''''''''''''''''''''''''''
| | | | | | | |
| Query Firmware Version | | | Query Firmware Version | |
|------------------------------------->| | |------------------------------------->| |
| Firmware Version A.B.C | | | Firmware Version A.B.C | |
|<-------------------------------------| | |<-------------------------------------| |
| | | | | | | |
| <<some time later>> | | | <<some time later>> | |
skipping to change at page 26, line 42 skipping to change at page 27, line 4
- Phillip Hallam-Baker - Phillip Hallam-Baker
- Marti Bolivar - Marti Bolivar
- Andrzej Puzdrowski - Andrzej Puzdrowski
- Markus Gueller - Markus Gueller
- Henk Birkholz - Henk Birkholz
- Jintao Zhu - Jintao Zhu
- Takeshi Takahashi - Takeshi Takahashi
- Jacob Beningo - Jacob Beningo
- Kathleen Moriarty
We would also like to thank the WG chairs, Russ Housley, David We would also like to thank the WG chairs, Russ Housley, David
Waltermire, Dave Thaler for their support and their reviews. Waltermire, Dave Thaler for their support and their reviews.
14. References 14. References
14.1. Normative References 14.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC7925] Tschofenig, H., Ed. and T. Fossati, "Transport Layer [RFC7925] Tschofenig, H., Ed. and T. Fossati, "Transport Layer
Security (TLS) / Datagram Transport Layer Security (DTLS) Security (TLS) / Datagram Transport Layer Security (DTLS)
Profiles for the Internet of Things", RFC 7925, DOI Profiles for the Internet of Things", RFC 7925, DOI
10.17487/RFC7925, July 2016, <https://www.rfc- 10.17487/RFC7925, July 2016, <https://www.rfc-
editor.org/info/rfc7925>. editor.org/info/rfc7925>.
14.2. Informative References 14.2. Informative References
[I-D.ietf-cose-hash-sig]
Housley, R., "Use of the HSS/LMS Hash-based Signature
Algorithm with CBOR Object Signing and Encryption (COSE)",
draft-ietf-cose-hash-sig-04 (work in progress), October
2019.
[I-D.ietf-suit-information-model] [I-D.ietf-suit-information-model]
Moran, B., Tschofenig, H., and H. Birkholz, "Firmware Moran, B., Tschofenig, H., and H. Birkholz, "Firmware
Updates for Internet of Things Devices - An Information Updates for Internet of Things Devices - An Information
Model for Manifests", draft-ietf-suit-information-model-03 Model for Manifests", draft-ietf-suit-information-model-03
(work in progress), July 2019. (work in progress), July 2019.
[I-D.ietf-teep-architecture] [I-D.ietf-teep-architecture]
Pei, M., Tschofenig, H., Wheeler, D., Atyeo, A., and D. Pei, M., Tschofenig, H., Wheeler, D., Atyeo, A., and D.
Liu, "Trusted Execution Environment Provisioning (TEEP) Liu, "Trusted Execution Environment Provisioning (TEEP)
Architecture", draft-ietf-teep-architecture-03 (work in Architecture", draft-ietf-teep-architecture-03 (work in
 End of changes. 26 change blocks. 
62 lines changed or deleted 88 lines changed or added

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