Re: [Suit] SUIT rechartering: proposed text

[Russ Housley <[e-mail]>]

I have tried to address the comments from Michael, Dave T., and Dave W.  The biggest change is int inclusion to an additional document for set of claims related for attesting to firmware update status.  This covers the SUIT-related claims that ware currently being considered in the RATS WG.

Please review and comment.

Russ

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Vulnerabilities in Internet of Things (IoT) devices have raised the need
for a secure firmware update mechanism that is also suitable for constrained
devices.  Security experts, researchers, and regulators recommend that all IoT
devices be equipped with such a mechanism.  While there are many proprietary
firmware update mechanisms in use today, there is no modern interoperable
approach allowing secure updates to firmware in IoT devices. In June 2016,
the Internet Architecture Board organized a workshop on 'Internet
of Things (IoT) Software Update (IOTSU)', and RFC 8240 documents various
requirements and challenges that are specific to IoT devices.

A firmware update solution consists of several components, including:
* A mechanism to transport firmware images to compatible devices.
* A manifest that provides meta-data about the firmware image (such as a
  firmware package identifier, the hardware the package needs to run, and
  dependencies on other firmware packages), as well as cryptographic
  information for protecting the firmware image in an end-to-end fashion.
* The firmware image itself.

The SUIT WG is defining a firmware update solution (taking into account past
learnings from RFC 4108 and other proprietary firmware update solutions) that
are usable on Class 1 (as defined in RFC 7228) devices, i.e., devices with
~10 KiB RAM and ~100 KiB flash.  The solution may apply to more capable devices
as well.  The SUIT WG is not defining any new transport or discovery mechanisms,
but may describe how to use existing mechanisms within the architecture.

The SUIT WG has already completed work on two documents:
* An IoT firmware update architecture that includes a description of the
  involved entities, security threats, and assumptions.
* An information model for the SUIT manifest.

Now that the information model is complete, the SUIT WG has selected the CBOR
serialization format and the associated COSE cryptographic mechanisms to
encode the SUIT manifest. The SUIT WG may consider a small number of additional
formats in the future; however, to reduce the complexity of a firmware
management solution, a very small number of formats is preferred to enable SUIT
maifest integration and interoperability with other IoT technologies and
ecosystems.  To support a wide range of deployment scenarios, the formats are
expected to be expressive enough to allow the use of different firmware sources
and permission models.

The SUIT WG does not aim to create a standard for a generic application
software update mechanism, but instead the SUIT WG is focusing on firmware
development practices in the embedded industry. Software update solutions that
target updating software other than the firmware binaries (e.g., applications)
are also out of scope.

To support the SUIT manifest format, the SUIT WG is also defining formats and
protocols that enable a SUIT Status Tracker to determine if a particular
manifest could be successfully deployed to a device and determine if an
operation was successful.

In addition, the SUIT WG will specify claims related to the SUIT Status Tracker
that can be used to provide evidence in support of the architecture defined by
the RATS WG.

The SUIT WG will continue to work with silicon vendors and OEMs that
develop IoT operating systems to produce implementations based on SUIT WG
specifications.  In particular, the SUIT WG plans to continue to participate
in IETF Hackathons.

The SUIT WG document deliverables are:
* A SUIT manifest format specification using CBOR.
* A firmware encryption specification for use with SUIT manifests.
* A secure for IoT device to reporting on firmware update status.
* A set of claims related for attesting to firmware update status.
* A SUIT manifest extension to include a MUD file as defined in RFC 8520.