Supply Chain Integrity, Transparency, and Trust
charter-ietf-scitt-01

Introduction
============
The Supply Chain Integrity, Transparency, and Trust (SCITT) WG will define a
set of interoperable building blocks that will allow implementers to build
integrity and accountability into software supply chain systems to help assure
trustworthy operation. For example, a public computer interface system could
report its software composition that can then be compared against known
software compositions or certifications for such a device thereby giving
confidence that the system is running the software expected and has not been
modified, either by attack or accident, in the supply chain.

Problem Statement
=================
Some of the fundamental security issues that face the supply chain ecosystem
today are as follows:

1. A single product is composed of multiple sub-products coming from different
suppliers. There are several standards to compose supply chain information with
different producers choosing different methods.

2. There are no uniform APIs or services to publish supply chain information to
third parties, nor are there ways to verify the integrity or date of
publication of that information.

3. There is a lack of decentralized, globally interoperable, transparent
services to publish supply chain data.

4. The lack of sufficient standards for independently verifying the presence of
supply chain data in tamper-proof data stores.

5. Fractured verification methodologies across software distribution ecosystems
create inconsistent security guarantees for end users.

6. Software consumers have no trustworthy way to verify that a software
signature on a software package is legitimate.

A minimal, simple, and concise set of building blocks that interact in a
standardized way will assure long-term accountability and interoperability for
supply chain components throughout their lifecycles across architecturally
diverse systems.

Goals
=====
Based on an input document on the architecture
(draft-birkholz-scitt-architecture), the WG will standardize the technical
flows for providing information about a software supply chain, which also
includes firmware, and covering the essential building blocks that make up the
architecture.

The WG will:
- reuse existing work from IETF WGs such as COSE and RATS, as appropriate,
- coordinate with other standards bodies, such as the OpenSSF, W3C, ISO, and
the Trusted Computing Group.

Non-Goals
=========
The WG does not:

1. make recommendations or suggestions on best practices on how to design the
supply chain,

2. establish a universal/centralized registry for supply chain data,

3. define methods to prevent authenticated supply chain issuers from making
false claims,

4. define data formats for payload content, such as Bills of Materials data
formats.

Program of Work
===============
Documents produced by the working group will address one or more of the
following programs of work:

## Architectural Model: Actors, Interactions, Terminology

The WG shall start by documenting and defining terms in an architectural model
for:

1. essential actors, such as the claim's "issuer"  (one which
generates supply chain artifacts and statements about them),
"notary", and "consumer" and

2. the basic interactions these have with other actors, and their duties in the
ecosystem.

The architectural model shall provide an aggregated overview of corresponding
actor-specific information models and interaction models. It will provide
examples of composition patterns that illustrate how to address a concise set
of use cases.

The architectural model shall include an abstract threat model that minimally
encompasses the initial use cases and will be based on a set of to be defined
security objectives.

## Consistent Actor Identification

The WG shall select (and potentially profile) acceptable common identity
format/formats that will be used to identify and authenticate various actors in
the SCITT ecosystem. The WG shall create guidance on how to create and manage
new identity documents, their trust anchors, and corresponding security
considerations in the context of supply chains.

## Information Models and Interaction Models for:

1. Registry: The WG shall define an Abstract Transparent Registry and also
define the interactions and conceptual messages that will be supported by
registries with an aim to generate homogeneity across multiple supply chains.

2. Notarization: The WG shall develop a specification that describes the
notarization information model and the interaction model a notary will use to
interact with supply chain entities.

3. Auditing: The WG shall develop standards to permit auditing of supply chain
claims that are introduced in the transparent registry. This will, in turn,
generate audit claims based on an information model (results of an audit),
which can be introduced in the same registry. A corresponding interaction model
will describe how audit information can be queried by supply chain consumers
(e.g., end customers) before making critical business decisions.

## Versatile Countersigning Format in Support of Transparency Services

The WG shall specify a standard format for authenticity data returned from the
transparent registry such as proofs, etc. The standard shall enable independent
verification of supply chain claims at a (much) later point on multiple
platforms across multiple geographical locations.

## Generic Protocol Bindings for Information Model and Interaction Models

The WG shall standardize request-response interactions ("external
API") and potentially other generic interaction schemes provided to
various external entities to interact with the supply chain ecosystem. This
includes standardizing inter-component messages (based on the interaction
models) and payload serialization between supply chain actors to support common
reference implementations of SCITT building blocks by various organizations to
expedite industry-wide adaptation.