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Rebooting the Web of Trust XI: The Hague (September 2022)

This repository contains documents related to RWOT11, the eleventh Rebooting the Web of Trust design workshop, which will be held in the Hague, Netherlands, September, 2022

The goal of the workshop is to generate five technical white papers and/or proposals on topics decided by the group that would have the greatest impact on the future.

Final Papers

Composing Credentials via LinkedClaims and Cryptographic Binding (Text)

by Phillip D. Long, Dmitri Zagidulin, and Golda Velez

The Verifiable Credential (VC) ecosystem has encountered several use cases that require a third-party assertion, or a linked claim to an existing object (another VC, a PDF, a web page, etc). Whether it is product reviews, linked claims of self-created credentials, provenance of academic paper reviews, or some other general purpose third-party assertion, these use cases have several requirements in common. Each use case may also require a domain-specific set of fields.

We propose a minimal format for connecting (and optionally cryptographically binding) credentials that will allow each use of third-party assertions to be represented as a set of LinkedClaims. Such a data set will enable verifiers to evaluate the credibility of claims, including those sourced from outside the Verifiable Credential ecosystem.

Further, we propose to demonstrate the ability to compose several Verifiable Credentials into a single domain-specific credential using the LinkedClaim vocabulary that will satisfy the domain requirements of the likely users.

This approach will enable rich shared datasets to inform trust decisions while satisfying the requirements of domain-specific end users. One of the intentions of LinkedClaims Verifiable Credentials is to give individuals the agency to make such claims about themselves and others on their own terms.

A Credential Profile Comparison Matrix to Facilitate Technical and Non-technical Decision Making (Text)

by Andre Kudra*, Torsten Lodderstedt, Paul Bastian, Mirko Mollik, Maaike van Leuken, and Caspar Roelofs

This paper introduces a comparison matrix for the wide variety of credential formats — such as W3C Verifiable Credentials, AnonCreds, and ISO-standard Mobile Driving License (mDL) — and the various related signing algorithms, revocation mechanisms, and key-management systems (collectively referred to as credential profiles). The credential profile comparison matrix is a living document that serves as an accessible resource for an in-depth evaluation of the technical requirements and their technical and non-technical implications for different use-cases and objectives. This paper also explains the rationale behind this matrix, describes the various properties that are included in the matrix and their definitions, and serves as an application guide on how to use the matrix for more informed technical and non-technical discussions and decision making.

This work is the outcome of a collaborative writing session during RWOT11 in September 2022 and continues the work kicked off in an IIW XXIV session in April 2022 and worked on offline afterwards. The work should be considered an iterative process, with the matrix being a living document that will require continuous updating while facilitating discussion among technical and non-technical experts.

Identifier Binding: defining the Core of Holder Binding (Text)

by Paul Bastian, Rieks Joosten, Zaïda Rivai, Oliver Terbu, Snorre Lothar von Gohren Edwin, Antonio Antonino, Nikos Fotiou, Stephen Curran, and Ahamed Azeem

The W3C Verifiable Credentials Data Model(VCDM) specifies Verifiable Credentials (VCs)[^1] as a collection of claims that are issued by a single party, and Verifiable Presentations (VPs) as a collection of claims that a holder can construct from different VCs issued by different parties. Over the last year(s), various issues have been raised that revolve around what has been called 'holder binding'. The term 'holder binding' itself isn't clearly defined, and is in fact quite contentious. This paper seeks to come to grips with this discussion. Our first contribution is the specification of a terminology, which is intended to help readers understand what we mean to say without requiring them to make assumptions about such meanings (as is often the case in discussions about 'holder binding'). Our second contribution is an analysis of a (fictitious) use-case that suggests that verifiers typically do not need to know who the holder is (i.e. who has presented the claims to be verified). This analysis shows that verifiers need capabilities to (a) learn which entity is the subject of a particular claim, and (b) to know whether or not two subject identifiers refer to the same entity or to different entities. Also, they may need assurances regarding the party on whose behalf the component that has electronically presented the claims, has been using those capabilities. Our third contribution is a proposal for the syntax and semantics of a new property that can be used in (different parts of) VCs/VPs, that will provide verifiers with such capabilities.

Linking Credentials with Data Exchange Agreements through Secured Inclusive Interfaces (Text)

by Lal Chandran, Lotta Lundin, Fredrik Lindén,  Philippe Page,  Paul Knowles, Víctor Martínez Jurado, Andrew Slack

On the need to link verifiable credentials with the right to use data in a secure, inclusive user interaction.

In this collaborative work from RWOT11, we revisit the issue of patient data exchange in a setting requiring cross-border, multi jurisdiction, and inclusive access to all participants. A fundamental problem in developing large-scale real-world solutions based on verifiable credentials is keeping the simplicity of usage for individuals in different contexts without sacrificing security.

We aim to highlight selected technical challenges and outline how the DEXA and OCA protocols contribute to scalable solutions.

On-chain Identity Proof Verification Design Patterns: An Evaluation of Different Strategies to Inject Digital Identity into Decentralized Applications (Text)

by Juan Caballero, Martin Riedel, Egidio Casati, Robert Mao, Fabrice Rochette, Andrea Scorza, Raphael Roullet

In recent months, a problem space has been roughly delineated and widely discussed under the rubric of "on-chain web3 identity." Marketing imperatives and the lack of familiarity with compliance and liability issues particular to identity have largely muddied the waters in the solution space, however, resulting in a reductive three-way rivalry between "soul-bound tokens", verifiable credentials, and loosely-defined "zero knowledge" solutions. Working at a high level, we tried to identify a taxonomy that would be more useful for mapping this solution space according to high-level patterns and tradeoffs.

We defined the problem space at the highest level thusly: various architectures deploy on-chain artefacts to aid in the verification of claims about a wallet's controller. From there, we tried to bucket these into patterns before identifying strengths and weaknesses of each against a short, exemplary list of use-cases. The goal was not so much evaluating these exhaustively, as any evaluation should be more squarely grounded in more detailed use-cases and non-technical requirements. Instead, we strove to identify traits inherent to each high-level pattern that could lead to high-level fitness-for-purpose evaluations, i.e. the "strengths and weaknesses" of each.

Taking out the CRUD: Five Fabulous DID Attacks (Text)

by Shannon Appelcline, Cihan Saglam, Kate Sills, Carsten Stöcker

Decentralized identity solutions, such as DID methods, tend to be designed to protect against certain attacks, but the purpose of that design usually is not explicitly stated in any architectural description or threat documentation. In particular, some DID methods have costly on-chain requirements that must have had a reasoning behind their requirement. We can today see that these DID methods were purposefully shaped, but it’s not clear why such decisions were made. The purpose of this paper is to describe a few colorful attacks on DID methods so that we can better understand what threats a system might be vulnerable to.

Although we derived the examples in this paper by examining current DID methods, we believe these attack vectors are more general, even for systems not using DIDs. The goal is to support engineers and developers who are developing decentralized identity solutions to safeguard their work and make it secure and compliant.

Verifiable Issuers & Verifiers (Text)

by Manu Sporny, Oskar van Deventer, Isaac Henderson Johnson Jeyakumar, Shigeya Suzuki, Konstantin Tsabolov, Line Kofoed, Rieks Joostena

Enabling anyone to share information about the Issuers and Verifiers for whom they assure trust

This work focuses on how a party or its agent can decide whether or not to engage with a counterparty in a transaction. The purpose of this work is to enable the sharing of a list of Verifiable Issuers and Verifiers in a way that is useful to a particular transaction. A set of use cases provide examples where verification of an Issuer ("Is that diploma from a recognized university?") or Verifier ("Should the wallet block an unauthorized Verifier?") is needed. The studied prior art highlights various solutions to verify Issuers and Verifiers and identifies a lack of standards. Important contributions from this paper include a unified set of requirements, a data model, and multiple serializations of the data model --- including but not limited to Verifiable Credentials, DNSSEC, and blockchain-based serializations --- that could then be incubated and sent onto the standards track at global standards setting organizations.

Advance Readings

In advance of the design workshop, all participants are invited to contribute a one-or-two page topic paper to be shared with the other attendees on either:

Please see the Advance Readings directory for all the current papers (and how to upload yours). Advance readings from RWOT10 (cancelled due to COVID) are also included.

Complete Rebooting the Web of Trust Listing

A different repository is available for each of the Rebooting the Web of Trust design workshops:

License

All of the contents of this directory are licensed Creative Commons CC-BY their contributors.