Love at First Sight? A User Experience Study of Self-Sovereign Identity Wallets

Today’s systems for digital identity management exhibit critical security, efficiency, and privacy issues. A new paradigm, called Self-Sovereign Identity (SSI), addresses these shortcomings by equipping users with mobile wallets and empowering them to manage their digital identities. Various companies and governments back this paradigm and promote its development and diffusion. User experience often plays a subordinate role in these efforts, even though it is crucial for user satisfaction and adoption. We thus conduct a comprehensive user experience study of four prominent SSI wallets using a mixed-method approach that involves moderated and remote interviews and the User Experience Questionnaire (UEQ). We find that the examined wallets already provide a decent level of user experience, yet further improvements need to be done. In particular, the examined wallets do not make their novelty and benefits sufficiently apparent to users. Our analysis contributes to user experience research and offers guidance for SSI practitioners

Transition Pathways towards Design Principles of Self-Sovereign Identity

Society\u27s accelerating digital transformation during the COVID-19 pandemic highlighted clearly that the Internet lacks a secure, efficient, and privacy-oriented model for identity. Self-sovereign identity (SSI) aims to address core weaknesses of siloed and federated approaches to digital identity management from both users\u27 and service providers\u27 perspectives. SSI emerged as a niche concept in libertarian communities, and was initially strongly associated with blockchain technology. Later, when businesses and governments began to invest, it quickly evolved towards a mainstream concept. To investigate this evolution and its effects on SSI, we conduct design science research rooted in the theory of technological transition pathways. Our study identifies nine core design principles of SSI as deployed in relevant applications, and discusses associated competing political and socio-technical forces in this space. Our results shed light on SSI\u27s key characteristics, its development pathway, and tensions in the transition between regimes of digital identity management

Verifying Accountability for Unbounded Sets of Participants

Little can be achieved in the design of security protocols without trusting at least some participants. This trust should be justified; or, at the very least, subject to examination. A way of strengthening trustworthiness is to hold parties accountable for their actions, as this provides strong incentives to refrain from malicious behavior. This has lead to an increased interest in accountability in the design of security protocols. In this work, we combine the accountability definition of K\"unnemann, Esiyok, and Backes, with the notion of case tests to extend its applicability to protocols with unbounded sets of participants. We propose a general construction of verdict functions and a set of verification conditions which achieve soundness and completeness. Expressing the verification conditions in terms of trace properties allows us to extend Tamarin---a protocol verification tool---with the ability to analyze and verify accountability properties in a highly automated way. In contrast to prior work, our approach is significantly more flexible and applicable to a wide range of protocols.Comment: 40 page

Transition Pathways towards Design Principles of Self-Sovereign Identity

Society’s accelerating digital transformation during the COVID-19 pandemic highlighted clearly that the Internet lacks a secure, efficient, and privacy-oriented model for identity. Self-sovereign identity (SSI) aims to address core weaknesses of siloed and federated approaches to digital identity management from both users’ and service providers’ perspectives. SSI emerged as a niche concept in libertarian communities, and was initially strongly associated with blockchain technology. Later, when businesses and governments began to invest, it quickly evolved towards a mainstream concept. To investigate this evolution and its effects on SSI, we conduct design science research rooted in the theory of technological transition pathways. Our study identifies nine core design principles of SSI as deployed in relevant applications, and discusses associated competing political and socio-technical forces in this space. Our results shed light on SSI’s key characteristics, its development pathway, and tensions in the transition between regimes of digital identity managemen

Automated Verification of Accountability in Security Protocols

Accountability is a recent paradigm in security protocol design which aims to eliminate traditional trust assumptions on parties and hold them accountable for their misbehavior. It is meant to establish trust in the first place and to recognize and react if this trust is violated. In this work, we discuss a protocol-agnostic definition of accountability: a protocol provides accountability (w.r.t. some security property) if it can identify all misbehaving parties, where misbehavior is defined as a deviation from the protocol that causes a security violation. We provide a mechanized method for the verification of accountability and demonstrate its use for verification and attack finding on various examples from the accountability and causality literature, including Certificate Transparency and Kroll’s Accountable Algorithms protocol. We reach a high degree of automation by expressing accountability in terms of a set of trace properties and show their soundness and completeness

Interaction Testing, Fault Location, and Anonymous Attribute-Based Authorization

abstract: This dissertation studies three classes of combinatorial arrays with practical applications in testing, measurement, and security. Covering arrays are widely studied in software and hardware testing to indicate the presence of faulty interactions. Locating arrays extend covering arrays to achieve identification of the interactions causing a fault by requiring additional conditions on how interactions are covered in rows. This dissertation introduces a new class, the anonymizing arrays, to guarantee a degree of anonymity by bounding the probability a particular row is identified by the interaction presented. Similarities among these arrays lead to common algorithmic techniques for their construction which this dissertation explores. Differences arising from their application domains lead to the unique features of each class, requiring tailoring the techniques to the specifics of each problem. One contribution of this work is a conditional expectation algorithm to build covering arrays via an intermediate combinatorial object. Conditional expectation efficiently finds intermediate-sized arrays that are particularly useful as ingredients for additional recursive algorithms. A cut-and-paste method creates large arrays from small ingredients. Performing transformations on the copies makes further improvements by reducing redundancy in the composed arrays and leads to fewer rows. This work contains the first algorithm for constructing locating arrays for general values of $d$ and $t$. A randomized computational search algorithmic framework verifies if a candidate array is $(\bar{d},t)$-locating by partitioning the search space and performs random resampling if a candidate fails. Algorithmic parameters determine which columns to resample and when to add additional rows to the candidate array. Additionally, analysis is conducted on the performance of the algorithmic parameters to provide guidance on how to tune parameters to prioritize speed, accuracy, or a combination of both. This work proposes anonymizing arrays as a class related to covering arrays with a higher coverage requirement and constraints. The algorithms for covering and locating arrays are tailored to anonymizing array construction. An additional property, homogeneity, is introduced to meet the needs of attribute-based authorization. Two metrics, local and global homogeneity, are designed to compare anonymizing arrays with the same parameters. Finally, a post-optimization approach reduces the homogeneity of an anonymizing array.Dissertation/ThesisDoctoral Dissertation Computer Science 201

Dual Form Signatures: An Approach for Proving Security from Static Assumptions

In this paper, we introduce the abstraction of Dual Form Signatures as a useful framework for proving security (existential unforgeability) from static assumptions for schemes with special structure that are used as a basis of other cryptographic protocols and applications. We demonstrate the power of this framework by proving security under static assumptions for close variants of pre-existing schemes: \begin{itemize} \item the LRSW-based Camenisch-Lysyanskaya signature scheme \item the identity-based sequential aggregate signatures of Boldyreva, Gentry, O\u27Neill, and Yum. \end{itemize} The Camenisch-Lysyanskaya signature scheme was previously proven only under the interactive LRSW assumption, and our result can be viewed as a static replacement for the LRSW assumption. The scheme of Boldyreva, Gentry, O\u27Neill, and Yum was also previously proven only under an interactive assumption that was shown to hold in the generic group model. The structure of the public key signature scheme underlying the BGOY aggregate signatures is quite distinctive, and our work presents the first security analysis of this kind of structure under static assumptions. We view our work as enhancing our understanding of the security of these signatures, and also as an important step towards obtaining proofs under the weakest possible assumptions. Finally, we believe our work also provides a new path for proving security of signatures with embedded structure. Examples of these include: attribute-based signatures, quoteable signatures, and signing group elements

Internet privacy protection

Anonymní autentizace slouží k autentizaci uživatelů bez odhalení jejich vlastních identifikačních údajů či osobních dat. Technologie Anonymních Autentizačních Systémů (AAS) poskytuje ochranu soukromí uživatelů a zároveň zajišťuje bezpečnost systému. Tato práce představuje základní kryptografická primitiva, kterými se anonymní autentizace může zajišťovat. Mezi tato primitiva patří některé asymetrické kryptosystémy, avšak nezbytnou součástí tvoří například protokoly na bázi nulové znalosti, slepá podpisová schémata, prahová skupinová schémata, atd., která jsou představena v kapitole 1. Obecně mají autentizační anonymní systémy uplatnění v aplikacích, jako jsou elektronické mince, elektronické hotovosti, skupinové elektronické podpisy, anonymní přístupové systémy, elektronické volby, atd., které jsou postupně analyzovány a představeny v kapitolách 2 a 3. V praktické části práce, která je popsána v kapitole 4, je představena implementace (v prostředí .NET v jazyce C#) systému AAS, který je vyvíjen na FEKT VUTBR.Anonymous authentication is a mean of authorizing a user without leakage of user personal information. The technology of Anonymous Authentication Systems (AAS) provides privacy of the user and yet preserves the security of the system. This thesis presents the basic cryptographic primitives, which can provide anonymous authentication. Among these primitives there are usually some asymmetric cryptosystems, but an essential part of anonymous authentication is based on zero knowledge protocols, blind signature schemes, threshold group schemes, etc., that are presented in Chapter 1. Generally, Anonymous Authentication Systems have application as electronic coin, electronic cash, group signatures, anonymous access systems, electronic vote, etc., which are analyzed and presented in Chapters 2 and 3. In the practical section, the implementation (in the environment .NET in C#) of the AAS system is presented and described in Chapter 4, which is being developed at the FEEC BUT.