The transition from centralized identity architecture to a decentralized one introduces profound shifts in the privacy protection of users’ data. Yet, as decentralized identity continues to mature, today’s online services still overwhelmingly depend on centralized and federated identity management solutions built on top of OpenID Connect (OIDC) as the most widespread solution. Ensuring privacy-preserving OIDC deployments is therefore critical for safeguarding users’ personal data and maintaining compliance with regulatory frameworks such as the General Data Protection Regulation (GDPR) and trust frameworks such as the Electronic Identification, Authentication and Trust Services (eIDAS). However, the current OIDC ecosystem lacks a coherent set of privacy Best Current Practices (BCPs) and a study of how widely these privacy-enhancing features are adopted in real-world deployments. To this end, this work addresses the aforementioned gaps on two fronts. First, we propose a structured set of privacy BCPs derived from official OIDC specifications and current implementation trends, identifying easy-to-deploy privacy-enhancing features that strengthen the OIDC deployments’ baseline privacy without altering the protocol or compromising interoperability. Furthermore, the BCPs also help achieve the GDPR privacy principles, such as data minimization, confidentiality, and unlinkability. Second, this work provides a comprehensive survey of OpenID Providers (OPs) in the wild to identify gaps in privacy-preserving configurations in both private and public (i.e., national) sectors OPs. The study employs a dual methodology: first, a manual review performed in 2022; subsequently, an automated compliance analysis performed in 2025 surveying a dataset of 10000 OPs worldwide. The results reveal a concerning lack of privacy-enhancing features among private OPs and a wide gap between private and national OPs, with the latter group providing, on average, much higher baseline privacy. We have also found a prevalence of OPs not complying with the OIDC specifications, resulting in misconfigured OPs hampering interoperability and, in some cases, security. The paper emphasizes the importance of adopting actionable BCPs to improve baseline privacy and demonstrates the need for an automated framework for ongoing privacy compliance assessments in OIDC ecosystems.

Abstract The European Digital Identity Wallet (EUDI Wallet) plays a pivotal role in shaping digital identity across the EU, necessitating a secure storage solution compliant with eIDAS2 regulation. In this study, we first analyze mobile secure storage solutions for the EUDI Wallet, identifying any gaps between current offerings and the EUDI Wallet’s requirements. Our analysis indicates a significant shortfall in the availability of mobile native solutions, with only approximately 10.5% of mobile phones in the Italian market currently adhering to the stringent requirements mandated by eIDAS2. Consequently, we explore and evaluate alternative design solutions in terms of their feasibility and integration potential.

Verifiable credentials are a digital analogue of physical credentials. Their authenticity and integrity are protected by means of cryptographic techniques, and they can be presented to verifiers to reveal attributes or even predicates about the attributes included in the credential. One way to preserve privacy during presentation consists in selectively disclosing the attributes in a credential. In this paper we present the most widespread cryptographic mechanisms used to enable selective disclosure of attributes identifying two categories: the ones based on hiding commitments - e.g., mdl ISO/IEC 18013-5 - and the ones based on non-interactive zero-knowledge proofs - e.g., BBS signatures. We also include a description of the cryptographic primitives used to design such cryptographic mechanisms. We describe the design of the cryptographic mechanisms and compare them by performing an analysis on their standard maturity in terms of standardization, cryptographic agility and quantum safety, then we compare the features that they support with main focus on the unlinkability of presentations, the ability to create predicate proofs and support for threshold credential issuance. Finally we perform an experimental evaluation based on the Rust open source implementations that we have considered most relevant. In particular we evaluate the size of credentials and presentations built using different cryptographic mechanisms and the time needed to generate and verify them. We also highlight some trade-offs that must be considered in the instantiation of the cryptographic mechanisms.

Authentication protocols represent the entry point to online services, so they must be sturdily designed in order to allow only authorized users to access the underlying data. However, designing authentication protocols is a complex process: security designers should carefully select the technologies to involve and integrate them properly in order to prevent potential vulnerabilities. In addition, these choices are usually restricted by further factors, such as the requirements associated with the scenario, the regulatory framework, the dimensions to balance (e.g., security vs. usability), and the standards to rely on. We come to the rescue by presenting an automated multi-layered methodology we have developed to assist security designers in this phase: by repeatedly evaluating their protocols, they can select the security mitigations to consider until they reach the desired security level, thus enabling a security-by-design approach. For concreteness, we also show how we have applied our methodology to a real use case scenario in the context of a collaboration with the Italian Government Printing Office and Mint.

An Attribute Authority is an entity responsible for establishing, maintaining, and sharing a subject’s qualified attributes, such as titles and qualifications. In the OpenID Connect digital identity ecosystem, In the OpenID Connect digital identity ecosystem, for privacy reasons, this entity is distinct from Identity Providers that manage only the basic identity profile information. A relevant scenario is as follows: the User first logs in to an online service using his/her identity managed by an Identity Provider. Then, the online service asks the Attribute Authority for the additional User’s attributes (e.g., entitlements) before granting access to its resources. In some high-sensitive cases, an Attribute Authority needs proof of the User’s authentication before releasing the User’s attributes to the online service. The challenge of this scenario involving usability, security, and privacy requirements lies in finding the right mechanism to share (the minimum and necessary set of) claims of the User who is currently authenticated with the online service across multiple domains without requiring his or her re-authentication. In this paper, we present the design of two solutions based on OpenID Connect to share User claims across domains. We provide security and privacy analysis for the two solutions and a brief comparison between them.

The eIDAS Regulation aims to provide an interoperable European framework to enable EU citizens to authenticate and communicate with services of other Member States by using their national electronic identity. While a set of high-level requirements (e.g., related to privacy and security) are established to make interoperability among Member States possible, the eIDAS Regulation does not explicitly specify the technologies that can be adopted during the development phase to meet the requirements as mentioned earlier. This paper considers the technological trends of (pre)notified eIDAS electronic identity schemes used by Member States, and they satisfy the eIDAS regulation requirements. We do this by defining a set of research questions that allow us to investigate the correlations between different design dimensions such as security, privacy, and usability. Based on these findings, we provide a set of lessons learned that can be used by the security community to protect interoperable national digital identities more efficiently.

While being both extremely powerful and popular, TLS is a protocol that is hard to securely deploy. On the one hand, system administrators are required to grasp several security concepts to fully understand the impact of each option and avoid misconfigurations. On the other hand, app developers should use cryptographic libraries in a secure way avoiding dangerous default settings or other subtleties (e.g., padding or modes of operations). To help secure TLS, we propose a modular framework, extensible with new features and capable of streamlining the mitigation process of known and newly discovered TLS attacks even for non-expert users.

To grasp the security implications of the various TLS configuration options, system administrators and app developers must be familiar with a wide range of concepts, including cryptography. To assist users in this task, we propose TLSAssistant- a modular and extensible framework designed to streamline the discovery and mitigation of potential vulnerabilities in TLS deployments. This demo will focus on two of the four available analysis types.

Several automated tools have been proposed to detect vulnerabilities. These tools are mainly evaluated in terms of their accuracy in detecting vulnerabilities, but the evaluation of their usability is a commonly neglected topic. Usability of automated security tools is particularly crucial when dealing with problems of cryptographic protocols for which even small—apparently insignificant—changes in their configuration can result in vulnerabilities that, if exploited, pave the way to attacks with dramatic consequences for the confidentiality and integrity of exchanged messages. This becomes even more acute when considering such ubiquitous protocols as the one for Transport Layer Security (TLS for short). In this paper, we present the design and the lessons learned of a user study, meant to compare two different approaches when reporting misconfigurations. Results reveal that including contextualized actionable mitigations in security reports significantly impact the accuracy and the time needed to patch TLS vulnerabilities. Along with the lessons learned, we share the experimental material that can be used during cybersecurity labs to let students configure and patch TLS first-hand.

With more systems becoming digitised, enterprises are adopting cloud technologies and outsourcing non-critical services to reduce the pressure on IT departments. In this process, it is crucial to achieving the right balance between costs, usability and security; prioritising security over the rest when handling sensitive data. Considering the print management, often off-premise, many enterprises report at least one print-related security incident that led to data loss in the past year. This problem can damage the enterprise business, especially considering the fines prescribed by current regulations or its reputation. Focusing on securing enterprise printing, pull printing is the set of technologies and processes that allow the release of print jobs according to specific conditions; typically user authentication and proximity to a printer. We design a software-oriented pull printing infrastructure that supports a print release mechanism using QR codes and electronic IDentity cards as a second-factor authenticator. Our solution addresses the costs, as any medium-size organisation can adopt our open-source solution without additional devices or access badges; and the user experience, as we offer a driverless print environment and a user-friendly mobile application.

More and more online services are characterised by the need for strongly verifying the real-world identity of end users, especially when sensitive operations have to be carried out: just imagine a fully-remote signature of a contract, and what could happen whether someone managed to perform it by using another person’s name. For this reason, the identity management lifecycle contains specific procedures – called enrollment or onboarding – providing a certain level of assurance on digital users’ real identities. These procedures must be as secure as possible to prevent frauds and identity thefts. In this paper, we present a framework composed of a specification language, a security analysis methodology and a risk analysis methodology for enrollment solutions. For concreteness, we apply our framework to a real use case (i.e., fully-remote solutions relying on electronic documents as identity evidence) in the context of a collaboration with an Italian FinTech startup. Beyond validating the framework, we analyse and highlight the essential role of mitigations on the overall security of enrollment procedures.

Everyday life is permeated by new technologies allowing people to perform almost any kind of operation from their smart devices. Although this is amazing from a convenience perspective, it may result in several security issues concerning the need for authenticating users in a proper and secure way. Electronic identity cards (also called eID cards) play a very important role in this regard, due to the high level of assurance they provide in identification and authentication processes. However, authentication solutions relying on them are still uncommon and suffer from many usability limitations. In this paper, we thus present the design and implementation of a novel passwordless, multi-factor authentication protocol based on eID cards. To reduce known usability issues while keeping a high level of security, our protocol leverages push notifications and mobile devices equipped with NFC, which can be used to interact with eID cards. In addition, we evaluate the security of the protocol through a formal security analysis and a risk analysis, whose results emphasize the acceptable level of security.

Over the last few years, there has been an almost exponential increase in the number of mobile applications that deal with sensitive data, such as applications for e-commerce or health. When dealing with sensitive data, classical authentication solutions based on username-password pairs are not enough, and multi-factor authentication solutions that combine two or more authentication factors of different categories are required instead. Even if several solutions are currently used, their security analyses have been performed informally or semiformally at best, and without a reference model and a precise definition of the multi-factor authentication property. This makes a comparison among the different solutions both complex and potentially misleading. In this article, we first present the design of two reference models for native applications based on the requirements of two real-world use-case scenarios. Common features between them are the use of one-time password approaches and the support of a single sign-on experience. Then, we provide a formal specification of our threat model and the security goals, and discuss the automated security analysis that we performed. Our formal analysis validates the security goals of the two reference models we propose and provides an important building block for the formal analysis of different multi-factor authentication solutions.

While there exist many secure authentication and authorization solutions for web applications, their adaptation in the mobile context is a new and open challenge. In this paper, we argue that the lack of a proper reference model for Single Sign-On (SSO) for mobile native applications drives many social network vendors (acting as Identity Providers) to develop their own mobile solution. However, as the implementation details are not well documented, it is difficult to establish the proper security level of these solutions. We thus provide a rational reconstruction of the Facebook SSO flow, including a comparison with the OAuth 2.0 standard and a security analysis obtained testing the Facebook SSO reconstruction against a set of identified SSO attacks. Based on this analysis, we have modified and generalized the Facebook solution proposing a native SSO solution capable of solving the identified vulnerabilities and accommodating any Identity Provider.