Concepts and Languages for Privacy-Preserving Attribute-Based Authentication

Abstract

Abstract. Existing cryptographic realizations of privacy-friendly authentication mechanisms such as anonymous credentials, minimal disclosure tokens, selfblindable credentials, and group signatures vary largely in the features they offer and in how these features are realized. Some features such as revocation or de-anonymization even require the combination of several cryptographic protocols. These differences and the complexity of the cryptographic protocols hinder the deployment of these mechanisms for practical applications and also make it almost impossible to switch the underlying cryptographic algorithms once the application has been designed. In this paper, we aim to overcome this issue and simplify both the design and deployment of privacy-friendly authentication mechanisms. We define and unify the concepts and features of privacy-preserving attribute-based credentials (Privacy-ABCs) and provide a language framework in XML schema. Our language framework enables application developers to use Privacy-ABCs with all their features without having to consider the specifics of the underlying cryptographic algorithms-similar to as they do today for digital signatures, where they do not need to worry about the particulars of the RSA and DSA algorithms either.

Privacy in the Smart City—Applications, Technologies, Challenges, and Solutions

“…Anonymous credentials [158] allow users to obtain credentials from authorities and use these credentials while ensuring that transactions cannot be linked to each other or to the user. Attribute-based credentials rely on anonymous credentials and add features for revocation and de-anonymization [159]. Attribute-based credentials have many potential uses in smart cities, for example to allow users to authenticate with cloud providers without revealing their identities [19].…”

“…Even in cases where authentication is required, it is not necessary to create a link between user and transaction. Instead, attribute-based credentials allow the system to cryptographically verify certain of the user's attributes (for example, a student or discounted fares attribute would indicate that the user is entitled to discounted bus fares) without revealing the user identity [159].…”

Can Cryptocurrencies Preserve Privacy and Comply With Regulations?

“…Individuals conducting transactions might not need to have accounts to exchange value with each other; we surmise that the regulated intermediary would perform the service for a fee. We also suggest that the intermediary would not be required to carry out strong identification of the sort required by the FATF recommendations (Financial Action Task Force, 2018) but might require a less-stringent form of identification, such as an attribute-backed credential indicating that either the sender or the receiver are eligible to transact (Camenisch et al, 2013). Regulated intermediaries could also provide token mixing services for groups of individuals who satisfy AML criteria, without explicitly requiring knowledge of their unitary identities.…”

Evaluation of Privacy-ABC Technologies - a Study on the Computational Efficiency

“…Such an architecture may optionally also include an entity that takes care of revocation of credentials, and another entity that can revoke the anonymity of otherwise anonymous users. The main interactions between Privacy-ABCs system entities [7] can be represented by the different stages of its lifecycle, that is, issuance, presentation, inspection, and revocation.…”