Towards Usable Interfaces for Proof Based Access Rights on Mobile Devices

Access rights management is in the middle of many collaboration forms such as group formation or sharing of information in different kinds of scenarios. There are some strong mechanisms to achieve this, like anonymous credential systems. However in general their usage is not very intuitive for lay users. In this paper we show the potential of using proof-based credential systems like Idemix to enhance the usability of privacy-respecting social interaction in different collaborative settings. For instance transparently performing authorization without any user intervention at the level of the user interface becomes possible. In order to improve the usability, we complement this by introducing a mental model for intuitive management of digital identities. The approach should also empower users to define their own access restrictions when sharing data, by building custom proof specifications on the fly. We show this exemplary with a developed prototype application for supporting collaborative scenarios on a mobile device. We also present first evaluation results of an early prototype and address current as well as future work

Evaluation of the di.me trust metric in CRM settings

The use and disclosure of personal information is a recognisable trend in modern information society. The integration and aggregation of such information introduces potentially critical privacy issues, like unintended information disclosure. The European research project digital.me is focused on the development of a tool empowering users to keep track of disclosed information by offering an intelligent UI and smart trust and privacy advisory. A user-centric trust metric has been developed as a central technique and is being utilised in order to give privacy advisory to users sharing sensitive information. Besides giving those advisory in private context, this functionality is being used in a business scenario, where the di.me platform is connected to a Customer Relationship Management (CRM) tool. In this context, the trust metric was validated against three mediating conditions for technology acceptance: utility, usability and privacy concerns. Field trials involving 447 CRM operators showed positive results for all three conditions

Privacy-preserving concepts for supporting recommendations in decentralized OSNs

Recommender systems depend on the amount of available and processable information for a given purpose. Trends towards decentralized online social networks (OSNs), promising more user control by means of privacy preserving mechanisms, lead to new challenges for (social) recommender systems. Information, recommender algorithms rely on, is no longer available, (i.e. central user registries, friends of friends), thus shared data is reduced and centralized processing becomes difficult. In this paper we address such drawbacks based on identified needs in the decentralized OSN di.me and present concepts overcoming those for selected functionalities. Besides this, we tackle the support of privacy advisory, warning the user of risks when sharing data

Enhancing privacy in collaborative scenarios utilising a flexible proxy layer

In this paper we present our approach for a flexible proxy layer, allowing the parallel use of anonymous and direct network communication depending on specific scenarios or user preferences. The requirements are derived from scenarios from the european research project di. me, targeting to support end users in keeping control of their personal data and digital footprints. In the targeted scenarios, the use of anonymous network communication is an essential prerequisite for certain use cases (e.g. like pseudonymous communication), because of the special architecture, where each user has its own server holding his private data. Especially, the presented approach solves linkability which could arise when using SSL certificates/x.509 certificates and addresses various potential attacks. A detailed specification is given and important implementation details are addressed