Attribute-based signatures with user-controlled linkability

In this paper, we introduce Attribute-Based Signatures with User-Controlled Linkability (ABS-UCL). Attribute-based signatures allow a signer who has enough credentials/attributes to anonymously sign a message w.r.t. some public policy revealing neither the attributes used nor his identity. User-controlled linkability is a new feature which allows a user to make some of his signatures directed at the same recipient linkable while still retaining anonymity. Such a feature is useful for many real-life applications. We give a general framework for constructing ABS-UCL and present an efficient instantiation of the construction that supports multiple attribute authorities