International Association
for Cryptologic Research

We propose a simple, general, and unified framework for constructing unique ring signatures that simplify and capture the spirit of linkable ring signatures. The framework, which can be efficiently instantiated in the random oracle and the standard model, is obtained by generalizing the Bellare-Goldwasser ``PRF made public\" paradigm. Security of the first instantiation can be tightly related to the DDH problem. The scheme leads to the most efficient linkable/unique ring signature in the random oracle model, for a given level of provable security. The second one based on stronger assumptions partly simplifies and slightly improves sublinear size traceable ring signature of Fujisaki. Both of the improvements would be difficult without the general framework in hand.