A new forward-secure threshold proxy re-signature scheme

A forward-secure threshold proxy re-signature scheme in the standard model is firstly proposed in this paper. The scheme has the property that it is infeasible to forge valid proxy re-signatures relating to the past even if more than or equal to the threshold proxies are corrupted. Re-signature keys are updated at regular periods of time. It implies that past proxy re-signatures remain secure if the current re-signature key is leaked. The scheme is provably robust, forward-secure and unforgettable without relying on the random oracle model. The scheme has many attractive applications, such as the construction of the interoperable system of digital rights management (DRM).