A Lattice-Based Universal Thresholdizer for Cryptographic Systems
We develop a general approach to thresholdizing a large class of (non-threshold) cryptographic schemes. We show how to add threshold functionality to CCA-secure public-key encryption (PKE), signature schemes, pseudorandom functions, and others primitives. To do so, we introduce a general tool, called a universal thresholdizer, from which many threshold systems are possible. The tool builds upon a latticebased fully-homomorphic encryption (FHE) system. Applying the tool to a (non-threshold) lattice-based signature, gives the first single-round threshold signature from the learning with errors problem (LWE). Applying the tool to a (non-threshold) lattice-base CCA-secure PKE, gives a single-round lattice-based threshold CCA-secure PKE.