Practical UC security with a Global Random Oracle

Contrary to prior belief, we show that there exist commitment, zero-knowledge and general function evaluation protocols with universally composable security, in a model where all parties and all protocols have access to a single, global, random oracle and no other trusted setup. This model provides significantly stronger composable security guarantees than the traditional random oracle model of Bellare and Rogaway [CCS'93] or even the common reference string model. Indeed, these latter models provide no security guarantees in the presence of arbitrary protocols that use the { same} random oracle (or reference string or hash function).