CSAR: A Practical and Provable Technique to Make Randomized Systems Accountable

The authors describe CSAR, a novel technique for generating cryptographically strong, accountable randomness. Using CSAR, they can generate a pseudo-random sequence and a proof that the elements of this sequence up to a given point have been correctly generated, while future values in the sequence remain unpredictable. CSAR enables accountability for distributed systems that use randomized protocols. External auditors can check if a node has deviated from its expected behavior without learning anything about the node's future random choices. In particular, an accountable node does not need to leak secrets that would make its future actions predictable.