The Blockchain Game: Synthesis of Byzantine Systems and Nash Equilibria

--This position paper presents a synthesis viewpoint of blockchains from two orthogonal perspectives: fault-tolerant distributed systems and game theory. Specifically, we formulate a new game-theoretical problem in the context of blockchains and sketch a closed-form Nash equilibrium to the problem. Blockchains have drawn much research interest, way beyond its first realization, Bitcoin [3], a cryptocurrency application built upon blockchains. From system perspectives, various facets, especially performance and scalability, have been intensively studied by multiple computer systems communities including but not limited to: computer security [7], distributed systems [11], and database systems [9]. Works on the theoretical foundation of blockchains are, however, comparatively limited, and mostly in the cryptocurrency context [6], [8], [10], usually in a permissionless setup where nodes are free to join or leave the blockchain network. In permissioned blockchains such as Hyperledger Fabric [2], where Practical Byzantine Fault-Tolerance [4] (PBFT) is the de facto consensus protocol, much work focused on PBFT and its variants without in-depth reasoning on the node's (or, user's) rationality--analyses simply assume that a node is either faulty or non-faulty.