The Balance Attack or Why Forkable Blockchains are Ill-Suited for Consortium

摘要: Most blockchain systems are forkable in that they require participants to agree on a chain out of multiple possible branches blocks. In this paper, we identify new form attack, called the Balance against these systems. The novelty attack consists delaying network communications between subgroups nodes with balanced mining power. Our theoretical analysis captures tradeoff delay and power attacker needed double-spend GHOST protocol high probability. We quantify our settings Ethereum testnet R3 consortium where show single machine needs messages for 20 minutes double spend while coalition third would simply need 4 94% success. experiment private before arguing non-forkable design protect attacks.