Lazy blockchains decouple consensus from transaction verification and execution to increase throughput. Although they can contain invalid transactions (e.g., double spends) as a result, these can easily be filtered out by full nodes that check if there have been previous conflicting transactions. However, creating light (SPV) clients that do not see the whole transaction history becomes a challenge: A record of a transaction on the chain does not necessarily entail transaction confirmation. In this paper, we devise a protocol that enables the creation of efficient light clients for lazy blockchains. The number of interaction rounds and the communication complexity of our protocol are logarithmic in the blockchain execution time. Our construction is based on a bisection game that traverses the Merkle tree containing the ledger of all - valid or invalid - transactions. We prove that our proof system is succinct, complete and sound, and empirically demonstrate the feasibility of our scheme.

翻译：懒惰区块链将共识机制与交易验证和执行解耦，以提高吞吐量。尽管这可能导致链上包含无效交易（例如双重支付），但全节点可通过检查是否存在冲突的历史交易记录轻松过滤这些交易。然而，设计无法查看完整交易历史的轻量级（SPV）客户端成为一项挑战：链上记录某笔交易并不等同于该交易已被确认。本文提出一种协议，能够为懒惰区块链创建高效的轻量级客户端。该协议的交互轮次数和通信复杂度均随区块链执行时间呈对数增长。我们的构建基于遍历包含所有（有效或无效）交易账本的默克尔树的二分博弈。我们证明该证明系统具备简洁性、完备性和可靠性，并通过实验验证了方案的实际可行性。