Research On Blockchain Payment Channel Supporting High-frequency And Cross-currency Transactions

The public blockchains remove the need of trust in central entities by introducing decentralized architectures,thereby reconstructing the existing currency system and trading model,and becoming an important technical support for Internet of Things ecosystem and decentralized finance.However,the problems of low throughput and high transaction fees faced by mainstream public blockchains have become a crucial bottleneck of public blockchains’ further development,making them unable to satisfy high-frequency and low-value transaction requirements.To solve these problems,researchers propose payment channel schemes that improve blockchain throughput through off-chain transactions.However,existing payment channel schemes have drawbacks such as the limitation on the number of participants,the unreliability of cross-channel pathfinding,and the lack of research on cross-blockchain channel switching.To address the above drawbacks,this thesis designs a novel multi-participants supported,high throughput,reliable cross-channel transaction supproted,and crosschain channel switching supported payment channel by introducing cutting-edge software and hardware technologies such as trusted hardware and adaptor signature.This thesis fills the deficiencies and gaps in the field of payment channel,so that the public blockchain can meet the needs of complex high-frequency payment scenarios such as large-scale Internet of Things ecosystem and decentralized finance.The work of this thesis can be divided into three steps:single-chain single-channel scenario,singlechain multi-channel scenario,and multi-chain multi-channel scenario according to its research scope.It gradually evolves from the simple scenario to the complex scenario,and finally constructs a complete payment channel arthitecture which meets the need of public blockchain.The main contributions of this thesis are summarized below.1.In order to solve the problems of payment channels in single-chain singlechannel scenarios such as the limitation on the number of participants,this thesis designs a payment channel framework that can accommodate multiple or even massive participants,which outsources the task of maintaining the payment channel to a set of trustless third-party service nodes running trusted hardware.To ensure the designed payment channel that accommodate massive participants can still provide enough offchain transaction throughput that meets user needs,this thesis designs the improved RAFT consensus algorithm based on the trusted monotonic counter provided by trusted hardware,thereby greatly improving the transaction throughput of the payment channel on the premise of ensuring the security of the channel.Further,this thesis designs a channel security assurance scheme based on trusted hardware and smart contract,so that users can perform efficient payment channel settlements when the service nodes are working normally,and have the right to settle off-chain transactions independently when the service nodes fail.2.In order to solve the problems of payment channels in single-chain multichannel scenarios such as the unreliability of cross-channel pathfinding,this thesis designs an atomic cross-channel transaction scheme based on a two-phase protocol,so that cross-channel transactions can be efficiently synchronized between input and output channels under the premise of high reliability.To solve the problem of excessive cross-channel fund transfer overhead introduced by the designed two-phase protocol,this thesis designs a cross-channel cooperative settlement algorithm based on netting strategy,which greatly reduces the on-chain cost of cross-channel fund transfer.Furthermore,due to the fact that the cross-channel cooperative settlement algorithm cannot be completed when the service nodes of corrosponding channels do not cooperate,this thesis proposes a single-channel independent settlement strategy based on the transaction chain that allows a channel to perform emergency settlement without cooperationg with other channels,and designs corresponding security guarantee schemes to ensure the security of all above schemes.3.In order to solve the problems of payment channels in multi-chain multi-channel scenarios such as the lack of research on cross-blockchain channel switching,this thesis designs a cross-currency payment channel architecture based on channel switching,so that users can complete the transfer of funds across currencies through digital asset exchange.Furthermore,in view of the privacy leakage problem existing in the mainstream digital asset exchange schemes,this thesis designs a privacy-protected channel switching algorithm based on adapter signature to ensure the privacy of the channel switching process.On the basis of the above designs,this thesis provids adapter signature algorithms for mainstream blockchain compatible signatures,so that the channel switching algorithm proposed in this thesis can be applied directly to the majority of existing public blockchains.