Page 111 - 《软件学报》2025年第10期
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4508                                                      软件学报  2025  年第  36  卷第  10  期


                 regarded  as  a  critical  foundation  for  security.  Energy  conservation  and  the  maximization  of  computing  power  support  have  been  identified
                 as  key  research  directions.  Therefore,  a  post-quantum  blockchain  system  featuring  diversified  computing  power  and  autonomous  post-
                 quantum  signature  is  proposed  in  this  study.  The  Dilithium  signature  scheme,  recommended  by  the  National  Institute  of  Standards  and
                 Technology  (NIST)  as  a  preferred  and  general-purpose  post-quantum  signature  standard,  relies  on  the  security  of  MLWE  and  MSIS
                 problems  in  power-of-two  cyclotomic  rings.  However,  similar  to  the  early  adoption  of  the  EC-DSA  standard  in  Bitcoin  without  adherence
                 to  the  NIST-specific  elliptic  curves,  the  rich  algebraic  structure  of  power-of-two  cyclotomic  rings  poses  greater  risks  and  uncertainties
                 regarding  long-term  security.  To  address  this,  a  more  conservative  and  secure  approach,  based  on  post-quantum  lattice-based  cryptography
                 with  fewer  algebraic  structures,  is  constructed.  In  this  study,  a  Dilithium  variant,  Dilithium-Prime,  based  on  a  large-Galois-group  prime-
                 degree  prime-ideal  field,  is  proposed  as  the  signature  algorithm  for  the  post-quantum  blockchain  system  to  ensure  high-confidence
                 transaction  signing  with  post-quantum  security.  To  maximize  the  computing  power  support  for  the  post-quantum  public  blockchain  and
                 address the current issue of declining mining pool and miner income, a multi-parent chain auxiliary proof-of-work consensus mechanism is
                 introduced.  This  mechanism  enables  the  request  of  computing  power  from  all  miners  using  Sha256  and  Scrypt  hash  calculations  to  assist
                 in  consensus  without  increasing  the  workload  for  existing  miners  and  mining  pools.  As  a  result,  the  source  of  computing  power  for  the
                 post-quantum  blockchain  is  expanded,  and  the  utilization  rate  of  existing  mining  pools  and  miners  is  improved.  In  addition,  a  block  and
                 transaction  structure,  along  with  a  difficulty  adjustment  algorithm  tailored  for  this  multi-parent  chain  auxiliary  proof-of-work  consensus
                 mechanism,  is  proposed.  This  system  stabilizes  the  block  production  ratio  and  production  time  across  different  levels  of  computing  power
                 and effectively responds to extreme cases, such as sudden surges or reductions in computing power, ensuring the system’s robustness.
                 Key words:  blockchain; post-quantum cryptography; consensus mechanism; auxiliary proof-of-work

                    区块链技术最早由       Nakamoto  在  2008  年提出  [1] , 以数字签名算法、共识机制等为基础, 具有去中心化、不可
                 篡改等性质, 广泛应用于数字资产管理、跨境支付、数据共享等方面. 其中, 比特币作为目前认可程度最高的公
                 链, 有数量众多的用户和一定的应用场景. 同时, 也出现了采用比特币相同的架构与共识算法的莱特币等公链.
                    以比特币为代表的这类区块链公链应用椭圆曲线数字签名算法, 在交易过程中用户通过私钥签名并提交数据
                 和签名到链上的方式, 有效保证区块链数据的安全性和正确性. 但是, 随着量子计算机的出现, 椭圆曲线数字签名
                 算法等传统密码的安全性不能在量子时代得到保证, 进而对区块链系统的安全性会产生严重影响.
                    此外, 比特币等区块链系统中采用工作量证明               (proof-of-work) 共识机制  [1] , 算法核心思想是计算满足一定难度
                 的哈希值, 计算成功的节点具有出块权. 工作量证明共识机制具有去中心化程度高等优点, 但也有利用率低、消耗
                 能源多等缺点. 随着比特币在         2024  年  4  月的第  4  次减半, 大部分现存的矿池和矿工的收益率大幅下降, 迫切希望在
                 不额外增加算力投入的前提下实现收入的多元化. 在量子计算机出现后, 也需要更多的算力提高区块链的安全性.
                    同时, 在共识中需要通过难度调整算法使得区块平均出块时间尽可能维持在目标值, 以此保证区块链系统的
                 稳定性. 而难度调整算法因为调整周期过长, 难以对全网算力的突然变化及时做出调整, 算力的突增突减都会对系
                 统的稳定性产生影响.
                    针对上述背景和问题, 本文在比特币类的采用工作量证明共识算法和                        UTXO  脚本的公链基础上设计了使用
                 后量子数字签名算法的支持多种算力共识的区块链系统, 主要具有以下                       3  点贡献.
                    (1) 设计并实现了多父链辅助工作量证明共识机制                 (multi-parent chain auxiliary proof-of-work consensus
                 algorithm, Mul-AuxPoW). 该共识机制使其他在工作量证明中采用          Sha256  和  Scrypt 哈希算法的公链作为父链提供
                 算力支持. 优势是复用父链为了共识消耗的能源, 子链本身并不需要额外的算力和能源消耗, 同时也可以解决现存
                 矿池和矿工收益率日益减少的困境, 使得他们在不额外增加算力和能源消耗的前提下实现更多收入.
                    (2) 基于多父链辅助工作量证明共识机制设计了难度调整算法. 算法支持不同算力来源的父链出块数保持在
                 一定比例以激励小算力. 算法通过对于出块边界值的计算, 更加灵活调整难度, 有效应对算力突增突减的情况.
                    (3) 在区块链中应用基于素阶数域的高效数字签名方案: Dilithium-Prime 算法              [2] . 相比于基于  power-of-two  分
                 圆环的   Dilithium  后量子签名标准, 其代数结构更少、置信度更高. 在算法应用中, 对区块链的交易脚本扩容, 适配
                 后量子数字签名算法.
                    本文第   1  节介绍工作量证明共识机制以及后量子签名在区块链系统应用的相关工作. 第                         2  节介绍架构以及相
                 关实现细节. 第    3  节对多父链辅助工作量证明共识机制以及难度调整算法的安全性与正确性进行理论分析以及效
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