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前语：区块链是一种分布式数据库，利用密码学技术进行安全的数据记录和验证。它可以用来创建可信赖的记录，并确保记录不可篡改。

区块链原理实际上是由一个个区块组成的链条。

前言

区块链是一种分布式数据库，使用密码学技术进行安全的数据记录和验证。它可以被用来创建可信赖的记录，并确保记录不可篡改。区块链的原理其实是一个又一个区块组成的链条。每一个区块中保存了一定的信息，它们按照各自产生的时间顺序连接成链条。这个链条被保存在所有的服务器中，只要整个系统中有一台服务器可以工作，整条区块链就是安全的。这些服务器在区块链系统中被称为节点，它们为整个区块链系统提供存储空间和算力支持。如果要修改区块链中的信息，必须征得半数以上节点的同意并修改所有节点中的信息，而这些节点通常掌握在不同的主体手中，因此篡改区块链中的信息是一件极其困难的事。相比于传统的网络，区块链具有两大核心特点：一是数据难以篡改、二是去中心化。基于这两个特点，区块链所记录的信息更加真实可靠，可以帮助解决人们互不信任的问题。

一、区块链的实现

1.定义区块模型

/// <summary> /// 区块数据模型 /// </summary> public struct Block { /// <summary> /// 区块位置 /// </summary> public int Index { get; set; } /// <summary> /// 区块生成时间戳 /// </summary> public string TimeStamp { get; set; } /// <summary> /// 心率数值 /// </summary> public int BPM { get; set; } /// <summary> /// 区块 SHA-256 散列值 /// </summary> public string Hash { get; set; } /// <summary> /// 前一个区块 SHA-256 散列值 /// </summary> public string PrevHash { get; set; } }

2.管理区块链

/// <summary> /// 管理区块链 /// </summary> public static class BlockGenerator { public static List<Block> _blockChain = new List<Block>(); /// <summary> /// 计算区块 HASH 值 /// </summary> /// <param name="block">区块实例</param> /// <returns>计算完成的区块散列值</returns> public static string CalculateHash(Block block) { string calculationStr = $"{block.Index}{block.TimeStamp}{block.BPM}{block.PrevHash}"; SHA256 sha256Generator = SHA256.Create(); byte[] sha256HashBytes = sha256Generator.ComputeHash(Encoding.UTF8.GetBytes(calculationStr)); StringBuilder sha256StrBuilder = new StringBuilder(); foreach (byte @byte in sha256HashBytes) { sha256StrBuilder.Append(@byte.ToString("x2")); } return sha256StrBuilder.ToString(); } /// <summary> /// 生成新的区块 /// </summary> /// <param name="oldBlock">旧的区块数据</param> /// <param name="BPM">心率</param> /// <returns>新的区块</returns> public static Block GenerateBlock(Block oldBlock, int BPM) { Block newBlock = new Block() { Index = oldBlock.Index + 1, TimeStamp = CalculateCurrentTimeUTC(), BPM = BPM, PrevHash = oldBlock.Hash }; newBlock.Hash = CalculateHash(newBlock); return newBlock; } /// <summary> /// 计算当前时间的 UTC 表示格式 /// </summary> /// <returns>UTC 时间字符串</returns> public static string CalculateCurrentTimeUTC() { DateTime startTime = new DateTime(1970, 1, 1, 0, 0, 0, 0); DateTime nowTime = DateTime.Now; long unixTime = (long)Math.Round((nowTime - startTime).TotalMilliseconds, MidpointRounding.AwayFromZero); return unixTime.ToString(); } /// <summary> /// 检验区块是否有效 /// </summary> /// <param name="newBlock">新生成的区块数据</param> /// <param name="oldBlock">旧的区块数据</param> /// <returns>有效返回 TRUE，无效返回 FALSE</returns> public static bool IsBlockValid(Block newBlock, Block oldBlock) { if (oldBlock.Index + 1 != newBlock.Index) return false; if (oldBlock.Hash != newBlock.PrevHash) return false; if (CalculateHash(newBlock) != newBlock.Hash) return false; return true; } /// <summary> /// 如果新的区块链比当前区块链更新，则切换当前区块链为最新区块链 /// </summary> /// <param name="newBlockChain">新的区块链</param> public static void SwitchChain(List<Block> newBlockChain) { if (newBlockChain.Count > _blockChain.Count) { _blockChain = newBlockChain; } } }

3.使用区块链

1、webapi相关代码

[ApiController] [Route("[controller]/[action]")] public class HomeController : ControllerBase { private readonly ILogger<HomeController> _logger; public HomeController(ILogger<HomeController> logger) { _logger = logger; } /// <summary> /// 设置10个区块 /// </summary> /// <param name="bpm"></param> /// <returns></returns> [HttpPost] [Route("/BlockChain")] public string BlockChain(int bpm) { // 增加区块链 if (BlockGenerator._blockChain.Count == 0) { Block firstBlock = new Block() { Index = 0, TimeStamp = BlockGenerator.CalculateCurrentTimeUTC(), BPM = 0, Hash = string.Empty, PrevHash = string.Empty }; BlockGenerator._blockChain.Add(firstBlock); return JsonConvert.SerializeObject(firstBlock); } else { Block oldBlock = BlockGenerator._blockChain.Last(); Block newBlock = BlockGenerator.GenerateBlock(oldBlock, bpm); if (BlockGenerator.IsBlockValid(newBlock, oldBlock)) { List<Block> newBlockChain = new List<Block>(); foreach (var block in BlockGenerator._blockChain) { newBlockChain.Add(block); } newBlockChain.Add(newBlock); BlockGenerator.SwitchChain(newBlockChain); } return JsonConvert.SerializeObject(newBlock); } } //提取区块链 [HttpGet] [Route("/BlockChains")] public string Validate() { return JsonConvert.SerializeObject(BlockGenerator._blockChain); } }

2、运行

[{ "Index": 0, "TimeStamp": "1676908972475", "BPM": 0, "Hash": "", "PrevHash": "" }, { "Index": 1, "TimeStamp": "1676908974139", "BPM": 1, "Hash": "fb3fdd06a2175b8531b44680ebbd846a080ba3262819bff8e78fd8fdb37ae5cb", "PrevHash": "" }, { "Index": 2, "TimeStamp": "1676908975705", "BPM": 2, "Hash": "c15d7d8f13cc0a74922ab7435df72c79751bf642c7636d839b41a047c257f9f5", "PrevHash": "fb3fdd06a2175b8531b44680ebbd846a080ba3262819bff8e78fd8fdb37ae5cb" }, { "Index": 3, "TimeStamp": "1676908980354", "BPM": 3, "Hash": "1a9da938bf89d57b3ee18a62b79b9be41424c2552dd1d0bfa15038be4faae504", "PrevHash": "c15d7d8f13cc0a74922ab7435df72c79751bf642c7636d839b41a047c257f9f5" }, { "Index": 4, "TimeStamp": "1676908981790", "BPM": 4, "Hash": "e37b72244f41ecdef2da0ef5ede0971560eec9a5144d935ac74f2ea9ece44b8e", "PrevHash": "1a9da938bf89d57b3ee18a62b79b9be41424c2552dd1d0bfa15038be4faae504" }, { "Index": 5, "TimeStamp": "1676908983222", "BPM": 5, "Hash": "87a91f780299618510befed23da583af035147f21f51e21866d2d0ad412485ee", "PrevHash": "e37b72244f41ecdef2da0ef5ede0971560eec9a5144d935ac74f2ea9ece44b8e" }, { "Index": 6, "TimeStamp": "1676908984659", "BPM": 6, "Hash": "960d8fb0f6c77a20a1b26a870f5a43489f39b2a22b382f413cb870d446afaecc", "PrevHash": "87a91f780299618510befed23da583af035147f21f51e21866d2d0ad412485ee" }]

可以看到生成7个区块链就像链条一样头尾相连。