区块链demo C#.NET版

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原文链接:https://www.cnblogs.com/myzony/p/8478789.html

文章原文来自:Code your own blockchain in less than 200 lines of Go!，原始文章是通过 Go 语言来实现自己的区块链的，这里我们参照该文章来使用 C# + Asp.Net Core 实现自己的区块链。在这里我也参考了 这篇译文 。

区块链网络相关原始文章已经更新，请查看这里。

1.项目配置

首先新建一个 Asp.Net Core 项目，然后选择 Empty Project(空项目) 类型，建立完成后无需进行任何配置。

2.数据模型

这里我们来创建一个具体的区块数据模型，使用的是 Struct 结构体。

<span class="hljs-keyword">public</span> <span class="hljs-keyword">struct</span> Block
{
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> 区块位置</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> Index { <span class="hljs-keyword">get</span>; <span class="hljs-keyword">set</span>; }
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> 区块生成时间戳</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">string</span> TimeStamp { <span class="hljs-keyword">get</span>; <span class="hljs-keyword">set</span>; }
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> 心率数值</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> BPM { <span class="hljs-keyword">get</span>; <span class="hljs-keyword">set</span>; }
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> 区块 SHA-256 散列值</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">string</span> Hash { <span class="hljs-keyword">get</span>; <span class="hljs-keyword">set</span>; }
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> 前一个区块 SHA-256 散列值</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">string</span> PrevHash { <span class="hljs-keyword">get</span>; <span class="hljs-keyword">set</span>; }
}

这里各个字段的含义已经在注释上方标明了，这里不在过多赘述。
之后我们新建一个 BlockGenerator 静态类用于管理区块链，并且使用一个 List 保存区块链数据。

<span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">class</span> <span class="hljs-title">BlockGenerator</span>
{
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> List&lt;Block&gt; _blockChain = <span class="hljs-keyword">new</span> List&lt;Block&gt;();
}

我们使用散列算法（SHA256）来确定和维护链中块和块正确的顺序，确保每一个块的 PrevHash 值等于前一个块中的 Hash 值，这样就以正确的块顺序构建出链:

4.散列与生成区块

使用散列是因为可以使用极少的控件生成每一个区块的唯一标识，而且可以维持整个区块链的完整性，通过每个区块存储的前一个链的散列值，我们就可以确保区块链当中每一个区块的正确性，任何针对区块的无效更改都会导致散列值的改变，也就破坏了区块链。
那么我们就在 BlockGenerator 当中添加一个函数用于计算 Block 的 Hash 值:

<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> 计算区块 HASH 值</span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="block"&gt;</span>区块实例<span class="hljs-doctag">&lt;/param&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;returns&gt;</span>计算完成的区块散列值<span class="hljs-doctag">&lt;/returns&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">string</span> <span class="hljs-title">CalculateHash</span>(<span class="hljs-params">Block block</span>)
</span>{
    <span class="hljs-keyword">string</span> calculationStr = $<span class="hljs-string">"{block.Index}{block.TimeStamp}{block.BPM}{block.PrevHash}"</span>;

    SHA256 sha256Generator = SHA256.Create();
    <span class="hljs-keyword">byte</span>[] sha256HashBytes = sha256Generator.ComputeHash(Encoding.UTF8.GetBytes(calculationStr));

    StringBuilder sha256StrBuilder = <span class="hljs-keyword">new</span> StringBuilder();
    <span class="hljs-keyword">foreach</span> (<span class="hljs-keyword">byte</span> @<span class="hljs-keyword">byte</span> <span class="hljs-keyword">in</span> sha256HashBytes)
    {
        sha256StrBuilder.Append(@<span class="hljs-keyword">byte</span>.ToString(<span class="hljs-string">"x2"</span>));
    }

    <span class="hljs-keyword">return</span> sha256StrBuilder.ToString();
}

这里的 CalculateHash 函数接收一个 Block 实例，通过该实例当中的 Index、TimeStamp、BPM、PrevHash 的值来计算出当前块的 SHA256 Hash 值，之后我们就可以来编写一个生成块的函数:

<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> 生成新的区块</span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="oldBlock"&gt;</span>旧的区块数据<span class="hljs-doctag">&lt;/param&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="BPM"&gt;</span>心率<span class="hljs-doctag">&lt;/param&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;returns&gt;</span>新的区块<span class="hljs-doctag">&lt;/returns&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> Block <span class="hljs-title">GenerateBlock</span>(<span class="hljs-params">Block oldBlock, <span class="hljs-keyword">int</span> BPM</span>)
</span>{
    Block newBlock = <span class="hljs-keyword">new</span> Block()
    {
        Index = oldBlock.Index + <span class="hljs-number">1</span>,
        TimeStamp = CalculateCurrentTimeUTC(),
        BPM = BPM,
        PrevHash = oldBlock.Hash
    };

    newBlock.Hash = CalculateHash(newBlock);
    <span class="hljs-keyword">return</span> newBlock;
}

这个函数需要接收前一个块对象的值，用于新区块的 Index 递增以及新的 SHA256 Hash 计算。
这里掺入了一个 CalculateCurrentTimeUTC 函数，该函数主要是用于将 DateTime.Now 时间转换为 UTC 时间，如下：

<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> 计算当前时间的 UTC 表示格式</span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;returns&gt;</span>UTC 时间字符串<span class="hljs-doctag">&lt;/returns&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">string</span> <span class="hljs-title">CalculateCurrentTimeUTC</span>()
</span>{
    DateTime startTime = <span class="hljs-keyword">new</span> DateTime(<span class="hljs-number">1970</span>, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>, <span class="hljs-number">0</span>, <span class="hljs-number">0</span>, <span class="hljs-number">0</span>, <span class="hljs-number">0</span>);
    DateTime nowTime = DateTime.Now;

    <span class="hljs-keyword">long</span> unixTime = (<span class="hljs-keyword">long</span>)Math.Round((nowTime - startTime).TotalMilliseconds, MidpointRounding.AwayFromZero);
    <span class="hljs-keyword">return</span> unixTime.ToString();
}

5.校验区块

每一个区块都是不可信的，所以我们需要在生成新的区块的时候对其进行校验，校验规则如下：

校验新区块与旧区块的 Index 是否正确递增
校验新区块的 Hash 值是否正确
校验新区块的 PrevHash 值是否与旧区块的 Hash 值匹配

有了上述几种条件，我们可以编写一个校验函数如下：

<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> 检验区块是否有效</span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="newBlock"&gt;</span>新生成的区块数据<span class="hljs-doctag">&lt;/param&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="oldBlock"&gt;</span>旧的区块数据<span class="hljs-doctag">&lt;/param&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;returns&gt;</span>有效返回 TRUE，无效返回 FALSE<span class="hljs-doctag">&lt;/returns&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">bool</span> <span class="hljs-title">IsBlockValid</span>(<span class="hljs-params">Block newBlock, Block oldBlock</span>)
</span>{
    <span class="hljs-keyword">if</span> (oldBlock.Index + <span class="hljs-number">1</span> != newBlock.Index) <span class="hljs-keyword">return</span> <span class="hljs-keyword">false</span>;
    <span class="hljs-keyword">if</span> (oldBlock.Hash != newBlock.PrevHash) <span class="hljs-keyword">return</span> <span class="hljs-keyword">false</span>;
    <span class="hljs-keyword">if</span> (CalculateHash(newBlock) != newBlock.Hash) <span class="hljs-keyword">return</span> <span class="hljs-keyword">false</span>;

    <span class="hljs-keyword">return</span> <span class="hljs-keyword">true</span>;
}

除开区块校验的问题之外，如果有两个节点被分别添加到各自的区块链上，我们应该始终以最长的那一条为主线，因为最长的那一条意味着他的区块数据始终是最新的。

So，我们还需要一个更新最新区块的函数:

<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> 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</span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
<span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="newBlockChain"&gt;</span>新的区块链<span class="hljs-doctag">&lt;/param&gt;</span></span>
<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">SwitchChain</span>(<span class="hljs-params">List&lt;Block&gt; newBlockChain</span>)
</span>{
    <span class="hljs-keyword">if</span> (newBlockChain.Count &gt; _blockChain.Count)
    {
        _blockChain = newBlockChain;
    }
}

6.集成到 Web 当中

现在整个区块链的基本操作已经完成，现在我们需要让他运转起来，我们来到 StartUp 当中，添加两个新的路由：

app.Map(<span class="hljs-string">"/BlockChain"</span>, _ =&gt;
{
    _.Run(<span class="hljs-keyword">async</span> context =&gt;
    {
        <span class="hljs-keyword">if</span> (context.Request.Method == <span class="hljs-string">"POST"</span>)
        {
            <span class="hljs-comment">// 增加区块链</span>
            <span class="hljs-keyword">if</span> (BlockGenerator._blockChain.Count == <span class="hljs-number">0</span>)
            {
                Block firstBlock = <span class="hljs-keyword">new</span> Block()
                {
                    Index = <span class="hljs-number">0</span>,
                    TimeStamp = BlockGenerator.CalculateCurrentTimeUTC(),
                    BPM = <span class="hljs-number">0</span>,
                    Hash = <span class="hljs-keyword">string</span>.Empty,
                    PrevHash = <span class="hljs-keyword">string</span>.Empty
                };

                BlockGenerator._blockChain.Add(firstBlock);

                <span class="hljs-keyword">await</span> context.Response.WriteAsync(JsonConvert.SerializeObject(firstBlock));
            }
            <span class="hljs-keyword">else</span>
            {
                <span class="hljs-keyword">int</span>.TryParse(context.Request.Form[<span class="hljs-string">"BPM"</span>][<span class="hljs-number">0</span>], <span class="hljs-keyword">out</span> <span class="hljs-keyword">int</span> bpm);

                Block oldBlock = BlockGenerator._blockChain.Last();
                Block newBlock = BlockGenerator.GenerateBlock(oldBlock, bpm);

                <span class="hljs-keyword">if</span> (BlockGenerator.IsBlockValid(newBlock, oldBlock))
                {
                    List&lt;Block&gt; newBlockChain = <span class="hljs-keyword">new</span> List&lt;Block&gt;();
                    <span class="hljs-keyword">foreach</span> (<span class="hljs-keyword">var</span> block <span class="hljs-keyword">in</span> BlockGenerator._blockChain)
                    {
                        newBlockChain.Add(block);
                    }

                    newBlockChain.Add(newBlock);
                    BlockGenerator.SwitchChain(newBlockChain);
                }

                <span class="hljs-keyword">await</span> context.Response.WriteAsync(JsonConvert.SerializeObject(newBlock));
            }
        }
    });
});

app.Map(<span class="hljs-string">"/BlockChains"</span>, _ =&gt;
{
    _.Run(<span class="hljs-keyword">async</span> context =&gt;
    {
        <span class="hljs-keyword">await</span> context.Response.WriteAsync(JsonConvert.SerializeObject(BlockGenerator._blockChain));
    });
});

7.最终效果

我们先通过 PostMan 来构建一个创世块：

然后我们尝试多添加几个之后，访问 BlockChain 来查看已经存在的区块链结构：

8.结语

通过以上代码我们完成了一个简陋的区块链，虽然十分简陋，但是已经具备了块生成，散列计算，块校验这些基本能力，你可以参考 GitHub 上面各种成熟的区块链实现来完成工作量证明、权益证明这样的共识算法，或者是智能合约、Dapp、侧链等等。

链接

近期文章

热门标签

新人福利，免费薅羊毛

区块链网络相关原始文章已经更新，请查看这里。

1.项目配置

2.数据模型

4.散列与生成区块

5.校验区块

6.集成到 Web 当中

7.最终效果

8.结语

============ 欢迎各位老板打赏~ ===========

与本文相关的文章

发表评论

链接

近期文章

热门标签

新人福利，免费薅羊毛

区块链网络相关原始文章已经更新，请查看 这里。

1.项目配置

2.数据模型

4.散列与生成区块

5.校验区块

6.集成到 Web 当中

7.最终效果

8.结语

============ 欢迎各位老板打赏~ ===========

与本文相关的文章

发表评论

区块链网络相关原始文章已经更新，请查看这里。