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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: SHA256 散列</title>
<link rel=stylesheet href="site.css">
</head>
<script>
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<body>
<div class="example" id="sha256-hashes">
<h2><a href="./">Go by Example 中文版</a>: SHA256 散列</h2>
<table>
<tr>
<td class="docs">
<p><a href="https://en.wikipedia.org/wiki/SHA-2"><em>SHA256 散列（hash）</em></a>
经常用于生成二进制文件或者文本块的短标识。
例如，TLS/SSL 证书使用 SHA256 来计算一个证书的签名。
这是 Go 中如何进行 SHA256 散列计算的例子。</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="https://play.studygolang.com/p/C6xVtmaC-23"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Go 在多个 <code>crypto/*</code> 包中实现了一系列散列函数。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kn">import</span> <span class="p">(</span>
<span class="s">"crypto/sha256"</span>
<span class="s">"fmt"</span>
<span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
<span class="nx">s</span> <span class="o">:=</span> <span class="s">"sha256 this string"</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>这里我们从一个新的散列开始。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">h</span> <span class="o">:=</span> <span class="nx">sha256</span><span class="p">.</span><span class="nf">New</span><span class="p">()</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>写入要处理的字节。如果是一个字符串，
需要使用 <code>[]byte(s)</code> 将其强制转换成字节数组。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">h</span><span class="p">.</span><span class="nf">Write</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>Sum</code> 得到最终的散列值的字符切片。<code>Sum</code> 接收一个参数，
可以用来给现有的字符切片追加额外的字节切片：但是一般都不需要这样做。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">bs</span> <span class="o">:=</span> <span class="nx">h</span><span class="p">.</span><span class="nf">Sum</span><span class="p">(</span><span class="kc">nil</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>SHA256 值经常以 16 进制输出，例如在 git commit 中。
我们这里也使用 <code>%x</code> 来将散列结果格式化为 16 进制字符串。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Printf</span><span class="p">(</span><span class="s">"%x\n"</span><span class="p">,</span> <span class="nx">bs</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
<p>运行程序计算散列值，并以可读的 16 进制格式输出。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="gp">$</span> go run sha256-hashes.go
<span class="go">sha256 this string
</span><span class="go">1af1dfa857bf1d8814fe1af8983c18080019922e557f15a8a...</span></pre>
</td>
</tr>
<tr>
<td class="docs">
<p>你可以使用和上面相似的方式来计算其他形式的散列值。
例如，计算 SHA512 散列，
引入 <code>crypto/sha512</code> 并使用 <code>sha512.New()</code> 方法。</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
<p>注意，如果你需要密码学上的安全散列，你需要仔细的研究一下
<a href="https://en.wikipedia.org/wiki/Cryptographic_hash_function">加密散列函数</a>。</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="base64-encoding.html">Base64 编码</a>
</p>
<p class="footer">
<a href="https://twitter.com/mmcgrana">@mmcgrana</a> 和<a href="https://eli.thegreenplace.net">Eli Bendersky</a>编写 | <a href="https://github.com/gobyexample-cn">gobyexample-cn</a> 翻译 | <a href="https://github.com/gobyexample-cn/gobyexample/issues">反馈</a> | <a href="https://github.com/gobyexample-cn/gobyexample">源码</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> </p>
</p>
</div>
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