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blog-public/posts/f8ce.html -rw-r--r-- 114.2 KiB
88eebf3d — Cytrogen Deploy 2026-02-19 08:34:27 3 days ago 
                                                                                
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class="container" id="main-content" tabindex="-1"><div class="post"><article class="post-block h-entry"><div class="post-meta p-author h-card visually-hidden"><img class="author-avatar u-photo" src="../favicon.png" alt="Cytrogen"><span class="p-name">Cytrogen</span><a class="u-url" href="https://cytrogen.icu">https://cytrogen.icu</a></div><a class="post-permalink u-url u-uid visually-hidden" href="https://cytrogen.icu/posts/f8ce.html">永久链接</a><div class="p-summary visually-hidden"><p>该文章记录了我如何逆向网易云<s>并制作一个简易的播放器（鸽了）</s>。</p></div><div class="visually-hidden"><a class="p-category" href="../categories/%E7%BC%96%E7%A8%8B%E7%AC%94%E8%AE%B0/">编程笔记</a><a class="p-category" href="../tags/Python/">Python</a><a class="p-category" href="../tags/JavaScript/">JavaScript</a><a class="p-category" href="../tags/%E7%BD%91%E9%A1%B5%E9%80%86%E5%90%91/">网页逆向</a></div><h1 class="post-title p-name">JS 逆向网易云音乐</h1><div class="post-info"><time class="post-date dt-published" datetime="2023-11-27T21:00:57.000Z">11/27/2023</time><time class="dt-updated visually-hidden" datetime="2026-02-09T17:16:54.729Z"></time></div><div class="post-content e-content"><html><head></head><body><p>该文章记录了我如何逆向网易云 <s>并制作一个简易的播放器（鸽了）</s>。</p>
<span id="more"></span>
<h1 id="逆向网易云"><a class="markdownIt-Anchor" href="#逆向网易云"></a> 逆向网易云</h1>
<p>用浏览器打开网易云的网站，随意挑选一首歌曲进行播放，同时检查网络选项卡中的响应。我们能看到媒体类型中有一个 <code>.m4a</code> 文件。直接用 Python 的 requests 爬取下来进行播放，够厚道，爬下来就能听。</p>
<p><img src="/posts/f8ce/1.png" alt=""><br>
<img src="/posts/f8ce/2.png" alt=""></p>
<p>当然在页面源代码里找这个 <code>.m4a</code> 文件是找不到的，不然也不会说要 <strong>逆向</strong> 网易云了。我们该如何找到这个 <code>.m4a</code> 文件的 URL 呢？继续看看网络选项卡里的请求：</p>
<p><img src="/posts/f8ce/3.png" alt=""></p>
<p>赫然出现这么一个请求，返回的 JSON 数据中有 <code>.m4a</code> 的链接。嗯，就是你了！看看负载：</p>
<p><img src="/posts/f8ce/4.png" alt=""></p>
<p><code>csrf_token</code> 为空，重点是表单数据的 <code>params</code> 和 <code>encSecKey</code>。其中的内容都是一大串反正不是明文的东西，那么逆向的目标就是找到这两个参数的生成方式。</p>
<p>原本想要直接在源代码里一个个找过去这两个参数，后来突然想到客户端反正都会朝 <code>https://music.163.com/weapi/song/enhance/player/url/v1?csrf_token=</code> 发送请求，那么直接在 XHR / 提取断点里选择所有包含着 <code>v1?csrf_token=</code> 的 URL 不就行了。</p>
<p>关注 <code>arguments</code> 的构造此时成为了我们的目标。</p>
<p><img src="/posts/f8ce/5.png" alt=""></p>
<p>用调用堆栈陆续向上查看，发现 <code>params</code> 和 <code>encSecKey</code> 依旧是加密过后的。哎，加把劲吧，继续向上查看。</p>
<p><img src="/posts/f8ce/6.png" alt=""></p>
<p>一直到这一步…… 观察其前面的代码能发现一个非常有意思的事情：</p>
<p><img src="/posts/f8ce/7.png" alt=""></p>
<ol>
<li>变量 <code>bKC1x</code> 被赋值</li>
<li><code>e1x.data</code> 被赋值时，<code>bKC1x</code> 被用到了，参数中还赫然写着 <code>params</code> 和 <code>encSecKey</code></li>
<li>根据我们之前查看的调用堆栈，<code>chF5K(X2x, e1x)</code> 的第二个参数必定是 <code>params</code> 和 <code>encSecKey</code> 的组合</li>
</ol>
<p>这说明什么？说明 <code>bKC1x</code> 就是生成 <code>params</code> 和 <code>encSecKey</code> 的关键！我们仔细分析一下它的构造：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">var</span> bKC1x = <span class="variable language_">window</span>.<span class="title function_">asrsea</span>(<span class="title class_">JSON</span>.<span class="title function_">stringify</span>(i1x), <span class="title function_">bvh3x</span>([<span class="string">"流泪"</span>, <span class="string">"强"</span>]), <span class="title function_">bvh3x</span>(<span class="title class_">Rf5</span>k.<span class="property">md</span>), <span class="title function_">bvh3x</span>([<span class="string">"爱心"</span>, <span class="string">"女孩"</span>, <span class="string">"惊恐"</span>, <span class="string">"大笑"</span>]));</span><br></pre></td></tr></tbody></table></figure>
<p>其中第三个参数所使用的 <code>Rf5k.md</code> 的内容如下：</p>
<p><img src="/posts/f8ce/10.png" alt=""></p>
<blockquote>
<p>很想吐槽…… 这些字符串的意义是什么？？？</p>
</blockquote>
<p><code>bKC1x</code> 本身会生成一个字典，其中包含 <code>encText</code> 和 <code>encSecKey</code> 两个键。而屡次出现的 <code>bvh3x()</code> 函数的构造如下：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">var</span> bvh3x = <span class="keyword">function</span>(<span class="params">chL5Q</span>) {</span><br><span class="line">    <span class="keyword">var</span> m1x = [];</span><br><span class="line">    j1x.<span class="title function_">bg2x</span>(chL5Q, <span class="keyword">function</span>(<span class="params">chK5P</span>) {</span><br><span class="line">        m1x.<span class="title function_">push</span>(<span class="title class_">Rf5</span>k.<span class="property">emj</span>[chK5P])</span><br><span class="line">    });</span><br><span class="line">    <span class="keyword">return</span> m1x.<span class="title function_">join</span>(<span class="string">""</span>)</span><br><span class="line">};</span><br></pre></td></tr></tbody></table></figure>
<p><img src="/posts/f8ce/8.png" alt=""></p>
<p>它的运作差不多是这样子的。</p>
<p><code>Rf5k.emj</code> 是一个字典，构造非常激寒：</p>
<p><img src="/posts/f8ce/9.png" alt=""></p>
<blockquote>
<p>…… 谁来告诉我这些键到底都是什么意思？？？</p>
</blockquote>
<p>也就是说 <code>bvh3x()</code> 函数接收参数，按照每个元素的字符串、对比 <code>Rf5k.emj</code> 字典中的键来返回对应的值，最后拼接成一个列表。</p>
<p>知道了 <code>bKC1x</code> 中后三个参数的生成方式，我们便只需要知道第一个参数 —— <code>JSON.stringify(i1x)</code> —— 是什么来头的了：</p>
<p><img src="/posts/f8ce/11.png" alt=""></p>
<p>手到擒来，这个 id 不就是歌曲 id 么？！</p>
<p>参数已经全部知晓，最后要看网易云如何加密它们。<code>window.asrsea()</code> 函数作为加密这些参数的老大哥，它的构造如下：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">function</span> <span class="title function_">d</span>(<span class="params">d, e, f, g</span>) {</span><br><span class="line">    <span class="keyword">var</span> h = {}</span><br><span class="line">        , i = <span class="title function_">a</span>(<span class="number">16</span>);</span><br><span class="line">    <span class="keyword">return</span> h.<span class="property">encText</span> = <span class="title function_">b</span>(d, g),</span><br><span class="line">    h.<span class="property">encText</span> = <span class="title function_">b</span>(h.<span class="property">encText</span>, i),</span><br><span class="line">    h.<span class="property">encSecKey</span> = <span class="title function_">c</span>(i, e, f),</span><br><span class="line">    h</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>
<p><code>d()</code> 函数需要好好说道说道。接收的四个参数我们已述说过，这里不废话了。<code>d()</code> 先创建了一个空字典 <code>h</code>，接着创建了一个 <code>i</code>。要知道 <code>i</code> 的值，我们需要知道 <code>a()</code> 的内容：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">function</span> <span class="title function_">a</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> d, e, b = <span class="string">"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"</span>, c = <span class="string">""</span>;</span><br><span class="line">    <span class="keyword">for</span> (d = <span class="number">0</span>; a &gt; d; d += <span class="number">1</span>)</span><br><span class="line">        e = <span class="title class_">Math</span>.<span class="title function_">random</span>() * b.<span class="property">length</span>,</span><br><span class="line">        e = <span class="title class_">Math</span>.<span class="title function_">floor</span>(e),</span><br><span class="line">        c += b.<span class="title function_">charAt</span>(e);</span><br><span class="line">    <span class="keyword">return</span> c</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>
<ul>
<li>变量 <code>d</code>、<code>e</code>、<code>b</code> 都是字符串</li>
<li><code>for</code> 循环中 <code>d</code> 变成整数 0，每次循环加 1，直到 <code>a</code> 的值，也就是上面 <code>d()</code> 函数中传入的整数 16</li>
<li><code>e</code> 在每次循环都是一个随机数，有着 <code>b</code> 的长度，并且会被 <code>Math.floor()</code> 函数取整</li>
<li><code>c</code> 是一个空字符串，每次循环都会被 <code>b</code> 的第 <code>e</code> 个字符所填充</li>
</ul>
<p>用人话来说便是：<code>a()</code> 函数会 <strong>生成一个长度为 16 的随机字符串</strong>。</p>
<p>回到 <code>d()</code> 函数，<code>h.encText</code> 的值是 <code>b(d, g)</code>，而 <code>b()</code> 函数的构造如下：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">function</span> <span class="title function_">b</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> c = <span class="title class_">CryptoJS</span>.<span class="property">enc</span>.<span class="property">Utf8</span>.<span class="title function_">parse</span>(b)</span><br><span class="line">        , d = <span class="title class_">CryptoJS</span>.<span class="property">enc</span>.<span class="property">Utf8</span>.<span class="title function_">parse</span>(<span class="string">"0102030405060708"</span>)</span><br><span class="line">        , e = <span class="title class_">CryptoJS</span>.<span class="property">enc</span>.<span class="property">Utf8</span>.<span class="title function_">parse</span>(a)</span><br><span class="line">        , f = <span class="title class_">CryptoJS</span>.<span class="property">AES</span>.<span class="title function_">encrypt</span>(e, c, {</span><br><span class="line">        <span class="attr">iv</span>: d,</span><br><span class="line">        <span class="attr">mode</span>: <span class="title class_">CryptoJS</span>.<span class="property">mode</span>.<span class="property">CBC</span></span><br><span class="line">    });</span><br><span class="line">    <span class="keyword">return</span> f.<span class="title function_">toString</span>()</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>
<blockquote>
<p><code>CryptoJS</code> 是一个 JavaScript 的加密算法库，这里不做过多介绍，后面会讲到如何引用。</p>
</blockquote>
<p>该函数先是声明了变量 <code>c</code>、<code>d</code> 和 <code>e</code> 这三个由不同的值被 UTF-8 编码后的字符串。接着声明了变量 <code>f</code> —— 一个由 AES.CBC 模式加密的 <code>e</code> —— 其密钥为 <code>c</code>、偏移量为 <code>d</code>。返回的 <code>f</code> 的字符串形式最终变成了我们的 <code>encText</code>。</p>
<p>值得注意的是，在 <code>d()</code> 函数里，<code>h.encText</code><strong>又</strong> 被塞进 <code>b()</code> 函数里加密了一次。</p>
<p>而 <code>h.encSecKey</code> 由 <code>c()</code> 函数生成，它的构造如下：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">function</span> <span class="title function_">c</span>(<span class="params">a, b, c</span>) {</span><br><span class="line">    <span class="keyword">var</span> d, e;</span><br><span class="line">    <span class="keyword">return</span> <span class="title function_">setMaxDigits</span>(<span class="number">131</span>),</span><br><span class="line">    d = <span class="keyword">new</span> <span class="title class_">RSAKeyPair</span>(b,<span class="string">""</span>,c),</span><br><span class="line">    e = <span class="title function_">encryptedString</span>(d, a)</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>
<p>在 <code>c()</code> 函数里，先是调用了 <code>setMaxDigits()</code> 函数；这个函数接收一个需要加密的字符串 <code>a</code>，一个公钥 <code>b</code>，以及生成 RSA 密钥对所需的另一个参数 <code>c</code>。它先是使用 <code>setMaxDigits()</code> 函数设置了 <code>BigInt</code> 可操作的最大位数为 131。然后使用提供的公钥 <code>b</code> 和参数 <code>c</code> 生成 RSA 密钥对 <code>d</code>。最后，它使用生成的密钥对加密了字符串 <code>a</code>。</p>
<p>问题又双叒叕来了，什么是 <code>setMaxDigits()</code>？什么是 <code>BigInt</code>？莫急，再再再来看一眼网易云的源代码：</p>
<p><img src="/posts/f8ce/12.png" alt=""></p>
<p><code>setMaxDigits()</code> 和以上提到的函数们有一个天大的区别：它是全局函数，无论在哪里都能被调用。而这种全局函数的定义在网易云的源代码中只有一处：第 89 行。我们可以直接把这第 89 行的内容全部复制粘贴下来使用。</p>
<details>
<summary>展开</summary>
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class="line">362</span><br><span class="line">363</span><br><span class="line">364</span><br><span class="line">365</span><br><span class="line">366</span><br><span class="line">367</span><br><span class="line">368</span><br><span class="line">369</span><br><span class="line">370</span><br><span class="line">371</span><br><span class="line">372</span><br><span class="line">373</span><br><span class="line">374</span><br><span class="line">375</span><br><span class="line">376</span><br><span class="line">377</span><br><span class="line">378</span><br><span class="line">379</span><br><span class="line">380</span><br><span class="line">381</span><br><span class="line">382</span><br><span class="line">383</span><br><span class="line">384</span><br><span class="line">385</span><br><span class="line">386</span><br><span class="line">387</span><br><span class="line">388</span><br><span class="line">389</span><br><span class="line">390</span><br><span class="line">391</span><br><span class="line">392</span><br><span class="line">393</span><br><span class="line">394</span><br><span class="line">395</span><br><span class="line">396</span><br><span class="line">397</span><br><span class="line">398</span><br><span class="line">399</span><br><span class="line">400</span><br><span class="line">401</span><br><span class="line">402</span><br><span class="line">403</span><br><span class="line">404</span><br><span class="line">405</span><br><span class="line">406</span><br><span class="line">407</span><br><span class="line">408</span><br><span class="line">409</span><br><span class="line">410</span><br><span class="line">411</span><br><span class="line">412</span><br><span class="line">413</span><br><span class="line">414</span><br><span class="line">415</span><br><span class="line">416</span><br><span class="line">417</span><br><span class="line">418</span><br><span class="line">419</span><br><span class="line">420</span><br><span class="line">421</span><br><span class="line">422</span><br><span class="line">423</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">function</span> <span class="title function_">RSAKeyPair</span>(<span class="params">a, b, c</span>) {</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">e</span> = <span class="title function_">biFromHex</span>(a),</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">d</span> = <span class="title function_">biFromHex</span>(b),</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">m</span> = <span class="title function_">biFromHex</span>(c),</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">chunkSize</span> = <span class="number">2</span> * <span class="title function_">biHighIndex</span>(<span class="variable language_">this</span>.<span class="property">m</span>),</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">radix</span> = <span class="number">16</span>,</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">barrett</span> = <span class="keyword">new</span> <span class="title class_">BarrettMu</span>(<span class="variable language_">this</span>.<span class="property">m</span>)</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">twoDigit</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">return</span> (<span class="number">10</span> &gt; a ? <span class="string">"0"</span> : <span class="string">""</span>) + <span class="title class_">String</span>(a)</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">encryptedString</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">for</span> (<span class="keyword">var</span> f, g, h, i, j, k, l, c = <span class="keyword">new</span> <span class="title class_">Array</span>, d = b.<span class="property">length</span>, e = <span class="number">0</span>; d &gt; e; )</span><br><span class="line">        c[e] = b.<span class="title function_">charCodeAt</span>(e),</span><br><span class="line">        e++;</span><br><span class="line">    <span class="keyword">for</span> (; <span class="number">0</span> != c.<span class="property">length</span> % a.<span class="property">chunkSize</span>; )</span><br><span class="line">        c[e++] = <span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span> (f = c.<span class="property">length</span>,</span><br><span class="line">    g = <span class="string">""</span>,</span><br><span class="line">    e = <span class="number">0</span>; f &gt; e; e += a.<span class="property">chunkSize</span>) {</span><br><span class="line">        <span class="keyword">for</span> (j = <span class="keyword">new</span> <span class="title class_">BigInt</span>,</span><br><span class="line">        h = <span class="number">0</span>,</span><br><span class="line">        i = e; i &lt; e + a.<span class="property">chunkSize</span>; ++h)</span><br><span class="line">            j.<span class="property">digits</span>[h] = c[i++],</span><br><span class="line">            j.<span class="property">digits</span>[h] += c[i++] &lt;&lt; <span class="number">8</span>;</span><br><span class="line">        k = a.<span class="property">barrett</span>.<span class="title function_">powMod</span>(j, a.<span class="property">e</span>),</span><br><span class="line">        l = <span class="number">16</span> == a.<span class="property">radix</span> ? <span class="title function_">biToHex</span>(k) : <span class="title function_">biToString</span>(k, a.<span class="property">radix</span>),</span><br><span class="line">        g += l + <span class="string">" "</span></span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> g.<span class="title function_">substring</span>(<span class="number">0</span>, g.<span class="property">length</span> - <span class="number">1</span>)</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">decryptedString</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> e, f, g, h, c = b.<span class="title function_">split</span>(<span class="string">" "</span>), d = <span class="string">""</span>;</span><br><span class="line">    <span class="keyword">for</span> (e = <span class="number">0</span>; e &lt; c.<span class="property">length</span>; ++e)</span><br><span class="line">        <span class="keyword">for</span> (h = <span class="number">16</span> == a.<span class="property">radix</span> ? <span class="title function_">biFromHex</span>(c[e]) : <span class="title function_">biFromString</span>(c[e], a.<span class="property">radix</span>),</span><br><span class="line">        g = a.<span class="property">barrett</span>.<span class="title function_">powMod</span>(h, a.<span class="property">d</span>),</span><br><span class="line">        f = <span class="number">0</span>; f &lt;= <span class="title function_">biHighIndex</span>(g); ++f)</span><br><span class="line">            d += <span class="title class_">String</span>.<span class="title function_">fromCharCode</span>(<span class="number">255</span> &amp; g.<span class="property">digits</span>[f], g.<span class="property">digits</span>[f] &gt;&gt; <span class="number">8</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span> == d.<span class="title function_">charCodeAt</span>(d.<span class="property">length</span> - <span class="number">1</span>) &amp;&amp; (d = d.<span class="title function_">substring</span>(<span class="number">0</span>, d.<span class="property">length</span> - <span class="number">1</span>)),</span><br><span class="line">    d</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">setMaxDigits</span>(<span class="params">a</span>) {</span><br><span class="line">    maxDigits = a,</span><br><span class="line">    <span class="variable constant_">ZERO_ARRAY</span> = <span class="keyword">new</span> <span class="title class_">Array</span>(maxDigits);</span><br><span class="line">    <span class="keyword">for</span> (<span class="keyword">var</span> b = <span class="number">0</span>; b &lt; <span class="variable constant_">ZERO_ARRAY</span>.<span class="property">length</span>; b++)</span><br><span class="line">        <span class="variable constant_">ZERO_ARRAY</span>[b] = <span class="number">0</span>;</span><br><span class="line">    bigZero = <span class="keyword">new</span> <span class="title class_">BigInt</span>,</span><br><span class="line">    bigOne = <span class="keyword">new</span> <span class="title class_">BigInt</span>,</span><br><span class="line">    bigOne.<span class="property">digits</span>[<span class="number">0</span>] = <span class="number">1</span></span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">BigInt</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">digits</span> = <span class="string">"boolean"</span> == <span class="keyword">typeof</span> a &amp;&amp; <span class="number">1</span> == a ? <span class="literal">null</span> : <span class="variable constant_">ZERO_ARRAY</span>.<span class="title function_">slice</span>(<span class="number">0</span>),</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">isNeg</span> = !<span class="number">1</span></span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biFromDecimal</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">for</span> (<span class="keyword">var</span> d, e, f, b = <span class="string">"-"</span> == a.<span class="title function_">charAt</span>(<span class="number">0</span>), c = b ? <span class="number">1</span> : <span class="number">0</span>; c &lt; a.<span class="property">length</span> &amp;&amp; <span class="string">"0"</span> == a.<span class="title function_">charAt</span>(c); )</span><br><span class="line">        ++c;</span><br><span class="line">    <span class="keyword">if</span> (c == a.<span class="property">length</span>)</span><br><span class="line">        d = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">else</span> {</span><br><span class="line">        <span class="keyword">for</span> (e = a.<span class="property">length</span> - c,</span><br><span class="line">        f = e % dpl10,</span><br><span class="line">        <span class="number">0</span> == f &amp;&amp; (f = dpl10),</span><br><span class="line">        d = <span class="title function_">biFromNumber</span>(<span class="title class_">Number</span>(a.<span class="title function_">substr</span>(c, f))),</span><br><span class="line">        c += f; c &lt; a.<span class="property">length</span>; )</span><br><span class="line">            d = <span class="title function_">biAdd</span>(<span class="title function_">biMultiply</span>(d, lr10), <span class="title function_">biFromNumber</span>(<span class="title class_">Number</span>(a.<span class="title function_">substr</span>(c, dpl10)))),</span><br><span class="line">            c += dpl10;</span><br><span class="line">        d.<span class="property">isNeg</span> = b</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> d</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biCopy</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> b = <span class="keyword">new</span> <span class="title class_">BigInt</span>(!<span class="number">0</span>);</span><br><span class="line">    <span class="keyword">return</span> b.<span class="property">digits</span> = a.<span class="property">digits</span>.<span class="title function_">slice</span>(<span class="number">0</span>),</span><br><span class="line">    b.<span class="property">isNeg</span> = a.<span class="property">isNeg</span>,</span><br><span class="line">    b</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biFromNumber</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> c, b = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">for</span> (b.<span class="property">isNeg</span> = <span class="number">0</span> &gt; a,</span><br><span class="line">    a = <span class="title class_">Math</span>.<span class="title function_">abs</span>(a),</span><br><span class="line">    c = <span class="number">0</span>; a &gt; <span class="number">0</span>; )</span><br><span class="line">        b.<span class="property">digits</span>[c++] = a &amp; maxDigitVal,</span><br><span class="line">        a &gt;&gt;= biRadixBits;</span><br><span class="line">    <span class="keyword">return</span> b</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">reverseStr</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> c, b = <span class="string">""</span>;</span><br><span class="line">    <span class="keyword">for</span> (c = a.<span class="property">length</span> - <span class="number">1</span>; c &gt; -<span class="number">1</span>; --c)</span><br><span class="line">        b += a.<span class="title function_">charAt</span>(c);</span><br><span class="line">    <span class="keyword">return</span> b</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biToString</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> d, e, c = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">for</span> (c.<span class="property">digits</span>[<span class="number">0</span>] = b,</span><br><span class="line">    d = <span class="title function_">biDivideModulo</span>(a, c),</span><br><span class="line">    e = hexatrigesimalToChar[d[<span class="number">1</span>].<span class="property">digits</span>[<span class="number">0</span>]]; <span class="number">1</span> == <span class="title function_">biCompare</span>(d[<span class="number">0</span>], bigZero); )</span><br><span class="line">        d = <span class="title function_">biDivideModulo</span>(d[<span class="number">0</span>], c),</span><br><span class="line">        digit = d[<span class="number">1</span>].<span class="property">digits</span>[<span class="number">0</span>],</span><br><span class="line">        e += hexatrigesimalToChar[d[<span class="number">1</span>].<span class="property">digits</span>[<span class="number">0</span>]];</span><br><span class="line">    <span class="keyword">return</span> (a.<span class="property">isNeg</span> ? <span class="string">"-"</span> : <span class="string">""</span>) + <span class="title function_">reverseStr</span>(e)</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biToDecimal</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> c, d, b = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">for</span> (b.<span class="property">digits</span>[<span class="number">0</span>] = <span class="number">10</span>,</span><br><span class="line">    c = <span class="title function_">biDivideModulo</span>(a, b),</span><br><span class="line">    d = <span class="title class_">String</span>(c[<span class="number">1</span>].<span class="property">digits</span>[<span class="number">0</span>]); <span class="number">1</span> == <span class="title function_">biCompare</span>(c[<span class="number">0</span>], bigZero); )</span><br><span class="line">        c = <span class="title function_">biDivideModulo</span>(c[<span class="number">0</span>], b),</span><br><span class="line">        d += <span class="title class_">String</span>(c[<span class="number">1</span>].<span class="property">digits</span>[<span class="number">0</span>]);</span><br><span class="line">    <span class="keyword">return</span> (a.<span class="property">isNeg</span> ? <span class="string">"-"</span> : <span class="string">""</span>) + <span class="title function_">reverseStr</span>(d)</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">digitToHex</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> b = <span class="number">15</span></span><br><span class="line">      , c = <span class="string">""</span>;</span><br><span class="line">    <span class="keyword">for</span> (i = <span class="number">0</span>; <span class="number">4</span> &gt; i; ++i)</span><br><span class="line">        c += hexToChar[a &amp; b],</span><br><span class="line">        a &gt;&gt;&gt;= <span class="number">4</span>;</span><br><span class="line">    <span class="keyword">return</span> <span class="title function_">reverseStr</span>(c)</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biToHex</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> d, b = <span class="string">""</span>;</span><br><span class="line">    <span class="keyword">for</span> (<span class="title function_">biHighIndex</span>(a),</span><br><span class="line">    d = <span class="title function_">biHighIndex</span>(a); d &gt; -<span class="number">1</span>; --d)</span><br><span class="line">        b += <span class="title function_">digitToHex</span>(a.<span class="property">digits</span>[d]);</span><br><span class="line">    <span class="keyword">return</span> b</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">charToHex</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> h, b = <span class="number">48</span>, c = b + <span class="number">9</span>, d = <span class="number">97</span>, e = d + <span class="number">25</span>, f = <span class="number">65</span>, g = <span class="number">90</span>;</span><br><span class="line">    <span class="keyword">return</span> h = a &gt;= b &amp;&amp; c &gt;= a ? a - b : a &gt;= f &amp;&amp; g &gt;= a ? <span class="number">10</span> + a - f : a &gt;= d &amp;&amp; e &gt;= a ? <span class="number">10</span> + a - d : <span class="number">0</span></span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">hexToDigit</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> d, b = <span class="number">0</span>, c = <span class="title class_">Math</span>.<span class="title function_">min</span>(a.<span class="property">length</span>, <span class="number">4</span>);</span><br><span class="line">    <span class="keyword">for</span> (d = <span class="number">0</span>; c &gt; d; ++d)</span><br><span class="line">        b &lt;&lt;= <span class="number">4</span>,</span><br><span class="line">        b |= <span class="title function_">charToHex</span>(a.<span class="title function_">charCodeAt</span>(d));</span><br><span class="line">    <span class="keyword">return</span> b</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biFromHex</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> d, e, b = <span class="keyword">new</span> <span class="title class_">BigInt</span>, c = a.<span class="property">length</span>;</span><br><span class="line">    <span class="keyword">for</span> (d = c,</span><br><span class="line">    e = <span class="number">0</span>; d &gt; <span class="number">0</span>; d -= <span class="number">4</span>,</span><br><span class="line">    ++e)</span><br><span class="line">        b.<span class="property">digits</span>[e] = <span class="title function_">hexToDigit</span>(a.<span class="title function_">substr</span>(<span class="title class_">Math</span>.<span class="title function_">max</span>(d - <span class="number">4</span>, <span class="number">0</span>), <span class="title class_">Math</span>.<span class="title function_">min</span>(d, <span class="number">4</span>)));</span><br><span class="line">    <span class="keyword">return</span> b</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biFromString</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> g, h, i, j, c = <span class="string">"-"</span> == a.<span class="title function_">charAt</span>(<span class="number">0</span>), d = c ? <span class="number">1</span> : <span class="number">0</span>, e = <span class="keyword">new</span> <span class="title class_">BigInt</span>, f = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">for</span> (f.<span class="property">digits</span>[<span class="number">0</span>] = <span class="number">1</span>,</span><br><span class="line">    g = a.<span class="property">length</span> - <span class="number">1</span>; g &gt;= d; g--)</span><br><span class="line">        h = a.<span class="title function_">charCodeAt</span>(g),</span><br><span class="line">        i = <span class="title function_">charToHex</span>(h),</span><br><span class="line">        j = <span class="title function_">biMultiplyDigit</span>(f, i),</span><br><span class="line">        e = <span class="title function_">biAdd</span>(e, j),</span><br><span class="line">        f = <span class="title function_">biMultiplyDigit</span>(f, b);</span><br><span class="line">    <span class="keyword">return</span> e.<span class="property">isNeg</span> = c,</span><br><span class="line">    e</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biDump</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">return</span> (a.<span class="property">isNeg</span> ? <span class="string">"-"</span> : <span class="string">""</span>) + a.<span class="property">digits</span>.<span class="title function_">join</span>(<span class="string">" "</span>)</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biAdd</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> c, d, e, f;</span><br><span class="line">    <span class="keyword">if</span> (a.<span class="property">isNeg</span> != b.<span class="property">isNeg</span>)</span><br><span class="line">        b.<span class="property">isNeg</span> = !b.<span class="property">isNeg</span>,</span><br><span class="line">        c = <span class="title function_">biSubtract</span>(a, b),</span><br><span class="line">        b.<span class="property">isNeg</span> = !b.<span class="property">isNeg</span>;</span><br><span class="line">    <span class="keyword">else</span> {</span><br><span class="line">        <span class="keyword">for</span> (c = <span class="keyword">new</span> <span class="title class_">BigInt</span>,</span><br><span class="line">        d = <span class="number">0</span>,</span><br><span class="line">        f = <span class="number">0</span>; f &lt; a.<span class="property">digits</span>.<span class="property">length</span>; ++f)</span><br><span class="line">            e = a.<span class="property">digits</span>[f] + b.<span class="property">digits</span>[f] + d,</span><br><span class="line">            c.<span class="property">digits</span>[f] = <span class="number">65535</span> &amp; e,</span><br><span class="line">            d = <span class="title class_">Number</span>(e &gt;= biRadix);</span><br><span class="line">        c.<span class="property">isNeg</span> = a.<span class="property">isNeg</span></span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> c</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biSubtract</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> c, d, e, f;</span><br><span class="line">    <span class="keyword">if</span> (a.<span class="property">isNeg</span> != b.<span class="property">isNeg</span>)</span><br><span class="line">        b.<span class="property">isNeg</span> = !b.<span class="property">isNeg</span>,</span><br><span class="line">        c = <span class="title function_">biAdd</span>(a, b),</span><br><span class="line">        b.<span class="property">isNeg</span> = !b.<span class="property">isNeg</span>;</span><br><span class="line">    <span class="keyword">else</span> {</span><br><span class="line">        <span class="keyword">for</span> (c = <span class="keyword">new</span> <span class="title class_">BigInt</span>,</span><br><span class="line">        e = <span class="number">0</span>,</span><br><span class="line">        f = <span class="number">0</span>; f &lt; a.<span class="property">digits</span>.<span class="property">length</span>; ++f)</span><br><span class="line">            d = a.<span class="property">digits</span>[f] - b.<span class="property">digits</span>[f] + e,</span><br><span class="line">            c.<span class="property">digits</span>[f] = <span class="number">65535</span> &amp; d,</span><br><span class="line">            c.<span class="property">digits</span>[f] &lt; <span class="number">0</span> &amp;&amp; (c.<span class="property">digits</span>[f] += biRadix),</span><br><span class="line">            e = <span class="number">0</span> - <span class="title class_">Number</span>(<span class="number">0</span> &gt; d);</span><br><span class="line">        <span class="keyword">if</span> (-<span class="number">1</span> == e) {</span><br><span class="line">            <span class="keyword">for</span> (e = <span class="number">0</span>,</span><br><span class="line">            f = <span class="number">0</span>; f &lt; a.<span class="property">digits</span>.<span class="property">length</span>; ++f)</span><br><span class="line">                d = <span class="number">0</span> - c.<span class="property">digits</span>[f] + e,</span><br><span class="line">                c.<span class="property">digits</span>[f] = <span class="number">65535</span> &amp; d,</span><br><span class="line">                c.<span class="property">digits</span>[f] &lt; <span class="number">0</span> &amp;&amp; (c.<span class="property">digits</span>[f] += biRadix),</span><br><span class="line">                e = <span class="number">0</span> - <span class="title class_">Number</span>(<span class="number">0</span> &gt; d);</span><br><span class="line">            c.<span class="property">isNeg</span> = !a.<span class="property">isNeg</span></span><br><span class="line">        } <span class="keyword">else</span></span><br><span class="line">            c.<span class="property">isNeg</span> = a.<span class="property">isNeg</span></span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> c</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biHighIndex</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">for</span> (<span class="keyword">var</span> b = a.<span class="property">digits</span>.<span class="property">length</span> - <span class="number">1</span>; b &gt; <span class="number">0</span> &amp;&amp; <span class="number">0</span> == a.<span class="property">digits</span>[b]; )</span><br><span class="line">        --b;</span><br><span class="line">    <span class="keyword">return</span> b</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biNumBits</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> e, b = <span class="title function_">biHighIndex</span>(a), c = a.<span class="property">digits</span>[b], d = (b + <span class="number">1</span>) * bitsPerDigit;</span><br><span class="line">    <span class="keyword">for</span> (e = d; e &gt; d - bitsPerDigit &amp;&amp; <span class="number">0</span> == (<span class="number">32768</span> &amp; c); --e)</span><br><span class="line">        c &lt;&lt;= <span class="number">1</span>;</span><br><span class="line">    <span class="keyword">return</span> e</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biMultiply</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> d, h, i, k, c = <span class="keyword">new</span> <span class="title class_">BigInt</span>, e = <span class="title function_">biHighIndex</span>(a), f = <span class="title function_">biHighIndex</span>(b);</span><br><span class="line">    <span class="keyword">for</span> (k = <span class="number">0</span>; f &gt;= k; ++k) {</span><br><span class="line">        <span class="keyword">for</span> (d = <span class="number">0</span>,</span><br><span class="line">        i = k,</span><br><span class="line">        j = <span class="number">0</span>; e &gt;= j; ++j,</span><br><span class="line">        ++i)</span><br><span class="line">            h = c.<span class="property">digits</span>[i] + a.<span class="property">digits</span>[j] * b.<span class="property">digits</span>[k] + d,</span><br><span class="line">            c.<span class="property">digits</span>[i] = h &amp; maxDigitVal,</span><br><span class="line">            d = h &gt;&gt;&gt; biRadixBits;</span><br><span class="line">        c.<span class="property">digits</span>[k + e + <span class="number">1</span>] = d</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> c.<span class="property">isNeg</span> = a.<span class="property">isNeg</span> != b.<span class="property">isNeg</span>,</span><br><span class="line">    c</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biMultiplyDigit</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> c, d, e, f;</span><br><span class="line">    <span class="keyword">for</span> (result = <span class="keyword">new</span> <span class="title class_">BigInt</span>,</span><br><span class="line">    c = <span class="title function_">biHighIndex</span>(a),</span><br><span class="line">    d = <span class="number">0</span>,</span><br><span class="line">    f = <span class="number">0</span>; c &gt;= f; ++f)</span><br><span class="line">        e = result.<span class="property">digits</span>[f] + a.<span class="property">digits</span>[f] * b + d,</span><br><span class="line">        result.<span class="property">digits</span>[f] = e &amp; maxDigitVal,</span><br><span class="line">        d = e &gt;&gt;&gt; biRadixBits;</span><br><span class="line">    <span class="keyword">return</span> result.<span class="property">digits</span>[<span class="number">1</span> + c] = d,</span><br><span class="line">    result</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">arrayCopy</span>(<span class="params">a, b, c, d, e</span>) {</span><br><span class="line">    <span class="keyword">var</span> g, h, f = <span class="title class_">Math</span>.<span class="title function_">min</span>(b + e, a.<span class="property">length</span>);</span><br><span class="line">    <span class="keyword">for</span> (g = b,</span><br><span class="line">    h = d; f &gt; g; ++g,</span><br><span class="line">    ++h)</span><br><span class="line">        c[h] = a[g]</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biShiftLeft</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> e, f, g, h, c = <span class="title class_">Math</span>.<span class="title function_">floor</span>(b / bitsPerDigit), d = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">for</span> (<span class="title function_">arrayCopy</span>(a.<span class="property">digits</span>, <span class="number">0</span>, d.<span class="property">digits</span>, c, d.<span class="property">digits</span>.<span class="property">length</span> - c),</span><br><span class="line">    e = b % bitsPerDigit,</span><br><span class="line">    f = bitsPerDigit - e,</span><br><span class="line">    g = d.<span class="property">digits</span>.<span class="property">length</span> - <span class="number">1</span>,</span><br><span class="line">    h = g - <span class="number">1</span>; g &gt; <span class="number">0</span>; --g,</span><br><span class="line">    --h)</span><br><span class="line">        d.<span class="property">digits</span>[g] = d.<span class="property">digits</span>[g] &lt;&lt; e &amp; maxDigitVal | (d.<span class="property">digits</span>[h] &amp; highBitMasks[e]) &gt;&gt;&gt; f;</span><br><span class="line">    <span class="keyword">return</span> d.<span class="property">digits</span>[<span class="number">0</span>] = d.<span class="property">digits</span>[g] &lt;&lt; e &amp; maxDigitVal,</span><br><span class="line">    d.<span class="property">isNeg</span> = a.<span class="property">isNeg</span>,</span><br><span class="line">    d</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biShiftRight</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> e, f, g, h, c = <span class="title class_">Math</span>.<span class="title function_">floor</span>(b / bitsPerDigit), d = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">for</span> (<span class="title function_">arrayCopy</span>(a.<span class="property">digits</span>, c, d.<span class="property">digits</span>, <span class="number">0</span>, a.<span class="property">digits</span>.<span class="property">length</span> - c),</span><br><span class="line">    e = b % bitsPerDigit,</span><br><span class="line">    f = bitsPerDigit - e,</span><br><span class="line">    g = <span class="number">0</span>,</span><br><span class="line">    h = g + <span class="number">1</span>; g &lt; d.<span class="property">digits</span>.<span class="property">length</span> - <span class="number">1</span>; ++g,</span><br><span class="line">    ++h)</span><br><span class="line">        d.<span class="property">digits</span>[g] = d.<span class="property">digits</span>[g] &gt;&gt;&gt; e | (d.<span class="property">digits</span>[h] &amp; lowBitMasks[e]) &lt;&lt; f;</span><br><span class="line">    <span class="keyword">return</span> d.<span class="property">digits</span>[d.<span class="property">digits</span>.<span class="property">length</span> - <span class="number">1</span>] &gt;&gt;&gt;= e,</span><br><span class="line">    d.<span class="property">isNeg</span> = a.<span class="property">isNeg</span>,</span><br><span class="line">    d</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biMultiplyByRadixPower</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> c = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">return</span> <span class="title function_">arrayCopy</span>(a.<span class="property">digits</span>, <span class="number">0</span>, c.<span class="property">digits</span>, b, c.<span class="property">digits</span>.<span class="property">length</span> - b),</span><br><span class="line">    c</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biDivideByRadixPower</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> c = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">return</span> <span class="title function_">arrayCopy</span>(a.<span class="property">digits</span>, b, c.<span class="property">digits</span>, <span class="number">0</span>, c.<span class="property">digits</span>.<span class="property">length</span> - b),</span><br><span class="line">    c</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biModuloByRadixPower</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> c = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">return</span> <span class="title function_">arrayCopy</span>(a.<span class="property">digits</span>, <span class="number">0</span>, c.<span class="property">digits</span>, <span class="number">0</span>, b),</span><br><span class="line">    c</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biCompare</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">if</span> (a.<span class="property">isNeg</span> != b.<span class="property">isNeg</span>)</span><br><span class="line">        <span class="keyword">return</span> <span class="number">1</span> - <span class="number">2</span> * <span class="title class_">Number</span>(a.<span class="property">isNeg</span>);</span><br><span class="line">    <span class="keyword">for</span> (<span class="keyword">var</span> c = a.<span class="property">digits</span>.<span class="property">length</span> - <span class="number">1</span>; c &gt;= <span class="number">0</span>; --c)</span><br><span class="line">        <span class="keyword">if</span> (a.<span class="property">digits</span>[c] != b.<span class="property">digits</span>[c])</span><br><span class="line">            <span class="keyword">return</span> a.<span class="property">isNeg</span> ? <span class="number">1</span> - <span class="number">2</span> * <span class="title class_">Number</span>(a.<span class="property">digits</span>[c] &gt; b.<span class="property">digits</span>[c]) : <span class="number">1</span> - <span class="number">2</span> * <span class="title class_">Number</span>(a.<span class="property">digits</span>[c] &lt; b.<span class="property">digits</span>[c]);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span></span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biDivideModulo</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> f, g, h, i, j, k, l, m, n, o, p, q, r, s, c = <span class="title function_">biNumBits</span>(a), d = <span class="title function_">biNumBits</span>(b), e = b.<span class="property">isNeg</span>;</span><br><span class="line">    <span class="keyword">if</span> (d &gt; c)</span><br><span class="line">        <span class="keyword">return</span> a.<span class="property">isNeg</span> ? (f = <span class="title function_">biCopy</span>(bigOne),</span><br><span class="line">        f.<span class="property">isNeg</span> = !b.<span class="property">isNeg</span>,</span><br><span class="line">        a.<span class="property">isNeg</span> = !<span class="number">1</span>,</span><br><span class="line">        b.<span class="property">isNeg</span> = !<span class="number">1</span>,</span><br><span class="line">        g = <span class="title function_">biSubtract</span>(b, a),</span><br><span class="line">        a.<span class="property">isNeg</span> = !<span class="number">0</span>,</span><br><span class="line">        b.<span class="property">isNeg</span> = e) : (f = <span class="keyword">new</span> <span class="title class_">BigInt</span>,</span><br><span class="line">        g = <span class="title function_">biCopy</span>(a)),</span><br><span class="line">        <span class="keyword">new</span> <span class="title class_">Array</span>(f,g);</span><br><span class="line">    <span class="keyword">for</span> (f = <span class="keyword">new</span> <span class="title class_">BigInt</span>,</span><br><span class="line">    g = a,</span><br><span class="line">    h = <span class="title class_">Math</span>.<span class="title function_">ceil</span>(d / bitsPerDigit) - <span class="number">1</span>,</span><br><span class="line">    i = <span class="number">0</span>; b.<span class="property">digits</span>[h] &lt; biHalfRadix; )</span><br><span class="line">        b = <span class="title function_">biShiftLeft</span>(b, <span class="number">1</span>),</span><br><span class="line">        ++i,</span><br><span class="line">        ++d,</span><br><span class="line">        h = <span class="title class_">Math</span>.<span class="title function_">ceil</span>(d / bitsPerDigit) - <span class="number">1</span>;</span><br><span class="line">    <span class="keyword">for</span> (g = <span class="title function_">biShiftLeft</span>(g, i),</span><br><span class="line">    c += i,</span><br><span class="line">    j = <span class="title class_">Math</span>.<span class="title function_">ceil</span>(c / bitsPerDigit) - <span class="number">1</span>,</span><br><span class="line">    k = <span class="title function_">biMultiplyByRadixPower</span>(b, j - h); -<span class="number">1</span> != <span class="title function_">biCompare</span>(g, k); )</span><br><span class="line">        ++f.<span class="property">digits</span>[j - h],</span><br><span class="line">        g = <span class="title function_">biSubtract</span>(g, k);</span><br><span class="line">    <span class="keyword">for</span> (l = j; l &gt; h; --l) {</span><br><span class="line">        <span class="keyword">for</span> (m = l &gt;= g.<span class="property">digits</span>.<span class="property">length</span> ? <span class="number">0</span> : g.<span class="property">digits</span>[l],</span><br><span class="line">        n = l - <span class="number">1</span> &gt;= g.<span class="property">digits</span>.<span class="property">length</span> ? <span class="number">0</span> : g.<span class="property">digits</span>[l - <span class="number">1</span>],</span><br><span class="line">        o = l - <span class="number">2</span> &gt;= g.<span class="property">digits</span>.<span class="property">length</span> ? <span class="number">0</span> : g.<span class="property">digits</span>[l - <span class="number">2</span>],</span><br><span class="line">        p = h &gt;= b.<span class="property">digits</span>.<span class="property">length</span> ? <span class="number">0</span> : b.<span class="property">digits</span>[h],</span><br><span class="line">        q = h - <span class="number">1</span> &gt;= b.<span class="property">digits</span>.<span class="property">length</span> ? <span class="number">0</span> : b.<span class="property">digits</span>[h - <span class="number">1</span>],</span><br><span class="line">        f.<span class="property">digits</span>[l - h - <span class="number">1</span>] = m == p ? maxDigitVal : <span class="title class_">Math</span>.<span class="title function_">floor</span>((m * biRadix + n) / p),</span><br><span class="line">        r = f.<span class="property">digits</span>[l - h - <span class="number">1</span>] * (p * biRadix + q),</span><br><span class="line">        s = m * biRadixSquared + (n * biRadix + o); r &gt; s; )</span><br><span class="line">            --f.<span class="property">digits</span>[l - h - <span class="number">1</span>],</span><br><span class="line">            r = f.<span class="property">digits</span>[l - h - <span class="number">1</span>] * (p * biRadix | q),</span><br><span class="line">            s = m * biRadix * biRadix + (n * biRadix + o);</span><br><span class="line">        k = <span class="title function_">biMultiplyByRadixPower</span>(b, l - h - <span class="number">1</span>),</span><br><span class="line">        g = <span class="title function_">biSubtract</span>(g, <span class="title function_">biMultiplyDigit</span>(k, f.<span class="property">digits</span>[l - h - <span class="number">1</span>])),</span><br><span class="line">        g.<span class="property">isNeg</span> &amp;&amp; (g = <span class="title function_">biAdd</span>(g, k),</span><br><span class="line">        --f.<span class="property">digits</span>[l - h - <span class="number">1</span>])</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> g = <span class="title function_">biShiftRight</span>(g, i),</span><br><span class="line">    f.<span class="property">isNeg</span> = a.<span class="property">isNeg</span> != e,</span><br><span class="line">    a.<span class="property">isNeg</span> &amp;&amp; (f = e ? <span class="title function_">biAdd</span>(f, bigOne) : <span class="title function_">biSubtract</span>(f, bigOne),</span><br><span class="line">    b = <span class="title function_">biShiftRight</span>(b, i),</span><br><span class="line">    g = <span class="title function_">biSubtract</span>(b, g)),</span><br><span class="line">    <span class="number">0</span> == g.<span class="property">digits</span>[<span class="number">0</span>] &amp;&amp; <span class="number">0</span> == <span class="title function_">biHighIndex</span>(g) &amp;&amp; (g.<span class="property">isNeg</span> = !<span class="number">1</span>),</span><br><span class="line">    <span class="keyword">new</span> <span class="title class_">Array</span>(f,g)</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biDivide</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">return</span> <span class="title function_">biDivideModulo</span>(a, b)[<span class="number">0</span>]</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biModulo</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">return</span> <span class="title function_">biDivideModulo</span>(a, b)[<span class="number">1</span>]</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biMultiplyMod</span>(<span class="params">a, b, c</span>) {</span><br><span class="line">    <span class="keyword">return</span> <span class="title function_">biModulo</span>(<span class="title function_">biMultiply</span>(a, b), c)</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biPow</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">for</span> (<span class="keyword">var</span> c = bigOne, d = a; ; ) {</span><br><span class="line">        <span class="keyword">if</span> (<span class="number">0</span> != (<span class="number">1</span> &amp; b) &amp;&amp; (c = <span class="title function_">biMultiply</span>(c, d)),</span><br><span class="line">        b &gt;&gt;= <span class="number">1</span>,</span><br><span class="line">        <span class="number">0</span> == b)</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        d = <span class="title function_">biMultiply</span>(d, d)</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> c</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">biPowMod</span>(<span class="params">a, b, c</span>) {</span><br><span class="line">    <span class="keyword">for</span> (<span class="keyword">var</span> d = bigOne, e = a, f = b; ; ) {</span><br><span class="line">        <span class="keyword">if</span> (<span class="number">0</span> != (<span class="number">1</span> &amp; f.<span class="property">digits</span>[<span class="number">0</span>]) &amp;&amp; (d = <span class="title function_">biMultiplyMod</span>(d, e, c)),</span><br><span class="line">        f = <span class="title function_">biShiftRight</span>(f, <span class="number">1</span>),</span><br><span class="line">        <span class="number">0</span> == f.<span class="property">digits</span>[<span class="number">0</span>] &amp;&amp; <span class="number">0</span> == <span class="title function_">biHighIndex</span>(f))</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        e = <span class="title function_">biMultiplyMod</span>(e, e, c)</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> d</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">BarrettMu</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">modulus</span> = <span class="title function_">biCopy</span>(a),</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">k</span> = <span class="title function_">biHighIndex</span>(<span class="variable language_">this</span>.<span class="property">modulus</span>) + <span class="number">1</span>;</span><br><span class="line">    <span class="keyword">var</span> b = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    b.<span class="property">digits</span>[<span class="number">2</span> * <span class="variable language_">this</span>.<span class="property">k</span>] = <span class="number">1</span>,</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">mu</span> = <span class="title function_">biDivide</span>(b, <span class="variable language_">this</span>.<span class="property">modulus</span>),</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">bkplus1</span> = <span class="keyword">new</span> <span class="title class_">BigInt</span>,</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">bkplus1</span>.<span class="property">digits</span>[<span class="variable language_">this</span>.<span class="property">k</span> + <span class="number">1</span>] = <span class="number">1</span>,</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">modulo</span> = <span class="title class_">BarrettMu</span>_modulo,</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">multiplyMod</span> = <span class="title class_">BarrettMu</span>_multiplyMod,</span><br><span class="line">    <span class="variable language_">this</span>.<span class="property">powMod</span> = <span class="title class_">BarrettMu</span>_powMod</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">BarrettMu_modulo</span>(<span class="params">a</span>) {</span><br><span class="line">    <span class="keyword">var</span> i, b = <span class="title function_">biDivideByRadixPower</span>(a, <span class="variable language_">this</span>.<span class="property">k</span> - <span class="number">1</span>), c = <span class="title function_">biMultiply</span>(b, <span class="variable language_">this</span>.<span class="property">mu</span>), d = <span class="title function_">biDivideByRadixPower</span>(c, <span class="variable language_">this</span>.<span class="property">k</span> + <span class="number">1</span>), e = <span class="title function_">biModuloByRadixPower</span>(a, <span class="variable language_">this</span>.<span class="property">k</span> + <span class="number">1</span>), f = <span class="title function_">biMultiply</span>(d, <span class="variable language_">this</span>.<span class="property">modulus</span>), g = <span class="title function_">biModuloByRadixPower</span>(f, <span class="variable language_">this</span>.<span class="property">k</span> + <span class="number">1</span>), h = <span class="title function_">biSubtract</span>(e, g);</span><br><span class="line">    <span class="keyword">for</span> (h.<span class="property">isNeg</span> &amp;&amp; (h = <span class="title function_">biAdd</span>(h, <span class="variable language_">this</span>.<span class="property">bkplus1</span>)),</span><br><span class="line">    i = <span class="title function_">biCompare</span>(h, <span class="variable language_">this</span>.<span class="property">modulus</span>) &gt;= <span class="number">0</span>; i; )</span><br><span class="line">        h = <span class="title function_">biSubtract</span>(h, <span class="variable language_">this</span>.<span class="property">modulus</span>),</span><br><span class="line">        i = <span class="title function_">biCompare</span>(h, <span class="variable language_">this</span>.<span class="property">modulus</span>) &gt;= <span class="number">0</span>;</span><br><span class="line">    <span class="keyword">return</span> h</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">BarrettMu_multiplyMod</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> c = <span class="title function_">biMultiply</span>(a, b);</span><br><span class="line">    <span class="keyword">return</span> <span class="variable language_">this</span>.<span class="title function_">modulo</span>(c)</span><br><span class="line">}</span><br><span class="line"><span class="keyword">function</span> <span class="title function_">BarrettMu_powMod</span>(<span class="params">a, b</span>) {</span><br><span class="line">    <span class="keyword">var</span> d, e, c = <span class="keyword">new</span> <span class="title class_">BigInt</span>;</span><br><span class="line">    <span class="keyword">for</span> (c.<span class="property">digits</span>[<span class="number">0</span>] = <span class="number">1</span>,</span><br><span class="line">    d = a,</span><br><span class="line">    e = b; ; ) {</span><br><span class="line">        <span class="keyword">if</span> (<span class="number">0</span> != (<span class="number">1</span> &amp; e.<span class="property">digits</span>[<span class="number">0</span>]) &amp;&amp; (c = <span class="variable language_">this</span>.<span class="title function_">multiplyMod</span>(c, d)),</span><br><span class="line">        e = <span class="title function_">biShiftRight</span>(e, <span class="number">1</span>),</span><br><span class="line">        <span class="number">0</span> == e.<span class="property">digits</span>[<span class="number">0</span>] &amp;&amp; <span class="number">0</span> == <span class="title function_">biHighIndex</span>(e))</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        d = <span class="variable language_">this</span>.<span class="title function_">multiplyMod</span>(d, d)</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> c</span><br><span class="line">}</span><br><span class="line"><span class="keyword">var</span> maxDigits, <span class="variable constant_">ZERO_ARRAY</span>, bigZero, bigOne, dpl10, lr10, hexatrigesimalToChar, hexToChar, highBitMasks, lowBitMasks, biRadixBase = <span class="number">2</span>, biRadixBits = <span class="number">16</span>, bitsPerDigit = biRadixBits, biRadix = <span class="number">65536</span>, biHalfRadix = biRadix &gt;&gt;&gt; <span class="number">1</span>, biRadixSquared = biRadix * biRadix, maxDigitVal = biRadix - <span class="number">1</span>, maxInteger = <span class="number">9999999999999998</span>;</span><br><span class="line"><span class="title function_">setMaxDigits</span>(<span class="number">20</span>),</span><br><span class="line">dpl10 = <span class="number">15</span>,</span><br><span class="line">lr10 = <span class="title function_">biFromNumber</span>(<span class="number">1e15</span>),</span><br><span class="line">hexatrigesimalToChar = <span class="keyword">new</span> <span class="title class_">Array</span>(<span class="string">"0"</span>,<span class="string">"1"</span>,<span class="string">"2"</span>,<span class="string">"3"</span>,<span class="string">"4"</span>,<span class="string">"5"</span>,<span class="string">"6"</span>,<span class="string">"7"</span>,<span class="string">"8"</span>,<span class="string">"9"</span>,<span class="string">"a"</span>,<span class="string">"b"</span>,<span class="string">"c"</span>,<span class="string">"d"</span>,<span class="string">"e"</span>,<span class="string">"f"</span>,<span class="string">"g"</span>,<span class="string">"h"</span>,<span class="string">"i"</span>,<span class="string">"j"</span>,<span class="string">"k"</span>,<span class="string">"l"</span>,<span class="string">"m"</span>,<span class="string">"n"</span>,<span class="string">"o"</span>,<span class="string">"p"</span>,<span class="string">"q"</span>,<span class="string">"r"</span>,<span class="string">"s"</span>,<span class="string">"t"</span>,<span class="string">"u"</span>,<span class="string">"v"</span>,<span class="string">"w"</span>,<span class="string">"x"</span>,<span class="string">"y"</span>,<span class="string">"z"</span>),</span><br><span class="line">hexToChar = <span class="keyword">new</span> <span class="title class_">Array</span>(<span class="string">"0"</span>,<span class="string">"1"</span>,<span class="string">"2"</span>,<span class="string">"3"</span>,<span class="string">"4"</span>,<span class="string">"5"</span>,<span class="string">"6"</span>,<span class="string">"7"</span>,<span class="string">"8"</span>,<span class="string">"9"</span>,<span class="string">"a"</span>,<span class="string">"b"</span>,<span class="string">"c"</span>,<span class="string">"d"</span>,<span class="string">"e"</span>,<span class="string">"f"</span>),</span><br><span class="line">highBitMasks = <span class="keyword">new</span> <span class="title class_">Array</span>(<span class="number">0</span>,<span class="number">32768</span>,<span class="number">49152</span>,<span class="number">57344</span>,<span class="number">61440</span>,<span class="number">63488</span>,<span class="number">64512</span>,<span class="number">65024</span>,<span class="number">65280</span>,<span class="number">65408</span>,<span class="number">65472</span>,<span class="number">65504</span>,<span class="number">65520</span>,<span class="number">65528</span>,<span class="number">65532</span>,<span class="number">65534</span>,<span class="number">65535</span>),</span><br><span class="line">lowBitMasks = <span class="keyword">new</span> <span class="title class_">Array</span>(<span class="number">0</span>,<span class="number">1</span>,<span class="number">3</span>,<span class="number">7</span>,<span class="number">15</span>,<span class="number">31</span>,<span class="number">63</span>,<span class="number">127</span>,<span class="number">255</span>,<span class="number">511</span>,<span class="number">1023</span>,<span class="number">2047</span>,<span class="number">4095</span>,<span class="number">8191</span>,<span class="number">16383</span>,<span class="number">32767</span>,<span class="number">65535</span>);</span><br></pre></td></tr></tbody></table></figure>
</details>
<p>至此，整个网易云逆向的思路已清晰。我们可以开始用 Python 来实现它了。</p>
<h1 id="用js生成数据"><a class="markdownIt-Anchor" href="#用js生成数据"></a> 用 JS 生成数据</h1>
<p>既然我们已经明白了网易云的加密方式，那么我们就可以先用 JS 来生成 <code>params</code> 和 <code>encSecKey</code>，然后再传到 Python 来发出请求。</p>
<blockquote>
<p>我使用的是 PyCharm；你可以新建一个 <code>.js</code> 文件并且使用 <code>node.exe</code> 来运行 JS 代码。</p>
</blockquote>
<p>首要的便是引入 <code>CryptoJS</code>，与 Python 导包一样，我们需要先下载它。在终端中输入：</p>
<figure class="highlight bash"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">npm install crypto-js</span><br></pre></td></tr></tbody></table></figure>
<p>之后便是引入它：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">var</span> <span class="title class_">CryptoJS</span> = <span class="built_in">require</span>(<span class="string">"crypto-js"</span>);</span><br></pre></td></tr></tbody></table></figure>
<p>接着复制粘贴之前说的那一大串全局函数以及 <code>a()</code>、<code>b()</code>、<code>c()</code>、<code>d()</code> 函数下去。</p>
<p><code>d()</code> 函数所需要的变量中有三个是固定的，我们可以先定义好：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">key_2 = <span class="string">'010001'</span>;</span><br><span class="line">key_3 = <span class="string">'00e0b509f6259df8642dbc35662901477df22677ec152b5ff68ace615bb7b725152b3ab17a876aea8a5aa76d2e417629ec4ee341f56135fccf695280104e0312ecbda92557c93870114af6c9d05c4f7f0c3685b7a46bee255932575cce10b424d813cfe4875d3e82047b97ddef52741d546b8e289dc6935b3ece0462db0a22b8e7'</span>;</span><br><span class="line">key_4 = <span class="string">'0CoJUm6Qyw8W8jud'</span>;</span><br></pre></td></tr></tbody></table></figure>
<p>而第一个参数中歌曲的 id 是动态的，我们可以先填写一个固定的 id 进去：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">key_1 = <span class="string">'{"ids": "[2094817741]", "level": "standard", "encodeType": "aac", "csrf_token": ""}'</span></span><br></pre></td></tr></tbody></table></figure>
<p>最后打印一下结果：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="variable language_">console</span>.<span class="title function_">log</span>(<span class="title function_">d</span>(key_1, key_2, key_3, key_4));</span><br></pre></td></tr></tbody></table></figure>
<p><code>params</code> 和 <code>encSecKey</code> 就这么简单地生成出来了。不过仅是生成出来是不够的，我们还需要把它们传到 Python 里去。</p>
<h1 id="用python发出请求"><a class="markdownIt-Anchor" href="#用python发出请求"></a> 用 Python 发出请求</h1>
<p>为了让 Python 那边取到的数据即拿即用，我悄咪咪地加了一个函数：</p>
<figure class="highlight js"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">function</span> <span class="title function_">main</span>(<span class="params">key</span>) {</span><br><span class="line">    result = <span class="title function_">d</span>(key, key_2, key_3, key_4);</span><br><span class="line">    <span class="keyword">return</span> {</span><br><span class="line">        <span class="string">'params'</span>: result[<span class="string">'encText'</span>],</span><br><span class="line">        <span class="string">'encSecKey'</span>: result[<span class="string">'encSecKey'</span>]</span><br><span class="line">    }</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>
<blockquote>
<p>参数 <code>key</code> 的内容会在 Python 中进行修改。</p>
</blockquote>
<p>那么要如何让 Python 调用这个函数呢？我们可以使用 <code>PyExecJS</code> 这个库：</p>
<figure class="highlight python"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">import</span> execjs</span><br><span class="line"></span><br><span class="line">js_code = <span class="built_in">open</span>(<span class="string">'文件.js'</span>, mode=<span class="string">'r'</span>, encoding=<span class="string">'utf-8'</span>).read()</span><br><span class="line">ctx = execjs.<span class="built_in">compile</span>(js_code)</span><br></pre></td></tr></tbody></table></figure>
<p>这样我们便可以调用 <code>.js</code> 文件中的 <code>main()</code> 函数了：</p>
<figure class="highlight python"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">song_id = <span class="built_in">input</span>(<span class="string">'输入歌曲id：'</span>)</span><br><span class="line">key = <span class="string">'{"ids": "[%s]", "level": "standard", "encodeType": "aac", "csrf_token": ""}'</span> % song_id</span><br><span class="line">result = ctx.call(<span class="string">'main'</span>, key)</span><br></pre></td></tr></tbody></table></figure>
<p>给网易云发送请求：</p>
<figure class="highlight python"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line">form_data = {</span><br><span class="line">    <span class="string">'params'</span>: result[<span class="string">'params'</span>],</span><br><span class="line">    <span class="string">'encSecKey'</span>: result[<span class="string">'encSecKey'</span>]</span><br><span class="line">}</span><br><span class="line">response = requests.post(</span><br><span class="line">    url=<span class="string">'https://music.163.com/weapi/song/enhance/player/url/v1?csrf_token='</span>,</span><br><span class="line">    headers=headers,  <span class="comment"># 自己定义</span></span><br><span class="line">    data=form_data</span><br><span class="line">).json()</span><br><span class="line">m4a_url = response[<span class="string">'data'</span>][<span class="number">0</span>][<span class="string">'url'</span>]</span><br></pre></td></tr></tbody></table></figure>
<p>拿到了我们的 <code>.m4a</code> 链接后，该怎么做嘛…… 我想也不用多说了吧。</p>
<figure class="highlight python"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line">m4a_response = requests.get(m4a_url, headers=headers).content</span><br><span class="line"><span class="keyword">if</span> <span class="keyword">not</span> os.path.exists(<span class="string">'music'</span>):</span><br><span class="line">    os.mkdir(<span class="string">'music'</span>)</span><br><span class="line"><span class="keyword">with</span> <span class="built_in">open</span>(<span class="string">'music/%s.m4a'</span> % song_id, mode=<span class="string">'wb'</span>) <span class="keyword">as</span> fp:</span><br><span class="line">    fp.write(m4a_response)</span><br></pre></td></tr></tbody></table></figure>
<p>网易云逆向大功告成！</p>
<h1 id="顺便逆向个歌曲id不过分吧"><a class="markdownIt-Anchor" href="#顺便逆向个歌曲id不过分吧"></a> 顺便逆向个歌曲 id 不过分吧</h1>
<p>在网易云中，当用户进行搜索时会出现这么一个请求：<code>https://music.163.com/weapi/search/suggest/web?csrf_token=</code>。和 <code>.m4a</code> 文件请求一样，这个请求也需要 <code>params</code> 和 <code>encSecKey</code> 两个参数。我们可以使用同样的方法来生成它们。</p>
<p>该请求会根据用户输入的关键词返回搜索结果：</p>
<figure class="highlight python"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">title = <span class="built_in">input</span>(<span class="string">'请输入歌曲名：'</span>)</span><br><span class="line">search_key = <span class="string">'{"s": "%s", "limit": "8", "csrf_token": ""}'</span> % title</span><br><span class="line">result = ctx.call(<span class="string">'main'</span>, search_key)</span><br></pre></td></tr></tbody></table></figure>
<p>然后我们就可以拿到搜索结果了：</p>
<figure class="highlight python"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line">response = requests.post(</span><br><span class="line">    url=<span class="string">'https://music.163.com/weapi/search/suggest/web?csrf_token='</span>,</span><br><span class="line">    params=result,</span><br><span class="line">    headers=headers</span><br><span class="line">).json()</span><br><span class="line"><span class="keyword">return</span> response[<span class="string">'result'</span>][<span class="string">'songs'</span>]  <span class="comment"># 返回歌曲列表，response['result']['songs'][数字]['id']就是我们上面自己定义的song_id，完全可以串起来用</span></span><br></pre></td></tr></tbody></table></figure></body></html></div></article></div></main><footer><div class="paginator"><a class="prev" href="2f6a.html">上一篇</a><a class="next" href="a4b5.html">下一篇</a></div><!-- Webmention 显示区域--><div class="webmention-section webmention-empty" data-page-url="posts/f8ce.html" data-full-url="https://cytrogen.icu/posts/f8ce.html" data-mode="static">
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