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161 lines
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HTML
161 lines
6.1 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>Generates cryptographically secure pseudo-random bytes</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.random-bytes" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">random_bytes</h1>
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<p class="verinfo">(PHP 7)</p><p class="refpurpose"><span class="refname">random_bytes</span> — <span class="dc-title">Generates cryptographically secure pseudo-random bytes</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.random-bytes-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>random_bytes</strong></span>
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( <span class="methodparam"><span class="type">int</span> <code class="parameter">$length</code></span>
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) : <span class="type">string</span></div>
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<p class="para rdfs-comment">
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Generates an arbitrary length string of cryptographic random bytes that are
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suitable for cryptographic use, such as when generating salts, keys or
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initialization vectors.
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</p>
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<p class="para">
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The sources of randomness used for this function are as follows:
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</p>
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<ul class="itemizedlist">
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<li class="listitem">
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<span class="simpara">
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On Windows,
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<a href="https://msdn.microsoft.com/en-us/library/windows/desktop/aa379942(v=vs.85).aspx" class="link external">» <span class="function"><strong>CryptGenRandom()</strong></span></a>
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will always be used. As of PHP 7.2.0, the
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<a href="https://docs.microsoft.com/en-us/windows/desktop/SecCNG/cng-portal" class="link external">» CNG-API</a>
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will always be used instead.
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</span>
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</li>
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<li class="listitem">
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<span class="simpara">
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On Linux, the
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<a href="http://man7.org/linux/man_pages/man2/getrandom.2.html" class="link external">» getrandom(2)</a>
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syscall will be used if available.
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</span>
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</li>
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<li class="listitem">
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<span class="simpara">
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On other platforms, <var class="filename">/dev/urandom</var> will be used.
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</span>
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</li>
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<li class="listitem">
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<span class="simpara">
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If none of the aforementioned sources are available, then an
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<a href="class.exception.html" class="classname">Exception</a> will be thrown.
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</span>
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</li>
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</ul>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<span class="simpara">
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Although this function was added to PHP in PHP 7.0, a
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<a href="https://github.com/paragonie/random_compat" class="link external">» userland implementation</a>
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is available for PHP 5.2 to 5.6, inclusive.
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</span>
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</p></blockquote>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.random-bytes-parameters">
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<h3 class="title">参数</h3>
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<dl>
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<dt>
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<code class="parameter">length</code></dt>
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<dd>
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<p class="para">
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The length of the random string that should be returned in bytes.
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</p>
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</dd>
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</dl>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.random-bytes-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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Returns a string containing the requested number of cryptographically
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secure random bytes.
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</p>
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</div>
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<div class="refsect1 errors" id="refsect1-function.random-bytes-errors">
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<h3 class="title">错误／异常</h3>
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<ul class="itemizedlist">
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<li class="listitem">
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<span class="simpara">
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If an appropriate source of randomness cannot be found,
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an <a href="class.exception.html" class="classname">Exception</a> will be thrown.
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</span>
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</li>
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<li class="listitem">
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<span class="simpara">
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If invalid parameters are given, a <strong class="classname">TypeError</strong>
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will be thrown.
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</span>
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</li>
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<li class="listitem">
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<span class="simpara">
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If an invalid <code class="parameter">length</code> of bytes is given, an
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<strong class="classname">Error</strong> will be thrown.
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</span>
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</li>
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</ul>
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</div>
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<div class="refsect1 examples" id="refsect1-function.random-bytes-examples">
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<h3 class="title">范例</h3>
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<div class="example" id="example-886">
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<p><strong>Example #1 <span class="function"><strong>random_bytes()</strong></span> example</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$bytes </span><span style="color: #007700">= </span><span style="color: #0000BB">random_bytes</span><span style="color: #007700">(</span><span style="color: #0000BB">5</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">bin2hex</span><span style="color: #007700">(</span><span style="color: #0000BB">$bytes</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程的输出类似于：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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string(10) "385e33f741"
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</pre></div>
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</div>
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</div>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.random-bytes-seealso">
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<h3 class="title">参见</h3>
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<ul class="simplelist">
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<li class="member"><span class="function"><a href="random_int.html" class="function" rel="rdfs-seeAlso">random_int()</a> - Generates cryptographically secure pseudo-random integers</span></li>
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<li class="member"><span class="function"><a href="openssl_random_pseudo_bytes.html" class="function" rel="rdfs-seeAlso">openssl_random_pseudo_bytes()</a> - 生成一个伪随机字节串</span></li>
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<li class="member"><span class="function"><a href="bin2hex.html" class="function" rel="rdfs-seeAlso">bin2hex()</a> - 函数把包含数据的二进制字符串转换为十六进制值</span></li>
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</ul>
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</div>
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</div></div></div></body></html> |